classful routes redux

Thu Nov 3 00:17:28 UTC 2005

On Nov 2, 2005, at 4:01 PM, Bill Woodcock wrote:

>       On Wed, 2 Nov 2005, Fred Baker wrote:
>> actually, no, I could compare a /48 to a class A.
>
> ...which makes the /32s-and-shorter that everybody's actually getting
> double-plus-As, or what?

A class A gives you 16 bits to enumerate 8 bit subnets. If you start  
from the premise that all subnets are 8 bits (dubious, but I have  
heard it asserted) in IPv4, and that all subnets in IPv6 are 16 bits  
(again dubious, given the recent suggestion of a /56 allocation to an  
edge network), a /48 is the counterpart of a class A. We just have a  
lot more of them.

All of which seems a little twisted to me. While I think /32, /48, / 
56, and /64 are reasonable prefix lengths for what they are proposed  
for, I have this feeling of early fossilization when it doesn't  
necessarily make sense.