Here are the answers to yesterday's Cisco practice questions. New questions later tonight!
CCNA:
By default, what traffic is considered "interesting" by a Cisco router?
A. All IP traffic
B. All ICMP traffic
C. All traffic
D. No traffic
E. Traffic defined with the dialer-group command
F. Traffic defined with the dialer-list command
Answer: D. By default, no traffic is considered interesting.
CCNP / BSCI:
Which of the following protocols will not advertise a redistributed route unless a seed metric is expressly assigned during redistribution? Choose all that apply.
A. RIPv1
B. RIPv2
C. OSPF
D. EIGRP
E. ISIS
F. IGRP
Answer: A, B, E, F. Both versions of RIP require this seed metric to be set, along with IGRP and EIGRP.
CCNP / BCMSN:
What command enables VRRP interface tracking?
A. (config-if)# vrrp tracking
B. (config)# vrrp tracking
C. (config-if)# standby 5 track serial0
D. (config) # standby 5 track serial0
E. VRRP doesn't have interface tracking capabilities.
Answer: E. A major drawback of VRRP is that it has no interface tracking capabilities, as HSRP does.
To your Cisco success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Sunday, April 30, 2006
Saturday, April 29, 2006
Passing the BSCI exam and earning your CCNP is all about knowing the details, and when it comes to EIGRP SIA routes, there are plenty of details to know. A quick check in a search engine for "troubleshoot SIA" will bring up quite a few matches. Troubleshooting SIA routes is very challenging in that there's no one reason they occur.
View the EIGRP topology table with the show ip eigrp topology command, and you'll see a code next to every successor and feasible successor. A popular misconception is that we want these routes to have an "A" next to them - so they're active. That's what we want, right? Active routes sound good, right?
Well, they sound good, but they're not. If a route shows as Active in the EIGRP topology table, that means that DUAL is currently calculating that route, and it's currently unusable. When a route is Passive ("P), that means it's not being recalculated and it's a usable route.
Generally, a route shown as Active is going to be there for a very short period of time. By the time you repeat the command, hopefully that Active route has gone Passive. Sometimes that doesn't happen, though, and the route becomes SIA - Stuck In Active.
A route becomes SIA when a query goes unanswered for so long that the neighbor relationship is reset. From experience, I can tell you that troubleshooting SIA routes is more of an art form than a science, but there are four main reasons a route becomes SIA:
The link is unidirectional, so the query can't possibly be answered.
The queried router's resources are unavailable, generally due to high CPU utilization.
The queried router's memory is corrupt or otherwise unable to allow the router to answer the query.
The link between the two routers is of low quality, allowing just enough packets through to keep the neighbor relationship intact, but not good enough to allow the replies through.
To sum it up, routes generally become SIA when a neighbor either doesn't answer a query, or either the query or reply took a wrong turn somewhere. I told you it wasn't the easiest thing to troubleshoot!
To your Cisco success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Getting Started With Hot Standby Routing Protocol (HSRP)
A CCNP / BCMSN Exam Tutorial
Defined in RFC 2281, HSRP is a Cisco-proprietary protocol in which routers are put into an HSRP router group. Along with dynamic routing protocols and STP, HSRP is considered a high-availability network service, since all three have an almost immediate cutover to a secondary path when the primary path is unavailable.
One of the routers will be selected as the primary ("Active", in HSRP terminology), and that primary will handle the routing while the other routers are in standby, ready to handle the load if the primary router becomes unavailable. In this fashion, HSRP ensures a high network uptime, since it routes IP traffic without relying on a single router.
The hosts using HSRP as a gateway don't know the actual IP or MAC addresses of the routers in the group. They're communicating with a pseudorouter, a "virtual router" created by the HSRP configuration. This virtual router will have a virtual MAC and IP adddres as well.
The standby routers aren't just going to be sitting there, though! By configuring multiple HSRP groups on a single interface, HSRP load balancing can be achieved.
Before we get to the more advanced HSRP configuration, we better get a basic one started! We'll be using a two-router topology here, and keep in mind that one or both of these routers could be multilayer switches as well. For ease of reading, I'm going to refer to them only as routers.
R2 and R3 will both be configured to be in standby group 5. The virtual router will have an IP address of 172.12.23.10 /24. All hosts in VLAN 100 should use this address as their default gateway.
R2(config)#interface ethernet0
R2(config-if)#standby 5 ip 172.12.23.10
R3(config)#interface ethernet0
R3(config-if)#standby 5 ip 172.12.23.10
The show command for HSRP is show standby, and it's the first command you should run while configuring and troubleshooting HSRP. Let's run it on both routers and compare results.
R2#show standby
Ethernet0 - Group 5
Local state is Standby, priority 100
Hellotime 3 sec, holdtime 10 sec
Next hello sent in 0.776
Virtual IP address is 172.12.23.10 configured
Active router is 172.12.23.3, priority 100 expires in 9.568
Standby router is local
1 state changes, last state change 00:00:22
R3#show standby
Ethernet0 - Group 5
Local state is Active, priority 100
Hellotime 3 sec, holdtime 10 sec
Next hello sent in 2.592
Virtual IP address is 172.12.23.10 configured
Active router is local
Standby router is 172.12.23.2 expires in 8.020
Virtual mac address is 0000.0c07.ac05
2 state changes, last state change 00:02:08
We can see that R3 has been selected as the Active router ("local state is Active"), the virtual router's IP is 172.12.23.10, and R2 is the standby router.
There are some HSRP values that you'll need to change from time to time. What if we want R2 to be the Active router instead? Can we change the MAC address of the virtual router? I'll answer those questions in the next part of this HSRP tutorial!
To your Cisco success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
A CCNP / BCMSN Exam Tutorial
Defined in RFC 2281, HSRP is a Cisco-proprietary protocol in which routers are put into an HSRP router group. Along with dynamic routing protocols and STP, HSRP is considered a high-availability network service, since all three have an almost immediate cutover to a secondary path when the primary path is unavailable.
One of the routers will be selected as the primary ("Active", in HSRP terminology), and that primary will handle the routing while the other routers are in standby, ready to handle the load if the primary router becomes unavailable. In this fashion, HSRP ensures a high network uptime, since it routes IP traffic without relying on a single router.
The hosts using HSRP as a gateway don't know the actual IP or MAC addresses of the routers in the group. They're communicating with a pseudorouter, a "virtual router" created by the HSRP configuration. This virtual router will have a virtual MAC and IP adddres as well.
The standby routers aren't just going to be sitting there, though! By configuring multiple HSRP groups on a single interface, HSRP load balancing can be achieved.
Before we get to the more advanced HSRP configuration, we better get a basic one started! We'll be using a two-router topology here, and keep in mind that one or both of these routers could be multilayer switches as well. For ease of reading, I'm going to refer to them only as routers.
R2 and R3 will both be configured to be in standby group 5. The virtual router will have an IP address of 172.12.23.10 /24. All hosts in VLAN 100 should use this address as their default gateway.
R2(config)#interface ethernet0
R2(config-if)#standby 5 ip 172.12.23.10
R3(config)#interface ethernet0
R3(config-if)#standby 5 ip 172.12.23.10
The show command for HSRP is show standby, and it's the first command you should run while configuring and troubleshooting HSRP. Let's run it on both routers and compare results.
R2#show standby
Ethernet0 - Group 5
Local state is Standby, priority 100
Hellotime 3 sec, holdtime 10 sec
Next hello sent in 0.776
Virtual IP address is 172.12.23.10 configured
Active router is 172.12.23.3, priority 100 expires in 9.568
Standby router is local
1 state changes, last state change 00:00:22
R3#show standby
Ethernet0 - Group 5
Local state is Active, priority 100
Hellotime 3 sec, holdtime 10 sec
Next hello sent in 2.592
Virtual IP address is 172.12.23.10 configured
Active router is local
Standby router is 172.12.23.2 expires in 8.020
Virtual mac address is 0000.0c07.ac05
2 state changes, last state change 00:02:08
We can see that R3 has been selected as the Active router ("local state is Active"), the virtual router's IP is 172.12.23.10, and R2 is the standby router.
There are some HSRP values that you'll need to change from time to time. What if we want R2 to be the Active router instead? Can we change the MAC address of the virtual router? I'll answer those questions in the next part of this HSRP tutorial!
To your Cisco success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
To pass the CCNA exam, you have to be able to write and troubleshoot access lists. As you climb the ladder toward the CCNP and CCIE, you'll see more and more uses for ACLs. Therefore, you had better know the basics!
The use of "host" and "any" confuses some newcomers to ACLs, so let's take a look at that first.
It is acceptable to configure a wildcard mask of all ones or all zeroes. A wildcard mask of 0.0.0.0 means the address specified in the ACL line must be matched exactly a wildcard mask of 255.255.255.255 means that all addresses will match the line.
Wildcard masks have the option of using the word host to represent a wildcard mask of 0.0.0.0. Consider a configuration where only packets from IP source 10.1.1.1 should be allowed and all other packets denied. The following ACLs both do that.
R3#conf t
R3(config)#access-list 6 permit 10.1.1.1 0.0.0.0
R3(config)#conf t
R3(config)#access-list 7 permit host 10.1.1.1
The keyword any can be used to represent a wildcard mask of 255.255.255.255.
R3(config)#access-list 15 permit any
Another often overlooked detail is the order of the lines in an ACL. Even in a two- or three-line ACL, the order of the lines in an ACL is vital.
Consider a situation where packets sourced from 172.18.18.0 /24 will be denied, but all others will be permitted. The following ACL would do that.
R3#conf t
R3(config)#access-list 15 deny 172.18.18.0 0.0.0.255
R3(config)#access-list 15 permit any
The previous example also illustrates the importance of configuring the ACL with the lines in the correct order to get the desired results. What would be the result if the lines were reversed?
R3#conf t
R3(config)#access-list 15 permit any
R3(config)#access-list 15 deny 172.18.18.0 0.0.0.255
If the lines were reversed, traffic from 172.18.18.0 /24 would be matched against the first line of the ACL. The first line is “permit any", meaning all traffic is permitted. The traffic from 172.18.18.0/24 matches that line, the traffic is permitted, and the ACL stops running. The statement denying the traffic from 172.18.18.0 is never run.
The key to writing and troubleshoot access lists is to take just an extra moment to read it over and make sure it's going to do what you intend it to do. It's better to realize your mistake on paper instead of once the ACL's been applied to an interface!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
The use of "host" and "any" confuses some newcomers to ACLs, so let's take a look at that first.
It is acceptable to configure a wildcard mask of all ones or all zeroes. A wildcard mask of 0.0.0.0 means the address specified in the ACL line must be matched exactly a wildcard mask of 255.255.255.255 means that all addresses will match the line.
Wildcard masks have the option of using the word host to represent a wildcard mask of 0.0.0.0. Consider a configuration where only packets from IP source 10.1.1.1 should be allowed and all other packets denied. The following ACLs both do that.
R3#conf t
R3(config)#access-list 6 permit 10.1.1.1 0.0.0.0
R3(config)#conf t
R3(config)#access-list 7 permit host 10.1.1.1
The keyword any can be used to represent a wildcard mask of 255.255.255.255.
R3(config)#access-list 15 permit any
Another often overlooked detail is the order of the lines in an ACL. Even in a two- or three-line ACL, the order of the lines in an ACL is vital.
Consider a situation where packets sourced from 172.18.18.0 /24 will be denied, but all others will be permitted. The following ACL would do that.
R3#conf t
R3(config)#access-list 15 deny 172.18.18.0 0.0.0.255
R3(config)#access-list 15 permit any
The previous example also illustrates the importance of configuring the ACL with the lines in the correct order to get the desired results. What would be the result if the lines were reversed?
R3#conf t
R3(config)#access-list 15 permit any
R3(config)#access-list 15 deny 172.18.18.0 0.0.0.255
If the lines were reversed, traffic from 172.18.18.0 /24 would be matched against the first line of the ACL. The first line is “permit any", meaning all traffic is permitted. The traffic from 172.18.18.0/24 matches that line, the traffic is permitted, and the ACL stops running. The statement denying the traffic from 172.18.18.0 is never run.
The key to writing and troubleshoot access lists is to take just an extra moment to read it over and make sure it's going to do what you intend it to do. It's better to realize your mistake on paper instead of once the ACL's been applied to an interface!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Here are some CCNA and CCNP practice questions to get your Saturday started off right. Look for new articles and tutorials later today!
CCNA:
By default, what traffic is considered "interesting" by a Cisco router?
A. All IP traffic
B. All ICMP traffic
C. All traffic
D. No traffic
E. Traffic defined with the dialer-group command
F. Traffic defined with the dialer-list command
CCNP / BSCI:
Which of the following protocols will not advertise a redistributed route unless a seed metric is expressly assigned during redistribution? Choose all that apply.
A. RIPv1
B. RIPv2
C. OSPF
D. EIGRP
E. ISIS
F. IGRP
CCNP / BCMSN:
What command enabled VRRP interface tracking?
A. (config-if)# vrrp tracking
B. (config)# vrrp tracking
C. (config-if)# standby 5 track serial0
D. (config) # standby 5 track serial0
E. VRRP doesn't have interface tracking capabilities.
See you later today!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
By default, what traffic is considered "interesting" by a Cisco router?
A. All IP traffic
B. All ICMP traffic
C. All traffic
D. No traffic
E. Traffic defined with the dialer-group command
F. Traffic defined with the dialer-list command
CCNP / BSCI:
Which of the following protocols will not advertise a redistributed route unless a seed metric is expressly assigned during redistribution? Choose all that apply.
A. RIPv1
B. RIPv2
C. OSPF
D. EIGRP
E. ISIS
F. IGRP
CCNP / BCMSN:
What command enabled VRRP interface tracking?
A. (config-if)# vrrp tracking
B. (config)# vrrp tracking
C. (config-if)# standby 5 track serial0
D. (config) # standby 5 track serial0
E. VRRP doesn't have interface tracking capabilities.
See you later today!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Friday, April 28, 2006
Here are the answers to Thursday's CCNA / CCNP practice questions. I'll have some more questions for you later tonight!
Thursday's CCNA And CCNP Practice Questions
CCNA:
Which of the following devices divides a single broadcast domain into smaller broadcast domains with no additional configuration? Choose all that apply.
A. Hubs
B. Repeaters
C. Switches
D. Routers
Answer: D. Only routers do this by default. Switches can divide a broadcast domain, but only with additional configuration (VLANs). Hubs and repeaters work at Layer 1 and are incapable of dividing broadcast domains.
CCNP / BSCI:
In ISIS terminology, what is an intermediate system?
A. An end host
B. A switch
C. A logical group of routers
D. A single router
E. A logical group of hosts
Answer: D. An intermediate system is a single router in ISIS.
CCNP / BCMSN:
The command show standby is used to verify the configuration of what protocol?
A. IRDP
B. HSRP
C. VRRP
D. GLBP
Answer: B. show standby is the "show ip protocols" of HSRP - it shows you everything you'd ever want to know about your HSRP configuration, and maybe a few things you don't want to know! ;)
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Thursday's CCNA And CCNP Practice Questions
CCNA:
Which of the following devices divides a single broadcast domain into smaller broadcast domains with no additional configuration? Choose all that apply.
A. Hubs
B. Repeaters
C. Switches
D. Routers
Answer: D. Only routers do this by default. Switches can divide a broadcast domain, but only with additional configuration (VLANs). Hubs and repeaters work at Layer 1 and are incapable of dividing broadcast domains.
CCNP / BSCI:
In ISIS terminology, what is an intermediate system?
A. An end host
B. A switch
C. A logical group of routers
D. A single router
E. A logical group of hosts
Answer: D. An intermediate system is a single router in ISIS.
CCNP / BCMSN:
The command show standby is used to verify the configuration of what protocol?
A. IRDP
B. HSRP
C. VRRP
D. GLBP
Answer: B. show standby is the "show ip protocols" of HSRP - it shows you everything you'd ever want to know about your HSRP configuration, and maybe a few things you don't want to know! ;)
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Thursday, April 27, 2006
Thursday's CCNA And CCNP Practice Questions
CCNA:
Which of the following devices divides a single broadcast domain into smaller broadcast domains with no additional configuration? Choose all that apply.
A. Hubs
B. Repeaters
C. Switches
D. Routers
CCNP / BSCI:
In ISIS terminology, what is an intermediate system?
A. An end host
B. A switch
C. A logical group of routers
D. A single router
E. A logical group of hosts
CCNP / BCMSN:
The command show standby is used to verify the configuration of what protocol?
A. IRDP
B. HSRP
C. VRRP
D. GLBP
Answers tomorrow - see you then!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
Which of the following devices divides a single broadcast domain into smaller broadcast domains with no additional configuration? Choose all that apply.
A. Hubs
B. Repeaters
C. Switches
D. Routers
CCNP / BSCI:
In ISIS terminology, what is an intermediate system?
A. An end host
B. A switch
C. A logical group of routers
D. A single router
E. A logical group of hosts
CCNP / BCMSN:
The command show standby is used to verify the configuration of what protocol?
A. IRDP
B. HSRP
C. VRRP
D. GLBP
Answers tomorrow - see you then!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Answers To Tuesday's Practice Questions
CCNA:
Which of the following is true of ISDN BRI? Choose all that apply.
A. There are three channels - one b-channel and two d-channels.
B. There are three channels - one d-channel and two b-channels.
C. The d-channel(s) set up the call.
D. The b-channel(s) set up the call.
E. The d-channel(s) carry the data, which can be voice or video.
F. The b-channel(s) carry the data, which can be voice or video.
G. The bandwidth is the same for all three channels.
H. The bandwidth differs between the three channels.
Answer: B, C, F, H. ISDN BRI has one D-channel and two B-channels, the D-channel sets up the call, the B-channels carry the voice and/or video data, and the bandwidth does differ between the three channels.
CCNP / BSCI:
You want an EIGRP-enabled interface, ethernet 0, to receive routing updates but not send them. What is the full command you would enter under the EIGRP process to do so?
Answer: passive-interface ethernet0
CCNP / BCMSN:
Which of the following must be agreed upon between switches running MST to be considered in the same region? Choose three.
A. Revision number
B. MST Autonomous System Number
C. MST Metric Weights
D. MST Region Name
E. MST Instance mapping digest
F. Interface VLAN1 must be on the same subnet
Answer: A, D, E. The revision number, region name, and the digest of the MST Instance - VLAN number mapping must match among routers in the same region.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
Which of the following is true of ISDN BRI? Choose all that apply.
A. There are three channels - one b-channel and two d-channels.
B. There are three channels - one d-channel and two b-channels.
C. The d-channel(s) set up the call.
D. The b-channel(s) set up the call.
E. The d-channel(s) carry the data, which can be voice or video.
F. The b-channel(s) carry the data, which can be voice or video.
G. The bandwidth is the same for all three channels.
H. The bandwidth differs between the three channels.
Answer: B, C, F, H. ISDN BRI has one D-channel and two B-channels, the D-channel sets up the call, the B-channels carry the voice and/or video data, and the bandwidth does differ between the three channels.
CCNP / BSCI:
You want an EIGRP-enabled interface, ethernet 0, to receive routing updates but not send them. What is the full command you would enter under the EIGRP process to do so?
Answer: passive-interface ethernet0
CCNP / BCMSN:
Which of the following must be agreed upon between switches running MST to be considered in the same region? Choose three.
A. Revision number
B. MST Autonomous System Number
C. MST Metric Weights
D. MST Region Name
E. MST Instance mapping digest
F. Interface VLAN1 must be on the same subnet
Answer: A, D, E. The revision number, region name, and the digest of the MST Instance - VLAN number mapping must match among routers in the same region.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Wednesday, April 26, 2006
CCNA / CCNP Practice Questions For Wednesday
Answers To Tuesday's Questions Will Be Posted Later Tonight!
CCNA:
Identify the three locations where a router can locate an IOS image during the boot process.
A. Flash
B. TFTP Server
C. FTP Server
D. ROM
E. RAM
F. NVRAM
G. A laptop configured as an IOS Server.
CCNP / BSCI:
One effect of configuring a router as an EIGRP Stub is to prevent it from receiving what kind of traffic?
A. LSAs
B. Hellos
C. DUAL Queries
D. Acks
E. Joins
CCNP / BCMSN
In a multilayer switch, what holds the routing information?
A. The route cache
B. The Attribute Table
C. The MAC Mapping Table
D. The Forwarding Information Base
E. The Adjacency Table
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Answers To Tuesday's Questions Will Be Posted Later Tonight!
CCNA:
Identify the three locations where a router can locate an IOS image during the boot process.
A. Flash
B. TFTP Server
C. FTP Server
D. ROM
E. RAM
F. NVRAM
G. A laptop configured as an IOS Server.
CCNP / BSCI:
One effect of configuring a router as an EIGRP Stub is to prevent it from receiving what kind of traffic?
A. LSAs
B. Hellos
C. DUAL Queries
D. Acks
E. Joins
CCNP / BCMSN
In a multilayer switch, what holds the routing information?
A. The route cache
B. The Attribute Table
C. The MAC Mapping Table
D. The Forwarding Information Base
E. The Adjacency Table
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
My Personal Motivational Library
Anyone who's read my articles knows that I'm very big on planning your success. If you want to drive across the country, you map out a plan to do so; if you want to get a CCNA, CCIE, or accomplish anything else in life, you've got to create a success plan for doing so.
If you've never done so, this can be a little tough at first. I'd like to recommend five of my personal favorite planning and/or motivation books that have helped me create plans for a successful career and life.
Brian Tracy's Goals! is a fantastic book for learning how to create a plan for professional and personal success. I highly recommend it, and you can learn more about this great book and Brian's other products at www.briantracy.com. His books are at amazon.com as well.
Mark Burnett, the creator of Survivor and The Apprentice -- well, you just have to read his story to believe it. You can read about his amazing career in Jump In!.
Donny Deutsch's book Often Wrong, Never In Doubt is quite inspiring for those of us creating our own path to professional success. Well worth a read. Warning: contains sexist content in places. Don't blame me, I didn't write it. :)
Nick Saban is the coach of the Miami Dolphins, and his book How Good Do You Want To Be? will help you break through the restraints that you may have put on your own career and accomplishments. This isn't the typical "sports coach rah rah" book so many successful coaches have written, and I'm sure you'll enjoy it.
I'll finish this list with a second Brian Tracy book, TurboCoach. I've actually bought two copies of this book, because I wore the first one out! There's no better way to achieve your dreams than to create a detailed, written plan for doing so, and this book will definitely help you do so.
So there you are! Whether you're looking for help in creating a study and success plan for your studies, or just a little friendly inspiration, these books are a great way to get what you need to succeed. And then it's up to you!
To your Cisco success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Anyone who's read my articles knows that I'm very big on planning your success. If you want to drive across the country, you map out a plan to do so; if you want to get a CCNA, CCIE, or accomplish anything else in life, you've got to create a success plan for doing so.
If you've never done so, this can be a little tough at first. I'd like to recommend five of my personal favorite planning and/or motivation books that have helped me create plans for a successful career and life.
Brian Tracy's Goals! is a fantastic book for learning how to create a plan for professional and personal success. I highly recommend it, and you can learn more about this great book and Brian's other products at www.briantracy.com. His books are at amazon.com as well.
Mark Burnett, the creator of Survivor and The Apprentice -- well, you just have to read his story to believe it. You can read about his amazing career in Jump In!.
Donny Deutsch's book Often Wrong, Never In Doubt is quite inspiring for those of us creating our own path to professional success. Well worth a read. Warning: contains sexist content in places. Don't blame me, I didn't write it. :)
Nick Saban is the coach of the Miami Dolphins, and his book How Good Do You Want To Be? will help you break through the restraints that you may have put on your own career and accomplishments. This isn't the typical "sports coach rah rah" book so many successful coaches have written, and I'm sure you'll enjoy it.
I'll finish this list with a second Brian Tracy book, TurboCoach. I've actually bought two copies of this book, because I wore the first one out! There's no better way to achieve your dreams than to create a detailed, written plan for doing so, and this book will definitely help you do so.
So there you are! Whether you're looking for help in creating a study and success plan for your studies, or just a little friendly inspiration, these books are a great way to get what you need to succeed. And then it's up to you!
To your Cisco success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Tuesday, April 25, 2006
Whether you're working on your CCNA or CCNP, Cisco certification exams are the most demanding computer certification exams in the IT field. Cisco exams are not a test of memorization, they're a test of your analytical skills. You'll need to look at configurations and console output and analyze them to identify problems and answer detailed questions. To pass these demanding exams, you've got to truly understand how Cisco routers and switches operate - and the key to doing so is right in front of you.
The debug command.
Of course, there is no single "debug" command. Using IOS Help, you can quickly see that there are hundreds of these debugs, and I want to mention immediately that you should never practice these commands on a production router. This is one major reason you need to get some hands-on experience with Cisco products in a home lab or rack rental. No software program or "simulator" is going to give you the debug practice you need.
Now, why am I so insistent that you use debugs? Because that's how you actually see what's going on. It's not enough to type a frame relay LMI command, you have to be able to see the LMIs being exchanged with "debug frame lmi". You don't want to just type a few network numbers in after enabling RIP, you want to see the routes being advertised along with their metrics with "debug ip rip". The list goes on and on.
By using debugs as part of your CCNA and CCNP studies, you're going beyond just memorizing commands and thinking you understand everything that's happening when you enter a command or two. You move to a higher level of understanding how routers, switches, and protocols work -- and that is the true goal of earning your CCNA and CCNP.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
The debug command.
Of course, there is no single "debug" command. Using IOS Help, you can quickly see that there are hundreds of these debugs, and I want to mention immediately that you should never practice these commands on a production router. This is one major reason you need to get some hands-on experience with Cisco products in a home lab or rack rental. No software program or "simulator" is going to give you the debug practice you need.
Now, why am I so insistent that you use debugs? Because that's how you actually see what's going on. It's not enough to type a frame relay LMI command, you have to be able to see the LMIs being exchanged with "debug frame lmi". You don't want to just type a few network numbers in after enabling RIP, you want to see the routes being advertised along with their metrics with "debug ip rip". The list goes on and on.
By using debugs as part of your CCNA and CCNP studies, you're going beyond just memorizing commands and thinking you understand everything that's happening when you enter a command or two. You move to a higher level of understanding how routers, switches, and protocols work -- and that is the true goal of earning your CCNA and CCNP.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNP / BSCI Exam Tutorial: Using The IP Default Next-Hop Command
Part of the challenge of passing the BSCI exam and earning your CCNP certification is learning that while there are some commands that look almost the same, and seem to do the same thing, they don't! The ip default next-hop command is one such command. There is also an "ip next-hop" command, but the default next-hop command operates differently.
If you set an "ip default next-hop" with a route map, that next-hop will be used ONLY if an explicit path to the destination network is not present in the routing table. An extended ACL must be used here, since a source and destination must be defined.
R2(config)#access-list 150 permit ip host 172.1.1.1 210.1.1.0 0.0.0.255
R2(config)#route-map DEFAULT_NEXT_HOP permit
R2(config-route-map)#match ip address 150
R2(config-route-map)#set ip default next-hop 100.1.1.3
R2(config)#interface e0
R2(config-if)#ip policy route-map DEFAULT_NEXT_HOP
When a packet comes into ethernet0 with a source IP of 172.1.1.1 and is destined for any host on the 210.1.1.0/24 network, the next-hop address will be set to 100.1.1.3 IF there is no entry in the routing table for that network.
That's a big "if" - so be careful!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Part of the challenge of passing the BSCI exam and earning your CCNP certification is learning that while there are some commands that look almost the same, and seem to do the same thing, they don't! The ip default next-hop command is one such command. There is also an "ip next-hop" command, but the default next-hop command operates differently.
If you set an "ip default next-hop" with a route map, that next-hop will be used ONLY if an explicit path to the destination network is not present in the routing table. An extended ACL must be used here, since a source and destination must be defined.
R2(config)#access-list 150 permit ip host 172.1.1.1 210.1.1.0 0.0.0.255
R2(config)#route-map DEFAULT_NEXT_HOP permit
R2(config-route-map)#match ip address 150
R2(config-route-map)#set ip default next-hop 100.1.1.3
R2(config)#interface e0
R2(config-if)#ip policy route-map DEFAULT_NEXT_HOP
When a packet comes into ethernet0 with a source IP of 172.1.1.1 and is destined for any host on the 210.1.1.0/24 network, the next-hop address will be set to 100.1.1.3 IF there is no entry in the routing table for that network.
