Re: The same prefix originated within two different ASs

[Tony Bates <[e-mail]>]

Check out 

	draft-ietf-idr-symm-multi-prov-01.txt

and referenced drafts which discusses this point at some length.

		--Tony.

 Photon - NOL Staff <[e-mail]> writes:
  * On Tue, 11 Jul 1995, Christopher D. Wheeler wrote:
  * 
  * > 
  * > 
  * > Can someone please reiterate to me, from experience, reasons why a prefix
  * > shouldn't be advertised as originating from two separate ASs?  I think 
  * > this is a bad thing and I understand that by advertising the prefix from 
  * > two separate ASs there is no way to distinguish the policies of that 
  * > prefix.  But, in today's Internet, does anyone have any experience with w
  * hat 
  * > kind of problems this equates to, so that I can forward them on to the 
  * > appropriate people.
  * > 
  * > I have a site that I am trying to convince that this is a bad thing and I
  * > would like some support.  The customer is a dual-homed site to provider A
  * > and provider B, but doesn't want to run BGP (fear of routing protocols I
  * > guess), rather just wants their prefixes advertised in both provider A an
  * d
  * > provider B ASs. 
  * > 
  * > Thanks.
  * > 
  * > -Chris
  * > 
  * > 
  * > -------------------------------------------------------------------------
  * ------
  * > Christopher D. Wheeler                 INTERNET: [e-mail]
  * > interGlobe Networks, Inc.	         OFFICE: 206.329.9266
  * > 1711 E. Olive Way, Suite 402		    FAX: [phone] 
  * > Seattle, WA  98102                 	   INFO: [e-mail] 
  * > 				            URL: http://www.interglobe.com
  * > 
  * > 
  * 
  * 
  * If you just need a reason to convince your customer, then routing symmetry
  * is probably your best answer.  If providers A and B both announce the
  * customers network, when provider C needs to send a packet to the network in
  * question (Provider C is some distant network with no direct connections to 
  * A
  * or B), there is no clear way determine which path to take.  The benefits of
  * and desirablilty of routing symmetry have been outlined in numerous places
  * by numerous people.  
  * 
  * For that matter, how is this customer planning to do their own routing over
  * two links without using BGP or something similar?  Are they default routing
  * to provider A and doing a large amount of static routes to the customers
  * of provider B?  Really, the idea of them _not_ using an intelligent routing
  * protocol in this situation seems silly.
  * 
  * Brandon
  * 
  * .-------------------------------- ------ ----- ---- --- -- -  -   -   - 
  * |      _____    _______   __  
  * |     |___  \  |_____  \ |__|          Brandon Lee Black                 .
  * |      __ \  \  __   \  : __                                             .
  * | --==|  |=|  ||  |==|  ||  |==] TCP/IP Networking - Unix Admin [=====-- :
  * :     |  | |  |:  `\/'  :|  :---.                                        :
  * :     |__| |__| \______/ |______|           Photon                       | 
  * .          Networks On-Line                                              |
  * .                                        [e-mail]                  |
  *        -   -  - -- --- ---- ----- ------ --------------------------------'
  *