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Loopback detected with uplink of two 2950-24s

2950-24 uplinked at fastethernet ports by standard crossover cable leads to loopback and shut down of port. Switches and cables has been replaced but problem repeats itself, using latest IOS release.

Any suggestions??

1 REPLY
Bronze

Re: Loopback detected with uplink of two 2950-24s

Hi,

Does the error message look like this?

ETHCNTR-3-LOOP_BACK_DETECTED:, Loop-back detected on [chars]. The port is forced to linkdown.

If this is the message that you are receiving then it might be might be caused by a balun cable being accidentally plugged into the port. Please check the cables and use the correct cable.

Also check for possible STP loops and disable keepalives since they might also cause loopbacks.

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