Subject: Re: Transport level multihoming

From: Iljitsch van Beijnum <[email-masked]>
Date: Mon, 3 Sep 2001 18:34:20 +0200 (CEST)

I'm way behind, trying to catch up, so I apologise if I'm repeating
something that has been said earlier, but...

On Tue, 7 Aug 2001, Ramakrishna Gummadi wrote:

> Another problem with the transport-level multihoming is that
> the number of failure modes that can be tolerated in a multi-tier
> multihoming are decreased. For
> example, consider the scenario where a site is dually-multihomed, while
> each of the providers are triply multihomed to three different providers
> each. The question is---how many addresses do the hosts in the site have?
> If it is two, then it means that the site can not tolerate failures in four of
> the providers twice removed from it. If it is six, then it means we are
> exposing the site to addressing issues not related to it.

Obviously, ISPs of a reasonable size should be able to get an address
block of their own. Obviously, the routing table will still continue to
grow under such a policy.

In the presence of a good multiple-addresses multihoming scheme, the
requirement for getting an address block could be being globally visible
over three or more transit networks. I would be very surprised if the
number of networks that qualify under these conditions is more than a few
thousand world wide.

A customer would then never have to use more than two address ranges over
a single ISP, or four when dual-homed.

Iljitsch van Beijnum