Subject: Re: IGP fast reroute

From: "Manral, Vishwas" <[email-masked]>
Date: Mon, 17 Mar 2003 23:05:09 -0500

Hi Kajol,

There is a document
http://www.ietf.org/internet-drafts/draft-kini-traf-restore-nsp-00.txt that
talks about non-shortest-path, which may be relevent to the discussion.

Besides the IS-IS base document, ISO-10589 talks about "downstream path". A
router calculates path to a destination from a neighbor(the LSDB in all
routers is the same), and any path to the destination that has a lesser cost
than from the calculating router itself is a downstream path.(if I remember
it right). The idea is to find non-looping alternate paths.

Thanks,
Vishwas

-----Original Message-----
From: kajol pattnaik [mailto:[email-masked]]
Sent: Tuesday, March 18, 2003 2:35 AM
To: [email-masked]
Subject: IGP fast reroute

Hello,
  Are there any IETF standard/document  for IGP/OSPF
fast reroute as has been presented by alex zinin and
chenigz in their presentation :"IGP Fast Reroute" ,
slides can be found at

http://www.packetdesign.com/news/presentations.html

This seems to be a good alternative to IGP fast
convergence, to achive sub-second re-routing wit IGPs,
by generating a two(or a fixed number of) best routes
rather than one best route.

If there are any IETF standards on this or, any work
in progress in IETF, please point me to the documents.
or, is this completely implementation specific.

Are there any vendor /academic implementation that
supports IGP/OSPF fast rerouting as presented above??

thanks,
kajol.

__________________________________________________
Do you Yahoo!?
Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop!
http://platinum.yahoo.com

---

From: mukul goyal <[email-masked]>
Date: Tue, 18 Mar 2003 07:31:21 -0500

A paper along similar lines is: Fortifying OSPF/IS-IS against link-failure
by M. Thorup (http://www.research.att.com/~mthorup/PAPERS/papers.html).
This paper talks about data structures that will allow a router to make a
constant time determination regarding an outgoing link to a destination
that avoids a given failed link. Thus, routing loops can be avoided in the
scenarios where a router has learnt about a failure but has not yet
updated the routing table.

Thanks,
Mukul