That's a big "if" - so be careful!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Cisco CCNP Exam / BCMSN Exam Tutorial: DiffServ And Integrated Services
To pass the CCNP exams, you’ve got to master Quality of Service, and the first step in doing so is knowing the differences between the different QoS types.
Now this being Cisco, we can't just have one kind of QoS! We've got best-effort delivery, Integrated Services, and Differentiated Services. Let's take a quick look at all three.
Best-effort is just what it sounds like - routers and switches making their "best effort" to deliver data. This is considered QoS, but it's kind of a "default QoS". Best effort is strictly "first in, first out" (FIFO).
An entire path from Point A to Point B will be defined in advance when Integrated Services are in effect. Integrated Services is much like the High-Occupancy Vehicle lanes found in many larger cities. If your car has three or more people in it, you're considered a "priority vehicle" and you can drive in a special lane with much less congestion than regular lanes. Integrated Services will create this lane in advance for "priority traffic", and when that traffic comes along, the path already exists. Integrated Services uses the Resource Reservation Protocol (RSVP) to create these paths. RSVP guarantees a quality rate of service, since this "priority path" is created in advance.
Integrated Services is defined in RFC 1613. Use your favorite search engine to locate a copy online and read more about this topic. It's a good idea to get into the habit of reading RFCs!
Of course, if you've got a lot of different dedicated paths being created that may or not be used very often, that's a lot of wasted bandwidth. That leads us to the third QoS model, the Differentiated Services model. Generally referred to as DiffServ, there are no advance path reservations and there's no RSVP. The QoS policies are written on the routers and switches, and they take action dynamically as needed. Since each router and switch can have a different QoS policy, DiffServ takes effect on a per-hop basis rather than the per-flow basis of Integrated Services. A packet can be considered "high priority" by one router and "normal priority" by the next.
Believe me, this is just the beginning when it comes to Quality of Service. It's a huge topic on your exams and in the real world's production networks, and as with all other Cisco topics, just master the fundamentals and build from there - and you're on your way to CCNP exam success!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
To pass the CCNP exams, you’ve got to master Quality of Service, and the first step in doing so is knowing the differences between the different QoS types.
Now this being Cisco, we can't just have one kind of QoS! We've got best-effort delivery, Integrated Services, and Differentiated Services. Let's take a quick look at all three.
Best-effort is just what it sounds like - routers and switches making their "best effort" to deliver data. This is considered QoS, but it's kind of a "default QoS". Best effort is strictly "first in, first out" (FIFO).
An entire path from Point A to Point B will be defined in advance when Integrated Services are in effect. Integrated Services is much like the High-Occupancy Vehicle lanes found in many larger cities. If your car has three or more people in it, you're considered a "priority vehicle" and you can drive in a special lane with much less congestion than regular lanes. Integrated Services will create this lane in advance for "priority traffic", and when that traffic comes along, the path already exists. Integrated Services uses the Resource Reservation Protocol (RSVP) to create these paths. RSVP guarantees a quality rate of service, since this "priority path" is created in advance.
Integrated Services is defined in RFC 1613. Use your favorite search engine to locate a copy online and read more about this topic. It's a good idea to get into the habit of reading RFCs!
Of course, if you've got a lot of different dedicated paths being created that may or not be used very often, that's a lot of wasted bandwidth. That leads us to the third QoS model, the Differentiated Services model. Generally referred to as DiffServ, there are no advance path reservations and there's no RSVP. The QoS policies are written on the routers and switches, and they take action dynamically as needed. Since each router and switch can have a different QoS policy, DiffServ takes effect on a per-hop basis rather than the per-flow basis of Integrated Services. A packet can be considered "high priority" by one router and "normal priority" by the next.
Believe me, this is just the beginning when it comes to Quality of Service. It's a huge topic on your exams and in the real world's production networks, and as with all other Cisco topics, just master the fundamentals and build from there - and you're on your way to CCNP exam success!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Cisco CCNA Exam Tutorial: Configuring Dialer Profiles
The most common method of configuring ISDN is with dialer maps, but dial information can also be configured on a logical interface. To pass the CCNA exam, you must know how to configure and troubleshoot both dialer maps and dialer profiles.
Dialer Profiles allow different dialing information to be configured onto logical interfaces. The logical interfaces may have different dialing destinations, different remote router names, etc., but they’ll be using the same physical interface.
Dialer strings are used on dialer profiles. Note that each logical interface has a different IP address, a different remote router to dial, and a different dialer string, but they will be using the same physical interface to dial out. The commands dialer pool and dialer pool-member are used to link the logical and physical interfaces. The number following each command must match for the logical interface to correctly bind to the physical interface.
R1(config)#interface dialer0
R1(config-if)#ip address 172.16.1.1 255.255.255.0
R1(config-if)#encapsulation ppp
<. The encapsulation type is placed on both the logical and physical interfaces. >
R1(config-if)#dialer remote-name Remote0
R1(config-if)#dialer pool 1
<>
R1(config-if)#dialer string 5551212
<>
R1(config-if)#dialer-group 1
<>
R1(config)#interface dialer1
R1(config-if)#ip address 172.16.1.2 255.255.255.0
R1(config-if)#encapsulation ppp
R1(config-if)#dialer remote-name Remote1
R1(config-if)#dialer pool 1
R1(config-if)#dialer string 5551234
R1(config-if)#dialer-group 1
R1(config)#interface bri0
R1(config-if)#no ip address
<>
R1(config-if)#encapsulation ppp
<>
R1(config-if)#dialer pool-member 1
<>
R1(config-if)#isdn spid1 0835866101
R1(config-if)#isdn spid2 0835866301
When configuring dialer profiles, the encapsulation type should be placed on both the physical BRI interface and the logical dialer interfaces. The SPIDs are configured on the physical interface as well.
Configuring dialer profiles can be a little tricky at first, and the best way to master this skill is to get real hands-on practice in your own CCNA / CCNP home lab or a rack rental service. Either way, hands-on is the best practice. Best of luck in your CCNA studies!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
The most common method of configuring ISDN is with dialer maps, but dial information can also be configured on a logical interface. To pass the CCNA exam, you must know how to configure and troubleshoot both dialer maps and dialer profiles.
Dialer Profiles allow different dialing information to be configured onto logical interfaces. The logical interfaces may have different dialing destinations, different remote router names, etc., but they’ll be using the same physical interface.
Dialer strings are used on dialer profiles. Note that each logical interface has a different IP address, a different remote router to dial, and a different dialer string, but they will be using the same physical interface to dial out. The commands dialer pool and dialer pool-member are used to link the logical and physical interfaces. The number following each command must match for the logical interface to correctly bind to the physical interface.
R1(config)#interface dialer0
R1(config-if)#ip address 172.16.1.1 255.255.255.0
R1(config-if)#encapsulation ppp
<. The encapsulation type is placed on both the logical and physical interfaces. >
R1(config-if)#dialer remote-name Remote0
R1(config-if)#dialer pool 1
<>
R1(config-if)#dialer string 5551212
<>
R1(config-if)#dialer-group 1
<>
R1(config)#interface dialer1
R1(config-if)#ip address 172.16.1.2 255.255.255.0
R1(config-if)#encapsulation ppp
R1(config-if)#dialer remote-name Remote1
R1(config-if)#dialer pool 1
R1(config-if)#dialer string 5551234
R1(config-if)#dialer-group 1
R1(config)#interface bri0
R1(config-if)#no ip address
<>
R1(config-if)#encapsulation ppp
<>
R1(config-if)#dialer pool-member 1
<>
R1(config-if)#isdn spid1 0835866101
R1(config-if)#isdn spid2 0835866301
When configuring dialer profiles, the encapsulation type should be placed on both the physical BRI interface and the logical dialer interfaces. The SPIDs are configured on the physical interface as well.
Configuring dialer profiles can be a little tricky at first, and the best way to master this skill is to get real hands-on practice in your own CCNA / CCNP home lab or a rack rental service. Either way, hands-on is the best practice. Best of luck in your CCNA studies!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Tuesday's CCNA And CCNP Practice Questions
The blog's back up, so look for new questions every day!
CCNA:
Which of the following is true of ISDN BRI? Choose all that apply.
A. There are three channels - one b-channel and two d-channels.
B. There are three channels - one d-channel and two b-channels.
C. The d-channel(s) set up the call.
D. The b-channel(s) set up the call.
E. The d-channel(s) carry the data, which can be voice or video.
F. The b-channel(s) carry the data, which can be voice or video.
G. The bandwidth is the same for all three channels.
H. The bandwidth differs between the three channels.
CCNP / BSCI:
You want an EIGRP-enabled interface, ethernet 0, to receive routing updates but not send them. What is the full command you would enter under the EIGRP process to do so?
CCNP / BCMSN:
Which of the following must be agreed upon between switches running MST to be considered in the same region? Choose three.
A. Revision number
B. MST Autonomous System Number
C. MST Metric Weights
D. MST Region Name
E. MST Instance mapping digest
F. Interface VLAN1 must be on the same subnet
Chris Bryant
CCIE #12932
www.thebryantadvantage.com
The blog's back up, so look for new questions every day!
CCNA:
Which of the following is true of ISDN BRI? Choose all that apply.
A. There are three channels - one b-channel and two d-channels.
B. There are three channels - one d-channel and two b-channels.
C. The d-channel(s) set up the call.
D. The b-channel(s) set up the call.
E. The d-channel(s) carry the data, which can be voice or video.
F. The b-channel(s) carry the data, which can be voice or video.
G. The bandwidth is the same for all three channels.
H. The bandwidth differs between the three channels.
CCNP / BSCI:
You want an EIGRP-enabled interface, ethernet 0, to receive routing updates but not send them. What is the full command you would enter under the EIGRP process to do so?
CCNP / BCMSN:
Which of the following must be agreed upon between switches running MST to be considered in the same region? Choose three.
A. Revision number
B. MST Autonomous System Number
C. MST Metric Weights
D. MST Region Name
E. MST Instance mapping digest
F. Interface VLAN1 must be on the same subnet
Chris Bryant
CCIE #12932
www.thebryantadvantage.com
Monday, April 24, 2006
Cisco CCNP / BCMSN Exam Tutorial: Getting Started With QoS Policies
QoS - Quality of Service - is a huge topic on both the BCMSN exam and real-world networks. QoS is so big today that Cisco's created separate specialist certifications that cover nothing but QoS! It can be an overwhelming topic at first, but master the fundamentals and you're on your way to exam and job success.
If you work with QoS at any level - and sooner or later, you will - you've got to know how to write and apply QoS policies.
Creating and applying such a policy is a three-step process.
Create a QoS class to identify the traffic that will be affected by the policy.
Create a QoS policy containing the actions to be taken by traffic identified by the class.
Apply the policy to the appropriate interfaces.
If the phrase "identify the traffic" sounds like it's time to write an access-list, you're right! Writing an ACL is one of two ways to classify traffic, and is the more common of the two. Before we get to the less-common method, let's take a look at how to use an ACL to classify traffic.
You can use either a standard or extended ACL with QoS policies. The ACL will be written separately, and then called from the class map.
SW1(config)#access-list 105 permit tcp any any eq 80
SW1(config)#class-map WEBTRAFFIC
SW1(config-cmap)#match access-group 105
Now that we've identified the traffic to be affected by the policy, we better get around to writing the policy! QoS policies are configured with the policy-map command, and each clause of the policy will contain an action to be taken to traffic matching that clause.
SW1(config)#policy-map LIMIT_WEBTRAFFIC_BANDWIDTH
SW1(config-pmap)#class WEBTRAFFIC
SW1(config-pmap-c)#police 5000000 exceed-action drop
SW1(config-pmap-c)#exit
This is a simple policy, but it illustrates the logic of QoS policies. The policy map LIMIT_WEBTRAFFIC_BANDWIDTH calls the map-class WEBTRAFFIC. We already know that all WWW traffic will match that map class, so any WWW traffic that exceeds the stated bandwidth limitation will be dropped.
Finally, apply the policy to the appropriate interface.
SW1(config-if)#service-policy LIMIT_WEBTRAFFIC_BANDWIDTH in
Getting your CCNP is a great way to boost your career, and learning QoS is a tremendous addition to your skill set. Like I said, learn the fundamentals, don't get overwhelmed by looking at QoS as a whole, and you're on your way to success!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
QoS - Quality of Service - is a huge topic on both the BCMSN exam and real-world networks. QoS is so big today that Cisco's created separate specialist certifications that cover nothing but QoS! It can be an overwhelming topic at first, but master the fundamentals and you're on your way to exam and job success.
If you work with QoS at any level - and sooner or later, you will - you've got to know how to write and apply QoS policies.
Creating and applying such a policy is a three-step process.
Create a QoS class to identify the traffic that will be affected by the policy.
Create a QoS policy containing the actions to be taken by traffic identified by the class.
Apply the policy to the appropriate interfaces.
If the phrase "identify the traffic" sounds like it's time to write an access-list, you're right! Writing an ACL is one of two ways to classify traffic, and is the more common of the two. Before we get to the less-common method, let's take a look at how to use an ACL to classify traffic.
You can use either a standard or extended ACL with QoS policies. The ACL will be written separately, and then called from the class map.
SW1(config)#access-list 105 permit tcp any any eq 80
SW1(config)#class-map WEBTRAFFIC
SW1(config-cmap)#match access-group 105
Now that we've identified the traffic to be affected by the policy, we better get around to writing the policy! QoS policies are configured with the policy-map command, and each clause of the policy will contain an action to be taken to traffic matching that clause.
SW1(config)#policy-map LIMIT_WEBTRAFFIC_BANDWIDTH
SW1(config-pmap)#class WEBTRAFFIC
SW1(config-pmap-c)#police 5000000 exceed-action drop
SW1(config-pmap-c)#exit
This is a simple policy, but it illustrates the logic of QoS policies. The policy map LIMIT_WEBTRAFFIC_BANDWIDTH calls the map-class WEBTRAFFIC. We already know that all WWW traffic will match that map class, so any WWW traffic that exceeds the stated bandwidth limitation will be dropped.
Finally, apply the policy to the appropriate interface.
SW1(config-if)#service-policy LIMIT_WEBTRAFFIC_BANDWIDTH in
Getting your CCNP is a great way to boost your career, and learning QoS is a tremendous addition to your skill set. Like I said, learn the fundamentals, don't get overwhelmed by looking at QoS as a whole, and you're on your way to success!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Cisco CCNP / BSCI Tutorial: Comparing IRDP and HSRP
To pass the BSCI exam, you need to know the difference between IRDP and HSRP. While they have the same basic function, the operation and configuration of each are totally different.
The aim of both is to allow hosts to quickly discover a standby router when the primary router fails. IRDP is commonly used by Windows DHCP clients and several Unix variations, but you do see it in Cisco routers as well. IRDP is defined in RFC 1256.
IRDP (ICMP Router Discovery Protocol) routers will multicast Hello messages that host devices hear. If a host hears from more than one IRDP router, it will choose one as its primary and will start using the other router if the primary it's chosen goes down.
HSRP (Hot Standby Routing Protocol) is a Cisco-proprietary protocol that is designed for quick cutover to a secondary router if the primary fails, but the host devices don't "see" either the primary or secondary router. The hosts use a virtual router as their default gateway. This virtual router has its own IP and MAC address! All the while, the router chosen as the primary is actually the one doing the routing. If the primary router goes down, the secondary router quickly takes over with no major interruption to network services.
The HSRP routers communicate by multicasting updates to 224.0.0.2, and its through these hellos that the HSRP routers decide which router is primary and which is secondary. HSRP is defined in RFC 2281.
The configuration of each of these will be covered in a future tutorial. In the meantime, I urge you to read the RFCs mentioned in this article, and visit www.cisco.com/univercd to read about the configurations and options available for both of these vital protocols.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
To pass the BSCI exam, you need to know the difference between IRDP and HSRP. While they have the same basic function, the operation and configuration of each are totally different.
The aim of both is to allow hosts to quickly discover a standby router when the primary router fails. IRDP is commonly used by Windows DHCP clients and several Unix variations, but you do see it in Cisco routers as well. IRDP is defined in RFC 1256.
IRDP (ICMP Router Discovery Protocol) routers will multicast Hello messages that host devices hear. If a host hears from more than one IRDP router, it will choose one as its primary and will start using the other router if the primary it's chosen goes down.
HSRP (Hot Standby Routing Protocol) is a Cisco-proprietary protocol that is designed for quick cutover to a secondary router if the primary fails, but the host devices don't "see" either the primary or secondary router. The hosts use a virtual router as their default gateway. This virtual router has its own IP and MAC address! All the while, the router chosen as the primary is actually the one doing the routing. If the primary router goes down, the secondary router quickly takes over with no major interruption to network services.
The HSRP routers communicate by multicasting updates to 224.0.0.2, and its through these hellos that the HSRP routers decide which router is primary and which is secondary. HSRP is defined in RFC 2281.
The configuration of each of these will be covered in a future tutorial. In the meantime, I urge you to read the RFCs mentioned in this article, and visit www.cisco.com/univercd to read about the configurations and options available for both of these vital protocols.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Cisco CCNA Certification Tutorial: Frame Relay DLCIs - How To Map 'Em And Use 'Em
Passing the CCNA is tough, and one of the toughest parts is keeping all the acronyms straight! Frame Relay has plenty of those, and today we're going to examine what DLCIs do and how they're mapped on a Cisco router.
Frame Relay VCs use Data-Link Connection Identifiers (DLCI - pronounced "del-see") as their addresses. Unlike other Cisco technologies, VCs have only a single DLCI in their header. They do not have a source and destination.
DLCIs have local significance only. DLCI numbers are not advertised to other routers, and other routers can use the same DLCI numbers without causing connectivity issues.
Cisco uses the term global addressing to describe a technique by which a router in a frame relay network is reached via the same DLCI number from each router in the network. For example, in a 25-router network, the same DLCI number would be used to reach “Router A” by each router.
Global Addressing is an organizational tool that does not affect the fact that DLCIs have local significance only.
The locally significant DLCI must be mapped to the destination router’s IP address. There are two options for this, Inverse ARP and static mapping.
In both of the following examples, the single physical Serial interface on Router 1 is configured with two logical connections through the frame relay cloud, one to Router 2 and one to Router 3.
Inverse ARP runs by default once Frame Relay is enabled, and starts working as soon as you open the interface. By running show frame-relay map after enabling Frame Relay, two dynamic mappings are shown on this router. If a dynamic mapping is shown, Inverse ARP performed it.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), dynamic,
broadcast,, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), dynamic,
broadcast,, status defined, active
Static mappings require the use of a frame map statement. To use static mappings, turn Inverse ARP off with the no frame-relay inverse-arp statement, and configure a frame map statement for each remote destination that maps the local DLCI to the remote IP address. Frame Relay requires the broadcast keyword to send broadcasts to the remote device.
R1#conf t
R1(config)#interface serial0
R1(config-if)#no frame-relay inverse-arp
R1(config-if)#frame map ip 200.1.1.2 122 broadcast
R1(config-if)#frame map ip 200.1.1.3 123 broadcast
The syntax of the frame map statement maps the remote IP address to the local DLCI.
Broadcasts will not be transmitted by default; the broadcast option must be configured.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), static,
broadcast,
CISCO, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), static,
broadcast,
CISCO, status defined, active
Hands-on practice is the best way to prepare for CCNA exam success. Working with Frame Relay in a lab environment practically guarantees that you'll truly master the concepts shown here - and then you're on your way to the CCNA and becoming a master network engineer.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Passing the CCNA is tough, and one of the toughest parts is keeping all the acronyms straight! Frame Relay has plenty of those, and today we're going to examine what DLCIs do and how they're mapped on a Cisco router.
Frame Relay VCs use Data-Link Connection Identifiers (DLCI - pronounced "del-see") as their addresses. Unlike other Cisco technologies, VCs have only a single DLCI in their header. They do not have a source and destination.
DLCIs have local significance only. DLCI numbers are not advertised to other routers, and other routers can use the same DLCI numbers without causing connectivity issues.
Cisco uses the term global addressing to describe a technique by which a router in a frame relay network is reached via the same DLCI number from each router in the network. For example, in a 25-router network, the same DLCI number would be used to reach “Router A” by each router.
Global Addressing is an organizational tool that does not affect the fact that DLCIs have local significance only.
The locally significant DLCI must be mapped to the destination router’s IP address. There are two options for this, Inverse ARP and static mapping.
In both of the following examples, the single physical Serial interface on Router 1 is configured with two logical connections through the frame relay cloud, one to Router 2 and one to Router 3.
Inverse ARP runs by default once Frame Relay is enabled, and starts working as soon as you open the interface. By running show frame-relay map after enabling Frame Relay, two dynamic mappings are shown on this router. If a dynamic mapping is shown, Inverse ARP performed it.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), dynamic,
broadcast,, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), dynamic,
broadcast,, status defined, active
Static mappings require the use of a frame map statement. To use static mappings, turn Inverse ARP off with the no frame-relay inverse-arp statement, and configure a frame map statement for each remote destination that maps the local DLCI to the remote IP address. Frame Relay requires the broadcast keyword to send broadcasts to the remote device.
R1#conf t
R1(config)#interface serial0
R1(config-if)#no frame-relay inverse-arp
R1(config-if)#frame map ip 200.1.1.2 122 broadcast
R1(config-if)#frame map ip 200.1.1.3 123 broadcast
The syntax of the frame map statement maps the remote IP address to the local DLCI.
Broadcasts will not be transmitted by default; the broadcast option must be configured.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), static,
broadcast,
CISCO, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), static,
broadcast,
CISCO, status defined, active
Hands-on practice is the best way to prepare for CCNA exam success. Working with Frame Relay in a lab environment practically guarantees that you'll truly master the concepts shown here - and then you're on your way to the CCNA and becoming a master network engineer.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Cisco CCNA Tutorial: Frame Relay DLCIs And Mapping
Passing the CCNA is tough, and one of the toughest parts is keeping all the acronyms straight! Frame Relay has plenty of those, and today we're going to examine what DLCIs do and how they're mapped on a Cisco router.
Frame Relay VCs use Data-Link Connection Identifiers (DLCI - pronounced "del-see") as their addresses. Unlike other Cisco technologies, VCs have only a single DLCI in their header. They do not have a source and destination.
DLCIs have local significance only. DLCI numbers are not advertised to other routers, and other routers can use the same DLCI numbers without causing connectivity issues.
Cisco uses the term global addressing to describe a technique by which a router in a frame relay network is reached via the same DLCI number from each router in the network. For example, in a 25-router network, the same DLCI number would be used to reach “Router A” by each router.
Global Addressing is an organizational tool that does not affect the fact that DLCIs have local significance only.
The locally significant DLCI must be mapped to the destination router’s IP address. There are two options for this, Inverse ARP and static mapping.
In both of the following examples, the single physical Serial interface on Router 1 is configured with two logical connections through the frame relay cloud, one to Router 2 and one to Router 3.
Inverse ARP runs by default once Frame Relay is enabled, and starts working as soon as you open the interface. By running show frame-relay map after enabling Frame Relay, two dynamic mappings are shown on this router. If a dynamic mapping is shown, Inverse ARP performed it.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), dynamic,
broadcast,, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), dynamic,
broadcast,, status defined, active
Static mappings require the use of a frame map statement. To use static mappings, turn Inverse ARP off with the no frame-relay inverse-arp statement, and configure a frame map statement for each remote destination that maps the local DLCI to the remote IP address. Frame Relay requires the broadcast keyword to send broadcasts to the remote device.
R1#conf t
R1(config)#interface serial0
R1(config-if)#no frame-relay inverse-arp
R1(config-if)#frame map ip 200.1.1.2 122 broadcast
R1(config-if)#frame map ip 200.1.1.3 123 broadcast
The syntax of the frame map statement maps the remote IP address to the local DLCI.
Broadcasts will not be transmitted by default; the broadcast option must be configured.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), static,
broadcast,
CISCO, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), static,
broadcast,
CISCO, status defined, active
Hands-on practice is the best way to prepare for CCNA exam success. Working with Frame Relay in a lab environment practically guarantees that you'll truly master the concepts shown here - and then you're on your way to the CCNA and becoming a master network engineer.
Passing the CCNA is tough, and one of the toughest parts is keeping all the acronyms straight! Frame Relay has plenty of those, and today we're going to examine what DLCIs do and how they're mapped on a Cisco router.
Frame Relay VCs use Data-Link Connection Identifiers (DLCI - pronounced "del-see") as their addresses. Unlike other Cisco technologies, VCs have only a single DLCI in their header. They do not have a source and destination.
DLCIs have local significance only. DLCI numbers are not advertised to other routers, and other routers can use the same DLCI numbers without causing connectivity issues.
Cisco uses the term global addressing to describe a technique by which a router in a frame relay network is reached via the same DLCI number from each router in the network. For example, in a 25-router network, the same DLCI number would be used to reach “Router A” by each router.
Global Addressing is an organizational tool that does not affect the fact that DLCIs have local significance only.
The locally significant DLCI must be mapped to the destination router’s IP address. There are two options for this, Inverse ARP and static mapping.
In both of the following examples, the single physical Serial interface on Router 1 is configured with two logical connections through the frame relay cloud, one to Router 2 and one to Router 3.
Inverse ARP runs by default once Frame Relay is enabled, and starts working as soon as you open the interface. By running show frame-relay map after enabling Frame Relay, two dynamic mappings are shown on this router. If a dynamic mapping is shown, Inverse ARP performed it.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), dynamic,
broadcast,, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), dynamic,
broadcast,, status defined, active
Static mappings require the use of a frame map statement. To use static mappings, turn Inverse ARP off with the no frame-relay inverse-arp statement, and configure a frame map statement for each remote destination that maps the local DLCI to the remote IP address. Frame Relay requires the broadcast keyword to send broadcasts to the remote device.
R1#conf t
R1(config)#interface serial0
R1(config-if)#no frame-relay inverse-arp
R1(config-if)#frame map ip 200.1.1.2 122 broadcast
R1(config-if)#frame map ip 200.1.1.3 123 broadcast
The syntax of the frame map statement maps the remote IP address to the local DLCI.
Broadcasts will not be transmitted by default; the broadcast option must be configured.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), static,
broadcast,
CISCO, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), static,
broadcast,
CISCO, status defined, active
Hands-on practice is the best way to prepare for CCNA exam success. Working with Frame Relay in a lab environment practically guarantees that you'll truly master the concepts shown here - and then you're on your way to the CCNA and becoming a master network engineer.
CCNA Certification Exam Tutorial: Frame Relay DLCIs And Mapping
Passing the CCNA is tough, and one of the toughest parts is keeping all the acronyms straight! Frame Relay has plenty of those, and today we're going to examine what DLCIs do and how they're mapped on a Cisco router.
Frame Relay VCs use Data-Link Connection Identifiers (DLCI - pronounced "del-see") as their addresses. Unlike other Cisco technologies, VCs have only a single DLCI in their header. They do not have a source and destination.
DLCIs have local significance only. DLCI numbers are not advertised to other routers, and other routers can use the same DLCI numbers without causing connectivity issues.
Cisco uses the term global addressing to describe a technique by which a router in a frame relay network is reached via the same DLCI number from each router in the network. For example, in a 25-router network, the same DLCI number would be used to reach “Router A” by each router.
Global Addressing is an organizational tool that does not affect the fact that DLCIs have local significance only.
The locally significant DLCI must be mapped to the destination router’s IP address. There are two options for this, Inverse ARP and static mapping.
In both of the following examples, the single physical Serial interface on Router 1 is configured with two logical connections through the frame relay cloud, one to Router 2 and one to Router 3.
Inverse ARP runs by default once Frame Relay is enabled, and starts working as soon as you open the interface. By running show frame-relay map after enabling Frame Relay, two dynamic mappings are shown on this router. If a dynamic mapping is shown, Inverse ARP performed it.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), dynamic,
broadcast,, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), dynamic,
broadcast,, status defined, active
Static mappings require the use of a frame map statement. To use static mappings, turn Inverse ARP off with the no frame-relay inverse-arp statement, and configure a frame map statement for each remote destination that maps the local DLCI to the remote IP address. Frame Relay requires the broadcast keyword to send broadcasts to the remote device.
