>-----Original Message----- >>> On Tue, 19 Aug 2008, [EMAIL PROTECTED] wrote: >>>>> I don't have a problem with assigning customers a /64 of v6 space. >>>> >>>> Why so little? Normally customers get a /48 except for residential >>>> customers who can be given a /56 if you want to keep track of >>>> different block sizes. If ARIN will give you a /48 for every >>>> customer, then why be miserly with addresses? >>> I don't operate an ISP network (not anymore, anyway...). My >>> customers are departments within my organization, so a /64 per >>> department/VLAN is more sane/reasonable for my environment. >> >> Uh, the lower 64 bits of an IP6 address aren't used for routing you >> know? They're essentially the mac address, or some other sort of >> autoconf'd host identifier. Last I heard, the smallest allocation is >> supposed to be a /48 -- I hadn't heard of the /56 thing that Michael >> was speaking of, though I'm not surprised. There's 64 bits for >> routing... no need to be so stingy :) > > >64 bits is not a magical boundary. > >112 bits is widely recommended for linknets, for example. > >64 bits is common, because of EUI-64 and friends. That's it. >There is nothing, anywhere, that says that the first 64 bits is for routing.
Just to be clear - this http://tools.ietf.org/html/rfc4291#section-2.5.4 does say: " All Global Unicast addresses other than those that start with binary 000 have a 64-bit interface ID field (i.e., n + m = 64), formatted as described in Section 2.5.1. Global Unicast addresses that start with binary 000 have no such constraint on the size or structure of the interface ID field." (And again - this is a case where the real world and the IETF may not agree 100% ...) /TJ
