OSPF ASBR Chinese Whispers

From: Salau, Yemi (yemi.salau@siemens.com)
Date: Wed Jul 04 2007 - 12:07:02 ART


Hello Guys,

Has anyone ever experience chinese whisperings with OSPF ASBR Link
States. Actually, I'm trying to get my head around what could cause this
problem in a Cisco environment.

By the way, Chinese Whipers are false link state advertisement in this
context, a situation where OSPF Routers have false external type-5 link
states within their database which was previously advertised by an ASBR
into the OSPF domain. I was told this is common with Nortel BayRS
routers, but is this possible with Cisco routers? If yes, what could
cause it.

My initial guess was that in such a massive multivendor environment,
things can jump out of sync sometimes or in other words, link state
changes don't sync up on time for these external type-5s to age out of
the OSPF database.

I understand that one of the ways you resolve is within Nortel is by
releiving the ASBR of it's duties and then promoting it back again,
another way could be rebooting the ASBR which literally triggers a link
state change on all OSPF Routers. But why would this happen faster than
the original triggers by Link State Changes.

Many Thanks

Yemi Salau



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