OSPF flapping

[Gastu]

Hello,

I have two OSPF-speaking core switches (A and B) connected via private Metro dark fiber. The link connecting them is a layer 3 routed link. The core switch "A" router ID is a nonexistent interface IP, which is a public IP address from the previous configuration. OSPF suddenly flapped on my "B" switches, and I lost adjacency with the core switch "A."

log:

OSPF: ST2-CMDR: ADJCHG: Neighbor with Router ID
60.145.11.xxx on vlan-176 moved to Down state - adjacency lost. // VLAN176 is the transit layer3 vlan between "A" and "B"

could you any of help me how to fix this issue? is this because switch "B" can not find the DR("A

Thanks, 

[MHM Cisco World]

Vlan176 is transit vlan between two sites and you use it for ospf ?

Mostly this issue from SP drop hello packet. 

When issue happened try ping ospf multicast IP see if there is reachability or not.

MHM

[balaji.bandi]

When you lost the adjuancy of OSPF

are you able to ping p2p IP address?

Do you see any interface errors ?

show interface x/x (from both the side will help to troubleshoot)

for monitoring keep EEM Script running ping and store the results so when OSPF failing confirm this is not lost connection ?