Subject: [Isis-wg] Forwarding database for IP only

From: <[email-masked]>
Date: Thu, 7 Feb 2002 17:56:18 -0800

Hi,
Thanks all for your replies. I have one more question.
RFC 1195 annex C explains the forwarding algorithm for both OSI and IP. I was wondering if it is possible to remove OSI computation from IP only router. Do we have any paper for the optimization for IP only routers in ISIS?
Regards
Amit

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From: Jeff Learman <[email-masked]>
Date: Fri, 08 Feb 2002 09:38:07 -0500

Amit,

>RFC 1195 annex C explains the forwarding algorithm for both OSI and IP. I was wondering if it is possible to remove OSI computation from IP only router. Do we have any paper for the optimization for…

While I haven't studied this with the diligence required for a scholarly
paper, I have given it a bit of thought.  My opinion is that, in a network
that is constructed according to RFC-1195's deployment rules, there would
be no observable behavior difference between a router that runs a protocol-
specific SPF per supported protocol and one that runs SPF including all
protocols.  The reason is simply that the deployment rules require all the
ISs in the subdomain (L1 area or L2 backbone) to support the same set of
protocols.

Regards,
Jeff

Disclaimer: I have not worked on IS-IS at Cisco.  My opinions are my
own and do not necessarily reflect those of my employer.