[86392] in North American Network Operators' Group
Re: classful routes redux
daemon@ATHENA.MIT.EDU (Stephen J. Wilcox)
Wed Nov 2 19:59:02 2005
Date: Thu, 3 Nov 2005 00:58:25 +0000 (GMT)
From: "Stephen J. Wilcox" <steve@telecomplete.co.uk>
To: Fred Baker <fred@cisco.com>
Cc: Bill Woodcock <woody@pch.net>, <bmanning@vacation.karoshi.com>,
Richard A Steenbergen <ras@e-gerbil.net>, <nanog@merit.edu>
In-Reply-To: <95CE0FD8-4576-42CE-8B65-D541453525F0@cisco.com>
Errors-To: owner-nanog@merit.edu
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
