From owner-freebsd-cluster Mon Oct 9 6:14:37 2000 Delivered-To: freebsd-cluster@freebsd.org Received: from fxp0.sds04.pangea.ca (fxp1-100M.sds05.pangea.ca [64.4.65.123]) by hub.freebsd.org (Postfix) with ESMTP id 3F7E837B503 for ; Mon, 9 Oct 2000 06:14:35 -0700 (PDT) Received: (qmail 531 invoked by uid 500); 9 Oct 2000 13:16:08 -0000 Date: Mon, 9 Oct 2000 08:16:08 -0500 (CDT) From: Curtis Coleman X-Sender: curtis@sds05.pangea.ca To: freebsd-cluster@freebsd.org Cc: curtis@pangea.ca Subject: Simple fallover using GateD and OSPF Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-cluster@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG I've been using a fallover scheme for a few (well, two) years now that is so simple, I wish I had thought of it myself. If you have a couple of hosts behind a router capable of running OSPF, you can use GateD to allow for fallover. The general premise is to have two or more hosts announce a stub host route for a loopback interface, with the same IP address on each machine, with differing costs large enough to be dominant over the link costs. If the primary host goes down, loses it's ethernets, or gated is otherwise killed, then the next highest cost route gets chosen. For example, a gated config for a loopback 172.16.0.1/32 would look something like this: ospf yes { backbone { interface fxp0 fxp1 cost 1; stubhosts { # for the backup host, change the # "cost" below to, say, 200 172.16.0.1 cost 100; }; }; }; export proto ospfase type 1 { proto direct { ALL metric 888; }; proto static { ALL metric 999; }; }; Aside from running OSPF, there is no special requirements of the gateway router(s). By binding a few loopbacks on each machine, it's not hard to extrapolate on this so that you can distribute load using DNS round-robin or some fancier source address-based policy routing. The idea was stolen from a message Danny McPherson of Genuity posted to the isp-caching list back in August '98. I believe that Vixie's j.root-servers.net has been doing something similar to this for quite a while. Curtis Coleman "Space is big. Really big. You just won't believe how Pangea.CA, Inc. vastly hugely mindboggingly big it is. I mean you may curtis@pangea.ca think it's a long way down the road to the chemist, but CC263 that's just peanuts to space. Listen..." -- HHGTTG To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-cluster" in the body of the message