Dual Homing Networks with DSL and Cable

[Lou Katz]

On Sun, Aug 15, 2004 at 01:00:02AM -0500, Eric Crist wrote:
> > -----Original Message-----
> > From: Lucas Holt [mailto:Luke at FoolishGames.com]
> > Sent: Sunday, August 15, 2004 12:29 AM
> > To: 'Eric Crist'; freebsd-questions at freebsd.org
> > Subject: RE: Dual Homing Networks with DSL and Cable
> >
> >
> > You will have difficulty with this setup.  Most large
> > providers require that you register your multihomed capacity
> > on a list.  Otherwise traffic won't know to come in on a
> > particular interface or that it can go either way.  I must
> > admit I'm going from memory here.  I used to work at an ISP
> > about 5 years ago.  At that time we went from a T3 with UUNET
> > to a multihomed setup with verio and uunet.  It was rather
> > odd actually.. 3 t1s connected us to our modem banks at the
> > telco and then we had an ethernet connection to verio's pipe,
> > plus the T3 in our main office.  Anyway, verio required us to
> > get on this list.  They told us that most large ISPs use it
> > for routing.  I suspect you will need static ips with the
> > cable provider to pull it off as well.
> 
> Actually, I was under the assumption that the multi-homed system would
> process outgoing traffic, and the incoming would just return on the
> appropriate IP.  In this scenario, there's no need to register hosts.

Some networks will not pass outbound traffic that has a source address
NOT in the correct net. I have more than one inbound net, and have found
that, for a small number of BSD machines, putting up IPFW and using the
'fwd' rules works.

For the case of three networks all with static IP addresses, my network
card is assigned three IP addresses in ifconfig which results in lines
in rc.firewall (for example):

net1ip="a.b.c.123"
net2ip="e.f.g.74"
net3ip="h.i.j.202"

Each of the networks has a different gateway with rc.firewall entries:

net1gw="a.b.c.1"
net2gw="e.f.g.1"
net3gw="h.i.j.1"


Packets coming in addressed to netX1ip are replied to from that IP address,
so the following rules direct them to the correct default routes: 

        ${fwcmd} add fwd  all from ${net1ip} to ${net1ip}
        ${fwcmd} add fwd  all from ${net2ip} to ${net23p}
        ${fwcmd} add fwd  all from ${net3ip} to ${net3ip}


Works fine for me. Haven't done this for NAT'd IP addresses, though.

> 
> Thanks,
> 
> Eric F Crist
> Best Access Systems
> 11300 Rupp Dr. Burnsville, MN 55337
> Phone: 952.894.3830
> Cell: 612.998.3588
> Fax: 952-894-1990
> 
> 
> _______________________________________________
> freebsd-questions at freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-questions
> To unsubscribe, send any mail to "freebsd-questions-unsubscribe at freebsd.org"

-- 
-=[L]=-