R1#conf t
R1(config)#interface serial0
R1(config-if)#no frame-relay inverse-arp
R1(config-if)#frame map ip 200.1.1.2 122 broadcast
R1(config-if)#frame map ip 200.1.1.3 123 broadcast
The syntax of the frame map statement maps the remote IP address to the local DLCI.
Broadcasts will not be transmitted by default; the broadcast option must be configured.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), static,
broadcast,
CISCO, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), static,
broadcast,
CISCO, status defined, active
Hands-on practice is the best way to prepare for CCNA exam success. Working with Frame Relay in a lab environment practically guarantees that you'll truly master the concepts shown here - and then you're on your way to the CCNA and becoming a master network engineer.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Hands-on practice is the best way to prepare for CCNA exam success. Working with Frame Relay in a lab environment practically guarantees that you'll truly master the concepts shown here - and then you're on your way to the CCNA and becoming a master network engineer.
Passing the CCNA is tough, and one of the toughest parts is keeping all the acronyms straight! Frame Relay has plenty of those, and today we're going to examine what DLCIs do and how they're mapped on a Cisco router.
Frame Relay VCs use Data-Link Connection Identifiers (DLCI - pronounced "del-see") as their addresses. Unlike other Cisco technologies, VCs have only a single DLCI in their header. They do not have a source and destination.
DLCIs have local significance only. DLCI numbers are not advertised to other routers, and other routers can use the same DLCI numbers without causing connectivity issues.
Cisco uses the term global addressing to describe a technique by which a router in a frame relay network is reached via the same DLCI number from each router in the network. For example, in a 25-router network, the same DLCI number would be used to reach “Router A” by each router.
Global Addressing is an organizational tool that does not affect the fact that DLCIs have local significance only.
The locally significant DLCI must be mapped to the destination router’s IP address. There are two options for this, Inverse ARP and static mapping.
In both of the following examples, the single physical Serial interface on Router 1 is configured with two logical connections through the frame relay cloud, one to Router 2 and one to Router 3.
Inverse ARP runs by default once Frame Relay is enabled, and starts working as soon as you open the interface. By running show frame-relay map after enabling Frame Relay, two dynamic mappings are shown on this router. If a dynamic mapping is shown, Inverse ARP performed it.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), dynamic,
broadcast,, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), dynamic,
broadcast,, status defined, active
Static mappings require the use of a frame map statement. To use static mappings, turn Inverse ARP off with the no frame-relay inverse-arp statement, and configure a frame map statement for each remote destination that maps the local DLCI to the remote IP address. Frame Relay requires the broadcast keyword to send broadcasts to the remote device.
R1#conf t
R1(config)#interface serial0
R1(config-if)#no frame-relay inverse-arp
R1(config-if)#frame map ip 200.1.1.2 122 broadcast
R1(config-if)#frame map ip 200.1.1.3 123 broadcast
The syntax of the frame map statement maps the remote IP address to the local DLCI.
Broadcasts will not be transmitted by default; the broadcast option must be configured.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), static,
broadcast,
CISCO, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), static,
broadcast,
CISCO, status defined, active
Hands-on practice is the best way to prepare for CCNA exam success. Working with Frame Relay in a lab environment practically guarantees that you'll truly master the concepts shown here - and then you're on your way to the CCNA and becoming a master network engineer.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Hands-on practice is the best way to prepare for CCNA exam success. Working with Frame Relay in a lab environment practically guarantees that you'll truly master the concepts shown here - and then you're on your way to the CCNA and becoming a master network engineer.
Learning The Basics Of Frame Relay DLCIs
Passing the CCNA is tough, and one of the toughest parts is keeping all the acronyms straight! Frame Relay has plenty of those, and today we're going to examine what DLCIs do and how they're mapped on a Cisco router.
Frame Relay VCs use Data-Link Connection Identifiers (DLCI - pronounced "del-see") as their addresses. Unlike other Cisco technologies, VCs have only a single DLCI in their header. They do not have a source and destination.
DLCIs have local significance only. DLCI numbers are not advertised to other routers, and other routers can use the same DLCI numbers without causing connectivity issues.
Cisco uses the term global addressing to describe a technique by which a router in a frame relay network is reached via the same DLCI number from each router in the network. For example, in a 25-router network, the same DLCI number would be used to reach “Router A” by each router.
Global Addressing is an organizational tool that does not affect the fact that DLCIs have local significance only.
The locally significant DLCI must be mapped to the destination router’s IP address. There are two options for this, Inverse ARP and static mapping.
In both of the following examples, the single physical Serial interface on Router 1 is configured with two logical connections through the frame relay cloud, one to Router 2 and one to Router 3.
Inverse ARP runs by default once Frame Relay is enabled, and starts working as soon as you open the interface. By running show frame-relay map after enabling Frame Relay, two dynamic mappings are shown on this router. If a dynamic mapping is shown, Inverse ARP performed it.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), dynamic,
broadcast,, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), dynamic,
broadcast,, status defined, active
Static mappings require the use of a frame map statement. To use static mappings, turn Inverse ARP off with the no frame-relay inverse-arp statement, and configure a frame map statement for each remote destination that maps the local DLCI to the remote IP address. Frame Relay requires the broadcast keyword to send broadcasts to the remote device.
R1#conf t
R1(config)#interface serial0
R1(config-if)#no frame-relay inverse-arp
R1(config-if)#frame map ip 200.1.1.2 122 broadcast
R1(config-if)#frame map ip 200.1.1.3 123 broadcast
The syntax of the frame map statement maps the remote IP address to the local DLCI.
Broadcasts will not be transmitted by default; the broadcast option must be configured.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), static,
broadcast, CISCO, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), static,
broadcast, CISCO, status defined, active
Hands-on practice is the best way to prepare for CCNA exam success. Working with Frame Relay in a lab environment practically guarantees that you'll truly master the concepts shown here - and then you're on your way to the CCNA and becoming a master network engineer.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Passing the CCNA is tough, and one of the toughest parts is keeping all the acronyms straight! Frame Relay has plenty of those, and today we're going to examine what DLCIs do and how they're mapped on a Cisco router.
Frame Relay VCs use Data-Link Connection Identifiers (DLCI - pronounced "del-see") as their addresses. Unlike other Cisco technologies, VCs have only a single DLCI in their header. They do not have a source and destination.
DLCIs have local significance only. DLCI numbers are not advertised to other routers, and other routers can use the same DLCI numbers without causing connectivity issues.
Cisco uses the term global addressing to describe a technique by which a router in a frame relay network is reached via the same DLCI number from each router in the network. For example, in a 25-router network, the same DLCI number would be used to reach “Router A” by each router.
Global Addressing is an organizational tool that does not affect the fact that DLCIs have local significance only.
The locally significant DLCI must be mapped to the destination router’s IP address. There are two options for this, Inverse ARP and static mapping.
In both of the following examples, the single physical Serial interface on Router 1 is configured with two logical connections through the frame relay cloud, one to Router 2 and one to Router 3.
Inverse ARP runs by default once Frame Relay is enabled, and starts working as soon as you open the interface. By running show frame-relay map after enabling Frame Relay, two dynamic mappings are shown on this router. If a dynamic mapping is shown, Inverse ARP performed it.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), dynamic,
broadcast,, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), dynamic,
broadcast,, status defined, active
Static mappings require the use of a frame map statement. To use static mappings, turn Inverse ARP off with the no frame-relay inverse-arp statement, and configure a frame map statement for each remote destination that maps the local DLCI to the remote IP address. Frame Relay requires the broadcast keyword to send broadcasts to the remote device.
R1#conf t
R1(config)#interface serial0
R1(config-if)#no frame-relay inverse-arp
R1(config-if)#frame map ip 200.1.1.2 122 broadcast
R1(config-if)#frame map ip 200.1.1.3 123 broadcast
The syntax of the frame map statement maps the remote IP address to the local DLCI.
Broadcasts will not be transmitted by default; the broadcast option must be configured.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), static,
broadcast, CISCO, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), static,
broadcast, CISCO, status defined, active
Hands-on practice is the best way to prepare for CCNA exam success. Working with Frame Relay in a lab environment practically guarantees that you'll truly master the concepts shown here - and then you're on your way to the CCNA and becoming a master network engineer.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Answers To Saturday's CCNA / CCNP Practice Questions
CCNA:
Which of the following is true of both IGRP and EIGRP? Choose all that apply.
A. They both understand VLSM.
B. They both allow the use of wildcard masks.
C. They both assume a serial interface is connected to a T1 line.
D. They both have topology tables.
E. They both choose successors and feasible successors.
F. They both use broadcasts to send routing updates.
Answer: B, E. Of the two, only EIGRP understands VLSM, allows the use of wildcard masks, and has a topology table. Only IGRP uses broadcasts to send routing updates.
CCNP / BSCI:
What does an IPv6 address beginning with 2002 and carrying a /48 prefix indicate?
A. The address is found on 6to4 tunnel access routers.
B. The address is found on 6to4 tunnel edge routers.
C. The address is a universal loopback address for IPv6.
D. The address is a multicast address for IPv6.
E. The address is a broadcast address for IPv6.
Answer: B. You'll find this address on a 6to4 tunnel edge router.
CCNP / BCMSN:
Which of the following commands applies a QoS policy to an interface?
A. qos-policy
B. service-policy
C. qos enable
D. access-group
E. access-class
Answer: B. The service-policy command is followed by the name of the policy map and the direction in which the policy will be applied (inbound or outbound).
Chris Bryant
CCIE #12933
http://www.thebryantadvantage.com/
CCNA:
Which of the following is true of both IGRP and EIGRP? Choose all that apply.
A. They both understand VLSM.
B. They both allow the use of wildcard masks.
C. They both assume a serial interface is connected to a T1 line.
D. They both have topology tables.
E. They both choose successors and feasible successors.
F. They both use broadcasts to send routing updates.
Answer: B, E. Of the two, only EIGRP understands VLSM, allows the use of wildcard masks, and has a topology table. Only IGRP uses broadcasts to send routing updates.
CCNP / BSCI:
What does an IPv6 address beginning with 2002 and carrying a /48 prefix indicate?
A. The address is found on 6to4 tunnel access routers.
B. The address is found on 6to4 tunnel edge routers.
C. The address is a universal loopback address for IPv6.
D. The address is a multicast address for IPv6.
E. The address is a broadcast address for IPv6.
Answer: B. You'll find this address on a 6to4 tunnel edge router.
CCNP / BCMSN:
Which of the following commands applies a QoS policy to an interface?
A. qos-policy
B. service-policy
C. qos enable
D. access-group
E. access-class
Answer: B. The service-policy command is followed by the name of the policy map and the direction in which the policy will be applied (inbound or outbound).
Chris Bryant
CCIE #12933
http://www.thebryantadvantage.com/
Answers To Saturday's CCNA / CCNP Practice Questions
CCNA:
Which of the following is true of both IGRP and EIGRP? Choose all that apply.
A. They both understand VLSM.
B. They both allow the use of wildcard masks.
C. They both assume a serial interface is connected to a T1 line.
D. They both have topology tables.
E. They both choose successors and feasible successors.
F. They both use broadcasts to send routing updates.
Answer: C, E. Of the two, only EIGRP understands VLSM, allows the use of wildcard masks, and has a topology table. Only IGRP uses broadcasts to send routing updates.
CCNP / BSCI:
What does an IPv6 address beginning with 2002 and carrying a /48 prefix indicate?
A. The address is found on 6to4 tunnel access routers.
B. The address is found on 6to4 tunnel edge routers.
C. The address is a universal loopback address for IPv6.
D. The address is a multicast address for IPv6.
E. The address is a broadcast address for IPv6.
ANSWER: This is an address you'll find on a 6to4 tunnel edge router.
CCNP / BCMSN:
Which of the following commands applies a QoS policy to an interface?
A. qos-policy
B. service-policy
C. qos enable
D. access-group
E. access-class
Answer: B. The service-policy command is followed by the name of the policy and the direction in which the policy will be applied.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
Which of the following is true of both IGRP and EIGRP? Choose all that apply.
A. They both understand VLSM.
B. They both allow the use of wildcard masks.
C. They both assume a serial interface is connected to a T1 line.
D. They both have topology tables.
E. They both choose successors and feasible successors.
F. They both use broadcasts to send routing updates.
Answer: C, E. Of the two, only EIGRP understands VLSM, allows the use of wildcard masks, and has a topology table. Only IGRP uses broadcasts to send routing updates.
CCNP / BSCI:
What does an IPv6 address beginning with 2002 and carrying a /48 prefix indicate?
A. The address is found on 6to4 tunnel access routers.
B. The address is found on 6to4 tunnel edge routers.
C. The address is a universal loopback address for IPv6.
D. The address is a multicast address for IPv6.
E. The address is a broadcast address for IPv6.
ANSWER: This is an address you'll find on a 6to4 tunnel edge router.
CCNP / BCMSN:
Which of the following commands applies a QoS policy to an interface?
A. qos-policy
B. service-policy
C. qos enable
D. access-group
E. access-class
Answer: B. The service-policy command is followed by the name of the policy and the direction in which the policy will be applied.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Saturday, April 22, 2006
Saturday's CCNA / CCNP Practice Questions
I apologize for the lack of questions yesterday!
CCNA:
Which of the following is true of both IGRP and EIGRP? Choose all that apply.
A. They both understand VLSM.
B. They both allow the use of wildcard masks.
C. They both assume a serial interface is connected to a T1 line.
D. They both have topology tables.
E. They both choose successors and feasible successors.
F. They both use broadcasts to send routing updates.
CCNP / BSCI:
What does an IPv6 address beginning with 2002 and carrying a /48 prefix indicate?
A. The address is found on 6to4 tunnel access routers.
B. The address is found on 6to4 tunnel edge routers.
C. The address is a universal loopback address for IPv6.
D. The address is a multicast address for IPv6.
E. The address is a broadcast address for IPv6.
CCNP / BCMSN:
Which of the following commands applies a QoS policy to an interface?
A. qos-policy
B. service-policy
C. qos enable
D. access-group
E. access-class
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
I apologize for the lack of questions yesterday!
CCNA:
Which of the following is true of both IGRP and EIGRP? Choose all that apply.
A. They both understand VLSM.
B. They both allow the use of wildcard masks.
C. They both assume a serial interface is connected to a T1 line.
D. They both have topology tables.
E. They both choose successors and feasible successors.
F. They both use broadcasts to send routing updates.
CCNP / BSCI:
What does an IPv6 address beginning with 2002 and carrying a /48 prefix indicate?
A. The address is found on 6to4 tunnel access routers.
B. The address is found on 6to4 tunnel edge routers.
C. The address is a universal loopback address for IPv6.
D. The address is a multicast address for IPv6.
E. The address is a broadcast address for IPv6.
CCNP / BCMSN:
Which of the following commands applies a QoS policy to an interface?
A. qos-policy
B. service-policy
C. qos enable
D. access-group
E. access-class
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Thursday, April 20, 2006
Here are the answers to the bonus questions I posted Wednesday.
CCNA:
What protocol uses the term cost to describe its metric?
A. OSPF
B. IGRP
C. EIGRP
D. RIPv1
E. RIPv2
Answer: B. OSPF refers to its metric as "cost".
CCNP / BSCI:
Which of the following phrases applies to the distribution layer of Cisco's three-layer networking model?
A. traffic filtering generally occurs here
B. end users interact with the network here
C. Internet access is granted here
D. traffic filtering should be avoided at this layer
Answer: A, C. Traffic filtering and internet access generally occur at the distribution layer of Cisco's three-layer model. Traffic filtering should be avoided at the core layer to spare core devices any unnecessary latency.
CCNP / BCMSN:
At what layer of the Cisco hierarchical networking model should traffic be classified and marked when appropriate?
A. Access
B. Distribution
C. Classification
D. Core
E. Policing
Answer: A. The classification and marking of traffic for QoS purposes should take place at the access layer - the layer closest to the end users.
Wednesday Morning's CCNA / CCNP Practice
CCNA:
What are the frame relay LMI types? Choose all that apply.
A. cisco
B. ansi
C. dlci
D. isl
E. q933a
F. dot1q
G. hdlc
H. ppp
Answer: A, B, E. Cisco is the default.
CCNP / BSCI:
There are 10 routers in a BGP AS. The number of separate BGP peer connections that would be needed for a full mesh is:
A. 90
B. 60
C. 100
D. 99
E. 45
F. 98
Answer: E. To calculate the number of separate TCP connections you'll need for a logical full mesh in a BGP AS, use this formula:
CCNP / BCMSN:
A packet enters a multilayer switch with a CoS of 2. Which of the following is true?
A. By default, the CoS value will be trusted.
B. By default, the CoS value will not be trusted.
C. If trusted, the CoS value will map to an internal DSCP value of 2.
D. If trusted, the CoS value will map to an internal DSCP value of 16.
E. If trusted, the CoS value will map to an internal DSCP value of 4.
Answer: B. The default behavior of the switch is to not trust incoming CoS values.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
What protocol uses the term cost to describe its metric?
A. OSPF
B. IGRP
C. EIGRP
D. RIPv1
E. RIPv2
Answer: B. OSPF refers to its metric as "cost".
CCNP / BSCI:
Which of the following phrases applies to the distribution layer of Cisco's three-layer networking model?
A. traffic filtering generally occurs here
B. end users interact with the network here
C. Internet access is granted here
D. traffic filtering should be avoided at this layer
Answer: A, C. Traffic filtering and internet access generally occur at the distribution layer of Cisco's three-layer model. Traffic filtering should be avoided at the core layer to spare core devices any unnecessary latency.
CCNP / BCMSN:
At what layer of the Cisco hierarchical networking model should traffic be classified and marked when appropriate?
A. Access
B. Distribution
C. Classification
D. Core
E. Policing
Answer: A. The classification and marking of traffic for QoS purposes should take place at the access layer - the layer closest to the end users.
Wednesday Morning's CCNA / CCNP Practice
CCNA:
What are the frame relay LMI types? Choose all that apply.
A. cisco
B. ansi
C. dlci
D. isl
E. q933a
F. dot1q
G. hdlc
H. ppp
Answer: A, B, E. Cisco is the default.
CCNP / BSCI:
There are 10 routers in a BGP AS. The number of separate BGP peer connections that would be needed for a full mesh is:
A. 90
B. 60
C. 100
D. 99
E. 45
F. 98
Answer: E. To calculate the number of separate TCP connections you'll need for a logical full mesh in a BGP AS, use this formula:
X (X - 1) / 2
"X" being the number of routers. With 10 routers, the result is 90 / 2, or 45.
CCNP / BCMSN:
A packet enters a multilayer switch with a CoS of 2. Which of the following is true?
A. By default, the CoS value will be trusted.
B. By default, the CoS value will not be trusted.
C. If trusted, the CoS value will map to an internal DSCP value of 2.
D. If trusted, the CoS value will map to an internal DSCP value of 16.
E. If trusted, the CoS value will map to an internal DSCP value of 4.
Answer: B. The default behavior of the switch is to not trust incoming CoS values.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Thursday's CCNA and CCNP Practice Questions
Answers to Wednesday's questions will be posted tonight!
CCNA:
A frame enters a switchport. The destination MAC address is known to the switch. The destination MAC address is found off a different port than the one that received the frame. What word best describes the action the switch will take on the frame?
A. Broadcast
B. Multicast
C. Unicast
D. Dropped
E. Filtered
CCNP / BSCI:
Which of the following EIGRP packet types are considered "unreliable"? Choose all that apply.
A. Hello
B. Ack
C. Update
D. Query
E. Reply
CCNP / BCMSN
The acronym "FIFO" relates to which one of the following QoS methodologies?
A. Best effort
B. Integrated Services
C. Differentiated Services
D. Coded Services
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Answers to Wednesday's questions will be posted tonight!
CCNA:
A frame enters a switchport. The destination MAC address is known to the switch. The destination MAC address is found off a different port than the one that received the frame. What word best describes the action the switch will take on the frame?
A. Broadcast
B. Multicast
C. Unicast
D. Dropped
E. Filtered
CCNP / BSCI:
Which of the following EIGRP packet types are considered "unreliable"? Choose all that apply.
A. Hello
B. Ack
C. Update
D. Query
E. Reply
CCNP / BCMSN
The acronym "FIFO" relates to which one of the following QoS methodologies?
A. Best effort
B. Integrated Services
C. Differentiated Services
D. Coded Services
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNP / BSCI Exam Tutorial: Broadcasts And The IP Helper-Address Command
As you know from your CCNA studies, while routers accept and generate broadcasts, they do not forward them. This can be quite a problem when a broadcast needs to get to a device such as a DHCP or TFTP server that's on one side of a router with other subnets on the other side.
If a PC attempts to locate a DNS server with a broadcast, the broadcast will be stopped by the router and will never get to the DNS server. By configuring the ip helper-address command on the router, UDP broadcasts such as this will be translated into a unicast by the router, making the communication possible. The command should be configured on the interface that will be receiving the broadcasts.
R1(config)#int e0
R1(config-if)#ip helper-address ?
A.B.C.D IP destination address
R1(config-if)#ip helper-address 100.1.1.2
Now, you may be wondering if this command covers all UDP services. Sorry, you're not getting off that easy! The command does forward eight common UDP service broadcasts, though.
TIME, port 37
TACACS, port 49
DNS, port 53
BOOTP/DHCP Server, port 67
BOOTP/DHCP Client, port 68
TFTP, port 69
NetBIOS name service, port 137
NetBIOS datagram service, port 138
That's going to cover most scenarios where the ip helper-address command will be useful, but what about those situations where the broadcast you need forwarded is not on this list? You can use the ip forward-protocol command to add any UDP port number to the list.
Additionally, to remove protocols from the default list, use the no ip forward-protocol command. In the following example, we'll add the Network Time Protocol port to the forwarding list while removing the NetBIOS ports. Remember, you can use IOS Help to get a list of commonly filtered ports!
R1(config)#ip forward-protocol udp ?
<0-65535> Port number
biff Biff (mail notification, comsat, 512)
bootpc Bootstrap Protocol (BOOTP) client (68)
bootps Bootstrap Protocol (BOOTP) server (67)
discard Discard (9)
dnsix DNSIX security protocol auditing (195)
domain Domain Name Service (DNS, 53)
echo Echo (7)
isakmp Internet Security Association and Key Management Protocol (500)
mobile-ip Mobile IP registration (434)
nameserver IEN116 name service (obsolete, 42)
netbios-dgm NetBios datagram service (138)
netbios-ns NetBios name service (137)
netbios-ss NetBios session service (139)
ntp Network Time Protocol (123)
pim-auto-rp PIM Auto-RP (496)
rip Routing Information Protocol (router, in.routed, 520)
snmp Simple Network Management Protocol (161)
snmptrap SNMP Traps (162)
sunrpc Sun Remote Procedure Call (111)
syslog System Logger (514)
tacacs TAC Access Control System (49)
talk Talk (517)
tftp Trivial File Transfer Protocol (69)
time Time (37)
who Who service (rwho, 513)
xdmcp X Display Manager Control Protocol (177)
R1(config)#ip forward-protocol udp 123
R1(config)#no ip forward-protocol udp 137
R1(config)#no ip forward-protocol udp 138
As you can see, the ip helper-address command helps work around the fact that broadcasts aren't forwarded by routers by default, and if you just need to send one or two broadcast types, the other types can be turned off easily.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
As you know from your CCNA studies, while routers accept and generate broadcasts, they do not forward them. This can be quite a problem when a broadcast needs to get to a device such as a DHCP or TFTP server that's on one side of a router with other subnets on the other side.
If a PC attempts to locate a DNS server with a broadcast, the broadcast will be stopped by the router and will never get to the DNS server. By configuring the ip helper-address command on the router, UDP broadcasts such as this will be translated into a unicast by the router, making the communication possible. The command should be configured on the interface that will be receiving the broadcasts.
R1(config)#int e0
R1(config-if)#ip helper-address ?
A.B.C.D IP destination address
R1(config-if)#ip helper-address 100.1.1.2
Now, you may be wondering if this command covers all UDP services. Sorry, you're not getting off that easy! The command does forward eight common UDP service broadcasts, though.
TIME, port 37
TACACS, port 49
DNS, port 53
BOOTP/DHCP Server, port 67
BOOTP/DHCP Client, port 68
TFTP, port 69
NetBIOS name service, port 137
NetBIOS datagram service, port 138
That's going to cover most scenarios where the ip helper-address command will be useful, but what about those situations where the broadcast you need forwarded is not on this list? You can use the ip forward-protocol command to add any UDP port number to the list.
Additionally, to remove protocols from the default list, use the no ip forward-protocol command. In the following example, we'll add the Network Time Protocol port to the forwarding list while removing the NetBIOS ports. Remember, you can use IOS Help to get a list of commonly filtered ports!
R1(config)#ip forward-protocol udp ?
<0-65535> Port number
biff Biff (mail notification, comsat, 512)
bootpc Bootstrap Protocol (BOOTP) client (68)
bootps Bootstrap Protocol (BOOTP) server (67)
discard Discard (9)
dnsix DNSIX security protocol auditing (195)
domain Domain Name Service (DNS, 53)
echo Echo (7)
isakmp Internet Security Association and Key Management Protocol (500)
mobile-ip Mobile IP registration (434)
nameserver IEN116 name service (obsolete, 42)
netbios-dgm NetBios datagram service (138)
netbios-ns NetBios name service (137)
netbios-ss NetBios session service (139)
ntp Network Time Protocol (123)
pim-auto-rp PIM Auto-RP (496)
rip Routing Information Protocol (router, in.routed, 520)
snmp Simple Network Management Protocol (161)
snmptrap SNMP Traps (162)
sunrpc Sun Remote Procedure Call (111)
syslog System Logger (514)
tacacs TAC Access Control System (49)
talk Talk (517)
tftp Trivial File Transfer Protocol (69)
time Time (37)
who Who service (rwho, 513)
xdmcp X Display Manager Control Protocol (177)
R1(config)#ip forward-protocol udp 123
R1(config)#no ip forward-protocol udp 137
R1(config)#no ip forward-protocol udp 138
As you can see, the ip helper-address command helps work around the fact that broadcasts aren't forwarded by routers by default, and if you just need to send one or two broadcast types, the other types can be turned off easily.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Cisco Home Lab Tutorial - 2501s In Your CCNA / CCNP Home Lab
To be truly prepared for your CCNA and CCNP exams, you need real hands-on experience with real Cisco routers and switches. However, a production network is a really bad place to practice your configurations, but an excellent way to get fired and/or sued. The key to becoming a true CCNA and CCNP is assembling your own Cisco home lab.
You don't have to spend a lot of money to do so; used Cisco equipment is cheaper than ever. It's robust as well - I've bought literally hundreds of used routers and switches over the years and have had very few problems. I owe much of my skill to practicing configurations and troubleshooting in my own home lab.
2501 routers are fantastic for CCNA and CCNP home labs. They come with two serial interfaces, allowing you to connect one interface directly to another router (you'll need a DTE/DCE cable for that, too) while connecting another to a frame relay switch if you like. If you don't have a frame relay switch, you can connect a 2501 directly to two other routers via the serial interfaces.
You also have an AUI port, which requires a transceiver to operate as your Ethernet interface. Transceivers are pretty cheap and readily available from Cisco resellers and ebay vendors, so pick one up for each 2503 you decide to buy.
2501 routers don't come with BRI interfaces, but not every router in your lab has to be ISDN-ready. If you choose not to have ISDN in your lab at all, 2501s are the way to go. If you do want to run ISDN and have an ISDN simulator device, you can get two 2503s and the rest of your routers can be 2501.
All in all, 2501 routers are great for your CCNA / CCNP home lab.
They cost less than $100 each on ebay, so they're also very affordable. There's no better training than training on your own CCNA or CCNP home lab, and you can always sell the equipment later if you like. Basically, you're renting the routers and switches, and the experience you get by working with the real deal is invaluable.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
To be truly prepared for your CCNA and CCNP exams, you need real hands-on experience with real Cisco routers and switches. However, a production network is a really bad place to practice your configurations, but an excellent way to get fired and/or sued. The key to becoming a true CCNA and CCNP is assembling your own Cisco home lab.
You don't have to spend a lot of money to do so; used Cisco equipment is cheaper than ever. It's robust as well - I've bought literally hundreds of used routers and switches over the years and have had very few problems. I owe much of my skill to practicing configurations and troubleshooting in my own home lab.
