show cdp neighbors problem

[mrkan]

1. After I run show cdp nei I don't get anything... like there is no neighbors. I know for sure that there are some.

show ip route shows nothing.

I enabled CDP with cdp run and I set v-2 advertising.

All my interfaces are down (Fa 0/0, Fa 0/1 and S 0/0)

Am I doing something wrong? How can I see what routers are in the neighborhood?

Based on the result (ip addresses) of the neigboring routers I have to come up with addresses for my interfaces so I can have them up and running.

Is there any other way to see if something is arround?

2. What is loopback and what is its purpose?

Thanks

 

[jimfixit]

CDP still requires that the interfaces be up...if you have no link you can't issued the CDP packets to the neighbor so naturally it can't reply either.... CHeck to be sure your interfaces aren't shut.

loop back serves many purposes. It can control what routers get elected to certain functions in specific protocols, it can also give you a convenient addresss to ping against that is NOT dependent upon a specific interface being "up".

 

[mrkan]

so, how can I make my interfaces running? Can I assign some ip addresses just to have them running? some random (this doesn't sound proper) ip address?

I assume after I would see my CDP neighbors, I would know what IP address to use for my interfaces. There is a rule (in my case that I have to use), that if neghbors address is x.x.x.254, router interface address is x.x.x.253 or vice versa.

Thanks.

 

[burtsbees]

The interface needs a "no shut", and the neighbor at least needs an IP address.

Burt