[c-nsp] Mysterious GRE tunnel flap

[Quinn Kuzmich]

I appreciate the reply - the tunne source locall is actually an HSRP virtual
interface, and it never goes down according to what I'm seeing.  And as far
as I can recall, we get no errors on the interface that is acting as the
active router.

Q

On Wed, Jul 21, 2010 at 6:00 PM, Graham Wooden <graham at g-rock.net> wrote:

> 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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