2501 routers are fantastic for CCNA and CCNP home labs. They come with two serial interfaces, allowing you to connect one interface directly to another router (you'll need a DTE/DCE cable for that, too) while connecting another to a frame relay switch if you like. If you don't have a frame relay switch, you can connect a 2501 directly to two other routers via the serial interfaces.
You also have an AUI port, which requires a transceiver to operate as your Ethernet interface. Transceivers are pretty cheap and readily available from Cisco resellers and ebay vendors, so pick one up for each 2503 you decide to buy.
2501 routers don't come with BRI interfaces, but not every router in your lab has to be ISDN-ready. If you choose not to have ISDN in your lab at all, 2501s are the way to go. If you do want to run ISDN and have an ISDN simulator device, you can get two 2503s and the rest of your routers can be 2501.
All in all, 2501 routers are great for your CCNA / CCNP home lab.
They cost less than $100 each on ebay, so they're also very affordable. There's no better training than training on your own CCNA or CCNP home lab, and you can always sell the equipment later if you like. Basically, you're renting the routers and switches, and the experience you get by working with the real deal is invaluable.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Wednesday, April 19, 2006
Wednesday's CCNA And CCNP Practice Questions - The Second Set Today! :)
CCNA:
What protocol uses the term cost to describe its metric?
A. ISIS
B. OSPF
C. IGRP
D. EIGRP
E. RIPv1
F. RIPv2
CCNP / BSCI:
Which of the following phrases applies to the distribution layer of Cisco's three-layer networking model?
A. traffic filtering generally occurs here
B. end users interact with the network here
C. Internet access is granted here
D. traffic filtering should be avoided at this layer
CCNP / BCMSN:
At what layer of the Cisco hierarchical networking model should traffic be classified and marked when appropriate?
A. Access
B. Distribution
C. Classification
D. Core
E. Policing
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
What protocol uses the term cost to describe its metric?
A. ISIS
B. OSPF
C. IGRP
D. EIGRP
E. RIPv1
F. RIPv2
CCNP / BSCI:
Which of the following phrases applies to the distribution layer of Cisco's three-layer networking model?
A. traffic filtering generally occurs here
B. end users interact with the network here
C. Internet access is granted here
D. traffic filtering should be avoided at this layer
CCNP / BCMSN:
At what layer of the Cisco hierarchical networking model should traffic be classified and marked when appropriate?
A. Access
B. Distribution
C. Classification
D. Core
E. Policing
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Wednesday Morning's CCNA / CCNP Practice Questions
Two sets of questions today - the second one will be posted this afternoon!
CCNA:
What are the frame relay LMI types? Choose all that apply.
A. cisco
B. ansi
C. dlci
D. isl
E. q933a
F. dot1q
G. hdlc
H. ppp
CCNP / BSCI:
There are 10 routers in a BGP AS. The number of separate BGP peer connections that would be needed for a full mesh is:
A. 90
B. 60
C. 100
D. 99
E. 45
F. 98
CCNP / BCMSN:
A packet enters a multilayer switch with a CoS of 2. Which of the following is true?
A. By default, the CoS value will be trusted.
B. By default, the CoS value will not be trusted.
C. If trusted, the CoS value will map to an internal DSCP value of 2.
D. If trusted, the CoS value will map to an internal DSCP value of 16.
E. If trusted, the CoS value will map to an internal DSCP value of 4.
Two sets of questions today - the second one will be posted this afternoon!
CCNA:
What are the frame relay LMI types? Choose all that apply.
A. cisco
B. ansi
C. dlci
D. isl
E. q933a
F. dot1q
G. hdlc
H. ppp
CCNP / BSCI:
There are 10 routers in a BGP AS. The number of separate BGP peer connections that would be needed for a full mesh is:
A. 90
B. 60
C. 100
D. 99
E. 45
F. 98
CCNP / BCMSN:
A packet enters a multilayer switch with a CoS of 2. Which of the following is true?
A. By default, the CoS value will be trusted.
B. By default, the CoS value will not be trusted.
C. If trusted, the CoS value will map to an internal DSCP value of 2.
D. If trusted, the CoS value will map to an internal DSCP value of 16.
E. If trusted, the CoS value will map to an internal DSCP value of 4.
Tuesday, April 18, 2006
Here are the answers to yesterday's CCNA / CCNP practice questions.
More free questions later tonight!
CCNA:
A RIP router recieves two routing updates for the same network at the exact same time. The metric for one of the routes is higher than the other. What will happen to the update with the higher metric?
A. It will be discarded.
B. It will be put into the routing table.
C. It will be placed into the topology table.
D. It will act as the feasible successor.
Answer: A. The update with the higher metric will be discarded. RIP doesn't use a topology table or a feasible successor.
CCNP / BSCI:
What combination of letters and symbols indicate a RIP route learned via redistribution?
A. R
B. R*
C. R IA
D. R EX
E. R IA*
Answer: A. RIP only has one code for its routes, regardless of how it was learned, and that's an "R".
CCNP / BCMSN:What command will hardcode a 3550 port into switching mode? Short answer, no choices given.
Answer: The interface-level command "switchport" places a 3550 port into switching mode.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
More free questions later tonight!
CCNA:
A RIP router recieves two routing updates for the same network at the exact same time. The metric for one of the routes is higher than the other. What will happen to the update with the higher metric?
A. It will be discarded.
B. It will be put into the routing table.
C. It will be placed into the topology table.
D. It will act as the feasible successor.
Answer: A. The update with the higher metric will be discarded. RIP doesn't use a topology table or a feasible successor.
CCNP / BSCI:
What combination of letters and symbols indicate a RIP route learned via redistribution?
A. R
B. R*
C. R IA
D. R EX
E. R IA*
Answer: A. RIP only has one code for its routes, regardless of how it was learned, and that's an "R".
CCNP / BCMSN:What command will hardcode a 3550 port into switching mode? Short answer, no choices given.
Answer: The interface-level command "switchport" places a 3550 port into switching mode.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA Home Lab Setup: The 2503 Router
I know from experience that part of the excitement and anxiety of putting together your own CCNA / CCNP home lab is deciding what to buy! While you can make a workable home lab out of almost any combination of Cisco routers and switches, some routers are better suited for home lab work than others because they can fill multiple roles.
When you buy CCNA or CCNP "lab kits" - bundles of routers and switches - you can get a little confused about whether you're getting a good deal. One router I get asked about quite a bit is the 2503.
2503 routers are fantastic for CCNA and CCNP home labs. They come with two serial interfaces, allowing you to connect one interface directly to another router (you'll need a DTE/DCE cable for that, too) while connecting another to a frame relay switch if you like. If you don't have a frame relay switch, you can connect a 2503 directly to two other routers via the serial interfaces.
You also have an AUI port, which requires a transceiver to operate as your Ethernet interface. Transceivers are pretty cheap and readily available from Cisco resellers and ebay vendors, so pick one up for each 2503 you decide to buy.
2503 routers also come with a BRI interface. Even though you may not have an ISDN simulator right now, you may choose to add one later. That makes a 2503 a great bet for future lab expansion.
All in all, 2503 routers are great for your CCNA / CCNP home lab. They run about $125 each on ebay, or less, so they're also very affordable. There's no better training than training on your own CCNA or CCNP home lab, and you can always sell the equipment later if you like. Basically, you're renting the routers and switches, and I can tell you from personal experience that the experience you get by working with the real deal is invaluable.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
I know from experience that part of the excitement and anxiety of putting together your own CCNA / CCNP home lab is deciding what to buy! While you can make a workable home lab out of almost any combination of Cisco routers and switches, some routers are better suited for home lab work than others because they can fill multiple roles.
When you buy CCNA or CCNP "lab kits" - bundles of routers and switches - you can get a little confused about whether you're getting a good deal. One router I get asked about quite a bit is the 2503.
2503 routers are fantastic for CCNA and CCNP home labs. They come with two serial interfaces, allowing you to connect one interface directly to another router (you'll need a DTE/DCE cable for that, too) while connecting another to a frame relay switch if you like. If you don't have a frame relay switch, you can connect a 2503 directly to two other routers via the serial interfaces.
You also have an AUI port, which requires a transceiver to operate as your Ethernet interface. Transceivers are pretty cheap and readily available from Cisco resellers and ebay vendors, so pick one up for each 2503 you decide to buy.
2503 routers also come with a BRI interface. Even though you may not have an ISDN simulator right now, you may choose to add one later. That makes a 2503 a great bet for future lab expansion.
All in all, 2503 routers are great for your CCNA / CCNP home lab. They run about $125 each on ebay, or less, so they're also very affordable. There's no better training than training on your own CCNA or CCNP home lab, and you can always sell the equipment later if you like. Basically, you're renting the routers and switches, and I can tell you from personal experience that the experience you get by working with the real deal is invaluable.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNP / BCMSN Exam Tutorial: An Introduction To CGMP
If a Layer Two switch doesn't have the capabilities to run IGMP Snooping, it will be able to run CGMP - Cisco Group Membership Protocol. CGMP allows the multicast router to work with the Layer Two switch to eliminate unnecessary multicast forwarding.
CGMP will be enabled on both the multicast router and the switch, but the router's going to do all the work. The router will be sending Join and Leave messages to the switch as needed. PIM must be running on the router interface facing the switch before enabling CGMP, as you can see:
R1(config)#int e0
R1(config-if)#ip cgmp
WARNING: CGMP requires PIM enabled on interface
R1(config-if)#ip pim sparse
R1(config-if)#ip cgmp
When CGMP is first enabled on both the multicast router and switch, the router will send a CGMP Join message, informing the switch that a multicast router is now connected to it. This particular CGMP Join will contain a Group Destination Address (GDA) of 0000.0000.0000 and the MAC address of the sending interface. The GDA is used to identify the multicast group, so when this is set to all zeroes, the switch knows this is an introductory CGMP Join, letting the switch know that the multicast router is online.
The switch makes an entry in its MAC table that this router can be found off the port that the CGMP Join came in on. The router will send a CGMP Join to the switch every minute to serve as a keepalive.
A workstation connected to the switch on port 0/5 now wishes to join multicast group 225.1.1.1. The Join message is sent to the multicast router, but first it will pass through the switch. The switch will do what you'd expect it to do - read the source MAC address and make an entry for it in the MAC address table as being off port fast 0/5 if there's not an entry already there. (Don't forget that the MAC address table is also referred to as the CAM table or the bridging table.)
The router will then receive the Join request, and send a CGMP Join back to the switch. This CGMP Join will contain both the multicast group's MAC address and the requesting host's MAC address. Now the switch knows about the multicast group 225.1.1.1 and that a member of that group is found off port fast 0/5. In the future, when the switch receives frames destined for that multicast group, the switch will not flood the frame as it would an unknown multicast. Instead, the switch will forward a copy of the frame to each port that it knows leads to a member of the multicast group.
Two major benefits of CGMP are the explicit Join and Leave Group messages. In the next part of this BCMSN exam tutorial, we’ll take a look at the Leave Group messages.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
If a Layer Two switch doesn't have the capabilities to run IGMP Snooping, it will be able to run CGMP - Cisco Group Membership Protocol. CGMP allows the multicast router to work with the Layer Two switch to eliminate unnecessary multicast forwarding.
CGMP will be enabled on both the multicast router and the switch, but the router's going to do all the work. The router will be sending Join and Leave messages to the switch as needed. PIM must be running on the router interface facing the switch before enabling CGMP, as you can see:
R1(config)#int e0
R1(config-if)#ip cgmp
WARNING: CGMP requires PIM enabled on interface
R1(config-if)#ip pim sparse
R1(config-if)#ip cgmp
When CGMP is first enabled on both the multicast router and switch, the router will send a CGMP Join message, informing the switch that a multicast router is now connected to it. This particular CGMP Join will contain a Group Destination Address (GDA) of 0000.0000.0000 and the MAC address of the sending interface. The GDA is used to identify the multicast group, so when this is set to all zeroes, the switch knows this is an introductory CGMP Join, letting the switch know that the multicast router is online.
The switch makes an entry in its MAC table that this router can be found off the port that the CGMP Join came in on. The router will send a CGMP Join to the switch every minute to serve as a keepalive.
A workstation connected to the switch on port 0/5 now wishes to join multicast group 225.1.1.1. The Join message is sent to the multicast router, but first it will pass through the switch. The switch will do what you'd expect it to do - read the source MAC address and make an entry for it in the MAC address table as being off port fast 0/5 if there's not an entry already there. (Don't forget that the MAC address table is also referred to as the CAM table or the bridging table.)
The router will then receive the Join request, and send a CGMP Join back to the switch. This CGMP Join will contain both the multicast group's MAC address and the requesting host's MAC address. Now the switch knows about the multicast group 225.1.1.1 and that a member of that group is found off port fast 0/5. In the future, when the switch receives frames destined for that multicast group, the switch will not flood the frame as it would an unknown multicast. Instead, the switch will forward a copy of the frame to each port that it knows leads to a member of the multicast group.
Two major benefits of CGMP are the explicit Join and Leave Group messages. In the next part of this BCMSN exam tutorial, we’ll take a look at the Leave Group messages.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Monday, April 17, 2006
Monday's CCNA And CCNP Practice Questions
CCNA:
A RIP router recieves two routing updates for the same network at the exact same time. The metric for one of the routes is higher than the other. What will happen to the update with the higher metric?
A. It will be discarded.
B. It will be put into the routing table.
C. It will be placed into the topology table.
D. It will act as the feasible successor.
CCNP / BSCI:
What combination of letters and symbols indicate a RIP route learned via redistribution?
A. R
B. R*
C. R IA
D. R EX
E. R IA*
CCNP / BCMSN:
What command will hardcode a 3550 port into switching mode? Short answer, no choices given.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
A RIP router recieves two routing updates for the same network at the exact same time. The metric for one of the routes is higher than the other. What will happen to the update with the higher metric?
A. It will be discarded.
B. It will be put into the routing table.
C. It will be placed into the topology table.
D. It will act as the feasible successor.
CCNP / BSCI:
What combination of letters and symbols indicate a RIP route learned via redistribution?
A. R
B. R*
C. R IA
D. R EX
E. R IA*
CCNP / BCMSN:
What command will hardcode a 3550 port into switching mode? Short answer, no choices given.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Here are the answers to Saturday's CCNA / CCNP Practice Questions.
More free questions coming later tonight!
CCNA:
Identify the true statements regarding an ISDN connection. Choose all that apply.
A. CHAP requires the passwords to be the same on each router.
B. CHAP allows the passwords to be different on each router.
C. CHAP can only run when HDLC is enabled.
D. CHAP can only run when PPP is enabled.
E. CHAP can run on PPP or HDLC.
F. CHAP requires the use of the ppp chap sent-username command.
G. CHAP does not use the ppp chap sent-username command.
Answer: A, D, G. CHAP does require that the password be the same on both involved routers. CHAP cannot run on HDLC and requires PPP. CHAP does not have a sent-username command, only PAP does.
CCNP / BSCI:
Examine the following configuration and identify the true statements.
router bgp 100
neighbor 10.1.1.2 remote-as 200
A. The local router is in AS 100.
B. The local router is in AS 200.
C. The remote router is an iBGP neighbor.
D. The remote router is an eBGP neighbor.
Answer: A, B, D. The local router's AS is in the first line, with the remote router's AS in the second line. Since they're in different Autonomous Systems, they're eBGP neighbors.
CCNP / BCMSN:Which of the following best describes the RPF Check?
A. The RPF check assures that the packet is on the way to the correct destination.
B. The RPF Check assures that the packet is flowing away from the source.
C. The RPF Check assures the router that the packet is indeed a multicast packet.
D. The RPF Check assures the router that the packet is not a broadcast packet.
E. The RPF Check assures the router that the packet is not a multicast packet.
Answer: B. The purpose of the RPF check is to make sure the multicast packet is flowing away from the source.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
More free questions coming later tonight!
CCNA:
Identify the true statements regarding an ISDN connection. Choose all that apply.
A. CHAP requires the passwords to be the same on each router.
B. CHAP allows the passwords to be different on each router.
C. CHAP can only run when HDLC is enabled.
D. CHAP can only run when PPP is enabled.
E. CHAP can run on PPP or HDLC.
F. CHAP requires the use of the ppp chap sent-username command.
G. CHAP does not use the ppp chap sent-username command.
Answer: A, D, G. CHAP does require that the password be the same on both involved routers. CHAP cannot run on HDLC and requires PPP. CHAP does not have a sent-username command, only PAP does.
CCNP / BSCI:
Examine the following configuration and identify the true statements.
router bgp 100
neighbor 10.1.1.2 remote-as 200
A. The local router is in AS 100.
B. The local router is in AS 200.
C. The remote router is an iBGP neighbor.
D. The remote router is an eBGP neighbor.
Answer: A, B, D. The local router's AS is in the first line, with the remote router's AS in the second line. Since they're in different Autonomous Systems, they're eBGP neighbors.
CCNP / BCMSN:Which of the following best describes the RPF Check?
A. The RPF check assures that the packet is on the way to the correct destination.
B. The RPF Check assures that the packet is flowing away from the source.
C. The RPF Check assures the router that the packet is indeed a multicast packet.
D. The RPF Check assures the router that the packet is not a broadcast packet.
E. The RPF Check assures the router that the packet is not a multicast packet.
Answer: B. The purpose of the RPF check is to make sure the multicast packet is flowing away from the source.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Cisco CCNA Exam Tutorial: IGRP Unequal-Cost Load Balancing And The Variance Command
To pass the CCNA exam, you've got to know how to work with IGRP and EIGRP unequal-cost load balancing. You may not see much IGRP in production networks anymore, but you'll see a lot of EIGRP, and part of fine-tuning your EIGRP network is making sure that all paths are in use while allowing for varying bandwidth rates.
Using the variance command is the easy part - it's getting the metric that's the hard part with IGRP. With EIGRP, you just look in the topology table and that's it. With IGRP, you've got to run a debug to get the right metric.
The variance command is a multiplier when the value supplied with the variance command is multiplied by the lowest-cost metric, it must exceed the higher-cost metric in order for the higher-cost route to be added.
If that sounds complicated, it's not. It's one of those things that sounds difficult, but isn't. Trust me!
In this example, R1 has two paths to 172.23.0.0, but is currently using only one. By looking in the IP routing table, we've seen that the lowest-cost metric for network 172.23.0.0 on R1 is 8576. This path goes through the 172.12.123.0 network. There is another valid path that uses the 172.12.13.0 network, but is not currently in use.
I 172.23.0.0/16 [100/8576] via 172.12.123.2, 00:00:53, Serial0
IGRP does not have a “show" command that displays all valid routes to a destination, as does EIGRP. The command debug ip igrp transactions will show the current metric of the routes using the 512 KBPS route.
R1#debug ip igrp transactions
IGRP protocol debugging is on
19:17:51: IGRP: broadcasting request on Loopback0
19:17:51: IGRP: broadcasting request on Serial0
19:17:51: IGRP: broadcasting request on Serial1
19:17:51: IGRP: received update from 172.12.13.3 on Serial1
19:17:51: subnet 172.12.13.0, metric 23531 (neighbor 21531)
19:17:51: subnet 172.12.123.0, metric 23531 (neighbor 8476)
19:17:51: network 1.0.0.0, metric 24031 (neighbor 8976)
19:17:51: network 2.0.0.0, metric 22131 (neighbor 1600)
19:17:51: network 3.0.0.0, metric 22031 (neighbor 501)
19:17:51: network 172.23.0.0, metric 21631 (neighbor 1100)
R1(config)#router igrp 1
R1(config-router)#variance 3
R1#show ip route 172.23.0.0
Routing entry for 172.23.0.0/16
Known via "igrp 1", distance 100, metric 8576
Redistributing via igrp 1
Advertised by igrp 1 (self originated)
Last update from 172.12.123.2 on Serial0, 00:00:01 ago
Routing Descriptor Blocks:
* 172.12.13.3, from 172.12.13.3, 00:00:20 ago, via Serial1
Route metric is 21631, traffic share count is 1
Total delay is 21000 microseconds, minimum bandwidth is 512 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 0
172.12.123.3, from 172.12.123.3, 00:00:20 ago, via Serial0
Route metric is 8576, traffic share count is 3
Total delay is 21000 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 0
172.12.123.2, from 172.12.123.2, 00:00:01 ago, via Serial0
Route metric is 8576, traffic share count is 3
Total delay is 21000 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 0
The metric for 172.23.0.0 through the direct connection is 21631. A variance of 3 means that any route with a metric less than the best metric multiplied by the variance (in this case, 8576 x 3 = 25728) will be entered into the routing table. R1 now has three unequal-cost paths to 172.23.0.0 in its routing table, and load balancing will take place.
IGRP unequal-cost load balancing takes some practice, but as you can see, once you get the metric it's easy to work with. Just make sure you know how to get that metric!
To your CCNA success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
To pass the CCNA exam, you've got to know how to work with IGRP and EIGRP unequal-cost load balancing. You may not see much IGRP in production networks anymore, but you'll see a lot of EIGRP, and part of fine-tuning your EIGRP network is making sure that all paths are in use while allowing for varying bandwidth rates.
Using the variance command is the easy part - it's getting the metric that's the hard part with IGRP. With EIGRP, you just look in the topology table and that's it. With IGRP, you've got to run a debug to get the right metric.
The variance command is a multiplier when the value supplied with the variance command is multiplied by the lowest-cost metric, it must exceed the higher-cost metric in order for the higher-cost route to be added.
If that sounds complicated, it's not. It's one of those things that sounds difficult, but isn't. Trust me!
In this example, R1 has two paths to 172.23.0.0, but is currently using only one. By looking in the IP routing table, we've seen that the lowest-cost metric for network 172.23.0.0 on R1 is 8576. This path goes through the 172.12.123.0 network. There is another valid path that uses the 172.12.13.0 network, but is not currently in use.
I 172.23.0.0/16 [100/8576] via 172.12.123.2, 00:00:53, Serial0
IGRP does not have a “show" command that displays all valid routes to a destination, as does EIGRP. The command debug ip igrp transactions will show the current metric of the routes using the 512 KBPS route.
R1#debug ip igrp transactions
IGRP protocol debugging is on
19:17:51: IGRP: broadcasting request on Loopback0
19:17:51: IGRP: broadcasting request on Serial0
19:17:51: IGRP: broadcasting request on Serial1
19:17:51: IGRP: received update from 172.12.13.3 on Serial1
19:17:51: subnet 172.12.13.0, metric 23531 (neighbor 21531)
19:17:51: subnet 172.12.123.0, metric 23531 (neighbor 8476)
19:17:51: network 1.0.0.0, metric 24031 (neighbor 8976)
19:17:51: network 2.0.0.0, metric 22131 (neighbor 1600)
19:17:51: network 3.0.0.0, metric 22031 (neighbor 501)
19:17:51: network 172.23.0.0, metric 21631 (neighbor 1100)
R1(config)#router igrp 1
R1(config-router)#variance 3
R1#show ip route 172.23.0.0
Routing entry for 172.23.0.0/16
Known via "igrp 1", distance 100, metric 8576
Redistributing via igrp 1
Advertised by igrp 1 (self originated)
Last update from 172.12.123.2 on Serial0, 00:00:01 ago
Routing Descriptor Blocks:
* 172.12.13.3, from 172.12.13.3, 00:00:20 ago, via Serial1
Route metric is 21631, traffic share count is 1
Total delay is 21000 microseconds, minimum bandwidth is 512 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 0
172.12.123.3, from 172.12.123.3, 00:00:20 ago, via Serial0
Route metric is 8576, traffic share count is 3
Total delay is 21000 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 0
172.12.123.2, from 172.12.123.2, 00:00:01 ago, via Serial0
Route metric is 8576, traffic share count is 3
Total delay is 21000 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 1/255, Hops 0
The metric for 172.23.0.0 through the direct connection is 21631. A variance of 3 means that any route with a metric less than the best metric multiplied by the variance (in this case, 8576 x 3 = 25728) will be entered into the routing table. R1 now has three unequal-cost paths to 172.23.0.0 in its routing table, and load balancing will take place.
IGRP unequal-cost load balancing takes some practice, but as you can see, once you get the metric it's easy to work with. Just make sure you know how to get that metric!
To your CCNA success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Saturday, April 15, 2006
Saturday's CCNA And CCNP Practice Questions
CCNA:
Identify the true statements regarding an ISDN connection. Choose all that apply.
A. CHAP requires the passwords to be the same on each router.
B. CHAP allows the passwords to be different on each router.
C. CHAP can only run when HDLC is enabled.
D. CHAP can only run when PPP is enabled.
E. CHAP can run on PPP or HDLC.
F. CHAP requires the use of the ppp chap sent-username command.
G. CHAP does not use the ppp chap sent-username command.
CCNP / BSCI:
Examine the following configuration and identify the true statements.
router bgp 100
neighbor 10.1.1.2 remote-as 200
A. The local router is in AS 100.
B. The local router is in AS 200.
C. The remote router is an iBGP neighbor.
D. The remote router is an eBGP neighbor.
CCNP / BCMSN:
Which of the following best describes the RPF Check?
A. The RPF check assures that the packet is on the way to the correct destination.
B. The RPF Check assures that the packet is flowing away from the source.
C. The RPF Check assures the router that the packet is indeed a multicast packet.
D. The RPF Check assures the router that the packet is not a broadcast packet.
E. The RPF Check assures the router that the packet is not a multicast packet.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
Identify the true statements regarding an ISDN connection. Choose all that apply.
A. CHAP requires the passwords to be the same on each router.
B. CHAP allows the passwords to be different on each router.
C. CHAP can only run when HDLC is enabled.
D. CHAP can only run when PPP is enabled.
E. CHAP can run on PPP or HDLC.
F. CHAP requires the use of the ppp chap sent-username command.
G. CHAP does not use the ppp chap sent-username command.
CCNP / BSCI:
Examine the following configuration and identify the true statements.
router bgp 100
neighbor 10.1.1.2 remote-as 200
A. The local router is in AS 100.
B. The local router is in AS 200.
C. The remote router is an iBGP neighbor.
D. The remote router is an eBGP neighbor.
CCNP / BCMSN:
Which of the following best describes the RPF Check?
A. The RPF check assures that the packet is on the way to the correct destination.
B. The RPF Check assures that the packet is flowing away from the source.
C. The RPF Check assures the router that the packet is indeed a multicast packet.
D. The RPF Check assures the router that the packet is not a broadcast packet.
E. The RPF Check assures the router that the packet is not a multicast packet.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Friday, April 14, 2006
Thursday's CCNA And CCNP Practice Questions
My apologies for these not being online yesterday, but blogger.com was having a little trouble yesterday!
CCNA:
What value serves as a keepalive for frame relay circuits?
A. ANSI
B. Cisco
C. LMI
D. DLCI
E. BECN
F. FECN
CCNP / BSCI:
Short Answer: What is the administrative distance of ISIS?
CCNP / BCMSN:
What must be configured on a Cisco router interface before enabling CGMP?
A. PIM
B. CDP
C. OSPF
D. A distance vector protocol, preferably RIP
E. IGMP Spoofing
F. Any multicasting protocol
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
My apologies for these not being online yesterday, but blogger.com was having a little trouble yesterday!
CCNA:
What value serves as a keepalive for frame relay circuits?
A. ANSI
B. Cisco
C. LMI
D. DLCI
E. BECN
F. FECN
CCNP / BSCI:
Short Answer: What is the administrative distance of ISIS?
CCNP / BCMSN:
What must be configured on a Cisco router interface before enabling CGMP?
A. PIM
B. CDP
C. OSPF
D. A distance vector protocol, preferably RIP
E. IGMP Spoofing
F. Any multicasting protocol
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Thursday, April 13, 2006
Answers To Yesterday's CCNA And CCNP Practice Questions
Today's Questions Coming Up Later Today!
CCNA:
Convert the dotted decimal address 240.53.51.254 to a binary string. (No choices given.)
Answer: 11110000 00110101 00110011 11111110
CCNP / BSCI:
An L1/L2 ISIS router can have an adjacency with what type or types of routers in its own area?
A. L1, L1/L2, L2
B. L1 only
C. L2 only
D. L1/L2 only
E. L1, L2
Answer: A. An L1/L2 router can form an adjacency with any of the three ISIS router types in its own area.
