Please excuse the previous incomplete email. Accidentally got sent out while composing!
Recently, we did some measurements on AS_SETs in the context of some SIDR WG questions pertaining to origin validation in BGP updates. There are fewer than 0.1% BGP updates or RIB entries that have AS_SETs in them. What you observed is correct. Within the few such updates, you would often find the same AS repeated multiple times inside the AS_SET (although not illustrated in my slides)! Please see slides 3 and 4 at this link; the general stats related to AS_SETs may be of interest. http://www.antd.nist.gov/~ksriram/AS_SET_Aggregator_Stats.pdf K. Sriram +1 301 975 3793 http://www.antd.nist.gov/~ksriram/ > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of Heath > Jones > Sent: Wednesday, September 22, 2010 9:25 AM > To: RRG > Subject: [rrg] Odd BGP AS Path > > Hi all, > > Probably a silly question, but can anyone explain to me this: 3561 > 3356 9031 {35821,35821,35821,35821} i > > 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? > > > ps. Is this the best list to post to for this type of thing, or can > someone recommend a better one? > Cheers > Heath > _______________________________________________ > rrg mailing list > [email protected] > http://www.irtf.org/mailman/listinfo/rrg _______________________________________________ rrg mailing list [email protected] http://www.irtf.org/mailman/listinfo/rrg
