Tunnel Flapping

[Ankit Kewalramani]

Hi Guys,b

                        I need help, In our Network environment  there are two tunnel configure in router.  But only one tunnel flapping other is not.  I have checked another end as well other tunnels are stable only that tunnel is flapping which is flapping at our end. both side A and B same tunnel is flapping others are stable. we are not sure what exactly problem is there. I need your help to troubleshoot this issue. 

[Michael Muenz]

Why don't you turn on debugging and post the results?

[Ankit Kewalramani]

michael ,

                        that router in production network.I cant turn on debug

[Michael Muenz]

Then you should post the corresponding configuration from both routers ... 

[Aditya Ganjoo]

Hi Ankit,

Could you tell us what sort of tunnel are you using?

Also do you see any logs at the time of the issue ?

Regards,

Aditya

Please rate helpful posts and mark correct answers.

[lethanhtung0131]

Ankit,

If you have ospf/eigrp over tunnel. please check if recursive routing is applicable in your case. 

[Ankit Kewalramani]

Hi  ,

             actually RIP protocol is running as routing routing protocol. 

[lethanhtung0131]

Same, do not use RIP or any dynamic routing protocol to learn the route to peer IP.

It mean the tunnel learn the peer IP (usually public IP) through the tunnel itself.

If the tunnel interface learns that the best path to the tunnel destination is through the tunnel itself, the interface shuts down temporarily.

Solution:

Static route to peer

Not advertise tunnel destinations to routing protocol

Filter tunnel destinations

To help confirm the issue:

What the error message appear when route is flapping?

Please paste the output of sh ip route here.