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
The slow-start scenario is valid, but only to a certain extent. My company was a "slow-start" company, requesting and validating to Management, ARIN, ISPs, and the guy working at the Quickie Mart. And although we've managed to get to the point of a /19 at a time, we still have a couple legacy /24s. What is one to do? Now, one network, one contiguous AS, has 15 network advertisements ranging from /24 to /18 when it could be one /15 with another year or two to grow. But we can't just pop off /15s to everyone who's promises to use it up, and I'm certainly not going to persuade thousands of customers to migrate their IPs to a new block. But why I say it is only valid to a certain extent is that you only have to "validate" a certain percentage of your existing IPs, that affords larger companies to have more flexibility and thus get away from adding /24s rather quickly. Does someone have some perl script handy that can aggregate from a hashlist dumped from router bgp output using NET::NETMASK? (I'd do it myself, but ...well, I suk!) JNULL PGP: 0x54B1A25C "There are 10 types of people: those that understand binary, and those that do not. -----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Phil Rosenthal Sent: Monday, July 29, 2002 9:58 PM To: 'Paul Schultz'; nanog@merit.edu Subject: RE: routing table size 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: 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 My last snapshot of the routing table is from the end of june, so may be (very slightly) outdated.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