Subject: solution to NAT and multihoming

From: Jon Crowcroft <[email-masked]>
Date: Tue, 23 Jan 2001 08:09:31 +0000

here's an idea

if multihoming is killing routing coz deautlk free zone routers have
too many entries
and NAT is killing users coz they can't get always on addresses
why not have multihomed sites (aren't they usually server/core
provider sites) LEASE their standby link address prefixes to access provider
sites - and swap the address prefixes when their default link failes
and they need to failover to the standby link/addresses...

symmetry dictates this ought to work out...and everyone wins

by setting uo as a market we could even make the incentives right...

 cheers

   jon

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From: Jon Crowcroft <[email-masked]>
Date: Fri, 26 Jan 2001 11:01:06 +0000

In message <[email-masked]>, Jon Crowcroft typed:

 >>if multihoming is killing routing coz default free zone routers have
 >>too many entries
 >>sites - and swap the address prefixes when their default link fails

 >>by setting uo as a market we could even make the incentives right...

i wasn't too clear about this (a bit like my lousy 1000 bit error in
the port nat message - that'll teach me to send emails before i've had
any coffee:-)

so after suitable basting by sean doran, here's the scoop:-

I like GSE; however we dont have v6 and we do have NATs; we also have
multihoming.

1/ consider global DHCP as a tool, and a mechanism for buying a
lease on an aggregate

2/ do NATting on aggregates

3/ design a BGP attribute (yech, i know) to inidcate that an address
range is "bank switchable" - this means that it is part of a lease
from one AS to another. This means that when told (via management, BGP
update, or designated "important" ingress or egress link failure), a
pair of domains then bank switch the address range, but enable NATing
on the range for exsting flows...

got it?

j.