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CDP Neighbor Device ID mystery

cajalat
Level 1
Level 1

I have several IOS based switches that when I issue the "show cdp nei detail" command I get a Device ID that includes the domain name of the device. I can't for the life of me get rid of the domain name (I don't want it to show). I've removed all references to any domain name from the switch config yet it still shows. Any idea how the domain name is being attached to the Device ID name when doing a show cdp neig?

1 Accepted Solution

Accepted Solutions

I had a look through some old cases and found a previous customer with the same problem.

Although the notes are sketchy, to fix the problem they changed their hostname, waited a minute and changed it back. They then rebooted the router and were unsure which step actually fixed it.

Can you try shutting cdp down, changing the hostname, starting cdp up again and see if that fixes it?

Thanks again,

Michael.

View solution in original post

20 Replies 20

vijayasankar
Level 4
Level 4

Hi,

The domain name that you get in show cdp nei detail" command is VTP domain name of the adjacent switch.

As long as you have a VTP domain name in the VTP server, it will be displayed via CDP exchange between the switches.

You cannot block it from getting displayed.

HTH

-VJ

I'm not running any VTP services (Only transparrent). Also my VTP domain is not the same as my DNS domain and what's showing in the Device ID is the DNS domain name. e.g.:

Router6509#sh cdp neighbors gigabitEthernet 1/22 detail

-------------------------

Device ID: cat4506ios.tch.harvard.edu

Entry address(es):

IP address: 10.64.0.212

Platform: cisco WS-C4506, Capabilities: Switch IGMP

Interface: GigabitEthernet1/22, Port ID (outgoing port): GigabitEthernet1/2

Holdtime : 146 sec

Version :

Cisco IOS Software, Catalyst 4000 L3 Switch Software (cat4000-I9S-M), Version 12.2(25)EWA4, RELEASE SOFTWARE (fc1)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2005 by Cisco Systems, Inc.

Compiled Fri 23-Sep-05 13:31 by ssearch

advertisement version: 2

VTP Management Domain: 'CH5'

Native VLAN: 2000

Duplex: full

Router6509#

So my question is how do I get rid of "tch.harvard.edu" from the device id?

Your switches are performing 'ip domain-lookup' to populate the Device ID: field.

Try to no ip domain-lookup command then clear the cdp table with the command:

clear cdp table.

Please rate helpful posts.

Thanks

I've removed all references to ip domain* as well as all references to DNS servers from the config days ago with no luck. This seems to only happen with 4500 with SUPII+'s. Other deivces such as 6509's running native do not have that problem. As a matter of fact, on native 6509 I can control that device ID by adding "ip domain-name" and I can remove it by removing that line pretty consistently. All the 4500's and 3560's are giving me trouble.

The main reason why I want to do this is because when I issue a "show cdp nei" command I want to see 1 line per CDP neighbor. With the domain name in there the line is broken into two so that now commands such as "sho cdp nei | inc SWITCHNAME" break when the DeviceID is on one line while the rest of the info on another line. On my 6509 I have dozens of neighbors and the output gets ugly really quick when each neighbor is split onto two lines.

HI

CDP updates should refresh for every update interval.

Can you try disabling CDP on the 4500 and enable it again, to see if it make changes.

-VJ

You really had my hopes up since I never thought to try that. Anyway, just tried it and waited for the holdtime timer to expire. Made sure the CDP info aged out of the 6509 and then re-enabled on the 4500 again. Same problem :(

So I decided this time to remove all dns related commands "no ip name-server" and "no ip domain*". Did a "no cdp run" and waited for the holdtime timer to expire and then re-enabled. Again, same problem :( This has got to be a software bug I'm thinking.

Did you try clearing the table with

'clear cdp table' ?

Oops. As you say, for me it appears to be a software bug.

I think the only to get rid of that is to remove the domain references in the config and reload the neighbor switch, to flush the stay details in the memory.

-VJ

I tried clearing "clear cdp tab" on both ends and removed all references to DNS but still it stays in memory it seems. I compared against another switch that is identical (4506 with SupII+) and that one works fine. The only difference is the code. Otherwise the configs are identical. That's why my hunch at this point is a software bug. Unfortunately I can't reload the switch tonight with new code so I'll have to wait for a maintenance window to reload it. I'll report back with what I find. Thanks for the suggestions.

Hello,

I would try (under global configuration mode),

no cdp run

cdp run

end

This will stop and start CDP along with clearing the table.

Already done that. See thread above for other things I've tried.

I had a look through some old cases and found a previous customer with the same problem.

Although the notes are sketchy, to fix the problem they changed their hostname, waited a minute and changed it back. They then rebooted the router and were unsure which step actually fixed it.

Can you try shutting cdp down, changing the hostname, starting cdp up again and see if that fixes it?

Thanks again,

Michael.

Just a wild guess, can you try to disable / enable cdp v2 and test again. i.e. if cdpv2 is enabled, then try to disable it; otherwise, enable it and try again.....

Moreover, is all CDP enabled w/ same ver. ?

Hope this helps.

YOU ARE MY HERO!!!!

I've been struggling with this for months now. It is FINALLY fixed. Thanks a million.

Here is exactly what I did:

- Changed the hostname

- waited for the holdtime timer to expire

- changed the hostname again

That did the trick. I didn't have to reload or disable CDP.

You ROCK.

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