[c-nsp] GRE tunnel flapping every 15 minutes

[Quinn Kuzmich]

 I had a similar issue with one of my tunnels, and it turned out to be bad
hardware on one end.

Q

On Mon, Feb 14, 2011 at 3:36 PM, schilling <schilling2006 at gmail.com> wrote:

> I have an ISR 871 behind Comcast residential cable modem with static
> IP address, and have GRE tunnel back to our headend. Just plain
> point-to-point GRE tunnel. Now it's flapping every 15 minutes, then
> comes back up after 30 seconds. debug ip routing just showed tunnel66
> down and refreshed the routing table. There is no route
> addition/removal or any interface down before the tunnel66 down.  When
> the tunnel is down, I am still able to ping the WAN gateway, but not
> the WAN IP on the ISR871.
>
> #remote end
> interface Tunnel66
>  bandwidth 8000
>  ip address 192.168.222 255.255.255.252
>  no ip redirects
>  ip tcp adjust-mss 1436
>  load-interval 30
>  keepalive 10 10
>  tunnel source FastEthernet4
>  tunnel destination 192.168.253.19
>  tunnel path-mtu-discovery
> end
> ip route 192.168.253.19 255.255.255.255 WANgateway
> ip route 0.0.0.0 0.0.0.0 WANgateway 250
> ip route 0.0.0.0 0.0.0.0 tunnel66
>
> #head end similar.
>
> Just upgraded the ISR871 to be running latest
> c870-advipservicesk9-mz.124-24.T4.bin, but the issue persists. We
> already tried reboot the modem and reboot the switch.
>
> Any insight?
>
> Thanks,
>
> Schilling
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