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sunilyk
Beginner

OSPF update

Hi All,

I have a query related to OSPF.

If I do a sh ip route x.y.z.w then it shows the route is learned by OSPF, and it shows that last update received from neighbour 5D12h ago.

Do you think there is a problem here, as the last update is received quite a long ago ???

But when I do the sh ip route for a perticular IP its taking the desired path learned from ospf.

Can some one please let me know regarding this ?

Regards,

Sunil

3 REPLIES 3
Georg Pauwen
VIP Master

Hello Sunil,

since OSPF only sends updates when it sees a change in the network, in a stable network you can see last updates being received that long ago.

HTH,

Georg

Richard Burts
Hall of Fame Guru

I think part of your concern results from confusion about the relationship between the OSPF Link State Data Base and the IP routing table. OSPF sends advertisements (LSAs) to update the Link State Data Base and will send advertisements to refresh the data base even if there are no changes. So if you were to check the data base you would find that all of the entries were relatively recent.

From the Link State Data Base OSPF calculates the best routes and uses that to update the IP routing table. There are updates to the IP routing table only when something changes.

So when you do a show ip route and see that some route has been in the IP routing table for 5 days it is an indication that your network is stable. Very few of us would think that this is a problem.

HTH

Rick

Thanks Richard, George for clarification.