OSPF neighbor status flapping

[Walid Amer]

one of the two neighbors doesn't receive hellos and belevies that its neighbor is down and change the state to DOWN.

R1

%OSPF-5-ADJCHG: Process 1, Nbr x.x.x.2 on Port-channel13 from FULL to DOWN, Neighbor Down: Dead timer expired

No errors on the two physical interfaces inside the port-channel

No drops with the control-plane policy

The other end R2 doesn’t feel interruption (still receiving hellos) until R1 declare the session down.

[lgijssel]

Sounds like a unidirectional link issue. This may be hard to detect in a channel....

You may consider to take one interface out of the channel and configure udld on both sides.

In that way you might be able to find whether this in is indeed the case.

Please post some config details when this does not help.

regards,

Leo

[jcozzupoli]

Hi,

Please post more details, eg configs, and how often the flapping is occuring.

- Joe.

[Walid Amer]

I have configured udld for the two links.

The flapping happened four times yesterday before configuring udld and it hasn’t happened again yet to check if there is unidirectional issue.

The neighbor session was being restored before I can ping the physical ip address of the neighbor.

[sfaizul]

Hi,

    %OSPF-5-ADJCHG: Process 1, Nbr x.x.x.2 on Port-channel13 from FULL to DOWN, Neighbor Down: Dead timer expired

check the layer 2 connectivity with the help of ping and see no ping packet drop.

Ping the ospf multicast address 224.0.0.5 from both direction and check the reply .

Regards

Syed.