IP renumbering timeframe

Thu May 30 15:27:49 UTC 2002

On Thu, May 30, 2002 at 10:58:31AM -0400, Leo Bicknell wrote:
> 
> In a message written on Thu, May 30, 2002 at 10:40:47AM -0400, Marshall Eubanks wrote:
> > It would add 30% to the number of BGP address blocks pretty much automatically.
> 
> How do you come up with that number?  Of course, we have an issue
> with reclaiming existing space, but I think there are a number of
> people who have /20's today who only need a /24.  Also, only
> allocated ASN's could anounce (what's that, 24k today?), and probably
> half or more of those would choose not to use this /24.  Why would
> say, UUnet with /12's need a /24?  So I'm thinking worst case this
> might be 5-15k new routes, which is probably 3-13% of the total
> space already announced.

To quote Philip Smith's routing table analysis:

Total ASes present in the Internet Routing Table:               13122
Origin-only ASes present in the Internet Routing Table:         11366
Origin ASes announcing only one prefix:                          4997
Transit ASes present in the Internet Routing Table:              1756
Transit-only ASes present in the Internet Routing Table:           53

So, only around 50% of the allocated ASNs are actually used, and 5000 of 
them are announcing only one prefix. So lets just take a rough guess and 
say the number of people who could benefit from having a single region to 
get /24s is around 5000, perhaps lower.

I'd be mildly concerned that people would see "free IP blocks" and start
using them even when not necessary. I think allocating them a /24 from
this block only when they have demonstrated need, and don't have any other
ARIN assigned blocks, would be far more efficient.

To further quote Philip Smith's routing table analysis:

Number of prefixes announced per prefix length (Global)
-------------------------------------------------------

 /1:0        /2:0        /3:0        /4:0        /5:0        /6:0
 /7:0        /8:20       /9:6       /10:7       /11:13      /12:34
/13:85      /14:231     /15:408     /16:7203    /17:1431    /18:2592
/19:7576    /20:7155    /21:5081    /22:7761    /23:9421    /24:62582
/25:219     /26:186     /27:83      /28:87      /29:47      /30:92
/31:0       /32:42

SIXTY TWO THOUSAND /24s (72000 if you count /23s as well)! And how many of
them do you think have a legitimate need? Not that many, according to my
analysis. The vast majority are people announcing something like 200 /24s
in a /16 they have been allocated, all with the exact same attributes, but
with just enough "holes" to prevent showing up in simple CIDR scanners. 

I've tried preparing lists of the worst offenders and emailing them, and 
the vast majority don't answer and do nothing about it. If we could 
seperate the people with legitimate needs from the net polluters, we could 
then proceed to filter with a vengence. 5000 for 62000 sounds like a good 
tradeoff to me. :)

-- 
Richard A Steenbergen <ras at e-gerbil.net>       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)