• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

Question about CDP neighbors...

This is one of those issues that is completely trivial and irrelevant to the function of the network, so it shouldn't bother me, but... Every time I see it, it annoys the crap out of me, and I want to fix it.

General network layout:

Router A and Router B are directly connected via serial. Router A is connected to a 2970 via Gigabit0/0. Routers A and B are both connected to a second 2970 both via Gigabit 0/1. Router B was previously connected to the first 2970 via it's own Gigabit0/0 as a redundant link, but that link is currently down. It detected the switch as a neighbor at the time.

The problem:

Routers A and B show each other as a CDP neighbor via serial. Router A shows the first 2970 (Gigabit0/0) as a neighbor. Neither Router A or B show the second 2970 (Gigabit0/1) as a CDP neighbor. However, said 2970 shows both routers as a CDP neighbor out the respective ports.

My question is... Why does CDP appear to only be functioning one-way, and how can I fix it?
 
It doesn't show disabled in the running config. If I remember correctly, default settings don't show up in the running config, which implies it's enabled, as that is the default. I can try enabling it when I get home, but I think I already tried that.
 
I'd do a:

NO CDP RUN

CDP RUN

WRITE MEMORY

and try again

also you may want to check CISCO for any bugs in the IOS you have installed pertaining to CDP
 
Back
Top