I don't actually mind the /64 basis, for the reasons that have been discussed by others. But I do wonder about the industry trend towards /56 per broadband service.

If I consider /64 as representing a physical or logical network segment (as essentially implied by RFC4291), then that means each broadband service with a /56 will have the capability to support 256 virtual or physical networks in the home. Even allowing in principle for different service sets to each have their own vlan, 256 vlans still seems a little excessive for the average home - most of which will probably only be using one network for a long time to come.

I would have thought that 16 vlans - i.e. a /60 - would be a good standard number to start with, especially if you assume dynamic prefix delegation would mean that you could readily upgrade a customer's address range to a shorter prefix if it really proved necessary.

Also, the implications on the number of customers that can be supported per /32 are significant; with /56 per service, you can only support 17M customers with a /32, but with /60 per service, that becomes 268M.

I agree with all the previous statements that this isn't going to unduly exhaust the IPv6 space any time soon, but like some others I wonder whether we are now tending towards excessive allocation sizes - and for me this is specifically about consumer services. As I said, I don't mind the basic /64 per network, and at the other end I don't mind a /48 per enterprise site, because I suspect the number of such sites is many orders of magnitude smaller than the numbers of consumers or small businesses. But 256 lans per domestic premise does make me wonder...

Having said all this, I likewise feel that the industry has made up its mind and we probably need to be consistent to avoid confusion while we're trying to get IPv6 out there.

But I would be interested in any other thoughts on this - would anyone else care to share their views as to whether /56 per broadband service seems too much (or too little) or just right?