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RE: IP announce DOS
From: "David Gillett" <gillettdavid () fhda edu>
Date: Fri, 10 Jun 2005 10:42:21 -0700

It most definitely is not possible to transfer IP ranges between ISP.

  Ahem.

  If you have done the necessary dance to get an AS number, you have your 
own block of addresses associated with it.  You then arrange with your 
ISP(s!) to "announce" your block as being reachable through them.

  If the rest of your message were correct, it would be impossible to 
achieve routing redundancy by advertising your corporate server addresses
via multiple ISPs.  (And it's NOT impossible; I've done it three times 
so far for different organizations.)

  While an ISP announces summarized routes to keep the core tables small,
there's no requirement that it (or any other AS) summarize down to a 
*single* address block.  A browse through a whois database will find
several major ISPs (and other large enterprises) who have multiple
non-contiguous address blocks assigned to them.

David Gillett



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