Policy Statement on Address Space Allocations

> > 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


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.


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