On Jul 23, 2010, at 1:26 PM, Matthew Kaufman wrote:
sthaug@nethelp.no 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