Subject: OSPFv3 query (link LSAs & link local addresses)

From: Arthur Dimitrelis <[email-masked]>
Date: Mon, 26 Aug 2002 19:56:47 +1000

Hi everyone,

I've got a query regarding OSPF for IPv6. With reference to RFC2740,
section 2.5 discusses how IPv6 link local addresses are used as the
source addresses in PDU exchanges between OSPFv3 speakers (including
HELLO packets), and goes on to state that an OSPFv3 router will learn
the link-local addresses of all other routers attached to its links. No
problems with all that.

Now, appendix A.4.8 defines the packet format of a link LSA, which
includes the link local address of its originating router. The
commentary in this section explains that one of the purposes of a link
LSA is to allow all routers on the link to learn the link-local address
of the LSA's originator. Could this information not have been deduced
from the Advertising Router ID field in the LSA's header (along with the
information gleaned from previously seen HELLO packets, ie from those
neighbors a router considers to be in the '2-way' state) ?

Anybody know about or have any ideas on this apparent (to me)
redundancy?

cheers,
arthur

---

From: Acee Lindem <[email-masked]>
Date: Wed, 28 Aug 2002 13:06:13 -0400

> Anybody know about or have any ideas on this apparent (to me)

Arthur,

Look at section 3.8.1.1 in RFC 2740. The link local address in the
Link LSA to calculate the next-hop on NBMA networks. Independent
of NBMA networks, I think it is conveinent to have it in the Link LSA
with the IPv6 prefixes.

> arthur

Thanks,
--
Acee