When the collector sees a route with AS-PATH length 5 with a community on it, that does not imply that the community traveled through 5 AS hops. The community could have been added at any of the ASes in the path. Where does the data show that any communities transited any AS boundaries?
Regards, Jakob. > On Apr 1, 2021, at 2:06 PM, Sriram, Kotikalapudi (Fed) > <kotikalapudi.sri...@nist.gov> wrote: > > There may be a knob that AS operators have for permitting transitivity, but > we need to look at measurements to understand whether or not operators > actually allow transitivity to EC and LC. > > NIST BGP measurements (thanks to my colleague Lilia Hannachi) were shared on > the GROW list in May 2020: > https://mailarchive.ietf.org/arch/msg/grow/JPD1-hhSvVXIZbUlNQ_1hmzD6IA/ > > A portion is copied below. The AS path length (# unique ASes) distributions > for BGP updates with Communities (Regular, Large, and Extended) are shown > here. It is evident that both LC and EC propagate multiple AS hops. Mass > stripping of LC or EC at the first hop is not evident. The peak happens at > AS path length 4 or 5 and that is good. That is the behavior that is helpful > for route leak solution. The solution can still function even if some ASes > strip. We can do some more detailed studies if needed. > > ********************************************************************* > RIPE-RIS: Community ANALYSIS (Collector : rrc03 From 2020-04-30 00:00 To > 2020-04-30 00:55) > ********************************************************************* > # Updates = 1075583 (Total) > # (Regular) COMMUNITY = 859239 (79.89%) > AS path length distribution = 1: 170 (0.02%) 2: 44803 (5.21%) 3: > 141072 (16.42%) 4: 276271 (32.15%) 5: 238325 (27.74%) 6: 114158 > (13.29%) 7: 31365 (3.65%) 8: 9018 (1.05%) 9: 2690 (0.31%) 10: 811 > (0.09%) 11: 358 (0.04%) 12: 169 (0.02%) 13: 22 (0%) 14: 7 (0%) > > # LARGE_COMMUNITY = 152818 (14.21%) > AS path length distribution = 2: 5655 (3.7%) 3: 17205 (11.26%) 4: > 54372 (35.58%) 5: 45492 (29.77%) 6: 22065 (14.44%) 7: 6422 (4.2%) > 8: 1068 (0.7%) 9: 397 (0.26%) 10: 71 (0.05%) 11: 35 (0.02%) 12: > 26 (0.02%) 13: 6 (0%) 14: 4 (0%) > > # EXTENDED COMMUNITIES = 44606 (4.15%) > AS path length distribution = 2: 2269 (5.09%) 3: 7435 (16.67%) 4: > 17657 (39.58%) 5: 11600 (26.01%) 6: 3967 (8.89%) 7: 1221 (2.74%) > 8: 371 (0.83%) 9: 57 (0.13%) 10: 19 (0.04%) 11: 8 (0.02%) 12: 1 > (0%) 13: 1 (0%) > ********************************************************************* > > Sriram _______________________________________________ GROW mailing list GROW@ietf.org https://www.ietf.org/mailman/listinfo/grow
