Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!cernvax!chx400!sicsun!sicsun.epfl.ch!goud
From: goud@sicsun.epfl.ch (Mireille Goud)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: gateways ignores ICMP redirect
Keywords: ip icmp
Message-ID: <1991May16.170108@sicsun.epfl.ch>
Date: 16 May 91 15:01:08 GMT
Sender: news@sicsun.epfl.ch
Reply-To: goud@sicsun.epfl.ch (Mireille Goud)
Organization: Ecole Polytechnique Federale de Lausanne
Lines: 49


Thanks to the people who answered my question.

I want to summarize here the answers and why I have the problem.

The problem :

   We have 2 parallel backbones in the school (One ethernet backbone
and one fddi backbone). The departments are all connected to the
backbones with a cisco router. Some departments are connected to the
two backbones (with only one router which has one fddi interface and
at least two ethernet interfaces) and the other departements are
connected only on the ethernet backbone (in the futur all the
departments will be connected on the two backbones). 
(Why 2 backbones ? because we had the ethernet backbone already and
it was not too expensive to keep that backbone as a spare backbone).

   For the departments connected to the 2 backbones we want the
traffic uses the fddi backbone if it is running and the traffic uses
the ethernet backbone only if the fddi backbone is down.

   We couldn't obtain this result with the rip protocol so we use the
igrp protocol.

   The cray is connected to the 2 backbones with 2 different NSC
routers. These routers do not understand igrp protocol. Our idea was
to give a default gateway to the NSC routers and they would have
learned the better routes by ICMP redirect from the default gateway.



The answers :
   
  ICMP redirects are sent only by routers and processed only by hosts.
  In RFC 1009 4.5.5 they say that dumb routers should pay attention
to redirects. 


Conclusion :
   Maybe, it is difficult to consider NSC routers as dumb routers.
   So I have to give all the static routes to the NSC routers. That
is the progress...


Thanks


Mireille Goud
Sic - EPFL              goud@sic.epfl.ch