CCNP / BCMSN
Which of the following does NOT describe a network that would be a good candidate for PIM Dense Mode?
A. Multiple recipients located on almost every subnet in the network
B. Only a few recipients overall
C. Bandwidth to spare to allow periodic flooding
D. These statements all describe networks that should run PIM Dense Mode.
Answer: B. If there are only a few recipients, PIM Sparse Mode would be a better choice.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Today's Questions Coming Up Later Today!
CCNA:
Convert the dotted decimal address 240.53.51.254 to a binary string. (No choices given.)
Answer: 11110000 00110101 00110011 11111110
CCNP / BSCI:
An L1/L2 ISIS router can have an adjacency with what type or types of routers in its own area?
A. L1, L1/L2, L2
B. L1 only
C. L2 only
D. L1/L2 only
E. L1, L2
Answer: A. An L1/L2 router can form an adjacency with any of the three ISIS router types in its own area.
CCNP / BCMSN
Which of the following does NOT describe a network that would be a good candidate for PIM Dense Mode?
A. Multiple recipients located on almost every subnet in the network
B. Only a few recipients overall
C. Bandwidth to spare to allow periodic flooding
D. These statements all describe networks that should run PIM Dense Mode.
Answer: B. If there are only a few recipients, PIM Sparse Mode would be a better choice.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNP / BCMSN Exam Tutorial: Introduction To Multicasting
Ever since you picked up your first CCNA book, you've heard about multicasting, gotten a fair idea of what it is, and you've memorized a couple of reserved multicasting addresses. Now as you prepare to pass the BCMSN exam and become a CCNP, you've got to take that knowledge to the next level and gain a true understanding of multicasting. Those of you with an eye on the CCIE will truly have to become multicasting experts!
Having said that, we're going to briefly review the basics of multicasting first, and then future tutorials will look at the different ways in which multicasting can be configured on Cisco routers and switches.
What Is Multicasting?
A unicast is data that is sent from one host to another, while a broadcast is data sent from a host that is destined for "all" host addresses. By "all", we can mean all hosts on a subnet, or truly all hosts on a network.
There's a quite a bit of a middle ground there! A multicast is that middle ground, as a multicast is data that is sent to a logical group of hosts, called a multicast group. Hosts that are not part of the multicast group will not receive the data.
Some other basic multicasting facts:
There's no limit on how many multicast groups a single host can belong to.
The sender is usually unaware of what host devices belong to the multicast group.
Multicast traffic is unidirectional. If the members of the multicast group need to respond, that reply will generally be a unicast.
The range of IP addresses reserved for multicasting is the Class D range, 224.0.0.0 - 239.255.255.255.
That range contains a couple of other reserved address ranges.
224.0.0.0 - 224.0.0.255 is reserved for network protocols only on a local network segment. Packets in this range will not be forwarded by routers, so these packets cannot leave the segment.
Just as Class A, Class B, and Class C networks have private address ranges, so does Class D. The Class D private address range is 239.0.0.0 - 239.255.255.255. Like the other private ranges, these addresses can't be routed, so they can be reused from one network to another.
The remaining addresses fall between 224.0.1.0 and 238.255.255.255. That's the "normal" range of multicast addresses. These addresses can be routed, so they must be unique and should not be duplicated from one network to the next.
In my next BCMSN / CCNP multicasting tutorial, we'll take a look at the different ways in which Cisco routers and switches interact to forward multicast traffic.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Ever since you picked up your first CCNA book, you've heard about multicasting, gotten a fair idea of what it is, and you've memorized a couple of reserved multicasting addresses. Now as you prepare to pass the BCMSN exam and become a CCNP, you've got to take that knowledge to the next level and gain a true understanding of multicasting. Those of you with an eye on the CCIE will truly have to become multicasting experts!
Having said that, we're going to briefly review the basics of multicasting first, and then future tutorials will look at the different ways in which multicasting can be configured on Cisco routers and switches.
What Is Multicasting?
A unicast is data that is sent from one host to another, while a broadcast is data sent from a host that is destined for "all" host addresses. By "all", we can mean all hosts on a subnet, or truly all hosts on a network.
There's a quite a bit of a middle ground there! A multicast is that middle ground, as a multicast is data that is sent to a logical group of hosts, called a multicast group. Hosts that are not part of the multicast group will not receive the data.
Some other basic multicasting facts:
There's no limit on how many multicast groups a single host can belong to.
The sender is usually unaware of what host devices belong to the multicast group.
Multicast traffic is unidirectional. If the members of the multicast group need to respond, that reply will generally be a unicast.
The range of IP addresses reserved for multicasting is the Class D range, 224.0.0.0 - 239.255.255.255.
That range contains a couple of other reserved address ranges.
224.0.0.0 - 224.0.0.255 is reserved for network protocols only on a local network segment. Packets in this range will not be forwarded by routers, so these packets cannot leave the segment.
Just as Class A, Class B, and Class C networks have private address ranges, so does Class D. The Class D private address range is 239.0.0.0 - 239.255.255.255. Like the other private ranges, these addresses can't be routed, so they can be reused from one network to another.
The remaining addresses fall between 224.0.1.0 and 238.255.255.255. That's the "normal" range of multicast addresses. These addresses can be routed, so they must be unique and should not be duplicated from one network to the next.
In my next BCMSN / CCNP multicasting tutorial, we'll take a look at the different ways in which Cisco routers and switches interact to forward multicast traffic.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
RIP isn't exactly the most complex routing protocol on the CCNA exam, but that makes it easy to overlook some of the important details you must keep in mind in order to pass the exam! To help you review for the exam, here are just a few of those details!
RIP’s default behavior is to send version 1 updates, but to accept both version 1 and 2 routing updates.
R2(config)#router rip
R2(config-router)#net 172.16.0.0
R2(config-router)#^Z
R2#show ip protocols
Routing Protocol is "rip"
Sending updates every 30 seconds, next due in 6 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Outgoing update filter list for all interfaces is
Incoming update filter list for all interfaces is
Redistributing: rip
Default version control: send version 1, receive any version
Interface Send Recv Key-chain
Serial0 1 1 2
By default, RIP v2 autosummarizes routing updates sent across classful network boundaries. To disable this behavior, run no auto-summary under the RIP process.
R1#conf t
R1(config)#router rip
R1(config-router)#version 2
R1(config-router)#no auto-summary
You do not specify a subnet mask or wildcard mask when configuring RIP – just the classful network, even if you’re running RIP v2.
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router rip
R1(config-router)#version 2
R1(config-router)#no auto-summary
R1(config-router)#network 172.10.0.0 ?
Debug ip rip displays the routing updates and metrics as the advertisements are sent and requested. To see this in action without waiting for the next regularly scheduled update, run clear ip route *.
R1#debug ip rip
RIP protocol debugging is on
R1#clear ip route *
01:16:54: RIP: sending v1 update to 255.255.255.255 via Loopback1 (1.1.1.1)
01:16:54: network 2.0.0.0, metric 201:16:54:
network 3.0.0.0, metric 201:16:54:
network 172.16.0.0, metric 101:16:54:
network 10.0.0.0, metric 201:16:54:
RIP: sending v1 update to 255.255.255.255 via Serial0 (172.16.123.1)
01:16:54: subnet 172.16.123.0, metric 1
01:16:54: network 1.0.0.0, metric 1
01:16:54: network 2.0.0.0, metric 2
01:16:54: network 3.0.0.0, metric 2
01:16:54: network 10.0.0.0, metric 2
To see only the routes discovered by a routing protocol, run show ip route followed by the name of the protocol:
R1#show ip route rip
R 2.0.0.0/8 [120/1] via 172.16.123.2, 00:00:26, Serial0
R 3.0.0.0/8 [120/1] via 172.16.13.2, 00:00:09, Serial1
[120/1] via 172.16.123.3, 00:00:09, Serial0
R 10.0.0.0/8 [120/1] via 172.16.13.2, 00:00:09, Serial1
[120/1] via 172.16.123.3, 00:00:09, Serial0
[120/1] via 172.16.123.2, 00:00:26, Serial0
And don't forget - to turn off all currently running debugs, run undebug all.
R1#undebug all
All possible debugging has been turned off
Don't overlook RIP and IGRP when it comes to the CCNA exam. OSPF and EIGRP are more complex to configure, but you need to understand how distance vector protocols work in order to pass the CCNA!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
RIP’s default behavior is to send version 1 updates, but to accept both version 1 and 2 routing updates.
R2(config)#router rip
R2(config-router)#net 172.16.0.0
R2(config-router)#^Z
R2#show ip protocols
Routing Protocol is "rip"
Sending updates every 30 seconds, next due in 6 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Outgoing update filter list for all interfaces is
Incoming update filter list for all interfaces is
Redistributing: rip
Default version control: send version 1, receive any version
Interface Send Recv Key-chain
Serial0 1 1 2
By default, RIP v2 autosummarizes routing updates sent across classful network boundaries. To disable this behavior, run no auto-summary under the RIP process.
R1#conf t
R1(config)#router rip
R1(config-router)#version 2
R1(config-router)#no auto-summary
You do not specify a subnet mask or wildcard mask when configuring RIP – just the classful network, even if you’re running RIP v2.
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router rip
R1(config-router)#version 2
R1(config-router)#no auto-summary
R1(config-router)#network 172.10.0.0 ?
Debug ip rip displays the routing updates and metrics as the advertisements are sent and requested. To see this in action without waiting for the next regularly scheduled update, run clear ip route *.
R1#debug ip rip
RIP protocol debugging is on
R1#clear ip route *
01:16:54: RIP: sending v1 update to 255.255.255.255 via Loopback1 (1.1.1.1)
01:16:54: network 2.0.0.0, metric 201:16:54:
network 3.0.0.0, metric 201:16:54:
network 172.16.0.0, metric 101:16:54:
network 10.0.0.0, metric 201:16:54:
RIP: sending v1 update to 255.255.255.255 via Serial0 (172.16.123.1)
01:16:54: subnet 172.16.123.0, metric 1
01:16:54: network 1.0.0.0, metric 1
01:16:54: network 2.0.0.0, metric 2
01:16:54: network 3.0.0.0, metric 2
01:16:54: network 10.0.0.0, metric 2
To see only the routes discovered by a routing protocol, run show ip route followed by the name of the protocol:
R1#show ip route rip
R 2.0.0.0/8 [120/1] via 172.16.123.2, 00:00:26, Serial0
R 3.0.0.0/8 [120/1] via 172.16.13.2, 00:00:09, Serial1
[120/1] via 172.16.123.3, 00:00:09, Serial0
R 10.0.0.0/8 [120/1] via 172.16.13.2, 00:00:09, Serial1
[120/1] via 172.16.123.3, 00:00:09, Serial0
[120/1] via 172.16.123.2, 00:00:26, Serial0
And don't forget - to turn off all currently running debugs, run undebug all.
R1#undebug all
All possible debugging has been turned off
Don't overlook RIP and IGRP when it comes to the CCNA exam. OSPF and EIGRP are more complex to configure, but you need to understand how distance vector protocols work in order to pass the CCNA!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Wednesday, April 12, 2006
Answers To Monday's CCNA And CCNP Practice Questions
CCNA:
The "NV" in "NVRAM" stands for non-volatile. What does this term mean? Choose all that apply.
A. The contents of NVRAM cannot be changed.
B. The contents of NVRAM are not lost on reboot.
C. The contents of NVRAM cannot be copied.
D. The contents of NVRAM cannot be erased.
ANSWER: B. Non-volatile RAM is so named because the contents are not lost on a reload. The contents of NVRAM can be changed, can be copied, and can be erased.
CCNP / BSCI:
Which of the following statements does NOT describe EIGRP? Choose all that apply.
A. Uses PDMs to support IP, IPX, and AppleTalk
B. Supports VLSM
C. Allows route summarization at the interface level
D. Fast convergence
E. Static neighbor discovery
ANSWER: E. EIGRP does use PDMs to support those three protocols, it does support VLSM, it does allow route summarization at the interface level, and it does converge quickly. There is no static neighbor discovery mechanism in EIGRP.
CCNP / BCMSN
At what layer of the Cisco three-layer hierarchical model should the root bridge be found?
A. Physical
B. Core
C. Distribution
E. Data Link
F. Access
G. End User
ANSWER: B. To optimize STP operation, the root switch should be found in the core layer of Cisco's three-layer hierarchical model.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
The "NV" in "NVRAM" stands for non-volatile. What does this term mean? Choose all that apply.
A. The contents of NVRAM cannot be changed.
B. The contents of NVRAM are not lost on reboot.
C. The contents of NVRAM cannot be copied.
D. The contents of NVRAM cannot be erased.
ANSWER: B. Non-volatile RAM is so named because the contents are not lost on a reload. The contents of NVRAM can be changed, can be copied, and can be erased.
CCNP / BSCI:
Which of the following statements does NOT describe EIGRP? Choose all that apply.
A. Uses PDMs to support IP, IPX, and AppleTalk
B. Supports VLSM
C. Allows route summarization at the interface level
D. Fast convergence
E. Static neighbor discovery
ANSWER: E. EIGRP does use PDMs to support those three protocols, it does support VLSM, it does allow route summarization at the interface level, and it does converge quickly. There is no static neighbor discovery mechanism in EIGRP.
CCNP / BCMSN
At what layer of the Cisco three-layer hierarchical model should the root bridge be found?
A. Physical
B. Core
C. Distribution
E. Data Link
F. Access
G. End User
ANSWER: B. To optimize STP operation, the root switch should be found in the core layer of Cisco's three-layer hierarchical model.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Tuesday's CCNA And CCNP Practice Questions And Answers
CCNA:
The "NV" in "NVRAM" stands for non-volatile. What does this term mean? Choose all that apply.
A. The contents of NVRAM cannot be changed.
B. The contents of NVRAM are not lost on reboot.
C. The contents of NVRAM cannot be copied.
D. The contents of NVRAM cannot be erased.
ANSWER: B. "non-volatile" means that the contents are not lost on a reload.
CCNP / BSCI:
Which of the following statements does NOT describe EIGRP? Choose all that apply.
A. Uses PDMs to support IP, IPX, and AppleTalk
B. Supports VLSM
C. Allows route summarization at the interface level
D. Fast convergence
E. Static neighbor discovery
ANSWER: E. EIGRP does use PDMs, it does support VLSM, it does allow route summarization at the interface level, and it converges quickly. It does not have static neighbor discovery.
CCNP / BCMSN
At what layer of the Cisco three-layer hierarchical model should the root bridge be found?
A. Physical
B. Core
C. Distribution
E. Data Link
F. Access
G. End User
ANSWER: B. The root bridge will ideally be found at the core layer.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
The "NV" in "NVRAM" stands for non-volatile. What does this term mean? Choose all that apply.
A. The contents of NVRAM cannot be changed.
B. The contents of NVRAM are not lost on reboot.
C. The contents of NVRAM cannot be copied.
D. The contents of NVRAM cannot be erased.
ANSWER: B. "non-volatile" means that the contents are not lost on a reload.
CCNP / BSCI:
Which of the following statements does NOT describe EIGRP? Choose all that apply.
A. Uses PDMs to support IP, IPX, and AppleTalk
B. Supports VLSM
C. Allows route summarization at the interface level
D. Fast convergence
E. Static neighbor discovery
ANSWER: E. EIGRP does use PDMs, it does support VLSM, it does allow route summarization at the interface level, and it converges quickly. It does not have static neighbor discovery.
CCNP / BCMSN
At what layer of the Cisco three-layer hierarchical model should the root bridge be found?
A. Physical
B. Core
C. Distribution
E. Data Link
F. Access
G. End User
ANSWER: B. The root bridge will ideally be found at the core layer.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Cisco Announces New Wireless Certifications
Demand for wireless specialists is growing every day, and Cisco has announced two new wireless certifications to help meet this demand. Read more about them and the requirements by following this link:
www.cisco.com/web/learning/le3/whats_new/new_wireless_certifications.html
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Demand for wireless specialists is growing every day, and Cisco has announced two new wireless certifications to help meet this demand. Read more about them and the requirements by following this link:
www.cisco.com/web/learning/le3/whats_new/new_wireless_certifications.html
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Wednesday's CCNA / CCNP Practice Questions
Answers to Tuesday's questions will be posted tonight.
CCNA:
Convert the dotted decimal address 240.53.51.254 to a binary string. (No choices given.)
CCNP / BSCI:
An L1/L2 ISIS router can have an adjacency with what type or types of routers in its own area?
A. L1, L1/L2, L2
B. L1 only
C. L2 only
D. L1/L2 only
E. L1, L2
CCNP / BCMSN
Which of the following does NOT describe a network that would be a good candidate for PIM Dense Mode?
A. Multiple recipients located on almost every subnet in the network
B. Only a few recipients overall
C. Bandwidth to spare to allow periodic flooding
D. These statements all describe networks that should run PIM Dense Mode.
Answers to Tuesday's questions will be posted tonight.
CCNA:
Convert the dotted decimal address 240.53.51.254 to a binary string. (No choices given.)
CCNP / BSCI:
An L1/L2 ISIS router can have an adjacency with what type or types of routers in its own area?
A. L1, L1/L2, L2
B. L1 only
C. L2 only
D. L1/L2 only
E. L1, L2
CCNP / BCMSN
Which of the following does NOT describe a network that would be a good candidate for PIM Dense Mode?
A. Multiple recipients located on almost every subnet in the network
B. Only a few recipients overall
C. Bandwidth to spare to allow periodic flooding
D. These statements all describe networks that should run PIM Dense Mode.
CCNP / BCMSN Exam Tutorial: The Core Layer Of The Cisco Three-Layer Hierarchical Model
In this section, you're going to be reintroduced to a networking model you first saw in your CCNA studies. No, it's not the OSI model or the TCP/IP model - it's the Cisco Three-Layer Hierarchical Model. Let's face it, just about all you had to do for the CCNA was memorize the three layers and the order they were found in that model, but the stakes are raised here in your CCNP studies. You need to know what each layer does, and what each layer should not be doing. This is vital information for your real-world network career as well, so let's get started with a review of the Cisco three-layer model, and then we'll take a look at each layer's tasks. Most of the considerations at each layer are common sense, but we'll go over them anyway!
Today we’ll take a look at the core layer of the Cisco model.
The term core switches refers to any switches found here. Switches at the core layer allow switches at the distribution layer to communicate, and this is more than a full-time job. It's vital to keep any extra workload off the core switches, and allow them to do what they need to do - switch! The core layer is the backbone of your entire network, so we're interested in high-speed data transfer and very low latency - that's it!
Core layer switches are usually the most powerful in your network, capable of higher throughput than any other switches in the network. Remember, everything we do on a Cisco router or switch has a cost in CPU or memory, so we're going to leave most frame manipulation and filtering to other layers. The exception is Cisco QoS, or Quality of Service. QoS is generally performed at the core layer. We'll go into much more detail regarding QoS in another tutorial, but for now, know that QoS is basically high-speed queuing where special consideration can be given to certain data in certain queues. (You’ll soon find that this is a very basic definition!)
We always want redundancy, but you want a lot of redundancy in your core layer. This is the nerve center of your entire network, so fault tolerance needs to be as high as you can possibly get it. Root bridges should also be located in the core layer.
The importance of keeping unnecessary workload off your core switches cannot be overstated. In the next part of this BCMSN tutorial, we’ll take a look at how the other layers of the Cisco three-part model do just that.
In this section, you're going to be reintroduced to a networking model you first saw in your CCNA studies. No, it's not the OSI model or the TCP/IP model - it's the Cisco Three-Layer Hierarchical Model. Let's face it, just about all you had to do for the CCNA was memorize the three layers and the order they were found in that model, but the stakes are raised here in your CCNP studies. You need to know what each layer does, and what each layer should not be doing. This is vital information for your real-world network career as well, so let's get started with a review of the Cisco three-layer model, and then we'll take a look at each layer's tasks. Most of the considerations at each layer are common sense, but we'll go over them anyway!
Today we’ll take a look at the core layer of the Cisco model.
The term core switches refers to any switches found here. Switches at the core layer allow switches at the distribution layer to communicate, and this is more than a full-time job. It's vital to keep any extra workload off the core switches, and allow them to do what they need to do - switch! The core layer is the backbone of your entire network, so we're interested in high-speed data transfer and very low latency - that's it!
Core layer switches are usually the most powerful in your network, capable of higher throughput than any other switches in the network. Remember, everything we do on a Cisco router or switch has a cost in CPU or memory, so we're going to leave most frame manipulation and filtering to other layers. The exception is Cisco QoS, or Quality of Service. QoS is generally performed at the core layer. We'll go into much more detail regarding QoS in another tutorial, but for now, know that QoS is basically high-speed queuing where special consideration can be given to certain data in certain queues. (You’ll soon find that this is a very basic definition!)
We always want redundancy, but you want a lot of redundancy in your core layer. This is the nerve center of your entire network, so fault tolerance needs to be as high as you can possibly get it. Root bridges should also be located in the core layer.
The importance of keeping unnecessary workload off your core switches cannot be overstated. In the next part of this BCMSN tutorial, we’ll take a look at how the other layers of the Cisco three-part model do just that.
Tuesday, April 11, 2006
A Quick Review Of The TCP/IP Networking Model
The OSI model is the model that most networking personnel are familiar with, but to earn your CCNA, you need to know the OSI model, the TCP/IP model, and how the two map to each other.
The four layers of the TCP/IP architecture can be compared to certain levels of the OSI model. It’s important to know what each level of the TCP/IP protocol architecture does, and how these layers map to the OSI model.
The Application Layer of the TCP/IP model performs much the same tasks as the Application, Presentation, and Session layers of the OSI model.
The Transport layer in the TCP/IP architecture is similar to the Transport layer in the OSI model. This layer can use TCP or UDP as well.
The Internetwork layer in the TCP/IP architecture uses IP addresses to determine how packets should be routed. Remember that the OSI model uses IP addresses, or “Layer 3 Addresses”, at the Network layer. The two layers do much the same thing. This layer is also referred to in the TCP/IP model as the Internet layer.
The Network Interface layer in the TCP/IP architecture serves to define the protocols and the hardware needed to actually deliver the data across the network. The Network Interface model does the work of both the Data Link and Physical Layers in the OSI model.
Keeping all this straight can be very confusing when you first start your CCNA studies. Concentrate on the OSI model in your studies, but make sure you know how the TCP/IP model maps to that model and you'll be ready for CCNA exam success!
To your Cisco success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
The OSI model is the model that most networking personnel are familiar with, but to earn your CCNA, you need to know the OSI model, the TCP/IP model, and how the two map to each other.
The four layers of the TCP/IP architecture can be compared to certain levels of the OSI model. It’s important to know what each level of the TCP/IP protocol architecture does, and how these layers map to the OSI model.
The Application Layer of the TCP/IP model performs much the same tasks as the Application, Presentation, and Session layers of the OSI model.
The Transport layer in the TCP/IP architecture is similar to the Transport layer in the OSI model. This layer can use TCP or UDP as well.
The Internetwork layer in the TCP/IP architecture uses IP addresses to determine how packets should be routed. Remember that the OSI model uses IP addresses, or “Layer 3 Addresses”, at the Network layer. The two layers do much the same thing. This layer is also referred to in the TCP/IP model as the Internet layer.
The Network Interface layer in the TCP/IP architecture serves to define the protocols and the hardware needed to actually deliver the data across the network. The Network Interface model does the work of both the Data Link and Physical Layers in the OSI model.
Keeping all this straight can be very confusing when you first start your CCNA studies. Concentrate on the OSI model in your studies, but make sure you know how the TCP/IP model maps to that model and you'll be ready for CCNA exam success!
To your Cisco success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Monday's CCNA / CCNP Questions And Answers
CCNA:
What devices typically make up a Frame Relay cloud?
A. Frame Relay routers (DCEs)
B. Frame Relay routers (DTEs)
C. Frame Relay switches (DCEs)
D. Frame Relay switches (DTEs)
ANSWER: C. Frame Relay clouds consist of Frame Relay switches, which are DCEs (which stands for Data Communications Equipment or Data Circuit-terminating Equipment, depending on which piece of documentation you're reading!).
BSCI:
What is the highest AS number available in the BGP private AS range?
A. 64512
B. 64555
C. 65535
D. 65555
E. 32768
ANSWER: C. The range of private AS numbers is 64512 - 65535.
BCMSN:
Which of the following interface-level commands enables Loop Guard?
A. spanning-tree loop guard
B. spanning-tree guard loop
C. loop guard run
D. loop guard enable
E. run loop guard
F. enable loop guard
ANSWER: B. Use the interface-level command spanning-tree guard loop to enable Loop Guard.
SW2(config-if)#int fast 0/5
SW2(config-if)#spanning-tree guard loop
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
What devices typically make up a Frame Relay cloud?
A. Frame Relay routers (DCEs)
B. Frame Relay routers (DTEs)
C. Frame Relay switches (DCEs)
D. Frame Relay switches (DTEs)
ANSWER: C. Frame Relay clouds consist of Frame Relay switches, which are DCEs (which stands for Data Communications Equipment or Data Circuit-terminating Equipment, depending on which piece of documentation you're reading!).
BSCI:
What is the highest AS number available in the BGP private AS range?
A. 64512
B. 64555
C. 65535
D. 65555
E. 32768
ANSWER: C. The range of private AS numbers is 64512 - 65535.
BCMSN:
Which of the following interface-level commands enables Loop Guard?
A. spanning-tree loop guard
B. spanning-tree guard loop
C. loop guard run
D. loop guard enable
E. run loop guard
F. enable loop guard
ANSWER: B. Use the interface-level command spanning-tree guard loop to enable Loop Guard.
SW2(config-if)#int fast 0/5
SW2(config-if)#spanning-tree guard loop
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Tuesday's CCNA / CCNP Practice Questions
Answers to Monday's questions will be posted later today!
CCNA:
The "NV" in "NVRAM" stands for non-volatile. What does this term mean? Choose all that apply.
A. The contents of NVRAM cannot be changed.
B. The contents of NVRAM are not lost on reboot.
C. The contents of NVRAM cannot be copied.
D. The contents of NVRAM cannot be erased.
CCNP / BSCI:
Which of the following statements does NOT describe EIGRP? Choose all that apply.
A. Uses PDMs to support IP, IPX, and AppleTalk
B. Supports VLSM
C. Allows route summarization at the interface level
D. Fast convergence
E. Static neighbor discovery
CCNP / BCMSN
At what layer of the Cisco three-layer hierarchical model should the root bridge be found?
A. Physical
B. Core
C. Distribution
E. Data Link
F. Access
G. End User
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Answers to Monday's questions will be posted later today!
CCNA:
The "NV" in "NVRAM" stands for non-volatile. What does this term mean? Choose all that apply.
A. The contents of NVRAM cannot be changed.
B. The contents of NVRAM are not lost on reboot.
C. The contents of NVRAM cannot be copied.
D. The contents of NVRAM cannot be erased.
CCNP / BSCI:
Which of the following statements does NOT describe EIGRP? Choose all that apply.
A. Uses PDMs to support IP, IPX, and AppleTalk
B. Supports VLSM
C. Allows route summarization at the interface level
D. Fast convergence
E. Static neighbor discovery
CCNP / BCMSN
At what layer of the Cisco three-layer hierarchical model should the root bridge be found?
A. Physical
B. Core
C. Distribution
E. Data Link
F. Access
G. End User
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Monday, April 10, 2006
CCNP / BCMSN Tutorial: BPDU Skew Detection
Okay, I know what you're thinking! "What the heck is a BPDU Skew, and why do I want to detect it?" There is no "BPDU Skew" -- what we're trying to detect are BPDUs that are not being relayed throughout the network as quickly as they should be.
The root bridge is the only switch that's sending original BPDUs; the non-root switches relay that BPDU down the STP tree. This should happen quickly thorughout the network, since the root bridge will be sending a BPDU every two seconds by default ("hello time"), and the switches should relay the BDPUs fast enough so every switch is seeing a BPDU every two seconds.
That's in a perfect world, though, and there are plenty of imperfect networks out there! You may have a busy switch that can't spare the CPU to relay the BDPU quickly, or a BPDU may just simply be lost in transmission. That two-second hello time value doesn't give the switches much leeway, but we don't want the STP topology recalculated unnecessarily either.
