FreeBSD router two DSL connections

[Danial Thom]

--- "Loren M. Lang" <lorenl at alzatex.com> wrote:

> On Sun, Dec 11, 2005 at 11:28:17PM -0800, Ted
> Mittelstaedt wrote:
> > 
> > If both DSL lines go to the same ISP it is
> easy, run
> > PPP on them and setup multilink PPP.  The ISP
> has to
> > do so also.
> > 
> > If they are going to different ISP's then you
> cannot
> > do it with any operating system or device
> save BGP - the idea is
> > completely -stupid- to put it simply.  If you
> think different,
> > then explain why and I'll shoot every
> networking scenario
> > you present so full of holes you will think
> it's swiss cheese.
> > And if you think your going to run BGP I'll
> shoot that full
> > of holes also.
> 
> I strongly disagree.  There are many reasons
> for this.  Two of which are
> increased throughoutput and redundancy.  The
> primary problem is that you
> need to make sure outgoing data for a
> connection is using the same line
> as the incoming connection.  If the majority to
> all connections are
> outgoing and both lines use NAT and have unique
> IP addresses, it's
> simpler to setup.  If you have incoming
> connections as well, either only
> one of the two lines will be used or you'll
> need BGP or some kind of
> static route setup by the two ISPs.  For an
> internet cafe, most
> connections will probably be outgoing so it
> won't be a problem.

Thats not right at all, although in *some* cases
it may be desirable. All upstream ISPs are
connected to everyone on the internet, so it
doesn't matter which you send your packets to
(the entire point of a "connectionless" network.
They both can forward your traffic to wherever
its going. For efficiencies sake, you may argue
that sending to the ISP that sent you the traffic
will be a "better path", but if one of your pipes
is saturated and the other running at 20% then
its likely more efficient to keep your pipes
filled and send to "either" isp. You can achieve
this with per-packet load-balancing with ciscos,
or bit-balancing with a product like ETs for
FreeBSD. Unless your 2 isps are connected
substantially differently (say if one is in
Europe and one in the US),  you'll do better
keeping your pipes balanced, as YOU are the
bottleneck, not the upstream, assuming you have
quality upstream providers.

Danial

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