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Re: classful routes redux
- From: Marshall Eubanks
- Date: Sat Nov 05 13:15:18 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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