North American Network Operators Group

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RE: AS announcement question (easy)

  • From: Pete Templin
  • Date: Mon Aug 04 14:56:34 2003

Is it a class C, or a /24?  

Regardless, longest match wins.  If old provider is announcing your space as part of a larger announcement, you'll be a bad netizen for a few days because you're violating the RFCs concerning inconsistent AS, but your traffic will swing almost entirely over to new provider, and rather quickly.  Traffic originating in old provider's network will likely still come in on your old link.  (I've done this for three new customers in the past month.)  If your old provider is specifically announcing your space as a /24, standard BGP path selection processes will take place all over the 'Net, and YMMV on the traffic balance.  On or before disconnecting the link to old provider (if they are specifically announcing your /24), be sure to have them stop announcing that /24.

Pete Templin
Senior Staff Engineer
TexLink Communications
(210) 892-4183
[email protected]

-----Original Message-----
From: Mike Donahue [mailto:[email protected]]
Sent: Monday, August 04, 2003 1:22 PM
To: '[email protected]'
Subject: AS announcement question (easy)

Hi, sorry for this low-level question, but at least I'm not posting in html.

My company owns a class C, and we're switching ISPs.  The "new" provider is
telling us that they can start announcing, without us having to tell the old
provider to stop announcing.  I.e., a 2-3 day period where both are
announcing our class C.

This conflicts with my extremely (admittedly)limited knowledge.  Can someone
let me know if this is OK/not OK?

Thanks in advance,


Michael Donahue
(949) 574-8500 x261