AS number inconsistencies

Philip Smith pfs at cisco.com
Tue Jul 9 04:10:52 UTC 2002


Hi Marwan,

At 09:55 08/07/2002 -0400, Marwan Fayed wrote:

>I am a CS PhD student trying to track ASes (for reasons I'm happy to
>discuss offline). There is a grave inconsistency I have come across and
>can't explain. Simply, there seems to be many AS numbers in the
>non-private range that come into use at some point in time and advertise a
>range of IPs, but these AS numbers are not allocated until much later.

Can you give examples? Both the CIDR-Report, posted to this list, and my 
own Routing Report (which I spare NANOG of, but is "inflicted" on ARIN's 
rtma, RIPE's routing-wg, and APOPS :), look up every single AS which is 
present in the BGP table - any AS which is announced and is unregistered in 
any of the three registry databases is flagged in the report.

And there are only two ASes which appear, and are not registered anywhere - 
one is intermittent, the other, AS5757, has been there since I started this 
over 3 years ago.

>Does any one have any explanations? Are network operators "notified" of
>their new AS number well in advance of the actual receipt of that number
>on paper, for example? Any help is appreciated (and hopefully this
>occurence is of interest to nanog).

That tends to happen, but in my experience APNIC, ARIN and the RIPE NCC 
will put the entry in their database before they inform their customer of 
the allocation.

So, examples would be good - send to me privately if you wish and I can 
cross reference with my own routing table views.

philip
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