Date: Wed, 2 Aug 2006 09:07:31 +0930 From: Malcolm Kay <malcolm.kay@internode.on.net> To: freebsd-questions@freebsd.org Cc: Joseph Gleason <fireduck@gmail.com>, questions@freebsd.org Subject: Re: multiple interfaces on same subnet? Message-ID: <200608020907.31695.malcolm.kay@internode.on.net> In-Reply-To: <7956f3200607311240g740c949cvbea994374967071f@mail.gmail.com> References: <7956f3200607311240g740c949cvbea994374967071f@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tue, 1 Aug 2006 05:10 am, Joseph Gleason wrote: > Is it possible to reach two hosts via two interfaces that are > both on the same subnet? > > Example: > em0: 172.20.0.1/16 > em1: 172.20.0.2/16 > > And I want to reach 172.20.0.3 via em0 and 172.20.0.4 via em1. > > From 'netstat -nr' I see a line like this: > 172.20/14 link#1 UC 0 0 > em0 > > This seems to say that anything on 172.20/14 should be reached > on em0. Is it possible to add a rule that says that 172.20.0.4 > should be reachable on em1? > I have no personal experience of doing this, but it seems to me you should be able to achieve your objective by using a specific netmask with ifconfig rather than the CIDR / notation: 172.20.0.1/16 -> 172.20.0.1 netmask 255.255.0.1 172.20.0.2/16 -> 172.20.0.1 netmask 255.255.0.1 Then as I understand it odd numbered addresses should be reached via 172.20.0.1 and even numbered addresses via 172.20.0.2 > I only care about the path of outbound packets. I don't care > which interface inbound traffic comes on. > > I am well aware that this is a fairly strange thing to do. > > My objective is to have a FreeBSD box balance outbound traffic > between two NICs, while being able to select from among many > routers that could be the default gateway and having the two > NICs connect to different switches for fault tolerance. (I > would do the fault tolerance via a watchdog script of some > sort) > > If it weren't for the many routers aspect, it would be > reasonable to create separate subnets. I need to be able to > select from a group of around 10 possible default gateways and > some of those routers I do not control so adding a subnet > would be trouble. I would expect that subnets in the routers would not be an issue so long as they encompass those set in ifconfig. Malcolm
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200608020907.31695.malcolm.kay>