BDPU Skew Detection is strictly a notification feature. Skew Detection will not take action to prevent STP recalculation when BDPUs are not being relayed quickly enough by the switches, but it will send a syslog message informing the network administrator of the problem. The amount of time between when the BDPU should have arrived and when it did arrive is referred to as skew time or BPDU latency.
A busy CPU could quickly find itself overwhelmed if it had to send a syslog message for every BPDU delivery that's skewed. The syslog messages will be limited to one every 60 seconds, unless the skew time is at a critical level. In that case, the syslog message will be sent immediately with no one-per-minute limit. By default, BPDU Skew Detection defines critical as any value greater than 1/2 of the MaxAge value, making the default critical skew time anything over 10 seconds.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Okay, I know what you're thinking! "What the heck is a BPDU Skew, and why do I want to detect it?" There is no "BPDU Skew" -- what we're trying to detect are BPDUs that are not being relayed throughout the network as quickly as they should be.
The root bridge is the only switch that's sending original BPDUs; the non-root switches relay that BPDU down the STP tree. This should happen quickly thorughout the network, since the root bridge will be sending a BPDU every two seconds by default ("hello time"), and the switches should relay the BDPUs fast enough so every switch is seeing a BPDU every two seconds.
That's in a perfect world, though, and there are plenty of imperfect networks out there! You may have a busy switch that can't spare the CPU to relay the BDPU quickly, or a BPDU may just simply be lost in transmission. That two-second hello time value doesn't give the switches much leeway, but we don't want the STP topology recalculated unnecessarily either.
BDPU Skew Detection is strictly a notification feature. Skew Detection will not take action to prevent STP recalculation when BDPUs are not being relayed quickly enough by the switches, but it will send a syslog message informing the network administrator of the problem. The amount of time between when the BDPU should have arrived and when it did arrive is referred to as skew time or BPDU latency.
A busy CPU could quickly find itself overwhelmed if it had to send a syslog message for every BPDU delivery that's skewed. The syslog messages will be limited to one every 60 seconds, unless the skew time is at a critical level. In that case, the syslog message will be sent immediately with no one-per-minute limit. By default, BPDU Skew Detection defines critical as any value greater than 1/2 of the MaxAge value, making the default critical skew time anything over 10 seconds.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Monday's CCNA / CCNP Practice Questions:
CCNA:
What devices typically make up a Frame Relay cloud?
A. Frame Relay routers (DCEs)
B. Frame Relay routers (DTEs)
C. Frame Relay switches (DCEs)
D. Frame Relay switches (DTEs)
BSCI:
What is the highest AS number available in the BGP private AS range?
A. 64512
B. 64555
C. 65535
D. 65555
E. 32768
BCMSN:
Which of the following interface-level commands enables Loop Guard?
A. spanning-tree loop guard
B. spanning-tree guard loop
C. loop guard run
D. loop guard enable
E. run loop guard
F. enable loop guard
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
What devices typically make up a Frame Relay cloud?
A. Frame Relay routers (DCEs)
B. Frame Relay routers (DTEs)
C. Frame Relay switches (DCEs)
D. Frame Relay switches (DTEs)
BSCI:
What is the highest AS number available in the BGP private AS range?
A. 64512
B. 64555
C. 65535
D. 65555
E. 32768
BCMSN:
Which of the following interface-level commands enables Loop Guard?
A. spanning-tree loop guard
B. spanning-tree guard loop
C. loop guard run
D. loop guard enable
E. run loop guard
F. enable loop guard
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Sunday, April 09, 2006
Answers To Saturday's CCNA / CCNP Practice Questions
CCNA:
Which two of the following phrases best describe fragment-free switching?
A. No error checking
B. Some error checking
C. Looks only at destination MAC before beginning to forward the frame
D. Looks at the first 64 bytes of the frame before beginning to forward the frame
ANSWER: B, D. Fragment-free switching looks at the first 64 bytes of the frame before forwarding it. This offers limited error protection, since most frame errors occur within the first 64 bytes. It's not as thorough as store-and-forward, which runs a Cyclical Redundancy Check before forwarding a frame, but it's better than cut-through switching, which offers no error checking.
BSCI:
By default, how does an OSPF routing table indicate routes that were learned via redistribution?
A. O E1
B. O E2
C. O EX
D. O
ANSWER: B. OSPF routes learned via redistribution are marked as O E2, or External type-2.
BCMSN:
What is the range of physical connections that can be bundled into an Etherchannel?
A. One to eight
B. Two to eight
C. Two to ten
D. Three to eight
E. Three to ten
ANSWER: B. Etherchannels can contain two to eight physical channels.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
Which two of the following phrases best describe fragment-free switching?
A. No error checking
B. Some error checking
C. Looks only at destination MAC before beginning to forward the frame
D. Looks at the first 64 bytes of the frame before beginning to forward the frame
ANSWER: B, D. Fragment-free switching looks at the first 64 bytes of the frame before forwarding it. This offers limited error protection, since most frame errors occur within the first 64 bytes. It's not as thorough as store-and-forward, which runs a Cyclical Redundancy Check before forwarding a frame, but it's better than cut-through switching, which offers no error checking.
BSCI:
By default, how does an OSPF routing table indicate routes that were learned via redistribution?
A. O E1
B. O E2
C. O EX
D. O
ANSWER: B. OSPF routes learned via redistribution are marked as O E2, or External type-2.
BCMSN:
What is the range of physical connections that can be bundled into an Etherchannel?
A. One to eight
B. Two to eight
C. Two to ten
D. Three to eight
E. Three to ten
ANSWER: B. Etherchannels can contain two to eight physical channels.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Saturday, April 08, 2006
CCNP / BCMSN Tutorial: UplinkFast
When you're studying for the BCMSN exam, you can get overwhelmed with trying to keep UplinkFast, PortFast, BDPU Guard, Loop Guard, and other guards and loops straight! Today, we'll spend a few minutes with an introduction to UplinkFast.
You remember from your CCNA studies that when a port goes through the transition from blocking to forwarding, you're looking at a 50-second delay before that port can actually begin forwarding frames. Configuring a port with PortFast is one way to get around that, but again, you can only use it when a single host device is found off the port. What if the device connected to a port is another switch?
A switch can be connected to two other switches, giving that local switch a redundant path to the root bridge, and that's great - we always want a backup plan! However, STP will only allow one path to be available, but if the available path to the root switch goes down, there will be a 50-second delay due to the STP timers MaxAge and ForwardDelay before the currently blocked path will be available. (The 50-second delay is a sum total of the 20-second MaxAge timer and the 15-second ForwardDelay timer, which will run twice - once for the listening state and once for the learning state.)
The delay is there to prevent switching loops, and we can't use PortFast to shorten the delay since these are switches, not host devices. What we can use is Uplinkfast.
The ports that a switch could potentially use to reach the root bridge are collectively referred to as an uplink group. The uplink group includes the ports in forwarding and blocking mode. If the forwarding port in the uplink group sees that the link has gone down, another port in the uplink group will be transitioned from blocking to forwarding immediately. Uplinkfast is pretty much PortFast for wiring closets. (Cisco recommends that Uplinkfast not be used on switches in the distribution and core layers.)
Some additional details regarding Uplinkfast:
The original root port will become the root port again when it detects that its link to the root switch has come back up. This does not take place immediately. The switch uses the following formula to determine how long to wait before transitioning back to the forwarding state:
( 2 x FwdDelay) + 5 seconds
Uplinkfast will take immediate action to ensure that the switch upon which it is configured cannot become the root switch. First, the switch priority will be set to 49,152, which means that if all other switches are still at their default priority, they'd all have to go down before this switch can possibly become the root switch. Additionally, the STP Port Cost will be increased by 3000, making it highly unlikely that this switch will be used to reach the root switch by any downstream switches.
And you just know there's got to be at least one option with this command, right? Let's run IOS Help and see.
SW2(config)#spanning-tree uplinkfast ?
When there is a direct link failure, dummy multicast frames are sent to the MAC destination 0100.0ccd.cdcd. The max-update-rate value determines how many of these frames will be sent in a 100-millisecond time period.
Mastering the details of UplinkFast, BackboneFast, BPDU Guard, and Loop Guard are vital to your success on the CCNP exams, and one or more of these features are in use on almost every network in the world. Learn these features for success in both the exam room and the real world!
When you're studying for the BCMSN exam, you can get overwhelmed with trying to keep UplinkFast, PortFast, BDPU Guard, Loop Guard, and other guards and loops straight! Today, we'll spend a few minutes with an introduction to UplinkFast.
You remember from your CCNA studies that when a port goes through the transition from blocking to forwarding, you're looking at a 50-second delay before that port can actually begin forwarding frames. Configuring a port with PortFast is one way to get around that, but again, you can only use it when a single host device is found off the port. What if the device connected to a port is another switch?
A switch can be connected to two other switches, giving that local switch a redundant path to the root bridge, and that's great - we always want a backup plan! However, STP will only allow one path to be available, but if the available path to the root switch goes down, there will be a 50-second delay due to the STP timers MaxAge and ForwardDelay before the currently blocked path will be available. (The 50-second delay is a sum total of the 20-second MaxAge timer and the 15-second ForwardDelay timer, which will run twice - once for the listening state and once for the learning state.)
The delay is there to prevent switching loops, and we can't use PortFast to shorten the delay since these are switches, not host devices. What we can use is Uplinkfast.
The ports that a switch could potentially use to reach the root bridge are collectively referred to as an uplink group. The uplink group includes the ports in forwarding and blocking mode. If the forwarding port in the uplink group sees that the link has gone down, another port in the uplink group will be transitioned from blocking to forwarding immediately. Uplinkfast is pretty much PortFast for wiring closets. (Cisco recommends that Uplinkfast not be used on switches in the distribution and core layers.)
Some additional details regarding Uplinkfast:
The actual transition from blocking to forwarding mode takes about three seconds.
Uplinkfast cannot be configured on a root switch.
Uplinkfast is configured globally. You can't run Uplinkfast on some ports or on a per-VLAN basis - it's all or nothing.
The original root port will become the root port again when it detects that its link to the root switch has come back up. This does not take place immediately. The switch uses the following formula to determine how long to wait before transitioning back to the forwarding state:
( 2 x FwdDelay) + 5 seconds
Uplinkfast will take immediate action to ensure that the switch upon which it is configured cannot become the root switch. First, the switch priority will be set to 49,152, which means that if all other switches are still at their default priority, they'd all have to go down before this switch can possibly become the root switch. Additionally, the STP Port Cost will be increased by 3000, making it highly unlikely that this switch will be used to reach the root switch by any downstream switches.
And you just know there's got to be at least one option with this command, right? Let's run IOS Help and see.
SW2(config)#spanning-tree uplinkfast ?
max-update-rate Rate at which station address updates are sent
When there is a direct link failure, dummy multicast frames are sent to the MAC destination 0100.0ccd.cdcd. The max-update-rate value determines how many of these frames will be sent in a 100-millisecond time period.
Mastering the details of UplinkFast, BackboneFast, BPDU Guard, and Loop Guard are vital to your success on the CCNP exams, and one or more of these features are in use on almost every network in the world. Learn these features for success in both the exam room and the real world!
Chris Bryant
CCIE #12933
Saturday's CCNA / CCNP Practice Questions
CCNA:
Which two of the following phrases best describe fragment-free switching?
A. No error checking
B. Some error checking
C. Looks only at destination MAC before beginning to forward the frame
D. Looks at the first 64 bytes of the frame before beginning to forward the frame
BSCI:
By default, how does an OSPF routing table indicate routes that were learned via redistribution?
A. O E1
B. O E2
C. O EX
D. O
BCMSN:
What is the range of physical connections that can be bundled into an Etherchannel?
A. One to eight
B. Two to eight
C. Two to ten
D. Three to eight
E. Three to ten
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
Which two of the following phrases best describe fragment-free switching?
A. No error checking
B. Some error checking
C. Looks only at destination MAC before beginning to forward the frame
D. Looks at the first 64 bytes of the frame before beginning to forward the frame
BSCI:
By default, how does an OSPF routing table indicate routes that were learned via redistribution?
A. O E1
B. O E2
C. O EX
D. O
BCMSN:
What is the range of physical connections that can be bundled into an Etherchannel?
A. One to eight
B. Two to eight
C. Two to ten
D. Three to eight
E. Three to ten
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Friday's CCNA / CCNP Questions And Answers
CCNA:
What is the network mask for a Class A address?
A. 255.255.255.255
B. 255.255.255.0
C. 255.255.0.0
D. 255.0.0.0
E. /8
F. /12
G. /16
H. /24
ANSWER: D, E. 255.0.0.0 and /8 are the classful masks for Class A networks. They're the same mask, expressed in both dotted decimal (255.0.0.0) and prefix notation (/8).
BSCI:
Which of the following values does NOT have to be agreed upon between potential OSPF neighbors in order for an adjacency to be created?
A. The process number.
B. The area number.
C. The hello and dead timers.
D. The stub flag setting.
ANSWER: A. The OSPF process number is locally significant only. Routers must agree on the area number, the timers, and the stub flag setting to become neighbors.
BCMSN:
Which of the following is designed to detect unidirectional links?
A. Root Guard
B. Loop Guard
C. BackboneFast
D. UDLD
E. UplinkFast
F. BPDU Guard
ANSWER: D. UDLD, or Unidirectional Link Detection, does just that!
CCNA:
What is the network mask for a Class A address?
A. 255.255.255.255
B. 255.255.255.0
C. 255.255.0.0
D. 255.0.0.0
E. /8
F. /12
G. /16
H. /24
ANSWER: D, E. 255.0.0.0 and /8 are the classful masks for Class A networks. They're the same mask, expressed in both dotted decimal (255.0.0.0) and prefix notation (/8).
BSCI:
Which of the following values does NOT have to be agreed upon between potential OSPF neighbors in order for an adjacency to be created?
A. The process number.
B. The area number.
C. The hello and dead timers.
D. The stub flag setting.
ANSWER: A. The OSPF process number is locally significant only. Routers must agree on the area number, the timers, and the stub flag setting to become neighbors.
BCMSN:
Which of the following is designed to detect unidirectional links?
A. Root Guard
B. Loop Guard
C. BackboneFast
D. UDLD
E. UplinkFast
F. BPDU Guard
ANSWER: D. UDLD, or Unidirectional Link Detection, does just that!
Cisco CCNA Tutorial: The OSPF RID
OSPF is a major topic on your CCNA exam, as well it should be. OSPF is a widely-used WAN protocol, and you need to learn the fundamentals before moving on to more complicated configurations. One such detail is the OSPF Router ID, or RID.
The RID is the dotted decimal value by which other OSPF routers will identify a given OSPF router. There are some interesting defaults for this value, and a command you should know to hardcode the RID. You had also better know what has to happen for this command to take effect!
In this example, R1 has an adjacency with R2 and R3 over the 172.12.123.0/24 frame network. R1 is the hub, with R2 and R3 as the spokes. No other interfaces are OSPF-enabled on any of the routers. Running show ip ospf neighbor on R1, we see some unusual values under "Neighbor ID", which is another name for the OSPF RID.
R1#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
3.3.3.3 0 FULL/DROTHER 00:01:57 172.12.123.3 Serial0
2.2.2.2 0 FULL/DROTHER 00:01:57 172.12.123.2 Serial0
Notice the Neighbor ID of each remote address is the loopback address. How can that be if they’re not OSPF-enabled?
When determining the Router ID (RID) of an OSPF-enabled router, OSPF will always use the numerically highest IP address on the router’s loopback interfaces, regardless of whether that loopback is OSPF-enabled.
What if there is no loopback? OSPF will then use the numerically highest IP address of the physical interfaces, regardless of whether that interface is OSPF-enabled.
BOTTOM LINE: An interface does not have to be running OSPF to have its IP address used as the OSPF RID.
The OSPF RID can be changed, but it requires a restart or to reinitialize the OSPF routing process. Use the router-id command to change the default RID of each router as shown, and clear the OSPF process to do so.
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router ospf 1
R1(config-router)#router-id 11.11.11.11
Reload or use "clear ip ospf process" command, for this to take effect
R1#clear ip ospf process
Reset ALL OSPF processes? [no]: yes
1d05h: %OSPF-5-ADJCHG: Process 1, Nbr 3.3.3.3 on Serial0 from 2WAY to
DOWN, Neighbor Down: Interface down or detached
1d05h: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on Serial0 from 2WAY to
DOWN, Neighbor Down: Interface down or detached
After entering the router-id command, the router console informed you that you have to reload the router or reset the OSPF processes for this to take effect. You enter the clear ip ospf process command to do this. Notice that when you’re asked if you really want to do this, the prompt is “no”? That’s because all the OSPF adjacencies on this router will be lost and will have to begin the process again. That’s OK on a practice rack, not good in a production network. Don’t use that one at work.
The OSPF RID is not a complicated concept, but the fact that an interface doesn't have to be OSPF-enabled in order to have its IP address act as the RID takes some getting used to. And remember - when the router or switch asks you a question and the prompted answer is "no", take one step back and make sure you really want to do what you're about to do!
OSPF is a major topic on your CCNA exam, as well it should be. OSPF is a widely-used WAN protocol, and you need to learn the fundamentals before moving on to more complicated configurations. One such detail is the OSPF Router ID, or RID.
The RID is the dotted decimal value by which other OSPF routers will identify a given OSPF router. There are some interesting defaults for this value, and a command you should know to hardcode the RID. You had also better know what has to happen for this command to take effect!
In this example, R1 has an adjacency with R2 and R3 over the 172.12.123.0/24 frame network. R1 is the hub, with R2 and R3 as the spokes. No other interfaces are OSPF-enabled on any of the routers. Running show ip ospf neighbor on R1, we see some unusual values under "Neighbor ID", which is another name for the OSPF RID.
R1#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
3.3.3.3 0 FULL/DROTHER 00:01:57 172.12.123.3 Serial0
2.2.2.2 0 FULL/DROTHER 00:01:57 172.12.123.2 Serial0
Notice the Neighbor ID of each remote address is the loopback address. How can that be if they’re not OSPF-enabled?
When determining the Router ID (RID) of an OSPF-enabled router, OSPF will always use the numerically highest IP address on the router’s loopback interfaces, regardless of whether that loopback is OSPF-enabled.
What if there is no loopback? OSPF will then use the numerically highest IP address of the physical interfaces, regardless of whether that interface is OSPF-enabled.
BOTTOM LINE: An interface does not have to be running OSPF to have its IP address used as the OSPF RID.
The OSPF RID can be changed, but it requires a restart or to reinitialize the OSPF routing process. Use the router-id command to change the default RID of each router as shown, and clear the OSPF process to do so.
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router ospf 1
R1(config-router)#router-id 11.11.11.11
Reload or use "clear ip ospf process" command, for this to take effect
R1#clear ip ospf process
Reset ALL OSPF processes? [no]: yes
1d05h: %OSPF-5-ADJCHG: Process 1, Nbr 3.3.3.3 on Serial0 from 2WAY to
DOWN, Neighbor Down: Interface down or detached
1d05h: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on Serial0 from 2WAY to
DOWN, Neighbor Down: Interface down or detached
After entering the router-id command, the router console informed you that you have to reload the router or reset the OSPF processes for this to take effect. You enter the clear ip ospf process command to do this. Notice that when you’re asked if you really want to do this, the prompt is “no”? That’s because all the OSPF adjacencies on this router will be lost and will have to begin the process again. That’s OK on a practice rack, not good in a production network. Don’t use that one at work.
The OSPF RID is not a complicated concept, but the fact that an interface doesn't have to be OSPF-enabled in order to have its IP address act as the RID takes some getting used to. And remember - when the router or switch asks you a question and the prompted answer is "no", take one step back and make sure you really want to do what you're about to do!
CCNP / BSCI Exam Tutorial: ISIS Router Types
To pass the BSCI exam and earn your CCNP, you've got to know ISIS inside and out. There are many similarities between ISIS and OSPF, but one major difference is that ISIS has three different types of routers - Level 1 (L1), Level 2 (L2), and L1/L2.
L1 routers are contained in a single area, and are connected to other areas by an L1/L2 router. The L1 uses the L1/L2 router as a default gateway to reach destinations contained in other areas, much like an OSPF stub router uses the ABR as a default gateway.
L1 routers have no specific routing table entries regarding any destination outside their own area; they will use an L1/L2 router as a default gateway to reach any external networks. ISIS L1 routers in the same area must synchronize their databases with each other.
Just as we have L1 routers, we also have L2 routers. Anytime we're routing between areas (inter-area routing), an L2 or L1/L2 router must be involved. All L2 routers will have synchronized databases as well.
Both L1 and L2 routers send out their own hellos. As with OSPF, hello packets allow ISIS routers to form adjacencies. The key difference here is that L1 routers send out L1 hellos, and L2 routers send out L2 hellos. If you have an L1 router and an L2 router on the same link, they will not form an adjacency.
An ISIS router can act as an L1 and an L2 router at the same time; these routers are L1/L2 routers. An L1/L2 router can have neighbors in separate ISIS areas. The L1/L2 router will have two separate databases, though - one for L1 routes and another for L2 routes. L1/L2 is the default setting for Cisco routers running ISIS. The L1/L2 router is the router that makes it possible for an L1 router to send data to another area.
In the next part of my ISIS tutorial, we'll take a more detailed look at those ISIS hellos!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
To pass the BSCI exam and earn your CCNP, you've got to know ISIS inside and out. There are many similarities between ISIS and OSPF, but one major difference is that ISIS has three different types of routers - Level 1 (L1), Level 2 (L2), and L1/L2.
L1 routers are contained in a single area, and are connected to other areas by an L1/L2 router. The L1 uses the L1/L2 router as a default gateway to reach destinations contained in other areas, much like an OSPF stub router uses the ABR as a default gateway.
L1 routers have no specific routing table entries regarding any destination outside their own area; they will use an L1/L2 router as a default gateway to reach any external networks. ISIS L1 routers in the same area must synchronize their databases with each other.
Just as we have L1 routers, we also have L2 routers. Anytime we're routing between areas (inter-area routing), an L2 or L1/L2 router must be involved. All L2 routers will have synchronized databases as well.
Both L1 and L2 routers send out their own hellos. As with OSPF, hello packets allow ISIS routers to form adjacencies. The key difference here is that L1 routers send out L1 hellos, and L2 routers send out L2 hellos. If you have an L1 router and an L2 router on the same link, they will not form an adjacency.
An ISIS router can act as an L1 and an L2 router at the same time; these routers are L1/L2 routers. An L1/L2 router can have neighbors in separate ISIS areas. The L1/L2 router will have two separate databases, though - one for L1 routes and another for L2 routes. L1/L2 is the default setting for Cisco routers running ISIS. The L1/L2 router is the router that makes it possible for an L1 router to send data to another area.
In the next part of my ISIS tutorial, we'll take a more detailed look at those ISIS hellos!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
To pass the CCNA exam, you've got to know the role of the bandwidth command with IGRP and EIGRP and when to use it. In this tutorial, we'll configure IGRP over a frame relay hub-and-spoke network using the following networks:
R1 (the hub), R2, and R3 are running IGRP over the 172.12.123.0 /24 network. This is a T1 line.
R1 and R3 are also connected on a different subnet, 172.12.13.0 /24. The bandwidth of this connection is 512 KBPS.
R2 and R3 are also connected by an Ethernet segment, 172.23.0.0 /16.
We'll configure IGRP on R1, R2, and R3 with the router igrp 1 command. IGRP will run on all interfaces in the 172.12.0.0 and 172.23.0.0 network.
R1#conf t
R1(config)#router igrp 1
R1(config-router)#network 172.12.0.0
The “1” in the router igrp command refers to the Autonomous System (AS). IGRP is a classful routing protocol, so wildcard masks are not used in the network statements.
R2#conf t
R2(config-if)#router igrp 1
R2(config-router)#network 172.12.0.0
R2(config-router)#network 172.23.0.0
R3#conf t
R3(config-if)#router igrp 1
R3(config-router)#network 172.12.0.0
R3(config-router)#network 172.23.0.0
Run show ip route on R1. R1 will see three equal-cost paths to the Ethernet network. IGRP supports load-sharing over up to four equal-cost paths by default, so all three paths appear in the routing table. R1 will also see a route to the loopback address on R2 and two routes to the loopback address on R3. (You can also run show ip route igrp in order to see only the IGRP routes, which is the command we'll use here.)
R1#show ip route igrp
I 172.23.0.0/16 [100/8576] via 172.12.123.2, 00:00:02, Serial0
[100/8576] via 172.12.13.3, 00:00:02, Serial1
[100/8576] via 172.12.123.3, 00:00:01, Serial0
Remember that the numbers in the brackets following the network number in the routes are the Administrative Distance and the IGRP metric, in that order.
Note that classful masks are in use. IGRP does not support variable-length subnet masks (VLSM).
There are two serial connections between R1 and R3. IGRP is assuming that both lines are T1 lines, running at 1544 KBPS. The 172.12.13.0 network is participating in equal-cost load sharing because of IGRP’s bandwidth assumption - that all serial interfaces are connected to T1 lines.
To give IGRP a more accurate picture of the network’s bandwidth, configure bandwidth 512 on R1 and R3’s Serial1 interface (the interfaces on the 172.12.13.0 network).
R1#conf t
R1(config)#interface serial1
R1(config-if)#bandwidth 512
R3#conf t
R3(config)#interface serial 1
R3(config-if)#bandwidth 512
IGRP’s assumption that all serial lines run at 1544 KBPS is overridden by the bandwidth 512 command. IGRP now believes this line runs at 512 KBPS.
To see the effect of this command, clear your routing table on R1.
R1#clear ip route *
R1#show ip route igrp
I 172.23.0.0/16 [100/8576] via 172.12.123.3, 00:00:24, Serial0/0
[100/8576] via 172.12.123.2, 00:00:17, Serial0/0
The routing table is cleared with clear ip route *. To see only the routes received in IGRP updates instead of the entire table, run show ip route igrp.
One of the paths to 172.23.0.0 is now gone - the route that went through the 172.12.13.0 network. Now that IGRP sees that link as slower than the others, equal-cost load balancing will not occur over the 172.12.13.0 network.
It’s important to understand that the bandwidth command does not actually change the bandwidth of the connection; it changes IGRP’s assumption of what the bandwidth is.
In the next part of this IGRP load-balancing tutorial, we'll take a look at how to configure unequal-cost load balancing. See you then!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
R1 (the hub), R2, and R3 are running IGRP over the 172.12.123.0 /24 network. This is a T1 line.
R1 and R3 are also connected on a different subnet, 172.12.13.0 /24. The bandwidth of this connection is 512 KBPS.
R2 and R3 are also connected by an Ethernet segment, 172.23.0.0 /16.
We'll configure IGRP on R1, R2, and R3 with the router igrp 1 command. IGRP will run on all interfaces in the 172.12.0.0 and 172.23.0.0 network.
R1#conf t
R1(config)#router igrp 1
R1(config-router)#network 172.12.0.0
The “1” in the router igrp command refers to the Autonomous System (AS). IGRP is a classful routing protocol, so wildcard masks are not used in the network statements.
R2#conf t
R2(config-if)#router igrp 1
R2(config-router)#network 172.12.0.0
R2(config-router)#network 172.23.0.0
R3#conf t
R3(config-if)#router igrp 1
R3(config-router)#network 172.12.0.0
R3(config-router)#network 172.23.0.0
Run show ip route on R1. R1 will see three equal-cost paths to the Ethernet network. IGRP supports load-sharing over up to four equal-cost paths by default, so all three paths appear in the routing table. R1 will also see a route to the loopback address on R2 and two routes to the loopback address on R3. (You can also run show ip route igrp in order to see only the IGRP routes, which is the command we'll use here.)
R1#show ip route igrp
I 172.23.0.0/16 [100/8576] via 172.12.123.2, 00:00:02, Serial0
[100/8576] via 172.12.13.3, 00:00:02, Serial1
[100/8576] via 172.12.123.3, 00:00:01, Serial0
Remember that the numbers in the brackets following the network number in the routes are the Administrative Distance and the IGRP metric, in that order.
Note that classful masks are in use. IGRP does not support variable-length subnet masks (VLSM).
There are two serial connections between R1 and R3. IGRP is assuming that both lines are T1 lines, running at 1544 KBPS. The 172.12.13.0 network is participating in equal-cost load sharing because of IGRP’s bandwidth assumption - that all serial interfaces are connected to T1 lines.
