OSPF Flaps after every 24 hours

[Guru Mysoruu]

Hi Frenz,

Have A strange issue where in , OSPF neighbors will go down exactly after 24 hours + 1 minute.

After that they re establish and comes up in a minute. We have two routers and two 4500 switches in square topology.During this event, I dont see any CPU Spikes nor memory Issues

In the logs it says dead timer expired and goes from full to down

%OSPF-5-ADJCHG: Process XXX, Nbr XXXX on Port-channel10 from FULL to DOWN, Neighbor Down: Dead timer expired

Looked into OSPF events and could see below logs.

Jun 21 09:40:54.323: Timer Exp: nbr_hold_dbd 0xAC1C0006
Jun 21 09:40:54.319: Timer Exp: nbr_hold_dbd 0xAC1C0003
Jun 21 09:40:54.319: Timer Exp: nbr_hold_dbd 0xAC1C0007
Jun 21 09:40:54.315: Timer Exp: nbr_hold_dbd 0xAC1C0001
Jun 21 09:40:54.311: Timer Exp: nbr_hold_dbd 0xAC1C0002
Jun 21 09:40:31.148: Timer Exp: if_ack_delayed 0x602BCF18
Jun 21 09:40:31.148: Timer Exp: if_ack_delayed 0x60CEC0E0
Jun 21 09:40:31.100: Timer Exp: if_ack_delayed 0x61588C30

[chrihussey]

Interesting problem. Guess the question to ask is what is happening when this occurs? Perhaps an SNMP get, large file transfer or backup.

Also, what is the topology? Are the routers the only ones doing OSPF through the 4500s, or are the 4500s participating in the OSPF? 

Might have a bug or something else going on, but additional info is needed to identify what is happening.

Regards