[40865] in North American Network Operators' Group

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Re: multi-homing fixes

daemon@ATHENA.MIT.EDU (Vijay Gill)
Thu Aug 23 21:46:54 2001

To: Daniel Hagerty <hag@linnaean.org>
Cc: nanog@nanog.org
From: Vijay Gill <vgill@vijaygill.com>
Date: 24 Aug 2001 01:45:59 +0000
In-Reply-To: Daniel Hagerty's message of "Thu, 23 Aug 2001 20:49:47 -0400"
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Errors-To: owner-nanog-outgoing@merit.edu


Daniel Hagerty <hag@linnaean.org> writes:


>     Take prefixes from both providers and use them.  Route your egress
> traffic appropriately.
> 
>     My point wasn't that "there is no need to BGP multihome", but that
> many seem to see this as the only way of achieving use of multiple
> providers worth of pipe.  There are other alternatives, depending on
> your application.

This is a possible solution (and similar ideas have been bought up in
the v6 arena as well).  This runs into two things:

1) it is hard to maintain and manage (you've doubled the counting,
storing and allocation burden on the end user), as well as debugging.
Having been on the enterprise side of things, I believe that these are
non trivial problems to solve for a large number of people.


2) proper end unit (host) source address selection.


the way around #2 is to use some sort of a NAT scheme, and number
internally out of say, net10, and NAT appropriately at the autonomous
system edge.  With the "servers" as it were (mail, http, ftp et al.) 
being configured to listen on public address or special ports, etc.

These impose a significant added burden upon the end user.

It costs them significantly less to "graze upong the commons" as Randy
so eloquently put it at the IETF plenary in london.

/vijay


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