--On Friday, 15 July, 2005 01:20 +0100 David Hopwood
<david(_dot_)nospam(_dot_)hopwood(_at_)blueyonder(_dot_)co(_dot_)uk> wrote:
The arguments for considering it to be in scope would have
been:
- the TCP and UDP "pseudo-headers" needed to be changed
anyway to
accomodate IPv6 addresses (see section 8.1 of RFC 2460);
- the pressure on well-known port numbers was obvious at the
time;
- supporting 32-bit port numbers in IPv6 stacks could have
been done
at very little incremental cost;
- a larger port space would have been an additional
incentive to
adopt IPv6;
- more ambitious changes to TCP would have a low probability
of
adoption within a relevant timeframe;
- it makes sense for the port number space to be the same
size for
UDP-over-IPv6 and TCP-over-IPv6.
And, for whatever it is worth, this is precisely why the "reg
policy" document tried to say "as soon as someone says
'scarcity', it is important to start thinking about the
appropriateness and mechanisms for an expansion plan". Now, the
mechanism stated there may not have been appropriate, or the
language might have been poorly-chosen, but the underlying point
is "oh, we are running out, we need to get more and more
restrictive" is generally not a solution. It may be a good
stopgap or conservation model while an alternative mechanism is
worked out (one could argue that CIDR bears exactly that
relationship to IPv6), but it is not a solution. Of course, the
conclusion from that thinking process could be, in some cases
"there won't be a problem, ever, if we are reasonably
conservative". But the evaluation is important and it is, IMO,
valuable to do it as soon as the signs or claim of scarcity
appear, not when we are looking at what gets the last two
possible allocations.
john
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