AS sets and sequences

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 09:32:14 2009