To give IGRP a more accurate picture of the network’s bandwidth, configure bandwidth 512 on R1 and R3’s Serial1 interface (the interfaces on the 172.12.13.0 network).
R1#conf t
R1(config)#interface serial1
R1(config-if)#bandwidth 512
R3#conf t
R3(config)#interface serial 1
R3(config-if)#bandwidth 512
IGRP’s assumption that all serial lines run at 1544 KBPS is overridden by the bandwidth 512 command. IGRP now believes this line runs at 512 KBPS.
To see the effect of this command, clear your routing table on R1.
R1#clear ip route *
R1#show ip route igrp
I 172.23.0.0/16 [100/8576] via 172.12.123.3, 00:00:24, Serial0/0
[100/8576] via 172.12.123.2, 00:00:17, Serial0/0
The routing table is cleared with clear ip route *. To see only the routes received in IGRP updates instead of the entire table, run show ip route igrp.
One of the paths to 172.23.0.0 is now gone - the route that went through the 172.12.13.0 network. Now that IGRP sees that link as slower than the others, equal-cost load balancing will not occur over the 172.12.13.0 network.
It’s important to understand that the bandwidth command does not actually change the bandwidth of the connection; it changes IGRP’s assumption of what the bandwidth is.
In the next part of this IGRP load-balancing tutorial, we'll take a look at how to configure unequal-cost load balancing. See you then!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Friday, April 07, 2006
Friday's CCNA / CCNP Practice Questions
CCNA:
What is the network mask for a Class A address?
A. 255.255.255.255
B. 255.255.255.0
C. 255.255.0.0
D. 255.0.0.0
E. /8
F. /12
G. /16
H. /24
BSCI:
Which of the following values does NOT have to be agreed upon between potential OSPF neighbors in order for an adjacency to be created?
A. The process number.
B. The area number.
C. The hello and dead timers.
D. The stub flag setting.
BCMSN:
Which of the following is designed to detect unidirectional links?
A. Root Guard
B. Loop Guard
C. BackboneFast
D. UDLD
E. UplinkFast
F. BPDU Guard
CCNA:
What is the network mask for a Class A address?
A. 255.255.255.255
B. 255.255.255.0
C. 255.255.0.0
D. 255.0.0.0
E. /8
F. /12
G. /16
H. /24
BSCI:
Which of the following values does NOT have to be agreed upon between potential OSPF neighbors in order for an adjacency to be created?
A. The process number.
B. The area number.
C. The hello and dead timers.
D. The stub flag setting.
BCMSN:
Which of the following is designed to detect unidirectional links?
A. Root Guard
B. Loop Guard
C. BackboneFast
D. UDLD
E. UplinkFast
F. BPDU Guard
Thursday's CCNA / CCNP Practice Questions And Answers
Friday's questions will be posted later this afternoon.
CCNA:
Which of the following statements will create a static route that will send packets to the destination IP address 2.2.2.2, but cannot be used to send packets to any other destination?
A. ip route 2.2.2.2 0.0.0.0 172.12.123.1
B. ip route 2.2.2.2 255.255.255.255 172.12.123.1
C. ip route 2.2.2.2 172.12.123.1 0.0.0.0
D. ip route 2.2.2.2 172.12.123.1 255.255.255.255
E. ip route 0.0.0.0 0.0.0.0 172.12.123.1
F. ip route 0.0.0.0 172.12.123.1 0.0.0.0
ANSWER: B. A route that matches a single host is a host route, and a static host route has 255.255.255.255 for a mask. The end IP address is the next-hop IP address. "E" is a default static route, which could be used to route packets to 2.2.2.2, but the question stated that a route should be selected that would match no other routes.
CCNP / BSCI:
What is the ISIS equivalent of OSPF's Area 0?
A. The L2 backbone.
B. The L1 backbone.
C. There is no backbone area in ISIS.
D. Area 0
E. Area 0000.0000.0000
ANSWER: A. The L2 backbone is the equivalent of OSPF's Area 0.
CCNP / BCMSN
A switch port is enabled with PortFast. You are concerned that another switch may one day be connected to that switch port and become the root bridge of your network. What STP feature is designed to prevent this from happening?
A. Switch Guard
B. Loop Guard
C. BPDU Guard
D. UplinkFast
E. BackboneFast
ANSWER: C. When PortFast is configured on a port, it may be advisable to configure BPDU Guard on that port as well. No device connected to a PortFast port should be sending BPDUs. When BPDU Guard sees a BPDU come in on such a port, the port will be placed into err-disabled state.
Friday's questions will be posted later this afternoon.
CCNA:
Which of the following statements will create a static route that will send packets to the destination IP address 2.2.2.2, but cannot be used to send packets to any other destination?
A. ip route 2.2.2.2 0.0.0.0 172.12.123.1
B. ip route 2.2.2.2 255.255.255.255 172.12.123.1
C. ip route 2.2.2.2 172.12.123.1 0.0.0.0
D. ip route 2.2.2.2 172.12.123.1 255.255.255.255
E. ip route 0.0.0.0 0.0.0.0 172.12.123.1
F. ip route 0.0.0.0 172.12.123.1 0.0.0.0
ANSWER: B. A route that matches a single host is a host route, and a static host route has 255.255.255.255 for a mask. The end IP address is the next-hop IP address. "E" is a default static route, which could be used to route packets to 2.2.2.2, but the question stated that a route should be selected that would match no other routes.
CCNP / BSCI:
What is the ISIS equivalent of OSPF's Area 0?
A. The L2 backbone.
B. The L1 backbone.
C. There is no backbone area in ISIS.
D. Area 0
E. Area 0000.0000.0000
ANSWER: A. The L2 backbone is the equivalent of OSPF's Area 0.
CCNP / BCMSN
A switch port is enabled with PortFast. You are concerned that another switch may one day be connected to that switch port and become the root bridge of your network. What STP feature is designed to prevent this from happening?
A. Switch Guard
B. Loop Guard
C. BPDU Guard
D. UplinkFast
E. BackboneFast
ANSWER: C. When PortFast is configured on a port, it may be advisable to configure BPDU Guard on that port as well. No device connected to a PortFast port should be sending BPDUs. When BPDU Guard sees a BPDU come in on such a port, the port will be placed into err-disabled state.
Thursday, April 06, 2006
Wednesday's CCNA / CCNP Practice Questions And Answers
CCNA:
EIGRP is considered a hybrid protocol. Why?
A. EIGRP has characteristics of IGRP, but has additional features as well.
B. EIGRP has characteristics of both link state and distance vector protocols.
C. EIGRP has characteristics of both IGRP and RIP.
D. EIGRP has characteristics of both OSPF and ISIS.
ANSWER: B. EIGRP is considered a hybrid of distance vector and link state protocols. The other statements are all true, but none of them is the reason EIGRP is considered a hybrid.
BSCI:
What UDP port does BGP use to allow peering relationships between routers?
A. 80
B. 8080
C. 179
D. 100
E. 254
F. None of the above.
ANSWER: F. BGP uses TCP port 179 for peering, not UDP.
BCMSN:
What STP port state or states are bypassed when a port is configured with PortFast? Choose all that apply.
A. Blocking
B. Listening
C. Learning
D. Forwarding
ANSWER: B, C. Portfast allows a port to bypass the listening and learning port states. Repeat after me - Portfast should only be configured on a port leading to a single host device!
CCNA:
EIGRP is considered a hybrid protocol. Why?
A. EIGRP has characteristics of IGRP, but has additional features as well.
B. EIGRP has characteristics of both link state and distance vector protocols.
C. EIGRP has characteristics of both IGRP and RIP.
D. EIGRP has characteristics of both OSPF and ISIS.
ANSWER: B. EIGRP is considered a hybrid of distance vector and link state protocols. The other statements are all true, but none of them is the reason EIGRP is considered a hybrid.
BSCI:
What UDP port does BGP use to allow peering relationships between routers?
A. 80
B. 8080
C. 179
D. 100
E. 254
F. None of the above.
ANSWER: F. BGP uses TCP port 179 for peering, not UDP.
BCMSN:
What STP port state or states are bypassed when a port is configured with PortFast? Choose all that apply.
A. Blocking
B. Listening
C. Learning
D. Forwarding
ANSWER: B, C. Portfast allows a port to bypass the listening and learning port states. Repeat after me - Portfast should only be configured on a port leading to a single host device!
Thursday's CCNA / CCNP Practice Questions
The answers to Wednesday's questions will be posted later today.
CCNA:
Which of the following statements will create a static route that will send packets to the destination IP address 2.2.2.2, but cannot be used to send packets to any other destination?
A. ip route 2.2.2.2 0.0.0.0 172.12.123.1
B. ip route 2.2.2.2 255.255.255.255 172.12.123.1
C. ip route 2.2.2.2 172.12.123.1 0.0.0.0
D. ip route 2.2.2.2 172.12.123.1 255.255.255.255
E. ip route 0.0.0.0 0.0.0.0 172.12.123.1
F. ip route 0.0.0.0 172.12.123.1 0.0.0.0
CCNP / BSCI:
What is the ISIS equivalent of OSPF's Area 0?
A. The L2 backbone.
B. The L1 backbone.
C. There is no backbone area in ISIS.
D. Area 0
E. Area 0000.0000.0000
CCNP / BCMSN
A switch port is enabled with PortFast. You are concerned that another switch may one day be connected to that switch port and become the root bridge of your network. What STP feature is designed to prevent this from happening?
A. Switch Guard
B. Loop Guard
C. BPDU Guard
D. UplinkFast
E. BackboneFast
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
The answers to Wednesday's questions will be posted later today.
CCNA:
Which of the following statements will create a static route that will send packets to the destination IP address 2.2.2.2, but cannot be used to send packets to any other destination?
A. ip route 2.2.2.2 0.0.0.0 172.12.123.1
B. ip route 2.2.2.2 255.255.255.255 172.12.123.1
C. ip route 2.2.2.2 172.12.123.1 0.0.0.0
D. ip route 2.2.2.2 172.12.123.1 255.255.255.255
E. ip route 0.0.0.0 0.0.0.0 172.12.123.1
F. ip route 0.0.0.0 172.12.123.1 0.0.0.0
CCNP / BSCI:
What is the ISIS equivalent of OSPF's Area 0?
A. The L2 backbone.
B. The L1 backbone.
C. There is no backbone area in ISIS.
D. Area 0
E. Area 0000.0000.0000
CCNP / BCMSN
A switch port is enabled with PortFast. You are concerned that another switch may one day be connected to that switch port and become the root bridge of your network. What STP feature is designed to prevent this from happening?
A. Switch Guard
B. Loop Guard
C. BPDU Guard
D. UplinkFast
E. BackboneFast
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Everything You Ever Wanted To Know About CDP
The Cisco Discovery Protocol (CDP) sure looks simple enough, but there are quite a few details to know for success on the CCNA exam. In your CCNP studies, you'll be introduced to additional uses for CDP, but for now it's enough to know that CDP is designed to give you information regarding directly connected Cisco routers and switches.
CDP runs by default between all directly connected Cisco devices. CDP is also a Cisco-proprietary protocol - if the directly connected device is not a Cisco device, you won't see the information you wanted.
The basic CDP command to display information about the directly connected neighbor is show cdp neighbor.
R2#show cdp neighbor
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater
Device ID Local Intrfce Holdtme Capability Platform Port ID
R1 BRI0 167 R 2521 Dialer1
This command is particularly helpful when troubleshooting Cisco switches. There’s no need to trace wiring in a rack of Cisco devices to see what routers are connected to a Cisco switch when show cdp neighbor can be used. In the above output, you can see the remote device's hostname, what interface on the remote device is connected to the local device, the capability of the remote device, the remote device’s hardware platform, and the local interface that is connected to the remote device.
CDP can be disabled at both the global and interface level. To disable CDP at the interface level, run no cdp enable on the interface, and cdp enable to turn it back on.
cdp timer defines how often CDP packets are transmitted, and cdp holdtime defines how long a device will hold a received packet.
To turn CDP off for the entire router, run no cdp run. To view the current global status of CDP, run show cdp.
R2#show cdp
Global CDP information:
Sending CDP packets every 60 seconds
Sending a holdtime value of 180 seconds
CDP is running by default.
R2#conf t
R2(config)#cdp timer 45
R2(config)#cdp holdtime 100
The CDP timers are changed.
R2#show cdp
Global CDP information:
Sending CDP packets every 45 seconds
Sending a holdtime value of 100 seconds
The CDP values have been successfully changed. “show cdp interface” will give the timer information for each interface on the router.
R2#conf t
R2(config)#interface bri0
R2(config-if)#no cdp enable
CDP is disabled on the BRI interface. This does NOT have to be done to keep the line from dialing.
R2#conf t
R2(config)#no cdp run
CDP is disabled globally.
R2#show cdp
% CDP is not enabled
CDP has been successfully disabled.
Show cdp neighbor gives you a great deal of information, but what if you need the neighbor’s IP address? Just run show cdp neighbor detail. You will get even more information about that directly connected neighbor, including its IP address.
SW2#show cdp neighbor detail
-------------------------
Device ID: R4Entry address(es):
IP address: 172.12.23.4
Platform: cisco 2520,
Capabilities: Router
Interface: FastEthernet0/4,
Port ID (outgoing port): Ethernet0
Holdtime : 158 sec
The details of CDP are important to you on the job and in the CCNA exam room. When you find yourself negotiating a badly documented network, you can use CDP to "walk" through the network and create a network map for your client as well. Sometimes the simplest protocols are the most helpful!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
The Cisco Discovery Protocol (CDP) sure looks simple enough, but there are quite a few details to know for success on the CCNA exam. In your CCNP studies, you'll be introduced to additional uses for CDP, but for now it's enough to know that CDP is designed to give you information regarding directly connected Cisco routers and switches.
CDP runs by default between all directly connected Cisco devices. CDP is also a Cisco-proprietary protocol - if the directly connected device is not a Cisco device, you won't see the information you wanted.
The basic CDP command to display information about the directly connected neighbor is show cdp neighbor.
R2#show cdp neighbor
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater
Device ID Local Intrfce Holdtme Capability Platform Port ID
R1 BRI0 167 R 2521 Dialer1
This command is particularly helpful when troubleshooting Cisco switches. There’s no need to trace wiring in a rack of Cisco devices to see what routers are connected to a Cisco switch when show cdp neighbor can be used. In the above output, you can see the remote device's hostname, what interface on the remote device is connected to the local device, the capability of the remote device, the remote device’s hardware platform, and the local interface that is connected to the remote device.
CDP can be disabled at both the global and interface level. To disable CDP at the interface level, run no cdp enable on the interface, and cdp enable to turn it back on.
cdp timer defines how often CDP packets are transmitted, and cdp holdtime defines how long a device will hold a received packet.
To turn CDP off for the entire router, run no cdp run. To view the current global status of CDP, run show cdp.
R2#show cdp
Global CDP information:
Sending CDP packets every 60 seconds
Sending a holdtime value of 180 seconds
CDP is running by default.
R2#conf t
R2(config)#cdp timer 45
R2(config)#cdp holdtime 100
The CDP timers are changed.
R2#show cdp
Global CDP information:
Sending CDP packets every 45 seconds
Sending a holdtime value of 100 seconds
The CDP values have been successfully changed. “show cdp interface” will give the timer information for each interface on the router.
R2#conf t
R2(config)#interface bri0
R2(config-if)#no cdp enable
CDP is disabled on the BRI interface. This does NOT have to be done to keep the line from dialing.
R2#conf t
R2(config)#no cdp run
CDP is disabled globally.
R2#show cdp
% CDP is not enabled
CDP has been successfully disabled.
Show cdp neighbor gives you a great deal of information, but what if you need the neighbor’s IP address? Just run show cdp neighbor detail. You will get even more information about that directly connected neighbor, including its IP address.
SW2#show cdp neighbor detail
-------------------------
Device ID: R4Entry address(es):
IP address: 172.12.23.4
Platform: cisco 2520,
Capabilities: Router
Interface: FastEthernet0/4,
Port ID (outgoing port): Ethernet0
Holdtime : 158 sec
The details of CDP are important to you on the job and in the CCNA exam room. When you find yourself negotiating a badly documented network, you can use CDP to "walk" through the network and create a network map for your client as well. Sometimes the simplest protocols are the most helpful!
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Wednesday, April 05, 2006
Tuesday's CCNA and CCNP Practice Questions And Answers
Wednesday's questions are in a post from earlier today.
CCNA:
How many ACLs can be applied to a Cisco router interface? Choose one answer.
A. One.
B. Two, one applied to incoming traffic and one applied to outgoing traffic.
C. Two, with no restrictions on direction.
D. As many as you'd like, although Cisco recommends you not use more than five on any single interface.
ANSWER: B. You can apply two ACLs to a single Cisco interface, one filtering incoming traffic and another filtering outgoing traffic.
BSCI:
EIGRP uses Protocol Dependent Modules to support what protocols? Choose all that apply.
A. DECNet
B. IP
C. IPX
D. AppleTalk
E. TCP
F. UDP
ANSWER: B, C, D. EIGRP uses PDMs to support IP, IPX, and AppleTalk. Hey, four acronyms in one sentence!
BCMSN:
Which of the following etherchannel options enables the formation of an etherchannel while preventing any etherchannel negotiations? Choose one answer.
A. active
B. auto
C. desirable
D. on
E. passive
ANSWER: D. The "on" setting allows an etherchannel to form without negotiations.
Wednesday's questions are in a post from earlier today.
CCNA:
How many ACLs can be applied to a Cisco router interface? Choose one answer.
A. One.
B. Two, one applied to incoming traffic and one applied to outgoing traffic.
C. Two, with no restrictions on direction.
D. As many as you'd like, although Cisco recommends you not use more than five on any single interface.
ANSWER: B. You can apply two ACLs to a single Cisco interface, one filtering incoming traffic and another filtering outgoing traffic.
BSCI:
EIGRP uses Protocol Dependent Modules to support what protocols? Choose all that apply.
A. DECNet
B. IP
C. IPX
D. AppleTalk
E. TCP
F. UDP
ANSWER: B, C, D. EIGRP uses PDMs to support IP, IPX, and AppleTalk. Hey, four acronyms in one sentence!
BCMSN:
Which of the following etherchannel options enables the formation of an etherchannel while preventing any etherchannel negotiations? Choose one answer.
A. active
B. auto
C. desirable
D. on
E. passive
ANSWER: D. The "on" setting allows an etherchannel to form without negotiations.
Wednesday's CCNA / CCNP Practice Questions
CCNA:
EIGRP is considered a hybrid protocol. Why?
A. EIGRP has characteristics of IGRP, but has additional features as well.
B. EIGRP has characteristics of both link state and distance vector protocols.
C. EIGRP has characteristics of both IGRP and RIP.
D. EIGRP has characteristics of both OSPF and ISIS.
BSCI:
What UDP port does BGP use to allow peering relationships between routers?
A. 80
B. 8080
C. 179
D. 100
E. 254
F. None of the above.
BCMSN:
What STP port state or states are bypassed when a port is configured with PortFast? Choose all that apply.
A. Blocking
B. Listening
C. Learning
D. Forwarding
The answers to Tuesday's questions will be posted later today.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
CCNA:
EIGRP is considered a hybrid protocol. Why?
A. EIGRP has characteristics of IGRP, but has additional features as well.
B. EIGRP has characteristics of both link state and distance vector protocols.
C. EIGRP has characteristics of both IGRP and RIP.
D. EIGRP has characteristics of both OSPF and ISIS.
BSCI:
What UDP port does BGP use to allow peering relationships between routers?
A. 80
B. 8080
C. 179
D. 100
E. 254
F. None of the above.
BCMSN:
What STP port state or states are bypassed when a port is configured with PortFast? Choose all that apply.
A. Blocking
B. Listening
C. Learning
D. Forwarding
The answers to Tuesday's questions will be posted later today.
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Cisco CCNA Exam Tutorial: Configuring Standard Access Lists
I'm going to tell you from experience - you must master access lists if you're going to earn a Cisco certification, or be able to work with Cisco technologies and protocols. Access lists are used to identify traffic for dozens of different Cisco router and switch features, and you're going to see more and more of them as you earn your CCNA, CCNP, and CCIE. Since they use wildcard masks, this is just another reason to get comfortable with binary conversions as well.
Today we're going to take a look at basic ACL theory, particularly that of standard ACLs.
Access Control Lists (ACLs) allow a router to permit or deny packets based on a variety of criteria. An ACL is configured in global configuration mode, but is applied at the interface level. An ACL does not take effect until it is expressly applied to an interface with the ip access-group command. Packets can be filtered as they enter or exit an interface.
If a packet enters or exits an interface with an ACL applied, the packet is compared against the criteria of the ACL. If the packet matches the first line of the ACL, the appropriate “permit” or “deny” action is taken. If there is no match, the second line’s criterion is examined. Again, if there is a match, the appropriate action is taken; if there is no match, the third line of the ACL is compared to the appropriate value(s) of the packet.
This process continues until a match is found, at which time the ACL stops running. If no match is found, a default “deny” takes place, and the packet will not be processed. When an ACL is configured, if a packet is not expressly permitted, it will be subject to the implicit deny at the end of every ACL. This is the default behavior of an ACL and cannot be changed.
A standard ACL is concerned with only one factor, the source IP address of the packet. The destination IP address is not considered. Extended ACLs consider both the source and destination of the packet, and can consider the port number as well. The numerical range used for each is different: standard ACLs use the ranges 1-99 and 1300-1399; extended lists use 100-199 and 2000 to 2699.
There are several points worth repeating before beginning to configure standard ACLs.
Standard ACLs consider only the source IP address for matches.
The ACL lines are run from top to bottom. If there is no match on the first line, the second is run; if no match on the second, the third is run, and so on until there is a match, or the end of the ACL is reached. This top-to-bottom process places special importance on the order of the lines.
There is an implicit deny at the end of every ACL. If packets are not expressly permitted, they are implicitly denied.
If Router 3’s Ethernet interface should only accept packets with a source network of 172.12.12.0, the ACL will be configured like this:
R3#conf t
R3(config)#access-list 5 permit 172.12.12.0 0.0.0.255
The ACL consists of only one explicit line, one that permits packets from source IP address 172.12.12.0 /24. The implicit deny, which is not configured or seen in the running configuration, will deny all packets not matching the first line.
The ACL is then applied to the Ethernet0 interface:
R3#conf t
R3(config)#interface e0
R3(config-if)#ip access-group 5 in
But before you write any ACLs, it's a really good idea to see what other ACLs are already running on the router! To see the ACLs running on the router, use the command show access-list.
R1#show access-list
Standard IP access list 1
permit 0.0.0.0
Standard IP access list 5
permit 172.1.1.1
Standard IP access list 7
permit 23.3.3.3
Extended IP access list 100
permit tcp any any lt www (26 matches)
permit tcp any any neq telnet (12 matches)
deny ip any any
Extended IP access list 105
deny tcp any any eq www
deny tcp any any eq telnet
You're going to use ACLs all the way up the Cisco certification ladder, and throughout your career. The importance of knowing how to write and apply ACLs is paramount, and it all starts with mastering the fundamentals!
To your Cisco certification success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
I'm going to tell you from experience - you must master access lists if you're going to earn a Cisco certification, or be able to work with Cisco technologies and protocols. Access lists are used to identify traffic for dozens of different Cisco router and switch features, and you're going to see more and more of them as you earn your CCNA, CCNP, and CCIE. Since they use wildcard masks, this is just another reason to get comfortable with binary conversions as well.
Today we're going to take a look at basic ACL theory, particularly that of standard ACLs.
Access Control Lists (ACLs) allow a router to permit or deny packets based on a variety of criteria. An ACL is configured in global configuration mode, but is applied at the interface level. An ACL does not take effect until it is expressly applied to an interface with the ip access-group command. Packets can be filtered as they enter or exit an interface.
If a packet enters or exits an interface with an ACL applied, the packet is compared against the criteria of the ACL. If the packet matches the first line of the ACL, the appropriate “permit” or “deny” action is taken. If there is no match, the second line’s criterion is examined. Again, if there is a match, the appropriate action is taken; if there is no match, the third line of the ACL is compared to the appropriate value(s) of the packet.
This process continues until a match is found, at which time the ACL stops running. If no match is found, a default “deny” takes place, and the packet will not be processed. When an ACL is configured, if a packet is not expressly permitted, it will be subject to the implicit deny at the end of every ACL. This is the default behavior of an ACL and cannot be changed.
A standard ACL is concerned with only one factor, the source IP address of the packet. The destination IP address is not considered. Extended ACLs consider both the source and destination of the packet, and can consider the port number as well. The numerical range used for each is different: standard ACLs use the ranges 1-99 and 1300-1399; extended lists use 100-199 and 2000 to 2699.
There are several points worth repeating before beginning to configure standard ACLs.
Standard ACLs consider only the source IP address for matches.
The ACL lines are run from top to bottom. If there is no match on the first line, the second is run; if no match on the second, the third is run, and so on until there is a match, or the end of the ACL is reached. This top-to-bottom process places special importance on the order of the lines.
There is an implicit deny at the end of every ACL. If packets are not expressly permitted, they are implicitly denied.
If Router 3’s Ethernet interface should only accept packets with a source network of 172.12.12.0, the ACL will be configured like this:
R3#conf t
R3(config)#access-list 5 permit 172.12.12.0 0.0.0.255
The ACL consists of only one explicit line, one that permits packets from source IP address 172.12.12.0 /24. The implicit deny, which is not configured or seen in the running configuration, will deny all packets not matching the first line.
The ACL is then applied to the Ethernet0 interface:
R3#conf t
R3(config)#interface e0
R3(config-if)#ip access-group 5 in
But before you write any ACLs, it's a really good idea to see what other ACLs are already running on the router! To see the ACLs running on the router, use the command show access-list.
R1#show access-list
Standard IP access list 1
permit 0.0.0.0
Standard IP access list 5
permit 172.1.1.1
Standard IP access list 7
permit 23.3.3.3
Extended IP access list 100
permit tcp any any lt www (26 matches)
permit tcp any any neq telnet (12 matches)
deny ip any any
Extended IP access list 105
deny tcp any any eq www
deny tcp any any eq telnet
You're going to use ACLs all the way up the Cisco certification ladder, and throughout your career. The importance of knowing how to write and apply ACLs is paramount, and it all starts with mastering the fundamentals!
To your Cisco certification success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Tuesday, April 04, 2006
The BGP MED Attribute
I know from experience that one of the hardest parts of earning your CCNP is mastering BGP and all the attributes, rules, aggregations, aggrevations, confederations, reflectors, and some other stuff I'm sure I left out! Today we're going to take a look at when and how to use the BGP MED attribute.
That sounds a little confusing on paper, so let's walk through an example. R1 is in AS 1, and R2, R3, and R4 are in AS 234. R4 is advertising its loopback interface (4.4.4.4) via BGP, and R1 has two possible next-hops to get to that loopback - R2 (172.12.123.2) and R3 (172.12.123.3). Let's see which of the two paths R1 is using.
R1#show ip bgp 4.4.4.4
BGP routing table entry for 4.4.4.4/32, version 8
Paths: (2 available, best #2, table Default-IP-Routing-Table)
172.12.123.3 from 172.12.123.3 (3.3.3.3)
Origin IGP, localpref 100, valid, external
172.12.123.2 from 172.12.123.2 (2.2.2.2)
Origin IGP, localpref 100, valid, external, best
R1 is using 172.12.123.2 as the next-hop to enter AS 234. If all values are left at their default, we could have 100 routes being advertised from AS 234 to AS 1 and the next-hop would remain the same.
We can configure R2 and R3 to send different MED values to R1, and the router sending the lowest MED would be the preferred next-hop. (The MED is a metric, and the lowest metric is always preferred.) We'll configure the MED attribute on both R2 and R3, sending a MED of 200 from R2 and 100 from R3.
R2(config)#route-map SET_MED_200 permit 10
R2(config-route-map)#set metric 200
R2(config-route-map)#router bgp 234
R2(config-router)#neighbor 172.12.123.1 route-map SET_MED_200 out
R3(config)#route-map SET_MED_100 permit 10
R3(config-route-map)#set metric 100
R3(config-route-map)#router bgp 234
R3(config-router)#neighbor 172.12.123.1 route-map SET_MED_100 out
After clearing the BGP table on R1, R1 will still see both next-hop addresses and will still consider both to be valid, but the path through R3 will be selected due to its lower metric.
