From owner-freebsd-current Thu Jun 29 08:26:31 1995 Return-Path: current-owner Received: (from majordom@localhost) by freefall.cdrom.com (8.6.10/8.6.6) id IAA27863 for current-outgoing; Thu, 29 Jun 1995 08:26:31 -0700 Received: from freebsd.netcraft.co.uk (lambda.demon.co.uk [158.152.17.124]) by freefall.cdrom.com (8.6.10/8.6.6) with ESMTP id IAA27854 ; Thu, 29 Jun 1995 08:26:14 -0700 Received: (from paul@localhost) by freebsd.netcraft.co.uk (8.6.11/8.6.9) id QAA13229; Thu, 29 Jun 1995 16:23:38 +0100 From: Paul Richards Message-Id: <199506291523.QAA13229@freebsd.netcraft.co.uk> Subject: Re: Paul Richards: sysconfig routed setting To: wollman@halloran-eldar.lcs.mit.edu (Garrett Wollman) Date: Thu, 29 Jun 1995 16:23:38 +0100 (BST) Cc: nate@sneezy.sri.com, wollman@halloran-eldar.lcs.mit.edu, rgrimes@gndrsh.aac.dev.com, jkh@freebsd.org, FreeBSD-current@freebsd.org In-Reply-To: <9506281839.AA01339@halloran-eldar.lcs.mit.edu> from "Garrett Wollman" at Jun 28, 95 02:39:20 pm Reply-to: paul@freebsd.org X-Mailer: ELM [version 2.4 PL24] MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Content-Length: 2165 Sender: current-owner@freebsd.org Precedence: bulk In reply to Garrett Wollman who said > > < > > Ethernet = > > SLIP/PPP * > > > machine-A<=>machine-B<=>machine-C<*>{internet} > > ^ > > * > > v > > Nate's box > > > Machine A is a router. It runs a routing protocol. I'm not even sure that is necessary, since Nate's box is the only machine hanging off the slip link proxy ARP would be a better set up. Machine A proxy-ARP's Nate's address so that Nate's box appears to be on the ethernet. Nate's box will obvious have a default route to machine A and if A has appropriate netmasks for it's two interfaces it will know that packet's for Nate's box go out the slip link. It's is a router but it wouldn't be necessary to run a routing deamon on it. > > > With your assumption, machine B does is not running any routing > > software, so therefore it does not know to send packets to machine A in > > order to get to my machine. > > Machine B has a default router R. R and A exchange routing protocol > packets to inform each other of their locations. When machine B sends > a packet for `Nate's box' to R, R sends an ICMP redirect back to B > telling it that `Nate's box' should be reached by way of A, and B > sends future packets directly. If A does proxy ARP then B will send packets to A and A will forward them across the slip link without having to run a routed. This is an exception though and Garrett's description above expalins the more general case, if for example there were several boxes off the slip link to Nate's machine. We're getting off the point a bit though, which is whether routed should be enabled by default. I still think the only time it should be run is if the box has a real need to exchange RIP info with other routers and in those cases the admin will know enough to make that decision. For most boxes it's not needed. -- Paul Richards, Bluebird Computer Systems. FreeBSD core team member. Internet: paul@FreeBSD.org, http://www.freebsd.org/~paul Phone: 0370 462071 (Mobile), +44 1222 457651 (home)