Hi,
On Wed, 2010-09-22 at 14:25 +0100, Heath Jones wrote:
> Probably a silly question, but can anyone explain to me this: 3561
> 3356 9031 {35821,35821,35821,35821} i
AS9031 has aggregated multiple prefixes advertised by 35821 into one
prefix. The _odd_ thing is repeating the same aggregated AS in the set.
Could this be bad configuration, or a bug?
> To explain it a bit better, I'm looking at real routing information
> from routeviews (#3).
>
> According to RFC 4271 (9.2.2.2 Aggregating Routing Information):
> > For the purpose of aggregating AS_PATH attributes, we model
> > each AS within the AS_PATH attribute as a tuple <type, value>,
> > where "type" identifies a type of the path segment the AS
> > belongs to (e.g., AS_SEQUENCE, AS_SET), and "value" identifies
> > the AS number.
> > ...
> > No tuple of type AS_SET with the same value SHALL appear
> > more than once in the aggregated AS_PATH.
>
> Am I misreading things, or is this path information out of spec?
I read it as saying no identical AS set shall be repeated. There is only
one AS set in the path above. Ergo, complaint, albeit odd.
> ps. Is this the best list to post to for this type of thing, or can
> someone recommend a better one?
I'm sure many here can answer the question better than I. If you want a
more interesting response, somebody subscribed to NANOG ought to be able
to give a good answer.
Cheers,
-S.
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