This sounds crazy, but I'm analyzing the raw RIS BGP announcement dataset and I spot this announcement:

BGP4MP|1543859911|A||51185||51185 9304 1161216244|INCOMPLETE||0|0||NAG||

This announcement is collected by AS 51185. Sometimes I spot the AS-path is 51185 following by a 'trash' ASN also, e.g.,

51185 1161216244

Is this ASN 1161216244 even possible? If this ASN is possible, can you guess who is doing this practice and why?


Since 2007 and RFC4893 AS Numbers can be 32 bits.

So 1161216244 is technically a valid AS number.

However according to this IANA page numbers between 399261 and 4199999999 are unallocated (and not reserved for private use).

So it seems somebody incorrectly used this number, maybe as a private AS number, and it was not filtered.

  • The RIS raw dataset seems to include all announcements received by all vantage points. The announcements that include these unallocated ASN are recorded by one single vantage point, but not accepted and propagated by any.
    – Muoi Tran
    Dec 28 '18 at 2:05

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