[c-nsp] 10gig Link Bouncing Consistently

Michele Bergonzoni bergonz at labs.it
Wed Apr 3 03:29:36 EDT 2013

> Beginning several days ago both links began flapping every 5 and a half
> hours, both links have this happen within a couple of minutes of each
> other.
> They will flap for several minutes and then return to normal operation
> requiring no user action and the ports never enter err-disable or show
> any other symptoms.

Your story popped me up a distant memory of a heating system that 
happened to leak steam on a fiber cable. That cable contained all the 4 
fibers of a presumed redundant connection.

I would not let the next predicted flapping time pass without:

* "show interface transc det" when everything works, and when things go bad
* technicians at both ends ready to disconnect one line and test the 
loss on the fibers with appropriate instruments, in the first window 
(~850 nm)
* physical inspection of the fiber run, if feasible

If the fibers turn out to be OK, when you have a Cisco 6509 on one end 
and a Netgear on the other, and you need to try to replace one of them, 
we all know where to start.


Ing. Michele Bergonzoni - Laboratori Guglielmo Marconi S.p.a.
Phone:+39-051-6781926 e-mail: bergonz at labs.it

More information about the cisco-nsp mailing list