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Bronze

CDP mismatch (Gigabit Ethernet half-duplex????)

HERE IS THE PROBLEM:

*Jun 14 12:25:54: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet4/10 (not full duplex), with 3550_2 GigabitEthernet0/1 (full duplex).

I am pretty sure it's something wrong with the setup of the trunking, but I have never seen "unknown 0" listed instead of "media-type LX" or whatever.

Below is the sh interfaces for each.

This is a link from a 4006 to a 3550. The 4006 shows tons of CRC errors, the 3550 does not.

Korr_4006P

interface GigabitEthernet4/10

switchport mode trunk

3550_2#

interface GigabitEthernet0/1

description Link to 4006

switchport trunk encapsulation dot1q

switchport mode trunk

no ip address

4 REPLIES
New Member

Re: CDP mismatch (Gigabit Ethernet half-duplex????)

I would try to nail down speed/duplex (100,FULL) on both ends of this connection. The errors you are seeing are consistent with speed/duplex issues.

Bronze

Re: CDP mismatch (Gigabit Ethernet half-duplex????)

Thank you for the response, but...

For a 100 meg connection yes, that is exactly what I would do. But this is a 1000Meg link. Longhaul gbics going fiber from switch to switch. There is no "duplex full" option.

I still think it's a problem with the setup of trunking, but I hope someone here will tell me!!!

Re: CDP mismatch (Gigabit Ethernet half-duplex????)

Hi,

I wouldn't think this is a trunk problem.

I would just for sure add

switchport trunk encapsulation dot1q

to 4006 config (I'm not sure is 4006 IOS provides ISL as default trunk encapsulation), but I don't think this is the problem.

If the 4006 shows tons of CRC errors, I'd consider either a cable or GBIC problem.

Regards,

Milan

Cisco Employee

Re: CDP mismatch (Gigabit Ethernet half-duplex????)

Some modules in CAT4k and 3550 do 10/100/1000. Can you paste the output of sh ver from 3550 and sh mod from 4000?

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