IPV6 OSPF neighbor state

[bryantsteve]

In troubleshooting OSPF IPV6 routing on C4500x switches (entservice license) having only Area0 backbone, the routes are being propagated ok but  I see the <show ipv6 ospf neighbor> output reflects all neighbors in the FULL state -No DR/BDR.  Could  this possibly be  a  correct status or  is it an indication that IPV6 OSPF routing is not configured properly/ working correctly?

[Peter Paluch]

Hello Steve,

Posting the show ipv6 ospf neighbor output would have  been helpful - but from what you write, it seems as if the interfaces were configured for a OSPF network type that does not elect DR/BDR, either point-to-point or point-to-multipoint. Would this be the case?

With these network types, the absence of DR/BDR is expected. Whether, however, those network types are used properly in your network is another question, and for that, we would need to know more about the topology.

Best regards,
Peter

[Jon Marshall]

Peter

Sorry, got distracted while posting and in the meantime you provided an answer.

Jon

[Peter Paluch]

Jon,

I am glad we have both responded :) This is all to Steve's benefit. And we may actually open up a nice can of worms if we touch something interesting in this particular case :-P

Best regards,
Peter

[Jon Marshall]

And we may actually open up a nice can of worms if we touch something interesting in this particular case

We can only hope although I'm not sure Steve would agree :)

Jon

[bryantsteve]

Paul

#sh ipv6 ospf neighbor

Neighbor ID     Pri   State           Dead Time   Interface ID    Interface
x.x.22.14      0   FULL/  -        00:01:45    51              VlanX
x.x.157.17     0   FULL/  -        00:01:35    2225            VlanY
x.x.201.15     0   FULL/  -        00:01:39    2225            VlanY
x.x.254.33     0   FULL/  -        00:01:59    27              VlanY
x.x.254.132    0   FULL/  -        00:01:57    39              VlanY
x.x.22.14      0   FULL/  -        00:01:35    50              VlanX
x.x.157.17     0   FULL/  -        00:01:55    2224            VlanX
x.x.201.15     0   FULL/  -        00:01:54    2224            VlanX
x.x.254.33     0   FULL/  -        00:01:47    26              VlanX
x.x .254.132    0   FULL/  -        00:01:41    38              VlanX

 All of the IPV6 ospf interfaces have this config applied:  <ipv6 ospf network point-to-multipoint>

[Jon Marshall]

Peter will probably give you a much better answer than me but what you are seeing is correct because with point-to-multipoint OSPF treats the links as point-to-point links and no DR/BDR is elected on those.

Jon

[Peter Paluch · Accepted solution]

Steve, Jon,

No need to add anything here. As Jon has explained, because of the point-to-multipoint network type, no DR/BDR elections are taking place.

Do you have an idea why these routers are configured for point-to-multipoint OSPF network type? This is not very usual especially over Ethernet VLANs - and I also dare to say that for Ethernet environments with full visibility between all attached routers, running point-to-multipoint OSPF makes little sense.

Best regards,
Peter

[bryantsteve]

Thanks gentlemen you are correct the point-to-multipoint configuration was a legacy configuration, I lab tested and see DR, BDR DROTHER /FULL/..  -rolled out the change into production

looks much better now

[Jon Marshall]

Do you have any vlans/IP subnets with multiple neighbors or is it all P2P links ?

If P2P links have you got "ipv6 ospf network point-to-point" under the interfaces ?

Jon