[c-nsp] Cat 3750E w/ MAC learning disabled shutting port?

Lukas Tribus luky-37 at hotmail.com
Fri Apr 24 11:40:44 EDT 2015


> Hello people,
>
> I am looking for an explanation for a strange port flap that I
> experienced this afternoon and out of desperation (and because I can not
> find an answer on Cisco, Google, you name it and I am not yet desperate
> enough to open a TAC case) I am posting here.
>
> Here is the situation:
> Catalyst 3750E has several VLANs. One VLAN has mac-learning disabled.
> The VLAN is tagged on one TenG interface and untagged on a GigE.
> The TenG interface went down due to a transmission problem. The GigE
> interface went Lineproto-down too. Thats weird.

I would guess that the box connected to the GigE interface has some
kind of heartbeat running towards the other end of the network and
resets itself (or the interface) in case the communication breaks. Like a
"suicide-is-better-than-a-split-brain" protection?

Seems strange for a Catalyst to drop the link in this case. Is the box
in a stack?



Lukas


 		 	   		  


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