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Archive for March, 2010
Weekly Open Ended Question #8
Mar 18th
The answer to the seventh question has been added to the post.
Eighth question:
Name different ways to enable OSPF on a router.
Please post answers in the comments (without Googling)!
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Highlight for answer:
OSPF can be enable from router configuration mode with the “network [network] [inverse mask] area [area number]” command, or at the interface level with “ip ospf [process id] area [area number]“.
Troubleshooting Lab #3
Mar 11th
This one is a little different (again). I’ll be posting the .net file with the configs, like last time. I will also have accessibility to the topology through a sandboxed Dynamips VM. This time you will be able to see the running config.
You can run the .net on your own Dynamips server or you can use mine. Run the topology and login with username “tshoot” and password “tshoot”. This user only has privilege level 1, so show commands will be available, but show run will not be. You can also login with username: “shrun” and password: “shrun”, this will print the running config and boot you out. I would like to grant full privilege 15 access, but I’m worried about people messing with the configs, this is after all a public post. Obviously you could get around this pretty easily, but that would defeat the purpose. 
Weekly Open Ended Question #7
Mar 9th
The answer to the sixth question has been added to the post.
Seventh question:
What is ODR? How does it work?
Please post answers in the comments (without Googling)!
Highlight for answer:
On-Demand Routing (ODR) is an enhancement to Cisco Discovery Protocol (CDP), a protocol used to discover other Cisco devices on either broadcast or non-broadcast media. ODR was added to CDP to advertise the connected IP prefix of a stub router via CDP.
Troubleshooting Lab #2
Mar 6th
I don’t usually post on weekends, but I want to try out an idea for troubleshooting labs (and I’m bored). This is the second in the series. We got a lot of answers for the last one, most all of which were correct. I’ve started requiring approval for all comments, this way the answer won’t be posted immediately after I make the post. I think this will be more fun and encourage more people to answer.
This time we’ll have the topology and a .net file, but I won’t be posting configs and you guys won’t be able to do “sh run”. I’ve saved the configs inside the .net file. Run the topology and login with username “tshoot” and password “tshoot”. This user only has privilege level 1, so show commands will be available, but show run will not be. Obviously you could get around this pretty easily, but that would defeat the purpose.
Troubleshooting Lab #1
Mar 5th
This will be the first in a series of troubleshooting labs. I will post a topology and the issue I’m seeing. Hopefully you guys will attempt to solve it and post your ideas, questions and solutions in the comments.
We’ll start with a relatively easy one. Today we are having an issue with BGP neighbor relationships not forming.
Here’s our Topology:
Here’s R1′s config:
hostname R1 ! ip cef ! interface Loopback0 ip address 1.1.1.1 255.255.255.255 ! interface Serial0/0 description To R2 ip address 10.1.1.2 255.255.255.254 ! router bgp 5000 no synchronization bgp log-neighbor-changes neighbor 2.2.2.2 remote-as 6000 neighbor 2.2.2.2 ebgp-multihop 2 neighbor 2.2.2.2 update-source Loopback0 no auto-summary ! ip route 0.0.0.0 0.0.0.0 10.1.1.3 |
And R2:
hostname R2 ! ip cef ! interface Loopback0 ip address 2.2.2.2 255.255.255.255 ! interface Serial0/0 description To R1 ip address 10.1.1.3 255.255.255.254 ! router bgp 6000 no synchronization bgp log-neighbor-changes neighbor 1.1.1.1 remote-as 5000 neighbor 1.1.1.1 ebgp-multihop 2 neighbor 1.1.1.1 update-source Loopback0 no auto-summary ! ip route 0.0.0.0 0.0.0.0 10.1.1.2 |
Now some show commands:
R2#sh ip bgp summ BGP router identifier 2.2.2.2, local AS number 6000 BGP table version is 1, main routing table version 1 Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd 1.1.1.1 4 5000 0 0 0 0 0 never Active R1#sh ip bgp summ BGP router identifier 1.1.1.1, local AS number 5000 BGP table version is 1, main routing table version 1 Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd 2.2.2.2 4 6000 0 0 0 0 0 never Active |
We see that the relationship will not form. You guys tell me why.
I’m attaching the .net file, with it and the configs above you should be able to replicate this easily.
The Troubleshooting Lab #1 .net file
(Don’t forget to change your paths)
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