OSPFv2 vs OSPFv3

This topic is to discuss the following lesson:

Hi Rene,

Links, not networks” what do mean at this point, can you please explain in detail ? and can you give me an example about multiple instance ID in the same link ?

Hello Hussein

This is essentially a change in semantics. In OSPFv2 we speak about networks. The destination network, the networks that are advertised. A network is expressed as, for example, 10.56.3.0/24. This is a destination or advertise network as far as OSPFv2 is concerned.

IN OSPFv3, the term that is used is link. This means that 2001:AB::0/64 found in the routing table for example is called a link in the context of OSPFv3.

The command to implement OSPFv3 on an interface is the following:

**ipv6 ospf** process-id area area-id [instance instance-id]

You can input this command several times with a different instance-id in each case and have the same interface (and subsequently its link) participate in multiple instances of OSPFv3.

I hope this has been helpful!

Laz

Thanks Laz

That was very helpful indeed.

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Hi all,
The flooding scope 0x2 says in the lesson that “is used for LSAs that are flooded throughout a single area”. LSA Type 3 and 4 are flooded throughout all ospf areas like the LSA Type5. Shouldn’t they also have the flooding scope 0x4?
Thanks in advance.

Hello Marios

Actually, if you take a closer look at Type 3 and Type 4 LSAs, you will find that they are not flooded throughout the whole AS scope. Looking at the related lesson about OSPFv2 LSAs, you can see that both are generated by an ABR that receives a Type 1 LSA. They are flooded to the rest of the network, but not in the OSPF area from which the Type 1 LSA is received.

The only LSA that truly exists throughout the whole AS in all OSPF areas is a Type 5 LSA, and it is the only one that begins with 0x4.

I hope this has been helpful!

Laz

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Hi,

Regarding the statement:

By separating the SPF tree and prefixes, OSPFv3 is more efficient. When the link-local address on an interface changes, the router only has to flood an updated link LSA and intra-area-prefix LSA. Since there are no changes to the topology, we don’t have to flood type 1 and 2 LSA(s). Other routers won’t have to run SPF in this case.

Is it also correct to say that is more efficient because prefix information is not being repeated, as Type-1 and Type-2 LSAs can contain the same network information. e.g. if router 1 and router 2 are connected network. Both their Type-1 LSAs contain the same prefixes for the same link.

Thanks

Sam

Hello Samir

Yes, what you say makes sense because you are not duplicating information that has already been sent.

Laz

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