nanog mailing list archives

Re: Confussion over multi-homing


From: Austin Schutz <tex () off org>
Date: Thu, 14 Sep 2000 23:47:41 -0700


Yep, this has been a topic here before...no real resolution. You didn't
really need to prove the case, it has already been proven.

No.  From a post I made to this list on 6/22/2000:

++> Here's the deal.  If you number out of Provider1's CIDR block
++> but advertise your more-specific to Provider2 and the two Providers
++> touch and Provider1 accepts the more-specific route from Provider2,
++> you should have no problem reaching anyone.
++> 
++> Here's the reason: Everyone accepts Provider1's announcement of the block.
++> When your link to P1 is up, any traffic they recieve for your prefix
++> gets routed over that link since they carry your more-specific internally.
++> However, if other providers here the more-specific from P2, they'll
++> send directly via P2 who sends it over the link to you.

        But if your chunk of space is greater than /20, the other providers
will filter P2's announcement of your space and you are back to square one.
        Well, at least you won't be cut off from the entire Internet, I guess
that's something. Square 1.5.

        Austin



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