We have been expereinceing a wierd

[junior238]

We have been expereinceing a wierd problem between a 3550 and a 2950G. Both switches are running 12.1(11)EA1 and are connected via LX gbics at 1 gig. Every so often the 3550 reports %ETHCNTR-3-LOOP_BACK_DETECTED and shuts down the interface connected to the 2950G. I can't find any other useful information besides the error message.

When I go to cisco and look at what the message means it says to check the cabling and see if a balan cable is connected. I'm lost, could someone lend a helping hand.

PJ

 

[TalktoMe]

This problem seems to be a looping problem of your network connectivity. The traffic in your network is flowing in a loop due to which the packet will be dropped after a certain amount of time. This happens because by default the spanning tree is on in the switch. I would recommend you that draw the topology of your network on a peice of paper by checking the cables connected into your network.

 

[TalktoMe]

This problem seems to be a looping problem of your network connectivity. The traffic in your network is flowing in a loop due to which the packet will be dropped after a certain amount of time. This happens because by default the spanning tree is on in the switch. I would recommend you that draw the topology of your network on a peice of paper by checking the cables connected into your network.
TalktoMe

 

[junior238]

I was going to try this, but cisco has gotten ride of the handy debug commands that show this. I was also searching for new commands that act like debug ethernet-controllers addr but couldn't find them.

 

[rcasta]

Exactly the same problem I had, check for VTP settings as well (2900 preferably should be set as Transparent).

It seems to be a STP issue.

cheers,