On 01/05/2010, at 2:59 AM, Sandra Murphy wrote:
> The draft-ietf-sidr-roa-validation-05 contains this same specification, in
> the section John Scudder pointed to in his message of 3 Apr (section 2, page
> 3).
>
> The difficulty lies in the fact that the AGGREGATOR attribute is only a "MAY
> attach" in RFC4271. The paragraph in draft-ietf-sidr-roa-validation-05 also
> contains a specification of what to do if there is no AGGREGATOR attribute
> available. As I view the conversation, John objected to this second part of
> the draft's specification, not the first part.
>
John suggested the following:
"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."
> But the conversation spiraled from there.
Evidently.
What do those folk who have opinions on the topic think about the following
text as a definition:
A route's "origin AS" is defined as follows: If the final
path segment of the AS_PATH is of type AS_SEQUENCE, the "origin
AS" is the first element of the sequence (i.e. the AS in the
rightmost position with respect to the position of octets in the
protocol message). If the final path segment of the AS_PATH is
of type AS_SET, indicating that the route is an aggregate, then
the origin AS is taken as the AS component of the AGGREGATOR
attribute [RFC4271], if present. Otherwise, the route's origin
AS cannot be determined.
Geoff
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