Policy Statement on Address Space Allocations

> 
> In message <199601291642.QAA09648 at diamond.xara.net>, "Alex.Bligh" writes:
> > Iljitsch van Beijnum <iljitsch at unix1.bart.nl> wrote:
> > 
> > > No they don't. You can ask the RIPE NCC for special PI space to assign to 
> > > this customer. It seems they have a "chemical waste dump" to satisfy 
> > > this kind of requests from.
> > 
> > Ah. That will be the "chemical waste dump" that Daniel K said
> > he didn't care about whether it got routed or not (no offence
> > Daniel - neither do I), and is all but unaggregatable so presumably
> > Sprintlink et al. won't want to waste their CPUs routing it as well.
> > What hope for a customer with those IP numbers?
> > 
> > Alex Bligh
> > Xara Networks
> 
> 
> Alex,
> 
> Here's my suggestion.
> 
> If you put that multi-homed customer in a larger aggregate (have them
> pick one of the providers and allocate from their address space) all
> of the providers must then announce the more specific.  Some providers
> will block the longer prefix.  The longer prefix will be preferred and
> traffic will avoid going through those providers that block it.  This
> might cause longer or suboptimal routing for the longer prefix.
> Providers everywhere will have either the shorter prefix or both, so
> full connectivity would exist.
> 
> If the multi-homing is sufficiently localized within the topology (for
> example, multiple providers in the same region or country) there might
> be a chance to draw an aggregation boundary around the whole thing and
> block the longer prefix outside of that locality and avoid the
> possibility of suboptimal routing due to long prefix filtering.
> 
> Curtis
> 

Except that if the shorter prefixed route goes down, half the world will
not be able to see any route to site, which sort of defeats the purpose
of being multi-homed.

Martha Greenberg
marthag at mit.edu