Customer AS

Paul Ferguson pferguso at
Sat Aug 17 01:45:23 UTC 1996

At 06:55 PM 8/16/96 -0400, Curtis Villamizar wrote:

>> I would make them renumber with a new class c that was not in your CIDR
>> block.
>> Maybe they could get a class C from the swamp?
>Are you suggesting that all dual homed networks should be renumbered
>such that they can't be aggregated and can't be reached from a good
>part of the Internet.  I don't think that is a good idea.
>Are suggesting punishing a customer for picking up a second provider
>by giving them an unroutable prefix?  I hope not.


Not sure what you mean here concerning 'unroutable' prefixes, but the
issue with obtaining an allocation for one of the upstream provider's
CIDR block when multihomed *does* have its drawbacks, at least from
the end-user perspective. If said prefix (let's say a /24) is announced
in the 'allocating' provider's aggregate, and the more specific is
announced via the 'other' provider, the more specific will always be

Of course, you can play a few tricks (AS_PATH prepend, etc.), but this
situation introduces unique problems.

In fact, the <draft-hubbard-registry-guidelines-05.txt> draft indicates
that this is one of the few acceptable instances when allocation can be
done by one of the various registries and not by (one of) the upstream
service provider(s). I think this is a contributing factor to the overall
growth of the global routing table(s), but this is an issue we need to
deal with. From an operational perspective, I'd opt for using a prefix
which was not allocated from either/any upstream provider. From a global
perspective, this contributes to route bloat.  :-/

- paul

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