On Wed, 2 Nov 2005, Fred Baker wrote: > A class A gives you 16 bits to enumerate 8 bit subnets. If you start > from the premise that all subnets are 8 bits (dubious, but I have > heard it asserted) in IPv4,
not according to my view of the internet.. /8: 18 /9: 5 /10: 8 /11: 17 /12: 79 /13: 179 /14: 335 /15: 651 /16: 8553 /17: 2855 /18: 4793 /19: 10791 /20: 11877 /21: 9990 /22: 13168 /23: 14299 /24: 93293 > and that all subnets in IPv6 are 16 bits > (again dubious, given the recent > suggestion of a /56 allocation to an edge network), a /48 is the counterpart > of a class A. We just have a lot more of them. well, /56 /48 /32 seem to have resonance but are not special in any way > All of which seems a little twisted to me. you think? :) > While I think /32, /48, / 56, and /64 are reasonable prefix lengths for what > they are proposed for, I have this feeling of early fossilization when it > doesn't necessarily make sense. classes are bad. but recognise v6 is a bit different, /48 or /56 is the per site bit which is not comparable to v4. then /32 is is largest generally accepted prefix for bgp. this suggests anything can happen from 0-32 in bgp and anything can happen in provider igp for 32-48 or 32-56 and again anything in end user igp for 48/56-128 repeat 3 times, twice daily. classes are bad, v6 is not v4 Steve