North American Network Operators Group
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Re: routing table size

  • From: Richard A Steenbergen
  • Date: Mon Jul 29 19:45:42 2002 
On Mon, Jul 29, 2002 at 03:35:19PM -0700, Brian wrote:
> 
> the large quantity of /24 announcements is, I suspect, from comapnies just
> large enough to want the benefits of multihoming.  You know, 2 t1s on a
> small router, and stuff like that..

Everyone and their mother says they "suspect" that, but noone ever proves
it. Ever wonder why?

Let's take it by the numbers:
Total ASes present in the Internet Routing Table:               13448
Origin-only ASes present in the Internet Routing Table:         11641
Origin ASes announcing only one prefix:                          5154
Transit ASes present in the Internet Routing Table:              1807

Even if every origin-only AS was a smalltime company with just enough IPs 
for a /24, it would take around 6-7 /24s each to account for the number of 
/24s announced. 

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.

Why attribute to functionality what can easily be explained by
incomptence. :)

-- 
Richard A Steenbergen <[email protected]>       http://www.e-gerbil.net/ras
PGP Key ID: 0x138EA177  (67 29 D7 BC E8 18 3E DA  B2 46 B3 D8 14 36 FE B6)