Re: AS sets and sequences

From: Renan M Alves <>
Date: 01/14/09
Message-ID: <>


the order of ASs in a AS path is totaly determined by the routing protocol,
commonly BGP, and represent the best path between two points (ASs).
Sflow can't do anything about this, it just show what BGP decide.

On Wed, Jan 14, 2009 at 3:29 PM, <> wrote:

> Hello,
> I may have missed something in the RFC, but I was not able to determine why
> the destination AS path can sometimes be represented as a set (unordered set
> of ASs) or sometimes as a sequence (ordered set of ASs). Is it bound to the
> proximity of the destination? For example, in a case where the packet is
> sampled far from its destination and there are still many ASs to cross, not
> ordering the ASs in the destination AS path may save processing time (?).
> Or is there a totally different reason to this distinction?
> Moreover, is it possible to force the AS path to be either one or the other
> in some sampling device implementations, especially routers? I can not
> recall anywhere to configure the way the AS path is exported on the devices
> I use. So I was wondering if it was automatically determined by an
> algorithm.
> Well, my reasoning is way too long. Sorry.
> Thanks for the answer,
> Gregory.
Received on Wed Jan 14 11:31:24 2009

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