Patrick W. Gilmore wrote: > On Feb 4, 2009, at 6:56 PM, Scott Howard wrote: >> On Mon, Feb 2, 2009 at 9:35 PM, Patrick W. Gilmore >> <patr...@ianai.net>wrote: >> >>> Except the RIRs won't give you another /48 when you have only used one >>> trillion IP addresses. >> >> Of course they will! A /48 is only the equivalent of 65536 "networks" >> (each >> network being a /64). Presuming that ISPs allocate /64 networks to each >> connected subscriber, then a /48 is only 65k subscribers, or say around a >> maximum of 200k IP addresses in use at any one time (presuming no NAT >> and an >> average of 3-4 IP-based devices per subscriber) >> >> IPv4-style utilization ratios do make some sense under IPv6, but not >> at the >> address level - only at the network level. > > First, it was (mostly) a joke. > > Second, where did you get 4 users per /64? Are you planning to hand > each cable modem a /64? >
That was the generally accepted subnet practice last time I had a discussion about it on the ipv6-ops list. I'm not an ISP, but I have a /48 and each subnet is a /64. Some devices will refuse to work if you subnet smaller than a /64. (Yes, poorly designed, etc.) ~Seth