Your neighbor table shows several neighbors stuck in 2WAY. Is that a problem?
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On a broadcast segment, usually not. DROTHERs only go Full with the DR and BDR and stay in 2WAY with each other by design. It is a problem only when a neighbor that should be Full is in 2WAY: no DR exists because every router has priority 0, or it is a two-router link where both sides are priority 0.
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Normal
R3# show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
1.1.1.1 1 FULL/DR 00:00:38 10.0.100.1 GigabitEthernet0/0/0
2.2.2.2 1 FULL/BDR 00:00:35 10.0.100.2 GigabitEthernet0/0/0
4.4.4.4 1 2WAY/DROTHER 00:00:31 10.0.100.4 GigabitEthernet0/0/0R3 and R4 are both DROTHERs. Their 2WAY is correct.
Not normal
R3# show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
4.4.4.4 0 2WAY/DROTHER 00:00:31 10.0.100.4 GigabitEthernet0/0/0No DR and no BDR on the segment, so nobody forms Full adjacencies. show ip ospf interface on R3 says
"No designated router on this network". Fix: give at least one router a non-zero priority, or make a
two-router link point-to-point.
They will ask next
How would you tell monitoring not to alert on DROTHER 2WAY states?
Alert on adjacencies that drop from Full, or on neighbors not Full where the neighbor is DR or BDR. The OSPF MIB and telemetry expose the neighbor state and the DR address on the interface.
Traps
- Clearing the OSPF process to "fix" a DROTHER 2WAY. It goes straight back to 2WAY and you caused an outage.