OSPFv3 and IPV6

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May 3rd, 2008
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Hi,have a simulated Frame-relay network. Router A is the hub and Router B the spoke. RTR A WAN is point-to-multipoint(NBMA interface) and RTR B WAN is a point-to-point interface.I have successfully formed a neighbor adjacency across the WAN but no ipv6 ospf routes are visible in either routing table. What am I missing?

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Istvan_Rabai Sat, 05/03/2008 - 04:51
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Hi Mary,


Do you use the "show ipv6 route" command instead of "show ip route" ?


Could you please post the running-config of both routers?


Thank you:

Istvan

maryodriscoll Sat, 05/03/2008 - 05:17
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Istvan


I managed to get routes propogated over the wan by adding ip ospf network point-to-multipoint at the hub end. Hub=Dublin and Spoke=Sligo. In a normal work scenario, I have always used point-to-point so just trying to understand IPV6/OSPFV3 over FR here for the lab. Configs attached.

So, working but don't quite understand it.

Thanks Mary

Sligo_R4#sh ipv6 ospf nei


Neighbor ID Pri State Dead Time Interface ID Interface

2.2.2.2 1 FULL/ - 00:00:35 13 Serial0.24

Sligo_R4#sh ipv6 ospf int s0.24

Serial0.24 is up, line protocol is up

Link Local Address FE80::211:21FF:FE94:B406, Interface ID 11

Area 24, Process ID 1, Instance ID 0, Router ID 4.4.4.4

Network Type POINT_TO_POINT, Cost: 64

Transmit Delay is 1 sec, State POINT_TO_POINT,

Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

Hello due in 00:00:07

Index 1/2/2, flood queue length 0

Next 0x0(0)/0x0(0)/0x0(0)

Last flood scan length is 1, maximum is 3

Last flood scan time is 0 msec, maximum is 0 msec

Neighbor Count is 1, Adjacent neighbor count is 1

Adjacent with neighbor 2.2.2.2

Suppress hello for 0 neighbor(s)

Dublin_R2#sh ipv6 ospf int s0/0/1.24

Serial0/0/1.24 is up, line protocol is up

Link Local Address FE80::217:EFF:FEE7:71E0, Interface ID 13

Area 24, Process ID 1, Instance ID 0, Router ID 2.2.2.2

Network Type POINT_TO_MULTIPOINT, Cost: 64

Transmit Delay is 1 sec, State POINT_TO_MULTIPOINT,

Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

Hello due in 00:00:07

Index 1/1/1, flood queue length 0

Next 0x0(0)/0x0(0)/0x0(0)

Last flood scan length is 1, maximum is 9

Last flood scan time is 0 msec, maximum is 0 msec

Neighbor Count is 1, Adjacent neighbor count is 1

Adjacent with neighbor 4.4.4.4

Suppress hello for 0 neighbor(s)

Dublin_R2#



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Istvan_Rabai Sat, 05/03/2008 - 05:41
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Hi Mary,


The explanation to why it did not work is the following:


In OSPF, multipoint interfaces and subinterfaces by default are treated as having "nonbroadcast" network type.


When nonbroadcast network type is used, you should identify the neighbor manually with the "neighbor" command under the ospf process.

No multicast hello packets are sent to build up the neighbor relationship.


When you switched to "ipv6 ospf network point-to-multipoint", the multicast hello packets were sent to the network, and they were received by Sligo router.


In addition, point-to-point and point-to-multipoint network types are compatible in that neither of them requires the election of a DR nor BDR.


So the neighbor relationship could be formed between them without DR/BDR election.


Anyway, if there is only one hub router (Sligo) connected to interface Serial0/0/1.24 on the Dublin router, then you can you configure the Serial0/0/1.24 subinterface as point-to-point.

OSPF will handle it by default as point-to-point and the build-up of neighbor relationship should be again successful.


Cheers:

Istvan




maryodriscoll Sat, 05/03/2008 - 06:17
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Istvan,

I did manage to get a OSPFv3 neighbor established across the wan from Dublin to Sligo before I manually added the ipv6 ospf network point-to-multipoint command though as I had manually configured the neighbors using the link-local address. My problem was that I wasn't receiving any routes in/out of dublin from sligo and vice versa. As soon as I enabled ip ospf network command, routes were propogated. So while I understand what you are saying in that multicast hello packets are not sent by default on a NBMA network, it doesn't explain how my neighbors were established but were not passing any routes?

I am running 12.4t IP

Regards

Mary

Harold Ritter Sat, 05/03/2008 - 06:31
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Mary,


Even if you get the adjacency to form using non-broadcast on one side and p2p on the other side, SPF will consider that link as invalid and will not use it as a transit link because of the type mismatch.


Regards,

Harold Ritter Sat, 05/03/2008 - 06:17
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Mary,


Did you mean that it doesn't work if you configure the hub with "ipv6 ospf network point-to-point". This should work as well.


Regards,

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