classful routes redux

Sat Nov 5 18:11:43 UTC 2005

Hello;

On Nov 5, 2005, at 12:01 PM, Geoff Huston wrote:

>
> At 03:09 AM 5/11/2005, Christopher L. Morrow wrote:
>
>
>
>
>> On Fri, 4 Nov 2005, Russ White wrote:
>> >
>> > - -- BGP is currently moving to a 2^32 space for AS numbers.  
>> That's odd,
>> > if there's only 18,044 origins in the current table, and it  
>> won't ever
>> > grow to much more--how'd we lose 40,000 or so AS numbers, that  
>> we now
>> > need more than 64,000?
>>
>> I think someone at CAIDA or even Renesys could put out some good  
>> numbers
>> for 'origin' AS counts and even 'AS in aspath' It's slightly  
>> higher than
>> 18k, but not 40k higher :) At last look (during arin/nanog  
>> meeting) it was
>> about 20k unique origins (from 701 perspective as seen through
>> routeviews)
>>
>
> As of a few minutes ago there are 21.042 unique ASs seen in Route- 
> Views.
>

 From the multicast status page,  http://www.multicasttech.com/status/

I get a total number of Active Unicast AS seen by BGP = 20660 (a  
little smaller than Route-Views), and a total
of 22038 having _ever_ been seen by BGP announcements here (since  
April, 2001).

There are clearly more AS's in use out there in non-public networks,  
as seen, e.g., by the steady
dribble of low number  DOD ASN's that leak out from time to time, but  
it does
not seem that this  pool is very large.

Regards
Marshall Eubanks

> 13,997 are origin onlu (i.e. they are not seen in the middle of an  
> AS path), 66 are transit only and 6.979 are mixes origin  + transit.
>
> 8,554 ASs announce a single prefix, while the average announcements  
> per origin AS is 9.1 (the reason is a heavy tail distribution where  
> a small number of ASs originate a very large number of prefixes)
>
> The average address span for an origin AS is 70,426 /32s (or  
> slightly larger than a /16) Again this is a heavy tail distribution.
>
> (more time series data on the routing table than you'd ever want is  
> at http://bgp.potaroo.net/as4637/ and http://bgp.potaroo.net/as6447)
>
> The overall trend is the association of fewer addresses per  
> originating AS, pointing to a trend to impose ever finer levels of  
> policy delineation within the inter-domain routing mesh at places  
> closer to the edge of the network - i.e. multi-homing and traffic  
> engineering within an increasingly dense interconnection mesh  
> appear to be one of the major motivations here for the continued  
> consumption of AS numbers. The CAIDA skitter graphs are perhaps the  
> most dramatic way I've encountered so far that clearly shows this  
> trend.
>
> regards
>
>    Geoff
>
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