Date: Fri, 27 Oct 2000 00:51:41 -0400 (EDT) From: "Richard A. Steenbergen" <ras@e-gerbil.net> To: Nick Rogness <nick@rapidnet.com> Cc: John Telford <j.telford@sympatico.ca>, freebsd-net@FreeBSD.ORG Subject: Re: Multihomed natd, nics and default gateways continued. Message-ID: <Pine.BSF.4.21.0010270036120.10623-100000@overlord.e-gerbil.net> In-Reply-To: <Pine.BSF.4.21.0010262159380.29371-100000@rapidnet.com>
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On Thu, 26 Oct 2000, Nick Rogness wrote: > > My tcp/ip is weak, how does applying a route for 128.0.0.0 work here ? or > > what happens in the box if ISP_A goes down ? > > > What happens is traffic normally flows to ISP A because it has a > more specific route to get to a any given network 0.0.0.0/8 & > 128.0.0.0/8. The reason for this is because FreeBSD doesn't have > support (yet) for 2 routes to the same network. Since 0.0.0.0/8 > & 128.0.0.0/8 are more specific routes to the 0.0.0.0/0 network > they take precedence. > > However, if ISP A becomes unreachable, FreeBSD will mark the route > for those networks (0.0.0.0/8 & 128.0.0.0/8) as unreachable. This > will force routing to use the next specific route (0.0.0.0/0) to > be triggered and traffic will start to flow across to ISP B and > start using the natd2 address translation. > > This is not a prefect design. Some things will break during the > switch-over (like FTP during a file transfer). However, things > should work after the switch over. I believe you're looking for /1 not /8 (mask 128.0.0.0)... Using NAT for redundancy is pretty difficult when using IPs from each respective ISP's IP space and not speaking BGP, since all established TCP connections will break. Load balancing is a much nicer application for it, since by design you can do per-connection selection of multiple interfaces. -- Richard A Steenbergen <ras@e-gerbil.net> http://www.e-gerbil.net/humble PGP Key ID: 0x138EA177 (67 29 D7 BC E8 18 3E DA B2 46 B3 D8 14 36 FE B6) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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