nanog mailing list archives
Re: Heads up: Long AS-sets announced in the next few days
From: Lorenzo Colitti <lorenzo () ripe net>
Date: Fri, 04 Mar 2005 00:09:44 +0100
David Schwartz wrote:
Prepending announcements with remote AS numbers has been a well-known technique for preventing prefixes from propagating to particular ASes for a long time.And therefore such use would not be considered experimental. We are talking about experimenting with routes that falsely claim to have passed through another autonymous system.
They are experimental in that yes, we are experimenting with a new technique for topology discovery which to our knowledge has not been proposed before.
As regards "falsely claim to have passed through an autonomous system", that is not accurate:
1. RFC 1771, paragraph 5.1.6 says that in the presence of an ATOMIC_AGGREGATE attribute, "the actual path to destinations, [...] may traverse ASs that are not listed in the AS_PATH attribute." So an AS-path does not claim to contain all the ASes that the announcement has passed through.
2. Given an AS-set such as {1,2}, if you concluded that the announcement had passed through both AS1 and AS2, you would be wrong (most of the time, at least). So an AS-path does not claim that all the ASes in the path are ASes that the announcement has passed through.
So, given these considerations, is everyone announcing an AS-set announcing "routes that falsely claim to have passed through another autonymous system"?
Every piece of BGP documentation I have ever seen says that this attribute documents the ASes that the route has actually passed through.
I think the above paragraph of RFC 1771 disagrees with you. Regards, Lorenzo
Current thread:
- Re: Heads up: Long AS-sets announced in the next few days, (continued)
- Message not available
- Re: Heads up: Long AS-sets announced in the next few days Kurt Erik Lindqvist (Mar 03)
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- Re: Heads up: Long AS-sets announced in the next few days Jeroen Massar (Mar 03)
- Re: Heads up: Long AS-sets announced in the next few days Blaine Christian (Mar 03)
- Re: Heads up: Long AS-sets announced in the next few days Jeroen Massar (Mar 03)
- Message not available
- Re: Heads up: Long AS-sets announced in the next few days Lorenzo Colitti (Mar 02)
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- Re: Heads up: Long AS-sets announced in the next few days Lorenzo Colitti (Mar 02)
- RE: Heads up: Long AS-sets announced in the next few days David Schwartz (Mar 02)
- Re: Heads up: Long AS-sets announced in the next few days Joe Abley (Mar 03)
- Re: Heads up: Long AS-sets announced in the next few days Jerry Pasker (Mar 03)
- RE: Heads up: Long AS-sets announced in the next few days David Schwartz (Mar 03)
- Re: Heads up: Long AS-sets announced in the next few days Lorenzo Colitti (Mar 03)
- Re: Heads up: Long AS-sets announced in the next few days Niels Bakker (Mar 03)
- Re: Heads up: Long AS-sets announced in the next few days Lorenzo Colitti (Mar 03)
- Re: Heads up: Long AS-sets announced in the next few days Niels Bakker (Mar 03)
- RE: Heads up: Long AS-sets announced in the next few days David Schwartz (Mar 03)
- RE: Heads up: Long AS-sets announced in the next few days David Schwartz (Mar 03)
- Re: Heads up: Long AS-sets announced in the next few days Lorenzo Colitti (Mar 03)
- RE: Heads up: Long AS-sets announced in the next few days David Schwartz (Mar 03)
- Re: Heads up: Long AS-sets announced in the next few days Randy Bush (Mar 03)
- Re: Heads up: Long AS-sets announced in the next few days Henk Uijterwaal (Mar 04)
- Re: Heads up: Long AS-sets announced in the next few days Lorenzo Colitti (Mar 09)