From owner-freebsd-hackers Fri Jan 24 04:46:14 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.5/8.8.5) id EAA26883 for hackers-outgoing; Fri, 24 Jan 1997 04:46:14 -0800 (PST) Received: from asstdc.scgt.oz.au (root@asstdc.scgt.oz.au [202.14.234.65]) by freefall.freebsd.org (8.8.5/8.8.5) with ESMTP id EAA26877 for ; Fri, 24 Jan 1997 04:46:10 -0800 (PST) Received: (from imb@localhost) by asstdc.scgt.oz.au (8.7.6/BSD4.4) id XAA08098 Fri, 24 Jan 1997 23:45:27 +1100 (EST) From: michael butler Message-Id: <199701241245.XAA08098@asstdc.scgt.oz.au> Subject: Re: Fault-tolerant network with 2 ethernets In-Reply-To: from Andrew Stesin at "Jan 24, 97 01:43:57 pm" To: stesin@gu.net (Andrew Stesin) Date: Fri, 24 Jan 1997 23:45:27 +1100 (EST) Cc: jdp@polstra.com, hackers@freebsd.org X-Mailer: ELM [version 2.4ME+ PL28 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk Andrew Stesin writes: > Yes. But make sure that a set of IP addresses > used for loopback-aliased router-IDs is _not_ covered > by any of the subnets (address ranges). You need to exercise some degree of caution with this. The temptation is to use a subnet with a netmask so small as to only accomodate that of the loopback interface (255.255.255.252 is commonly used on Ciscos). This is all well and good when everything else listening to your IGP understands what it means. If you have "legacy" hardware lying about (some terminal servers and Cisco 1003s come to mind), you need to be very careful about what you propagate into other, classful IGPs (such as RIPv1 or IGRP) so that they too can understand how to forward packets properly. I suggest trying to arrange things such that appropriate route summarisation can be achieved by judicious rules in gated.conf on suitable (and comprehensible) subnet boundaries. In my case, it was easy - such hardware only gets a default route and nothing else :-) michael