On Jul 23, 2010, at 1:26 PM, Matthew Kaufman wrote: > [email protected] wrote: >>> It is not about how many devices, it is about how many subnets, because you >>> may want to keep them isolated, for many reasons. >>> >>> It is not just about devices consuming lots of bandwidth, it is also about >>> many small sensors, actuators and so. >>> >> >> I have no problems with giving the customer several subnets. /56 is >> just fine for that. > /56? How about /62? That certainly covers "several"... and if you're really > worried they might have too many subnets for that to work, how about /60?
/60 at a bare minimum since you can do RDNS delegation on /x boundaries where x%4==0. RDNS for a /62 is do-able, but, it requires 4 zone files and 4 sets of parent NS records instead of 1. /62 for 4 customers ends up requiring 16 zone files and 16 sets of parent NS records instead of 4. >> I haven't seen any kind of realistic scenarios >> which require /48 for residential users *and* will actually use lots >> and lots of subnets - without requiring a similar amount of manual >> configuration on the part of the customer. >> >> So we end up with /56 for residential users. >> > Only because people think that the boundaries need to happen at easy-to-type > points given the textual representation. /56 is still overkill for a house. > And there's several billion houses in the world to hook up. > Yes... Overkill is a good thing in IPv6. Even with this level of overkill, fully deploying the current world with a /48 for every house consumes less than 0.1% of the address space. (Apprximately 4x10^9 households on earth getting a /48 each = roughly one /16 which is 1/65,536th of the total address space and 1/8192nd of 2000::/3) What is the harm in doing so? Why not minimize provisioning effort and maximize user flexibility by consuming a very tiny fraction of a plentiful resource which costs virtually nothing? Owen
