Re: Policy Statement on Address Space Allocations
In message <199601291642.QAA09648@diamond.xara.net>, "Alex.Bligh" writes:
Iljitsch van Beijnum <iljitsch@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@mit.edu
In message <9601301900.AA16710@maze.MIT.EDU>, marthag@MIT.EDU writes:
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@mit.edu
True. What this protects against is losing the tail circuit to either provider. If the primary provider is single homed to the rest of the world or is otherwise unreliable and their entire aggregate disappears from global routing, then you lose connectivity to providers blocking long prefixes. I think that is the best you can do as long as some providers plan to block your long prefix. Pick a very stable aggregate to cover your long prefix. Curtis
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Curtis Villamizar -
marthag＠MIT.EDU