From owner-freebsd-net@FreeBSD.ORG Fri Jun 23 14:04:25 2006 Return-Path: X-Original-To: freebsd-net@freebsd.org Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 56D2416A494 for ; Fri, 23 Jun 2006 14:04:25 +0000 (UTC) (envelope-from outsidefactor@iinet.net.au) Received: from mail-ihug.icp-qv1-irony5.iinet.net.au (ihug-mail.icp-qv1-irony5.iinet.net.au [203.59.1.199]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4CE0143D53 for ; Fri, 23 Jun 2006 14:04:23 +0000 (GMT) (envelope-from outsidefactor@iinet.net.au) Received: from 124-168-19-56.dyn.iinet.net.au (HELO SAURON) ([124.168.19.56]) by mail-ihug.icp-qv1-irony5.iinet.net.au with ESMTP; 23 Jun 2006 22:04:21 +0800 Message-Id: <53binj$o6s2np@iinet-mail.icp-qv1-irony5.iinet.net.au> X-BrightmailFiltered: true X-Brightmail-Tracker: AAAAAA== X-IronPort-AV: i="4.06,169,1149436800"; d="scan'208"; a="812518137:sNHT18389364" From: "Christopher Martin" To: "'Claudio Jeker'" , Date: Sat, 24 Jun 2006 00:04:25 +1000 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook, Build 11.0.5510 In-Reply-To: <20060623135144.GD12611@diehard.n-r-g.com> Thread-Index: AcaWzGsKWBmWhgS7Tle4xlcR/ce61QAAGlRg X-MimeOLE: Produced By Microsoft MimeOLE V6.00.3790.2663 Cc: Subject: RE: Multiple routes to the same destination X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 23 Jun 2006 14:04:25 -0000 > I doubt that. Doing a per packet round robin over different pathes will > kill your tcp performance because of out of order packets. Noted. That's a very good reason. Maybe if there was a may to round robin on a session basis to mitigate this. Not really going to be an easy fix, however, so your point is very valid. > > > > It would seem that you are assuming that I want to load balance two > internet > > connections which are NATed, in which case round robin might have issues > > with lost TCP sessions and weird reactions from servers as the apparent > > source address changes from packet to packet, but in a routed internal > > network the source address will not be changed by the router, thus > negating > > that issue. > > > > It did seem at some stage someone was going to include it in OpenBSD: > > http://undeadly.org/cgi?action=article&sid=20040425183024&mode=expanded > > > > That's just part of the it. The rest was added in the last couple of days > because multipath routing and accepting more than one route per > destination is a scary thing. Additionally dead nexthop detection is not > available. I would have thought OSPF would have provided your dead hop issues, however it does not resolve your point above, so we still seem out of luck. > > To quote: > > "...OSPF also supports multipath equal cost routing". > > > > Yes it does but often you try to avoid that. Because of your point above? Besides that, can you provide a couple of examples of why we would try and avoid it? > > It's more of a case where we would like to use BSD as a router/packet > > filtering firewall for sites with multiple WAN links between each site, > of > > equal size, and not have one site idle until the other fails over. Round > > robin is better than what we have: nothing. > > OpenBSD is on the way to support this but it is still a long journey till > all issues are resolved. Btw. OpenBSD uses a hash-threshold mechanism to > select paths based on source/destination IP address pairs (round robin > will never be supported). Again, another good point. And it also answers the other query as to the level of work involved in making it work. Thanks Claudio!