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OSPF Troubleshooting

We have a small setup for OSPF between two internet routers and a Firewall.  We started having some drop issues today and I saw the dead times keep changing, not sure if that is a sign of an issue or just a common ocurrance.

 

router#show ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface
X.X.X.x  1 FULL/BDR 00:00:39 C.C.C.C  TenGigabitEthernet0/0/0
X.X.X.255 FULL/DROTHER 00:00:32 c.c.c.255 TenGigabitEthernet0/0/0

then I show again and the timers change to less and they never get more than what is above.  The State never changes from Full and I tried a couple debugs and show nothing.   Just looking for some direction of the dead timers changing is common or if they should be staying stable?

 

 

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VIP Advocate

Re: OSPF Troubleshooting

Hi,

I hope everything is fine in the OSPF. As you shared some details which are looking very important as

Neighbor ID Pri State Dead Time Address Interface
X.X.X.x  1 FULL/BDR 00:00:39 C.C.C.C  TenGigabitEthernet0/0/0
X.X.X.255 FULL/DROTHER 00:00:32 c.c.c.255 TenGigabitEthernet0/0/0

By default, the dead timer interval is four times the hello timer interval means 40 seconds. Again, after 10 seconds it will receive the hello and dead timer reset to 40 seconds. I can say that in a health lab or network dead timer will not go less than 30 seconds.

 

Now, As I am looking that Status of peer also good because you lab might be like:

 

RouterA is connected to a Switch and Router B and Router C is also connected to the switch and all are in the same network.

If yes then, here is the meaning of by you can not see Full/DR on this router because this router is elected DR in the network and another two routers elected as Backup DR (X.X.X.x ) and  FULL/DROTHER (X.X.X.255) and it is default behavior. 

 

FULL/BDR: Backup Designated Router (BDR) is elected to replace DR should DR fail. Hence DRother routers also form an adjacency with BDR.

 

FULL/DROTHER: DRothers will form an adjacency with DR and BDR only. DRother is a router that’s neither a DR nor a BDR.

 

As you are facing drops then please share logs and OSPF outputs. Have you noticed any Drop on the interface?

Regards,
Deepak Kumar,
Don't forget to vote and accept the solution If this comment will make help you!
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VIP Advisor

Re: OSPF Troubleshooting

Those times are correct, OSPF has the ability to check neighbour live dead timers, they count down and keep checking hello-interval that is normal.

 

Since you configured broadcast domain not as a point to point they elect DR / BDR process to become DR this is normal in OSPF process.

 

if you looking to FULL/ FULL - you need to configure the interface as point-to-point

 

Drops could be the reason lost connection, what is your Logs show, is the OSPF neighbourship DOWN and UP ?

 

 

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