Mismatch on FastEth

[fernandoschmitt]

Do anybody know why I receive these messages if the inteerface FastEthernet is configred with speed auto and duplex auto?

Nov 24 11:11:35.913: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on FastEthernet0/0 (not half duplex), with Filial_RJO Ethernet0 (half duplex).

Nov 24 11:11:43.953: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on FastEthernet0/0 (not half duplex), with Trt_Intermedica Ethernet0 (half duplex).

Nov 24 11:11:44.181: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on FastEthernet0/0 (not half duplex), with Tr_Mercure Ethernet0 (half duplex).

Nov 24 11:11:50.753: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on FastEthernet0/0 (not half duplex), with 55busc4 FastEthernet0/0 (half duplex).

[Kevin Dorrell]

It is probably because the switch thinks it is full duplex on F0/0, and the Ethernet at the other end cannot support it. Furthermore, it looks like you are attached to a hub, which can only support half-duplex. You could try forcing half-10 on F0/0.

There is one other possibility: that you have all four machines attached to a non-Cisco switch that is terminating each connection correctly, but is passing CDP by flooding it. In this case, disable CDP. But before you do that, make absolutely sure

that it is a switch, and not a hub, otherwise you will start losing frames because of the duplex mismatch.

Kevin Dorrell

Luxembourg

P;S. I remember some bug about CDP duplex reporting. I'll look it up and report back to you. What model of switch and IOS do you have?

[fernandoschmitt]

The F0/0 is configured with speed auto and duplex auto. It's a AS5350 with IOS C5350-is-mz.12.3(10).

[Kevin Dorrell]

Here are a couple of bugs that might explain it:

http://www.cisco.com/cgi-bin/Support/Bugtool/onebug.pl?bugid=CSCin14749

http://www.cisco.com/cgi-bin/Support/Bugtool/onebug.pl?bugid=CSCdp30476

Kevin Dorrell

Luxembourg