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GEC and dot1Q on 6500 sups

I have (2) links set up between a pair of 6500 chassis configured for GEC and dot1Q. If for whatever reason one of the fiber pairs goes errdisable, should the remaining link automatically revert to a single dot1Q trunked link?

This doesn't seem to be the case and am having to make the case for redundancy vs. load balancing.


Re: GEC and dot1Q on 6500 sups

It depends on the version of software you have, prior to 6.3 it would unbundle the link and revert to a single connection causing the port to go through the listening / learning / forwarding process. From 6.3 the link remains as part of a 1 port bundle thus avoiding the listening / learning / forwarding process.

· EtherChannel enhancements

An EtherChannel is preserved even if it contains only one port. In software releases prior to 6.3(1), if you have a 2-port channel and one link is removed, the remaining link is removed and added back to spanning tree, which causes a loss of connection on the channel until the link is forwarding again.

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Re: GEC and dot1Q on 6500 sups


That being the case it looks like there are other issues that may be causing the link to stay down and not re-initiate. When one link goes down usually both links go down but never come back up. It requires a manual intervention. I'll have to look at the errdisable log next time it happens.



Re: GEC and dot1Q on 6500 sups

There is set command that will try to bring up the errdisable port after a configured amount of time but this off by default .

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