Subject: Forwarding address

From: "Seema Rao (Infosys)" <[email-masked]>
Date: Thu, 30 May 2002 12:02:22 -0400

Hi,

I have a doubt in section 16.4 of RFC 2328. This regarding the
forwarding address in the ASE LSA.

The following is the extract from the RFC

************
Look up the routing table entry for the destination N.  If           no
entry exists for N, install the AS external path to N,            with
next hop equal to the list of next hops to the            forwarding
address, and advertising router equal to ASBR.
************************

Now consider a scenario as follows.

rtr1----ethernet hub----rtr2
        |
        |--------rtr3----Dest-N

1] rtr1 and rtr2 are doing OSPF.
2] rtr2 has a static route to reach Dest-N via rtr3.
3] rtr2 is also redistributing this static route into OSPF.
4] The ASE-LSA rxed by rtr1 will have the forwarding address set to
rtr3.
5] rtr1 will look up its routing table and will find a direct route to
rtr3 network.

Now as per the RFC rtr1 will need to install the route to Dest-N, with
next hop equal to the list of next hops to the forwarding address. In
this case, since the forwarding address is directly connected, is it
correct for rtr1 to install a route to Dest-N with next hop none?

TIA,
Seema

---

From: Acee Lindem <[email-masked]>
Date: Thu, 30 May 2002 13:41:27 -0400

> The following is the extract from the RFC

No - the next hop will be the rtr3's IP address for the ethernet
segment. Without the forwarding address you'd need to take the shortest
path to rtr2 (the advertising ASBR) and then rtr3.

--
Acee