[c-nsp] Mysterious GRE tunnel flap

[Graham Wooden]

I'll take a stab at this ... I think it's something physical at one of the
sites.  Does any of the two interfaces has their line protocol go down? Can
you access down the link, outside the tunnel, ie. Ping your next hop during
this? 

I had something similar happen with some collocated gear at a remote site.
Around the same time everynight, err counters on an interface would go nuts
for about 2 minutes. Lots of finger pointing between LEC and us. Well, come
to find out that the building's emergency lighting would be tested at this
time, and it's cable run ran next to our T1s for a short distance before
going into our room.

Long story short here is check the physical layer first!

-graham

On 7/21/10 1:17 PM, "Quinn Kuzmich" <lostinmoscow at gmail.com> wrote:

> Ok, I have a problem that I'm hoping someone can help out with.  I have two
> 1841s seperated by a Metro-E WAN.  Over this is a GRE tunnel to route
> multicast.  Every morning at 8AM EST, give or take 3 minutes, the tunnel
> will go down for about 30 seconds.  This happens every morning at this time,
> there are no errors in EIGRP, nor on the WAN side (plenty of tickets opened
> and we were watching the circuit when the flap happened, no dice) and we're
> at a real loss.  Maybe a bug in the IOS?  An angry voodoo priest somewhere?
> 
> 
> Ideas?  Thanks in advance!
> 
> Q
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