CDP-4-DUPLEX_MISMATCH errors

[admin_2]

Hi All,

I am hoping for some help with a "duplex mismatch" problem I'm having.

I have 2 switches (a Catalyst WS-C2924M-XL with a WS-X2922-XL-V module, & a Catalyst WS-C1924C-EN) connected via fibre. The 2924 port is configured as "100/full" while the 1924 port is configured as "Full duplex-flow control".

I regularly get the folowing message in the 2924's log buffer:

%CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on FastEthernet2/1 (not half duplex), with JNR_LIB_SW A (half duplex).

Now as far as I can see both ends are configured for full duplex. If I configure the 1924's port to be "half duplex" the messages stop. Network performance is poor either way.

Can anyone tell me what's going wrong here, & how to fix it? Many thanks in advance for any help provided.

Cheers,

Dirk

[Georg Pauwen]

Hello Dirk,

what happens if you change the settings on the 1924 port to duplex full instead of duplex full-flow-control ?

Regards,

GP

[#3]

Hi GP,

Unfortunately changing the 1924 port to "duplex full" makes no difference. Our 2924 is the main switch on our network, & it has 6 other switches (all Cisco 19xx & 29xx) linked via fibre to it. I am getting the same message on 2 other switches, both of which are 19xx.

I would love to be able to fix this as our network performance on these links is poor.

Cheers,

Dirk