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 <matt...@matthew.at> wrote: > >> sth...@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 > > http://www.ipinc.net/IPv4.GIF