GRE Tunnels Flapping

Unanswered Question
Jul 17th, 2009
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Hi I'm having a problem establishing a stable GRE tunnel and was wondering if anyone could help?


Both Routers are 7200s. RouterA is running IOS rev 12.3(4r) and RouterB is running IOS rev: 12.2(5d). Both sides of the tunnel show as UP/UP until I enable keepalives on RouterA (RouterB doesn't seem to support them), then RouterA predictably shows the tunnel as UP/DOWN.


I can ping the local interface on RouterA, but RouterB can't seem to ping it's local interface.


I've changed the IPs, but the config on the tunnels is attached (RouterA.txt & RouterB.txt).


Running a debug on the tunnel produces nothing useable. IP ICMP Debug just shows RouterB encapsulating messages, but nothing is returned.


Setting tunnel mode to be ip-ip allows RouterB to ping it's local interface and allows us to ping down the tunnel.


Any ideas are most welcome!



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Leo Laohoo Fri, 07/17/2009 - 15:46
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Can you please post your config? For confidentiality purposes, you can black out the IP Addresses, crypto keys, passwords and other details.

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