I tend to think a /60 is a reasonable allocation for a residential user. In my home I have two subnets and will in time likely add two more: - general network access - my office (required to be separate by Cisco Information Security policy) - (future) would likely want routable separate bandwidth for A/V at some point - (future) Smart Grid HAN will likely be its own subnet If my wife went to work for a company with an infosec policy like Cisco's, that becomes a fifth subnet. Yes, 16 to choose from seems reasonable. /56 seems appropriate to a small company, /48 for a larger company, and I could see a market for a /52. A company that needs more than a /48 is likely to also be using ULAs for some of its areas, which is an automatic extension, and could always justify another /48 (or one per continent) if it really needed them. Could I do all this within a /64? Of course, with some thought, and by getting the Smart Grid and office prefixes from other sources (Cisco, my utility) and running them over a VPN (which I do anyway). The question is why I should have to. Why four bit boundaries? Because we're using hexadecimal, and each character identifies four bits. It makes tracking numbers simple - no "remember to count by N" as in IPv4. It's not magic, but to my small mind - and especially for of non-technical residential customers - it seems reasonable. And yes, I think the logic behind a 48 bit MAC address is reasonable too. On Jul 24, 2010, at 7:50 AM, Mark Smith wrote:
On Fri, 23 Jul 2010 13:26:43 -0700 Matthew Kaufman <matthew@matthew.at> 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? 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.
So you're also strongly against 48 bit Ethernet MAC addresses? Dropping the two bits for group and local addresses, that's 70 368 744 177 664 nodes per LAN. How ridiculous! What were those idiots+ thinking!
"48-bit Absolute Internet and Ethernet Host Numbers", by Yogan K. Dalal, Robert S. Printis, *July 1981*
http://ethernethistory.typepad.com/papers/HostNumbers.pdf
+ not actually idiots