Date: Sat, 24 Jun 2006 00:04:25 +1000 From: "Christopher Martin" <outsidefactor@iinet.net.au> To: "'Claudio Jeker'" <cjeker@diehard.n-r-g.com>, <freebsd-net@freebsd.org> Subject: RE: Multiple routes to the same destination Message-ID: <53binj$o6s2np@iinet-mail.icp-qv1-irony5.iinet.net.au> In-Reply-To: <20060623135144.GD12611@diehard.n-r-g.com>
next in thread | previous in thread | raw e-mail | index | archive | help
> 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!
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?53binj$o6s2np>