/8s and filtering
tme at multicasttech.com
Tue Dec 10 14:53:36 UTC 2002
Here is one reason for some to care :
If you want to do interdomain multicast, and your
address space is not announced globally (say because you have a /24 that
not from the swamp), you are likely to be black-holed
due to RPF failures (as your unicast and multicast routing is likely to
This has caused problems from time to time...
On Tuesday, December 10, 2002, at 05:58 AM, David Schwartz wrote:
>> 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
> 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.
> learn to multihome at your client's expense. ;)
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