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Dual Homing Networks with DSL and Cable



it was said:
> Lou Katz wrote:
>
>On Sun, Aug 15, 2004 at 01:00:02AM -0500, Eric Crist wrote:
>>> -----Original Message-----
>>> From: Lucas Holt [mailto:Luke_(_at_)_FoolishGames_(_dot_)_com]
>>> Sent: Sunday, August 15, 2004 12:29 AM
>>> To: 'Eric Crist'; freebsd-questions_(_at_)_freebsd_(_dot_)_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

Hello,

I believe that this setup works for redundancy but does not aggregate
bandwidth. You need some sort of muxing mechanism, nee? What I mean is,
if each link is 1.5 Mbps, you could have three simultaneous users each
getting 1.5 Mbps, but if you had only one user, he/she would still get
only 1.5, not 4.5 Mbps. I think that what Mr Crist was asking is how to
get the 4.5 Mbps.
I have never done this in FreeBSD, but I recall some work to do this
very thing being done in altq (on OpenBSD) and perhaps dummynet has
this capability. 
What Mr Holt is talking about is getting an ASN from ARIN. This is for
inbound redundancy on a multi-homed network. Should one of your links
go down, its IP space would still be reachable via your other link(s).
This is not applicable to Mr Crist's situation, if I understand what he
is trying to accomplish.

HTH,

Stheg


		
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