Geoff: George: Are you leaning towards an "Invalid" or "Unknown" for the decision when an AS set is found for the origin AS in an update? I think when we had a discussion on this topic long time ago, the thinking was that we should try to discourage the usage of AS sets. I am trying to figure if that meant calling the update "Invaid" in this situation?
Sriram ________________________________________ From: [email protected] [[email protected]] On Behalf Of Geoff Huston [[email protected]] Sent: Sunday, April 04, 2010 5:24 AM To: John G. Scudder Cc: [email protected]; [email protected] Subject: Re: [sidr] Comment on draft-ietf-sidr-roa-validation-05 On 04/04/2010, at 10:39 AM, John G. Scudder wrote: > Geoff and George, > > I noticed the following in Section 2 of draft-ietf-sidr-roa-validation-05: > > A route's "origin AS" is the final element of the route object's > AS_PATH attribute. If the final AS_PATH element is an AS Set, > indicating that the route is an aggregate, then the origin AS is > taken as the AS component of the AGGREGATOR attribute [RFC4271]. In > the case where there is an AS Set as the final AS_PATH element and no > AGGREGATOR attribute is present then the origin AS is the AS > immediately preceding the AS Set in the AS_PATH, and if there is no > such AS then the route's origin AS cannot be determined. > > Granted this is a corner case, but nonetheless I can't see what the reason > would be for considering an intermediate AS (albeit the first one contained > in an AS_SEQUENCE) to be the origin. I suggest revising as follows: Consider > the origin AS to be the contents of the AS_SET if it's a singleton set. > Otherwise the origin cannot be determined. > > Given that it's a corner case, you could also cut right to the chase and just > call it undetermined if the path starts (or ends, in your parlance) with an > AS_SET, period. Thanks for this comment John. As a background here I had performed a brief search through what I though was the obvious RFCs and related drafts to find a definition of the "Origin AS" and came up with nothing I could readily reference in this draft, so I found that I had to provide a workable definition of an "origin AS". The definition as stated in the draft is an uncomfortable hybrid in so far as it conflates an originator with an aggregator, and in the light of your comments, thats probably a step too far. So how about I take your advice and cut to the chase with: "A route's "origin AS" is the final element of the route object's AS_PATH attribute. If the final AS_PATH element is an AS Set, indicating that the route is an aggregate, then the origin AS cannot be determined." Does that work? kind regards, Geoff _______________________________________________ sidr mailing list [email protected] https://www.ietf.org/mailman/listinfo/sidr _______________________________________________ sidr mailing list [email protected] https://www.ietf.org/mailman/listinfo/sidr
