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DUPLEX_MISMATCH 2924XL

dennisbarnes
Beginner
Beginner

Hi,

I am having issues with Cisco 2924XL switch,

Its keep giving me these messages on console,

00:38:44: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on FastEthernet0/1

(not full duplex), with SIP00036B75B6DE Port 1 (full duplex).

00:39:44: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on FastEthernet0/1

(not full duplex), with SIP00036B75B6DE Port 1 (full duplex).

My current IOS version is "c2900xl-c3h2s-mz.120-5.WC10.bin"..

Please advice me how can I rectify this problem.

Regards,

Dennis

1 Accepted Solution

Accepted Solutions

glen.grant
Advisor
Advisor

Set port f0/1 to full duplex on the 2924.

View solution in original post

8 Replies 8

alex.alexander
Beginner
Beginner

Did you check the duplex config. of the device connected on port f0/1?

The device connected to the port 0/1 is Netgear switch, and on my Cisco Switch I put auto, doesn't mean it should negotiate the duplex settings,,

Experience has shown that auto negotiation between different vendors is very hit and miss. Best bet is to hard code the speed and duplex on the Cisco equipment to avoid any conflicts like you are seeing.

The autonegotiation usually works well, but only if both sides support it and are configured for it. If one side is configured auto, and the other side is forced (or does not support auto), then autonegotiation does not take place. In this case, the auto side reverts to the default, which is half-duplex.

The result is that if one side is auto, and the other side is forced full-duplex, then there will be a duplex mismatch. I'm pretty sure that is what was happening here.

Kevin Dorrell

Luxembourg

glen.grant
Advisor
Advisor