Thank you for this information Stephan,
Usually, error-disable conditions due to "link-flap" mean that either the local switch port or remote switch port bounced a number of times, in a very short period of time. As a protection mechanism, in order to prevent network instability (in terms of STP, for example), the switch sends the port into an err-disable state to prevent any further flapping.
The majority of the times this points to a L1 issue, so the troubleshooting methodology would happen as follows:
- Make sure the fiber is clean and if possible clean it/replace it.
- Make sure any media distributor/patch panel in between is clean and healthy too.
- Move the connection from the local site to a different port. See if it comes up.
- Move the connection from the remote site to a different port. See if it comes up.
- Use different transceivers (same model), in the local site and then in the remote site.
Once the issue is isolated to a switch (which, looks like you have done all that shown above already) per the case notes), further troubleshooting can happen at that switch.
Going forward, the case notes show that the issue seems to be related to bug CSCvg04687. Although I am aware the switch was upgraded to 15.2(6)E, it looks like the bug is not fully fixed there. It looks like the current TAC engineer is already in talks with our internal teams for confirmation. I would let the current TAC engineer continue to work so they can let you know if there is some other OS with the fix.
As an interim workaround, you may want to change the err-disable link-flap timers to be less aggressive, at least until there is feedback from that TAC engineer.
I apologize about not being able to help further.
Hope this helps.
Eduardo.
