On Wed, Jun 5, 2013 at 11:54 PM, Ted Lemon <ted.le...@nominum.com> wrote:
> I still don't understand. What the above sentences seem to be saying is > that "there are bits available for semantic prefix assignment because RIRs > assume /48 but users don't actually get /48". Is that your point? > > > No. There are bits available because (1) RIRs may well allocate them even > to ISPs that assign /48s to end-users > Actually, assigning more than a /48 user is substantially harder. Just to take the APNIC policy, for example: === 5.5 Assignment by LIRs LIRs must make IPv6 assignments in accordance with the following provisions. 5.5.1 Assignment address space size The exact size of the assignment is a local decision for the LIR or ISP to make, using a minimum value of a /64 (when only one subnet is anticipated for the end site) up to the normal maximum of /48, except in cases of extra large end sites where a larger assignment can be justified." 5.5.2 Assignment of multiple /48s to a single end site When a single end site requires an additional /48 address block, it must request the assignment with documentation or materials that justify the request. Requests for multiple or additional /48s will be processed and reviewed (i.e., evaluation of justification) at the RIR/NIR level." === Thus, using semantic prefixes makes it much harder to assign /48s to users - indeed, the letter of the policy above suggests that a /48 is acceptable only in the case of "extra large end sites", and that *every single* user that needs more than a /48 needs to be separately justified. That's obviously not going to fly for a mass-market ISP. So basically, unless you want to go through reams of paperwork, you can either assign a /48 to each user, or you can use semantic prefixes, but not both.
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