Subject: ASE/Network LSAs with same LS ID but different masks

From: Ashish Zalani <[email-masked]>
Date: Mon, 1 Jul 2002 13:17:56 -0400

Suppose a router is advertising two AS External (or Network Summary)
LSAs  for networks 192.168.0.0/16 and 192.168.0.0/24.
Then the two LSAs it will create will have the same Link State ID
(192.168.0.0) but different Network Masks.

My question is, how does a receiving router distinguish between the two LSAs?

AFAIK, any router that receives those two LSAs will use the Link State ID
and Advertising Router fields to check if it already has an instance of the
LSA in its database. Since both the LS ID and the Advertising Router are
the same for both LSAs, it will determine that one of the LSAs is just
another instance of the other one and discard one or the other LSA.

I looked through the RFC but could not find any information on how to
handle this situation. Am I missing something?

TIA,
-Ashish.
Ashish Zalani
Modeling Engineer
OPNET Technologies, Inc.
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From: "Joyal, Daniel R (Daniel)" <[email-masked]>
Date: Mon, 1 Jul 2002 13:28:47 -0400

Look at Appendix E in the OSPFv2 RFC.

-Dan

-----Original Message-----
From: Ashish Zalani [mailto:[email-masked]]
Sent: Monday, July 01, 2002 1:18 PM
To: [email-masked]
Subject: ASE/Network LSAs with same LS ID but different masks

My question is, how does a receiving router distinguish between the two
LSAs?

TIA,
-Ashish.
Ashish Zalani
Modeling Engineer
OPNET Technologies, Inc.