RE: routing table size

["Phil Rosenthal" <pr () isprime com>]

Now the question is, of that 70% figure, how much of that is
aggregateable?

--Phil

-----Original Message-----
From: owner-nanog () merit edu [mailto:owner-nanog () merit edu] On Behalf Of
Paul Schultz
Sent: Monday, July 29, 2002 10:28 PM
To: nanog () merit edu
Subject: Re: routing table size





On Mon, 29 Jul 2002, Richard A Steenbergen wrote:

> If someone has done an actual study of where these /24s (and probably 
> /23s
> too) come from, please point it out. Until then, my money is on
clueless
> redist connected/statics, large cable/dsl providers who announce a /24
per
> pop/city/whatever to their single transit provider, and general
ignorance.

To ease my own curiousity I kludged together a script to look at how
much of /24 land is taken up by smalltimers announcing few prefixes, and
larger networks announcing many.  My last snapshot of the routing table
is from the end of june, so may be (very slightly) outdated.



Data from June 29, 2002

Total /24's: 61931
ASN's announcing /24's: 8645


Number of /24's announced by AS breakdown

/24's   ASN Count
======= =========
1       3474
2       1662
3       740
4       533
5       377
6       236
7       203
8       164
9       113
10-14   421
15-19   184
20-29   199
30-39   101
40-49   57
50-59   41
60-69   29
70-79   21
80-89   12
90-99   11
100-149 20
150-199 17
200+    29

Those "basement multihomers" announcing 1-5 /24's only account for ~20%
of the total number of /24's out there.  Multihomers with slightly
larger basements (6-10 /24's) account for 10% of the total.  That leaves
the remaining 70% of /24's in the DFZ announced by people pushing out
over 10 /24's from their AS.  Interpret however you will (I tend to lean
towards Richard's take on the situation.)



- Paul