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Date:      Mon, 30 Apr 2001 21:32:03 -0700
From:      "Ted Mittelstaedt" <tedm@toybox.placo.com>
To:        "Chris Shenton" <chris@Shenton.Org>, "Kulraj Gurm (bosa.ca account)" <kulraj@bosa.ca>
Cc:        "Ken Bolingbroke" <hacker@bolingbroke.com>, <questions@FreeBSD.ORG>
Subject:   RE: Redundant Internet connections
Message-ID:  <000301c0d1f7$abef7c20$1401a8c0@tedm.placo.com>
In-Reply-To: <87y9si9igi.fsf@thanatos.shenton.org>

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>-----Original Message-----
>From: Chris Shenton [mailto:chris@Shenton.Org]
>Sent: Monday, April 30, 2001 2:38 PM
>To: Kulraj Gurm (bosa.ca account)
>Cc: Ken Bolingbroke; Ted Mittelstaedt; questions@FreeBSD.ORG
>Subject: Re: Redundant Internet connections
>
>
>"Kulraj Gurm (bosa.ca account)" <kulraj@bosa.ca> writes:
>
>> I am a little confused however; maybe just my lack of
>understanding, but all
>> your discussion on redundancy has been focussed on out bound
>traffic - where
>> I can conceptually see it working. But what are the DNS implications?
>
>It's not DNS, per se. Rather: how do packetss coming to your network
>know which path to take?
>

Aaahh, someone who has a clue here, give that man a cigar!

>If you have connections to ISP-1 and ISP-2, and ISP-1 dies, how does
>traffic on the net know how to reach you via ISP-2, its network, and
>its network provider?
>
>If your host has IP 1.2.3.4 and that IP address space belongs to
>ISP-1, I don't see how a connection to ISP-2 is going to help when
>your connection to ISP-1 dies.
>
>
>
>Now perhaps you could have a box with an IP for ISP-1 and one for
>ISP-2, and NAT your internal network so neither ISP sees your real LAN
>addresses. Then have DNS list both and when ISP-1 dies, change the IPs
>in your DNS and quickly push them out... This seems kind of a hack
>though.
>

Yes, your catching on to what he has in mind.

It is an extreme hack but the only one that he can implement.  Fortunately
the DNS isn't this bad because at least with e-mail you can list a secondary
MX host,
and with FTP and WWW you can offload those to a virtual host at an ISP.
But,
it's still out of the question for 99% of the people who connect to the
Internet
because the physical circuits are so expensive you cannot possibly justify
having
2 and only one being active.  These sorts of ugly hacks are only possible
when
the physical circuit costs are next to nothing (ie: DSL, Cable) or are
transient or metered (dialup V90 or ISDN)

Ted Mittelstaedt                      tedm@toybox.placo.com
Author of:          The FreeBSD Corporate Networker's Guide
Book website:         http://www.freebsd-corp-net-guide.com



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