ospf issue 2way

[Mary]

my ospf neighbor today is in 2WAY/DROTHER state,the ospf has running for four years and no issue,  the ospf interface is up/up, but log says : neighbor from 2WAY to DOWN, Neighbor Down: Dead timer expired, what's the possible reason? how to fix

[Meheretab Mengistu]

Hi,

You need to provide us more information. How many devices are in the segment? Was there any configuration change? Is the process restarted?
Please provide us: show ip ospf neigh, show run | inc ospf, sh run | sec router ospf, ...

HTH,
Meheretab

[Mark Malone]

Yes usually its because no dr/bdr but something would have changed to cause that if it was already working to get stuck in 2 way state
This is how it occurs see the doc for clear explanation
https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/13683-11.html

[Mary]

that core switch all neighbor become ospf 2 way suddenly, no configuration change, can't figured out why it happens

[Meheretab Mengistu]

Could you share part of your config related with OSPF?

[Julio E. Moisa]

Hi

Also verify the ospf network type under the interfaces. 

Also you can run a: debug ip ospf adj   (recommended after business hours)