OSPF routes updating every 10 seconds

[thomuff]

We are starting having issues with a remote location and we noticed that in the route table on the 6509 MSFC, the routes are updating every 10 seconds. First, is that normal? Second, HELP! Thanks Tom

[smif101]

The every 10 seconds you are seeing are the hello's between the two routers. They send them every 10 seconds to ensure connectivity. What is the actual problem that you are having?

[thomuff]

In a nutshell, they are seeing "Host Busy" on 3270 sessions and maybe some poor performance on the RX clients. The SNA gets there via DLSW by peering with a router at the hosting site. Below are the log messages we see when debup ip ospf mon is turned on?

Sep 21 11:43:36.103: OSPF: Begin SPF at 2789410.428ms, process time 4713168ms

Sep 21 11:43:36.103: spf_time 4w4d, wait_interval 10s

Sep 21 11:43:36.119: OSPF: End SPF at 2789410.444ms, Total elapsed time 16ms

Sep 21 11:43:36.119: Intra: 0ms, Inter: 4ms, External: 12ms

Sep 21 11:43:36.119: R: 0, N: 0, Stubs: 0

Sep 21 11:43:36.119: SN: 138, SA: 43, X5: 416, X7: 0

Sep 21 11:43:36.119: SPF suspends: 0 intra, 0 total

Sep 21 11:43:41.247: OSPF: Schedule SPF in area dummy area

Change in LS ID 0.0.0.0, LSA type X

[smif101]

Well it isn't your OSPF process that is running all the time. If you look at the 3rd line with the End SPF, that is the last time it actually saw an event that made it run SPF which was 2789410 seconds, which is around 30 days. So the problem is most likely somewhere else. What is the utilization of the link between the sites? What is the delay between the clients?

[thomuff]

the utilization between us and the remote site is minimal. I will have to check the utilization between us and the hosting site. I am working on getting the delays. By the way, thanks for the help.

[Harold Ritter]

2789410 is just a timestamp representing the number of seconds since the router last came up.

We can see in this output that an external LSA is responsible the SPF being scheduled.

If you want to see how often the SPF runs, you can do a "show ip ospf stat", which will give you the last 10 times the SPF was executed and the reason for it.

Once you have clearly identify the frequence and that the cause for the last 10 SPF run is indeed an external LSA, you can use a "deb ip ospf spf ext" to

determine the culprit LSA.

Hope this helps,

[thomuff]

I ran the debug ip ospf spf ext but I am not sure what I am looking for.

[Harold Ritter]

Could you please post the output of the debug command.

Thanks,

[thomuff]

I have attached the output of the debug

[smif101]

Well you definetly have a problem with your network because your neighbors are going down. What is the config of those four routers. The other thing is, are you having problems with all of the routers dropping there connections to each other or just the routes to MHS-MDF55-6509-MSFC2. Also what is the IOS release with each of these routers.

[thomuff]

Here is where it gets interesting. If you are refering to the 10.68.x.x routers, they are at a health system that connects to us They redistribute EIGRP into OSPF and we redistribute OSPF into EIGRP. I do not have access to those routers but I can get changes done. Please let me know and thanks again

Tom

[Harold Ritter]

In your original posting, you mentionned that this recalculation happens every ten seconds but in the output you attached we only see one occurence. If the routes are flapping from one ASBR to another, it would be good to observe at least two occurences.

Thanks,

[thomuff]

I will run a longer debug and post it

[thomuff]

Sorry for the delay, I am posting debug tomorrow.

[thomuff]

Here is the new debug log.