In message <20100127160401.1a963...@opy.nosense.org>, Mark Smith writes: > Sure. However I think people are treating IPv6 as just IPv4 with larger > addresses, yet not even thinking about what capabilities that larger > addressing is giving them that don't or haven't existed in IPv4 for a > very long time. People seem to be even ignoring the maths of how big a > single /48 is, just in terms subnets. I've never worked on an > individual network with 65K subnets (with the Internet being a network > of networks), and I doubt many people on this list have. Yet people > seem to treating a /48 as though all networks will have 65K subnets, > and therefore they'd better start of using longer than /64s because > they might run out of subnets. > > I care about this because I don't want to see people have to change > their addressing in the future to /64s, because of that will typically > involve a lot of out of hours work (which could include me if I > inherit a network that has had longer than /64s deployed (there's my > bias)). I'd prefer to see people go the other way - deploy /64s > everywhere, as per the IPv6 Addressing Architecture, and if that proves > to be the wrong case, then go to the effort of deploying longer > prefixes. I think going from /64s to longer prefixes is far less likely > going to be needed than the other way around.
And if you have more than 65K networks you have the justification for a second /48 at which time you can decide whether to request a /47 and renumber into it or just use two non-contiguous /48's. Mark -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org