Warren,
Thanks for the additional data/suggestions. Comments below.
......
>> Some recent measurements we have at NIST about this are as follow:
>> (thanks to Lilia Hannachi - my colleague)
>>
>
>This is nice, but what would make it more useful would be if it also
>reported if there are *useful* AS_SETS / if the AS_SET means anything.
>
>For example, from Jared's email below:
>AS path: 14061 3356 6762 23487 27738 27738 27738 27738 27738 27738
>{27738} -- the 27738 AS already shows up as a non-AS_SET in the path.
>
>I've also seen a number of instances where the AS_SET contains many
>repeated instances, e.g:
>AS path: 6939 3356 42020 39010 {39275 39275 39275 39275 39275 39275
>39275 39275 39275 39275} -- this doesn't seem to actually mean
>anything...
>
>Looking at the top few AS paths with AS_SETs I see:
> 28 12127
> 27 27738
> 24 11139
> 17 23383
> 13 12849
>
>AS12127 - Telefonica Moviles El Salvador S.A. de C.V., SV (these are
>all behind AS263783 - Telefonica Moviles El Salvador S.A. de C.V., SV
>)
>AS27738 - Ecuadortelecom S.A., EC
>AS11139 - CWC-ROC-11139 - Cable & Wireless Dominica, DM
>AS23383 - METRORED S.A. DE C.V., HN (this also seems to provide
>transit to AS267737? (advertising 45.168.172.0/24))
>AS12849 HOTNET-IL AMS-IX Admin LAN, IL
.....
Interesting! We can extend our analysis at NIST to examine these things as
needed.
In the data that I shared earlier, another thing you might have noticed
is that there are ~ 350 instances where special purpose ASNs occur in AS_SETs.
An earlier study we did and presented at IETF is here:
https://www.nist.gov/sites/default/files/documents/itl/antd/AS_SET_Aggregator_Stats-2.pdf
There we noticed other strange things:
In some cases, AS in the AGGREGATOR doesn't match the right most AS in the
AS_PATH
that follows the AS_SET. So AGGREGATOR is different from the AS that created
the AS_SET! Hmm..!
In the slides, we also reported numbers on private ASNs seen in AS_SETs.
Sriram
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