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CDP Neighbor Device ID mystery

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
Bronze

Re: CDP Neighbor Device ID mystery

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.

20 REPLIES

Re: CDP Neighbor Device ID mystery

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

New Member

Re: CDP Neighbor Device ID mystery

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?

Hall of Fame Super Bronze

Re: CDP Neighbor Device ID mystery

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

New Member

Re: CDP Neighbor Device ID mystery

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.

Re: CDP Neighbor Device ID mystery

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

New Member

Re: CDP Neighbor Device ID mystery

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.

Hall of Fame Super Bronze

Re: CDP Neighbor Device ID mystery

Did you try clearing the table with

'clear cdp table' ?

Re: CDP Neighbor Device ID mystery

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

New Member

Re: CDP Neighbor Device ID mystery

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.

Bronze

Re: CDP Neighbor Device ID mystery

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.

New Member

Re: CDP Neighbor Device ID mystery

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

Bronze

Re: CDP Neighbor Device ID mystery

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.

Silver

Re: CDP Neighbor Device ID mystery

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.

New Member

Re: CDP Neighbor Device ID mystery

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.

Silver

Re: CDP Neighbor Device ID mystery

This is great.

Michael, can you advise is this procedure documented in CCO or somewhere else ? It is very useful. Thx.

New Member

Re: CDP Neighbor Device ID mystery

One other thing....

You need to make sure NOT to use "ip domain-name my.domain.com" form of the command as this will append the domain name to the DeviceID. I use the "ip domain-list my.domain.com" form instead. Also, you need to pay SPECIAL ATTENTION to VOIP gateways and Call Manager configs. For VOIP gateways such as 2851's using MGCP the Call manager will configure the gateway with whatever name you gave it originally. So if you change (remove) the domain name then you'll need to make sure the call manager's config is also changed within CallManager otherwise the callmanager will unregister the gateway.

Bronze

Re: CDP Neighbor Device ID mystery

Glad to know it fixed the problem!

Jack, as far as I'm aware this is not documented on cisco.com anywhere however I did find a bug associated to this problem. Later versions of code should have this fixed.

Thanks again,

Michael.

Silver

Re: CDP Neighbor Device ID mystery

Thanks a lot for your clarification. Could you advise is there any bug ID for this issue ? In some support activities, we require vendor info. to support our solution, so if there is a bug ID then it is easier for us to search. Many Thx.

Bronze

Re: CDP Neighbor Device ID mystery

Certainly,

The bug numbers include: CSCsc41856 and CSCee50559. Note that the first one is a duplicate of the second, but it's the only one externally visible to you guys through the Bug system.

Cheers,

Michael

Silver

Re: CDP Neighbor Device ID mystery

Thx. a lot.

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