Michel,
In any case, a modest suggestion: Let's separate
the GUPI prefix generation and registration processes,
and make them sequential.
I have another suggestion: Let's split the FEC0::/10 space in two parts:
One for the unregistered "good-enough" and one for the registered truly
unique. By default, the "good enough" would be used and a random/hash
method would be used. But the network administrator would have a choice
of getting a truly unique registered prefix instead. This would likely
need to access some web page and pay a nominal fee.
If the address space is split, then we have a guarantee that the hash
process used for "good enough" will not grab addresses in the range that
is used for truly unique.
Let me try to briefly analyse the differences between the methods,
the "mixed space"" and the "split space" methods:
- In either method, you can generate a prefix and register
it as a GUPI prefix belonging to you right away.
- In the mixed space method, you may have to need a couple of
prefixes before you get one registered. OTOH, if you really
need a registered prefix, you can combine generation and
registration, and start configuring your routers only once
you have got a prefix registered. Thus, no big difference
in practise.
- In the mixed space method, you can generate a prefix now and
try to register it later, with a fairly large probability
of succeeding. In the split space method, if you only later
need a genuinely globally unique address and are not willing to
pay for one now, you have to renumber.
- In the split space method, you can tell directly from a prefix
whether it is genuinely globally unique or not. In the mixed
space method you can query the registry whether the prefix has
been registered, but even if it is, there may be also other sites
that are using the prefix. The probability of the existence
of such sites is low, though.
- In the split space method, you can be almost sure that nobody
else is using your globally unique prefix, and if they do,
they do it in error. In the mixed space method, you cannot be
sure that nobody else is using your prefix, but if they do,
you know that they cannot register it.
Thus, from my point of view, the differences seem to boil down
into two issues:
1. In the mixed space method, you can defer your registration and
still have a fairly large probability of succeeding later in
registration.
2. In the split space method, you can have more confidence that
no-one else is using your truly unique prefix.
I can't say which is better.
--Pekka Nikander
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