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Re: [Ietf] 240.0.0.0/4

2004-04-20 02:22:51
Hi Iljitsch, 

On Tue, 20 Apr 2004 10:19:49 +0200
Iljitsch van Beijnum <iljitsch(_at_)muada(_dot_)com> wrote:

I was wondering if there are any plans to change the status of
the class E address space (240.0.0.0 - 255.255.255.255).

Currently, there are approximately 221 usable /8s: classes A
(125), B (64) and C (32). (0.0.0.0/8, 10.0.0.0/8 and
127.0.0.0/8 aren't usable at this time.) Adding 16 /8s from
class E space would increase this by 7%, and increase the
unused address space with something like 20%.

However, it's almost certain that there are implementations out
there that won't accept 224.0.0.0/4 as regular unicast address
space. So if we want to be able to use class E space as such,
it is imperative that we announce this a *very* long time in
advance.

Two other possible uses:

It seems that there are now organizations who want/need more
private address space than is available as per RFC 1918. Using
class E space for this would make a lot of sense as this allows
for a lot of private space without sacrificing usable unicast
space.

Presuming this extra "RFC1918" address space is going to be used
in conjunction with NAT (a reasonable assumption I would
suspect), I'd question any IETF endorsed measures which would
encourage further adoption or use of NAT.

I would suggest that if all the RFC1918 address space isn't big
enough, it is time for the organisation in question to start
deploying IPv6. Plenty of address space there, and no NAT
uglyness.

HTH,
Mark.


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