Re: /8s and filtering

[David Schwartz <davids () webmaster com>]

> I was also curious about this - if I am a customer who wants to
> multihome and can justify only a /24, I would go to an ISP
> which has an allocation from the Class C space rather than one from the
> Class A space.

        It doesn't matter. For all practical purposes, basement multihomers only
care that their two or three providers have their route.

> Do ISPs get to choose where the allocation comes from?

        Ask your ISP if they'll let you choose. But it usually doesn't matter, if
you can only justify a /24, you'll find about the same filtering policies in
both traditional class A space and class C space.

        But again, it doesn't matter. So long as each of your providers will honor
your route (and why wouldn't they, you're paying them to)  you shouldn't have
a problem.

        Just pick your most reliable provider, and the one you're pretty sure you're
going to stay with the longest, and get your IP space from them. Make sure
they don't mind you advertising your block through other providers.

        And give some thought to hiring a competent consultant to help you. You can
hire a consultant even if you are the consultant. In fact, no competent
consultant would do otherwise outside his or her area of expertise. Don't
learn to multihome at your client's expense. ;)

        DS