Just keep in mind that the MED is actually a metric, and lower metrics are more desirable in path selection. That will put you one step closer to passing the BSCI and earning your CCNP certification!
If there's one thing I can tell you about BGP, it's that you can definitely learn it if you take it piece by piece. Looking at BGP as a whole can be very intimidating, but learning one attribute and rule at a time is the secret to mastering BGP.
To your Cisco certification success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
I know from experience that one of the hardest parts of earning your CCNP is mastering BGP and all the attributes, rules, aggregations, aggrevations, confederations, reflectors, and some other stuff I'm sure I left out! Today we're going to take a look at when and how to use the BGP MED attribute.
That sounds a little confusing on paper, so let's walk through an example. R1 is in AS 1, and R2, R3, and R4 are in AS 234. R4 is advertising its loopback interface (4.4.4.4) via BGP, and R1 has two possible next-hops to get to that loopback - R2 (172.12.123.2) and R3 (172.12.123.3). Let's see which of the two paths R1 is using.
R1#show ip bgp 4.4.4.4
BGP routing table entry for 4.4.4.4/32, version 8
Paths: (2 available, best #2, table Default-IP-Routing-Table)
172.12.123.3 from 172.12.123.3 (3.3.3.3)
Origin IGP, localpref 100, valid, external
172.12.123.2 from 172.12.123.2 (2.2.2.2)
Origin IGP, localpref 100, valid, external, best
R1 is using 172.12.123.2 as the next-hop to enter AS 234. If all values are left at their default, we could have 100 routes being advertised from AS 234 to AS 1 and the next-hop would remain the same.
We can configure R2 and R3 to send different MED values to R1, and the router sending the lowest MED would be the preferred next-hop. (The MED is a metric, and the lowest metric is always preferred.) We'll configure the MED attribute on both R2 and R3, sending a MED of 200 from R2 and 100 from R3.
R2(config)#route-map SET_MED_200 permit 10
R2(config-route-map)#set metric 200
R2(config-route-map)#router bgp 234
R2(config-router)#neighbor 172.12.123.1 route-map SET_MED_200 out
R3(config)#route-map SET_MED_100 permit 10
R3(config-route-map)#set metric 100
R3(config-route-map)#router bgp 234
R3(config-router)#neighbor 172.12.123.1 route-map SET_MED_100 out
After clearing the BGP table on R1, R1 will still see both next-hop addresses and will still consider both to be valid, but the path through R3 will be selected due to its lower metric.
Just keep in mind that the MED is actually a metric, and lower metrics are more desirable in path selection. That will put you one step closer to passing the BSCI and earning your CCNP certification!
If there's one thing I can tell you about BGP, it's that you can definitely learn it if you take it piece by piece. Looking at BGP as a whole can be very intimidating, but learning one attribute and rule at a time is the secret to mastering BGP.
To your Cisco certification success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Tuesday's CCNA and CCNP Practice Questions
CCNA:
How many ACLs can be applied to a Cisco router interface? Choose one answer.
A. One.
B. Two, one applied to incoming traffic and one applied to outgoing traffic.
C. Two, with no restrictions on direction.
D. As many as you'd like, although Cisco recommends you not use more than five on any single interface.
BSCI:
EIGRP uses Protocol Dependent Modules to support what protocols? Choose all that apply.
A. DECNet
B. IP
C. IPX
D. AppleTalk
E. TCP
F. UDP
BCMSN:
Which of the following etherchannel options enables the formation of an etherchannel while preventing any etherchannel negotiations? Choose one answer.
A. active
B. auto
C. desirable
D. on
E. passive
CCNA:
How many ACLs can be applied to a Cisco router interface? Choose one answer.
A. One.
B. Two, one applied to incoming traffic and one applied to outgoing traffic.
C. Two, with no restrictions on direction.
D. As many as you'd like, although Cisco recommends you not use more than five on any single interface.
BSCI:
EIGRP uses Protocol Dependent Modules to support what protocols? Choose all that apply.
A. DECNet
B. IP
C. IPX
D. AppleTalk
E. TCP
F. UDP
BCMSN:
Which of the following etherchannel options enables the formation of an etherchannel while preventing any etherchannel negotiations? Choose one answer.
A. active
B. auto
C. desirable
D. on
E. passive
CCNA / CCNP Home Lab Tutorial: Using 2520s In Your Home Lab
I'm really glad to see so many CCNA and CCNP candidates investing in themselves by purchasing real Cisco routers and switches for a home practice lab. I can tell you from experience that when the time comes to perform - either in the exam room, on the job, and particularly during a job interview - certified individuals who have worked with lab equipment are far, far ahead of people who depended on "router simulators".
I know from experience that part of the excitement and anxiety of putting together your own CCNA / CCNP home lab is deciding what to buy! While you can make a workable home lab out of almost any combination of Cisco routers and switches, some routers are better suited for home lab work than others because they can fill multiple roles.
My personal favorite is the Cisco 2520. This router has four serial interfaces, making it an ideal frame relay switch. Don't forget that just because you're using a router as a frame switch, you can still use its routing capabilities. One setup I use is to use three of the four serial interfaces for frame switching and the fourth interface as a point-to-point network with another router. All you need is some DTE/DCE cables and you're all set.
The 2520 also comes with one ethernet interface and an ISDN interface, so that gives you even more options. Even if you're not planning to run ISDN in your home lab right now, you may choose to do so in the future - and with a 2520, you've already got the right router to do so. Keep in mind that if you are going to run ISDN in your home lab, you’ll need an ISDN device such as an ISDN simulator in your lab. (ISDN simulators are physical devices and are plentiful on ebay – they’re no relation to “router simulators”.)
Again, I want to reiterate that you can work any Cisco router into a CCNA / CCNP home lab - there's no "right" or "wrong" combination of equipment. But as with anything else, some combinations are better than others, so consider adding some 2520s to your home lab! This router gives you a great combination of interfaces and capabilities, plus the most important factor of all - real hands-on experience during your CCNA and CCNP exam preparation!
To your Cisco success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
I'm really glad to see so many CCNA and CCNP candidates investing in themselves by purchasing real Cisco routers and switches for a home practice lab. I can tell you from experience that when the time comes to perform - either in the exam room, on the job, and particularly during a job interview - certified individuals who have worked with lab equipment are far, far ahead of people who depended on "router simulators".
I know from experience that part of the excitement and anxiety of putting together your own CCNA / CCNP home lab is deciding what to buy! While you can make a workable home lab out of almost any combination of Cisco routers and switches, some routers are better suited for home lab work than others because they can fill multiple roles.
My personal favorite is the Cisco 2520. This router has four serial interfaces, making it an ideal frame relay switch. Don't forget that just because you're using a router as a frame switch, you can still use its routing capabilities. One setup I use is to use three of the four serial interfaces for frame switching and the fourth interface as a point-to-point network with another router. All you need is some DTE/DCE cables and you're all set.
The 2520 also comes with one ethernet interface and an ISDN interface, so that gives you even more options. Even if you're not planning to run ISDN in your home lab right now, you may choose to do so in the future - and with a 2520, you've already got the right router to do so. Keep in mind that if you are going to run ISDN in your home lab, you’ll need an ISDN device such as an ISDN simulator in your lab. (ISDN simulators are physical devices and are plentiful on ebay – they’re no relation to “router simulators”.)
Again, I want to reiterate that you can work any Cisco router into a CCNA / CCNP home lab - there's no "right" or "wrong" combination of equipment. But as with anything else, some combinations are better than others, so consider adding some 2520s to your home lab! This router gives you a great combination of interfaces and capabilities, plus the most important factor of all - real hands-on experience during your CCNA and CCNP exam preparation!
To your Cisco success,
Chris Bryant
CCIE #12933
www.thebryantadvantage.com
Monday's CCNA / CCNP Questions And Answers
Tuesday's Questions Will Be Posted Before Noon EST.
CCNA:
No choices on this one, my friends. What's the dotted decimal equivalent of the following binary string? 11110000 00110101 00110011 11111101
Answer: 240.53.51.253
CCNP / BSCI:What command will show you the route maps applied to interface ethernet 0?
A. show ip policy
B. show interface ethernet 0
C. show route map
D. show route map policy ethernet 0
ANSWER: A. As shown below, the show ip policy command will display this information.
R1#show ip policy
Interface Route map
Ethernet0 PASSTHEBSCI
CCNP / BCMSN:
Which of the following is true of IEEE 802.1Q?
A. This protocol encapsulates frames before they're sent across a trunk.
B. This protocol places a header on frames before they're sent across a trunk.
C. This protocol places a trailer on frames before they're sent across a trunk.
D. This protocol places no additional overhead on a frame before sending it across a trunk.
E. This protocol is appropriate for use in a multivendor environment.
F. This protocol is not appropriate for use in a multivendor environment.
ANSWER: E. Generally referred to as "dot1q", IEEE 802.1Q actually embeds trunking information into the frame. This process is referred to as tagging. The dreaded phrase "industry standard" applies to dot1q, and that means that it's appropriate for use in a multivendor environment.
Tuesday's Questions Will Be Posted Before Noon EST.
CCNA:
No choices on this one, my friends. What's the dotted decimal equivalent of the following binary string? 11110000 00110101 00110011 11111101
Answer: 240.53.51.253
CCNP / BSCI:What command will show you the route maps applied to interface ethernet 0?
A. show ip policy
B. show interface ethernet 0
C. show route map
D. show route map policy ethernet 0
ANSWER: A. As shown below, the show ip policy command will display this information.
R1#show ip policy
Interface Route map
Ethernet0 PASSTHEBSCI
CCNP / BCMSN:
Which of the following is true of IEEE 802.1Q?
A. This protocol encapsulates frames before they're sent across a trunk.
B. This protocol places a header on frames before they're sent across a trunk.
C. This protocol places a trailer on frames before they're sent across a trunk.
D. This protocol places no additional overhead on a frame before sending it across a trunk.
E. This protocol is appropriate for use in a multivendor environment.
F. This protocol is not appropriate for use in a multivendor environment.
ANSWER: E. Generally referred to as "dot1q", IEEE 802.1Q actually embeds trunking information into the frame. This process is referred to as tagging. The dreaded phrase "industry standard" applies to dot1q, and that means that it's appropriate for use in a multivendor environment.
Monday, April 03, 2006
A Subnetting Question (And Answer!)
This past week, I had a customer email me with a binary math question from a website that he couldn't quite figure out how to approach. (I am a big believer in the Non-Disclosure Agreement, and this question was not from a braindump site.) I showed him how to approach the question, and I thought I'd share our work with you. But before you look at the answer and how I got there, why not try the question on your own?
Here is the question:
Assuming four bits have been borrowed for subnets, identify the subnet network addresses. Choose three.
A: 192.168.14.8
B: 192.168.14.16
C: 192.168.14.24
D: 192.168.14.32
E: 192.168.14.148
F: 192.168.14.208
The approach:
You know this is a Class C address, so we've got eight host bits to begin with: 00000000
The question says four bits have been borrowed for subnetting, so we'll put the subnet bits in bold : 00000000
With all subnet bits set to zero, we get this: 192.168.14.0. That's the first network number, but it's not in the list.
Now set the smallest subnet bit to one - 00010000 - we get 192.168.14.16. That's one on the list.
The next smallest subnet bit combination is 00100000 - we get 192.168.14.32. That's two on the list.
The next smallest subnet bit combination is 00110000 - we get 192.168.14.48. You probably notice a pattern here. :) Each subsequent network number is going up by 16 in that last octet. Going up by 16 from here, we get... 48, 64, 80, 96, 112, 128, 144, 160, 176, 192, 208 --- 208 is the final choice from that list.
The hardest part of solving Cisco's CCNA subnetting questions is having a practiced approach. Believe me, it's not enough to know how to subnet, and you don't have time to figure an approach out in the exam room.
My Binary Math And Subnetting Success Ebook Library has helped CCNAs around the world conquer their binary math anxiety - and as a bonus to you for reading my blog, I'll give you two free days of CCNA Rack Rental time if you order the Binary Math Success Ebook Library within the next 24 hours. Follow the link below to read all about it, and claim your FREE rack rental time!
http://www.thebryantadvantage.com/TheBryantAdvantageMasterySeries.html
Free questions and free rack time. Pretty good deal! :)
To your Cisco success,
Chris Bryant
CCIE #12933
chris@thebryantadvantage.com
This past week, I had a customer email me with a binary math question from a website that he couldn't quite figure out how to approach. (I am a big believer in the Non-Disclosure Agreement, and this question was not from a braindump site.) I showed him how to approach the question, and I thought I'd share our work with you. But before you look at the answer and how I got there, why not try the question on your own?
Here is the question:
Assuming four bits have been borrowed for subnets, identify the subnet network addresses. Choose three.
A: 192.168.14.8
B: 192.168.14.16
C: 192.168.14.24
D: 192.168.14.32
E: 192.168.14.148
F: 192.168.14.208
The approach:
You know this is a Class C address, so we've got eight host bits to begin with: 00000000
The question says four bits have been borrowed for subnetting, so we'll put the subnet bits in bold : 00000000
With all subnet bits set to zero, we get this: 192.168.14.0. That's the first network number, but it's not in the list.
Now set the smallest subnet bit to one - 00010000 - we get 192.168.14.16. That's one on the list.
The next smallest subnet bit combination is 00100000 - we get 192.168.14.32. That's two on the list.
The next smallest subnet bit combination is 00110000 - we get 192.168.14.48. You probably notice a pattern here. :) Each subsequent network number is going up by 16 in that last octet. Going up by 16 from here, we get... 48, 64, 80, 96, 112, 128, 144, 160, 176, 192, 208 --- 208 is the final choice from that list.
The hardest part of solving Cisco's CCNA subnetting questions is having a practiced approach. Believe me, it's not enough to know how to subnet, and you don't have time to figure an approach out in the exam room.
My Binary Math And Subnetting Success Ebook Library has helped CCNAs around the world conquer their binary math anxiety - and as a bonus to you for reading my blog, I'll give you two free days of CCNA Rack Rental time if you order the Binary Math Success Ebook Library within the next 24 hours. Follow the link below to read all about it, and claim your FREE rack rental time!
http://www.thebryantadvantage.com/TheBryantAdvantageMasterySeries.html
Free questions and free rack time. Pretty good deal! :)
To your Cisco success,
Chris Bryant
CCIE #12933
chris@thebryantadvantage.com
The Blinky Thing
I don't care how many times I've seen the Cisco ad with the boss coming down to the network room, the line about their security being in "the blinky thing next to the doohickey" still cracks me up.
But seriously, is there anything scarier than the non-technical boss coming into the server room? :)
I don't care how many times I've seen the Cisco ad with the boss coming down to the network room, the line about their security being in "the blinky thing next to the doohickey" still cracks me up.
But seriously, is there anything scarier than the non-technical boss coming into the server room? :)
Sunday's Free CCNA And CCNP Questions And Answers
CCNA:
When a frame enters a switch, the first value the switch looks at is the:
A. source IP address
B. destination IP address
C. source MAC address
D. destination MAC address
ANSWER: A. The switch will look at the source MAC address before anything else.
BSCI:
Which of the following network topologies is best suited for ODR?
A. hub-and-spoke
B. broadcast
C. point-to-point
D. point-to-multipoint
ANSWER: A. On-Demand Routing (ODR) isn't just best suited for a hub-and-spoke network, but that's the only network ODR is suited for.
BCMSN:
What protocol uses the mulicast address 01-80-c2-00-00-00?
A. CDP
B. TCP
C. STP
D. HDLC
E. PPP
ANSWER: C. More specifically, this is the multicast address used for Bridge Protocol Data Unit (BPDU) transmission.
CCNA:
When a frame enters a switch, the first value the switch looks at is the:
A. source IP address
B. destination IP address
C. source MAC address
D. destination MAC address
ANSWER: A. The switch will look at the source MAC address before anything else.
BSCI:
Which of the following network topologies is best suited for ODR?
A. hub-and-spoke
B. broadcast
C. point-to-point
D. point-to-multipoint
ANSWER: A. On-Demand Routing (ODR) isn't just best suited for a hub-and-spoke network, but that's the only network ODR is suited for.
BCMSN:
What protocol uses the mulicast address 01-80-c2-00-00-00?
A. CDP
B. TCP
C. STP
D. HDLC
E. PPP
ANSWER: C. More specifically, this is the multicast address used for Bridge Protocol Data Unit (BPDU) transmission.
Monday's Free CCNA / CCNP Exam Questions
CCNA:
No choices on this one, my friends. What's the dotted decimal equivalent of the following binary string?
11110000 00110101 00110011 11111101
CCNP / BSCI:
What command will show you the route maps applied to interface ethernet 0?
A. show ip policy
B. show interface ethernet 0
C. show route map
D. show route map policy ethernet 0
CCNP / BCMSN:
Which of the following is true of IEEE 802.1Q?
A. This protocol encapsulates frames before they're sent across a trunk.
B. This protocol places a header on frames before they're sent across a trunk.
C. This protocol places a trailer on frames before they're sent across a trunk.
D. This protocol places no additional overhead on a frame before sending it across a trunk.
E. This protocol is appropriate for use in a multivendor environment.
F. This protocol is not appropriate for use in a multivendor environment.
CCNA:
No choices on this one, my friends. What's the dotted decimal equivalent of the following binary string?
11110000 00110101 00110011 11111101
CCNP / BSCI:
What command will show you the route maps applied to interface ethernet 0?
A. show ip policy
B. show interface ethernet 0
C. show route map
D. show route map policy ethernet 0
CCNP / BCMSN:
Which of the following is true of IEEE 802.1Q?
A. This protocol encapsulates frames before they're sent across a trunk.
B. This protocol places a header on frames before they're sent across a trunk.
C. This protocol places a trailer on frames before they're sent across a trunk.
D. This protocol places no additional overhead on a frame before sending it across a trunk.
E. This protocol is appropriate for use in a multivendor environment.
F. This protocol is not appropriate for use in a multivendor environment.
Using The IP Name-Server Command
I'll have a couple of exclusive Cisco tutorials up later today, along with the free questions of the day - and an exclusive subnetting review as well.
When I started studying for the CCNA, it just seemed like there were a hundred different ways to configure DNS options on a Cisco router. Use broadcasts to find the DNS server, don't use a DNS server at all, use a local table, etc.... so today, to help you keep the DNS stuff straight, here's a tutorial on the ip name-server command.
And there really aren't a hundred different DNS options - it just seems that way! ;)
When a command is mistyped on a Cisco router - and we all do that, don't we? - the default behavior of the router is to attempt to resolve it via DNS. First, the router looks for an IP Host table on the local router to perform this resolution – that’s what the “translating” word in the output is referring to. If there’s no IP Host table or the IP Host table doesn’t contain an entry for what you typed, the router will send a broadcast in an attempt to resolve this name through a remote DNS server. To prevent this broadcast, enter the global command no ip domain-lookup. Of course, to use DNS to resolve hostnames, ip domain-lookup would have to be reenabled if it’s been turned off.
I'll just enter a few random letters so you can see what's going on.
R2#contin
Translating "contin"...domain server (255.255.255.255)
% Unknown command or computer name, or unable to find computer address
A command is mistyped as “contin”. The Cisco router’s default behavior is to resolve this entry locally via an IP Host table, which isn't present on the router. (See where the router output says Translating "contin"? That's the router looking for a matching entry in an IP Host table.)
In this case, there is no IP Host table, so a broadcast is then sent out to find a DNS server to perform the name resolution. The DNS lookup attempt must time out before the configuration can continue.
R2#conf t
R2(config)#no ip domain-lookup
R2#contin
Translating "contin"
% Unknown command or computer name, or unable to find computer address
With “no ip domain-lookup” configured, the router doesn’t attempt to find a remote DNS server. It sees there is no local resolution configured and almost immediately sends a message to the console that the name can’t be resolved.
R2#conf t
R2(config)#ip domain-lookup
R2(config)#ip name-server 10.1.1.1
R2#contin
Translating "contin"...domain server (10.1.1.1)
A DNS server is installed on the network with the IP address 10.1.1.1. DNS lookup is reenabled with the command ip domain-lookup, and the IP address of the DNS server is specified with the ip name-server command.
I'll have a couple of exclusive Cisco tutorials up later today, along with the free questions of the day - and an exclusive subnetting review as well.
When I started studying for the CCNA, it just seemed like there were a hundred different ways to configure DNS options on a Cisco router. Use broadcasts to find the DNS server, don't use a DNS server at all, use a local table, etc.... so today, to help you keep the DNS stuff straight, here's a tutorial on the ip name-server command.
And there really aren't a hundred different DNS options - it just seems that way! ;)
When a command is mistyped on a Cisco router - and we all do that, don't we? - the default behavior of the router is to attempt to resolve it via DNS. First, the router looks for an IP Host table on the local router to perform this resolution – that’s what the “translating” word in the output is referring to. If there’s no IP Host table or the IP Host table doesn’t contain an entry for what you typed, the router will send a broadcast in an attempt to resolve this name through a remote DNS server. To prevent this broadcast, enter the global command no ip domain-lookup. Of course, to use DNS to resolve hostnames, ip domain-lookup would have to be reenabled if it’s been turned off.
I'll just enter a few random letters so you can see what's going on.
R2#contin
Translating "contin"...domain server (255.255.255.255)
% Unknown command or computer name, or unable to find computer address
A command is mistyped as “contin”. The Cisco router’s default behavior is to resolve this entry locally via an IP Host table, which isn't present on the router. (See where the router output says Translating "contin"? That's the router looking for a matching entry in an IP Host table.)
In this case, there is no IP Host table, so a broadcast is then sent out to find a DNS server to perform the name resolution. The DNS lookup attempt must time out before the configuration can continue.
R2#conf t
R2(config)#no ip domain-lookup
R2#contin
Translating "contin"
% Unknown command or computer name, or unable to find computer address
With “no ip domain-lookup” configured, the router doesn’t attempt to find a remote DNS server. It sees there is no local resolution configured and almost immediately sends a message to the console that the name can’t be resolved.
R2#conf t
R2(config)#ip domain-lookup
R2(config)#ip name-server 10.1.1.1
R2#contin
Translating "contin"...domain server (10.1.1.1)
A DNS server is installed on the network with the IP address 10.1.1.1. DNS lookup is reenabled with the command ip domain-lookup, and the IP address of the DNS server is specified with the ip name-server command.
Sunday, April 02, 2006
Sunday's Free CCNA / CCNP Questions
CCNA:
When a frame enters a switch, the first value the switch looks at is the:
A. source IP address
B. destination IP address
C. source MAC address
D. destination MAC address
BSCI:
Which of the following network topologies is best suited for ODR?
A. hub-and-spoke
B. broadcast
C. point-to-point
D. point-to-multipoint
BCMSN
What protocol uses the mulicast address 01-80-c2-00-00-00?
A. CDP
B. TCP
C. STP
D. HDLC
E. PPP
CCNA:
When a frame enters a switch, the first value the switch looks at is the:
A. source IP address
B. destination IP address
C. source MAC address
D. destination MAC address
BSCI:
Which of the following network topologies is best suited for ODR?
A. hub-and-spoke
B. broadcast
C. point-to-point
D. point-to-multipoint
BCMSN
What protocol uses the mulicast address 01-80-c2-00-00-00?
A. CDP
B. TCP
C. STP
D. HDLC
E. PPP
Saturday, April 01, 2006
Today's Free CCNA / CCNP Questions
I'll have a few more tutorials up later today, and a bonus subnetting feature over the weekend as well.
Today's CCNA Question:
Which of the following are held in RAM?
A. The startup configuration.
B. The running configuration.
C. The routing tables.
D. The IOS images.
E. The POST programs.
Today's BSCI Question:
You're running RIPv2 and OSPF on a single router. Your RIP domain is carrying VLSM information in its updates and you want those subnets to be seen by all routers in your OSPF domain. What command will perform this task?
A. redistribute
B. redistribute rip
C. redistribute rip subnets
D. redistribute ospf rip subnets
Today's BCMSN Question:
Which of the following statements are true of the Forward Delay value? Choose all that apply.
A. This is the interval between BPDUs.
B. This is the length of time of both the listening and learning port states.
C. This is the length of time a switch will retain the "best" BPDU's contents.
D. The default is 2 seconds.
E. The default is 10 seconds.
F. The default is 15 seconds.
G. To change this value for a particular switch, change the value on that switch only.
H. To change this value for a particular switch, the change must be made on the root bridge.
Yesterday's Questions And Answers:
CCNA
What term describes the amount of bandwidth that will be available to a frame relay provider's customer?
A. BA
B. DE
C. DC
D. CIR
E. BE
F. BC
ANSWER: D. The Committed Information Rate, or CIR, is the minimum amount of bandwidth a frame relay provider guarantees a customer.
BSCI
Cisco OSPF design guidelines state that a router should be in no more than how many areas?
A. Two
B. Three
C. Four
D. Five
ANSWER: B. As with all design guidelines, they were created to be broken. ;) But the official Cisco word is that no router should be in more than three areas.
BCMSN
Which of the following switches will become the root bridge?
A. Switch A, with a BID of 24768:aa-aa-aa-aa-aa-aa
B. Switch B, with a BID of 24768:bb-bb-bb-bb-bb-bb
C. Switch C, with a BID of 24768:cc-cc-cc-cc-cc-cc
D. Switch D, with a BID of 32768:dd-dd-dd-dd-dd-dd
ANSWER: A. This should look familiar to you from your CCNA studies. The BID is a combination of the switch's MAC address and a priority value, which by default is 32768. The MAC address only comes into play when two or more switches have the same priority. Since the first three switches do have the same priority, the switch with the lowest MAC address will become the root bridge - and in hex, aa-aa-aa-aa-aa-aa is lower than bb-bb-bb-bb-bb-bb and cc-cc-cc-cc-cc-cc.
I'll have a few more tutorials up later today, and a bonus subnetting feature over the weekend as well.
Today's CCNA Question:
Which of the following are held in RAM?
A. The startup configuration.
B. The running configuration.
C. The routing tables.
D. The IOS images.
E. The POST programs.
Today's BSCI Question:
You're running RIPv2 and OSPF on a single router. Your RIP domain is carrying VLSM information in its updates and you want those subnets to be seen by all routers in your OSPF domain. What command will perform this task?
A. redistribute
B. redistribute rip
C. redistribute rip subnets
D. redistribute ospf rip subnets
Today's BCMSN Question:
Which of the following statements are true of the Forward Delay value? Choose all that apply.
A. This is the interval between BPDUs.
B. This is the length of time of both the listening and learning port states.
C. This is the length of time a switch will retain the "best" BPDU's contents.
D. The default is 2 seconds.
E. The default is 10 seconds.
F. The default is 15 seconds.
G. To change this value for a particular switch, change the value on that switch only.
H. To change this value for a particular switch, the change must be made on the root bridge.
Yesterday's Questions And Answers:
CCNA
What term describes the amount of bandwidth that will be available to a frame relay provider's customer?
A. BA
B. DE
C. DC
D. CIR
E. BE
F. BC
ANSWER: D. The Committed Information Rate, or CIR, is the minimum amount of bandwidth a frame relay provider guarantees a customer.
BSCI
Cisco OSPF design guidelines state that a router should be in no more than how many areas?
A. Two
B. Three
C. Four
D. Five
ANSWER: B. As with all design guidelines, they were created to be broken. ;) But the official Cisco word is that no router should be in more than three areas.
BCMSN
Which of the following switches will become the root bridge?
A. Switch A, with a BID of 24768:aa-aa-aa-aa-aa-aa
B. Switch B, with a BID of 24768:bb-bb-bb-bb-bb-bb
C. Switch C, with a BID of 24768:cc-cc-cc-cc-cc-cc
D. Switch D, with a BID of 32768:dd-dd-dd-dd-dd-dd
ANSWER: A. This should look familiar to you from your CCNA studies. The BID is a combination of the switch's MAC address and a priority value, which by default is 32768. The MAC address only comes into play when two or more switches have the same priority. Since the first three switches do have the same priority, the switch with the lowest MAC address will become the root bridge - and in hex, aa-aa-aa-aa-aa-aa is lower than bb-bb-bb-bb-bb-bb and cc-cc-cc-cc-cc-cc.
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