I have a 7500 router connected to 2500 router using OSPF across the WAN link. For some reason, with OSPF running it drops the WAN link. Making the interfaces passive, and using static routes brings the link back up.
This has been working fine in the past.
The WAN link is a standard 2m circuit with no extra config other than IP address and keepalives.
Has anyone seen something similar?
This sounds quite strange and I believe that I have never seen anything quite like it. Are you saying that when you configure OSPF over the serial link that the interface actually goes up/down? Or are you just saying that if you configure OSPF that you have problems with connectivity over the link?
It might be helpful if you could post output of show interface from both routers and perhaps the output of show cdp neighbor detail.
OSPF was previously working fine, but for some reason now seeing interface resets (not carrier transitions).
OSPF adjacency comes up and then once traffic is being sent down the link it drops the link altogether.
Sep 28 10:59:50: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial4/1, chan
ged state to up
Sep 28 10:59:59: %OSPF-5-ADJCHG: Process 1, Nbr 10.46.3.254 on Serial4/1 from LO
ADING to FULL, Loading Done
Sep 28 11:00:07: %OSPF-5-ADJCHG: Process 1, Nbr 10.46.3.254 on Serial4/1 from FU
LL to DOWN, Neighbor Down: Interface down or detached
HAVR701#sh int s4/1
Serial4/1 is up, line protocol is up
Hardware is cxBus Serial
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/91/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 2000 bits/sec, 4 packets/sec
530173 packets input, 154898786 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 1 ignored, 0 abort
2250585 packets output, 268154242 bytes, 0 underruns
0 output errors, 0 collisions, 12 interface resets
Any ideas why this may be happening? I'm planning on swapping out the serial card on the 7500, as this is the only part of the 7500 that has not been replaced recently. Definitely a strange one...
I agree that it seems to be a strange one. I can see that interface resets could impact OSPF neighbor relationship, I am not clear how OSPF running on the interface would cause resets (but strange things do sometimes happen).
Can you clarify something: are you saying that if you remove OSPF that the interface is stable? and that if you enable OSPF the interface becomes unstable?
If you remove OSPF and run extended ping with lots of data (and perhaps varying the payload to check for ones density - data pattern of 0101 and data pattern of FEFE) does anything unusual show up on the serial?
Yep - OSPF is currently set as passive on the interface, with static routes (redistributed in OSPF) providing the routing across the link.
Tried the pings - nothing unusual seen, no errors, dropped packets etc. I think this is one for a Cisco TAC.
In the meantime I intend to swap out the serial linecard on the 7500 (this is the only part of the router that hasn't been replaced recently).
Did you carry any IOS upgrade recently ? I beleive it is either IOS bug (if IOS changed) or the hardware failure.
Moreover, did you face the same problem if you reboot the router ?
If you replace the serial interface but still not solve the problem. Try to solve the VIP at the same time and test.
Hope this helps and wait for your update.
After going through the thread, just wanted to check if you have ruled out the possibility of a circuit flap?
Also, would be nice if you could post 'sh logs' output from the concerned routers.
Not seeing carrier transitions just interface resets - so circuit looks ok.
No IOS upgrade taken place - nothing changed at all on the routers. Swapping out card tonight so hopefully this will work.
Thanks for posting back to the forum and indicating that the problem is resolved and that swapping the card was the fix. It makes the forum more useful when we can read about a problem and can find what the solution to the problem was.