What does Joe Sixpack do at home with a /48 that he cannot do with a /56 or a /60?
Flexibility. With dhcpv6 prefix delegation, you are going to want devices to be able to request (at least) /60s for further delegation (and better yet /56s to allow them to delegate /60s with further delegation when needed).
While Joe may not have as complex of an environment as his neighbor Sue, should we target the common Joe, or the advanced Sue? As I suspect Owen will say, there is no reason *not* to give out /48s (ipv6 space is huge), and this is good opportunity to enable the residential user to not have to work around artificial limits in the future.
Gary
Prefix delegation for what? What does Sue do at home that requires 2 levels of prefix delegation inside the house? Does Sue really need to be able to have 65536 subnets instead of 256 in her home? Nathan