Trunk Causing Swtich To Reboot????

Unanswered Question
Jul 28th, 2008


I have two Catalyst 4948's and I have a L2 trunk between the two of them. Evey time I hook that trunk up one of my switches reboots and it won't stop rebooting until I disconnect the trunk. Has anyone seen this before?

I have this problem too.
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lamav Fri, 08/01/2008 - 05:18


So what?

Those misconfigs are not going to cause a switch to reboot.

He should open a Cisco TAC case because something bizarre is occuring.


srivkind Fri, 08/01/2008 - 10:00

Console into the switch that fails and see what errors come up. Try doing a show stacks command on the switch that fails after it reloads and put the output thru the output interpreter and see what comes up. Maybe try doing a show tech as well and put it thru the output interpreter and see what info you can glean. Also as previously suggested open a TAC case and see if there are any bugs or something.

Giuseppe Larosa Sat, 08/02/2008 - 09:46

Hello Mario,

how is built your L2 trunk ?

are you using an etherchannel with two or more parallel links ?

If so never modify the vlan allowed lists on a member link do it only on the logical port-channel interface.

We faced two times this problem on C6509 and we had to have someone unplug the fibers of all the links to recover.

If your trunk is made of a single link I agree you should open a TAC case.

Hope to help


mrashby Tue, 08/05/2008 - 17:54


Thanks for the input after all the troubleshooting it turned out to be a bad ten gig module.


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