[Hipsec] what fraction of IPv6 address space for HITs?

Section 3.1 of draft-moskowitz-hip-06.txt proposes that we occupy the center half of the IPv6 address space with HITs (in 4000::/2 and in 8000::/2). If any one else proposed to take that much IPv6 address space, I would object. Why shouldn't everyone else not object to us doing this? (IMHO, they should.)

I propose that we fit ourselves into an IPv6 /16 prefix (perhaps 0001::/16 in particular) unless we can explain why 112 bits of hash are not sufficient. I chose that by thinking of the largest allocation for which I expect that no one will object to an allocation of that size.

*If* we can explain why 112 bits is not sufficient, then perhaps we could ask for something bigger, like maybe 0100::/8 if we thought that 120 bits of hash would be sufficient. A request for a prefix that short (or shorter) would (I expect) need to be accompanied by a justification of why a longer prefix would not be sufficient.

So the specific question I believe we need to answer first is:

        Is a /16 IPv6 prefix (yielding a 112 bits of hash) sufficient?

And can we (to simplify the discusssion) assume that if we are going to have HAA assigned space, that we'll do that in a seperate (perhaps adjacent) /16 prefix?

			-Tim Shepard
			 shep@alum.mit.edu
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