[ppml] Solicing comments: IPv4 to IPv6 Migration IncentiveAddress Space

Howard, W. Lee Lee.Howard at stanleyassociates.com
Wed Jun 27 09:58:06 EDT 2007

> -----Original Message-----
> From: ppml-bounces at arin.net [mailto:ppml-bounces at arin.net] On 
> Behalf Of William Herrin
> Sent: Tuesday, June 26, 2007 11:51 PM
> To: Scott Leibrand
> Cc: ppml at arin.net
> Subject: Re: [ppml] Solicing comments: IPv4 to IPv6 Migration 
> IncentiveAddress Space
> >     * While reservation of a /32 is trivial space-wise, 
> reservation of
> >       that many distinct IPv6 netblocks, with the 
> expectation that they
> >       can all be routed, will accelerate routing table growth.
>  Since IPv6 
> addresses are 4 times the size of IPv4 addresses, that would 
> increase the memory demand on routers by a factor of 4. A 
> factor of 5 if you consider that they also have to maintain 
> the IPv4 table.

"2 to the 64th power" is significantly more than 
"4 times (2 to the 32nd power)."
There are roughly 4 billion addresses in IPv4.  
There are roughly 18 quintillion subnets in IPv6.

18,000,000,000,000,000,000 > 4*4,000,000,000 

Regarding upper limits on the routing table:
*  Assuming one and only one contiguous assignment per entity,
and assuming each entity announces only their aggregate, then
if multihoming were not a requirement for a direct assignment,
the 65,000 ASNs is not an upper limit; in fact, the upper 
limit is bound by available prefixes.
*  These are questionable assumptions.
*  CPU is at least as constraining as memory.


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