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virtual port-channel on 6500 core was created after port-channel on edge switch was changed



The problem:  On the edge switch while online, I created a port-channel 1 to replace port-channel 12.  I changed all the trunks to port-channel 1 one by one, so there was no downtime as it is dual-home trunked to the VSS 6500 core.  After the change, the connection is fine.  However on the core, the port-channel 134, which is dedicated for this edge switch, says it is down.  I see another port-channel 134b created, which physically does not exist.  All the trunks were moved to this virtual port-channel 134b.   I believe a reboot will fix this problem to move all the trunks back to the physical port-channel.  I will not be able to do this until the next downtime.  I would like to fix this problem while it is still online.  Please help if you have seen this before.  If this is not clear to explain the problem, please let me know.  Thank you.

2 Replies 2

Balaji K
Cisco Employee
Cisco Employee


yes a reload or a switchover will help as it will initiate the the idb table to be populated again.

also did you try to create the port-channel 134 now, this should give you the error message "idb creation failed".

also which image is the switch running.


Thank you for your reply.

On the 6504, I have s72033-ipservicesk9_wan-mz.122-33.SXH6.bin

On the 3750's stack, I have c3750-ipbasek9-mz.122-55.SE1.bin

The next downtime will be 30 days.  I assume that it will fix the problem after I will reboot the stack during the next downtime.  If there is a solution to fix it while the stack is still online, that will be nice.

I have done some tests.  I have 3 trunks for this port-channel.  I have tried to shut the trunks one by one (always leave one online) to see if these trunks would jump back to the original port-channel.  When I shut one trunk down, I saw the trunk actually jumped back to the original port-channel 134.  However, it jumped to the 134b again, after I bring it up online.

I might have to wait for the next downtime.

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