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GRE Tunnels Flapping

Pr0m3theus
Level 1
Level 1

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!

2 Replies 2

Jerry Ye
Cisco Employee
Cisco Employee

Hi Ray,

Without seeing your routing configuration, I can only think of the recursive routing problem. You can check out this document

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094690.shtml

HTH,

jerry

Leo Laohoo
Hall of Fame
Hall of Fame

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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