From: Mark Smith (no email)
Date: Tue Oct 06 2009 - 17:40:40 EDT
On Tue, 6 Oct 2009 09:25:44 -0500
Dan White <> wrote:
> On 05/10/09 23:23 -0400, Ricky Beam wrote:
> > You underestimate the power of the marketing department and the bean
> > counters. I assure you, residential ISPs are looking for schemes to give
> > out as little address space as possible.
> That has not been my (limited) experience. If you are aware of any ISPs
> which are not handing out a reasonable address space to customers, please
> call them out.
Once one of them actually realises how much address space they've been
given, and that giving more perceived value to a customer will win them
the business, I think they will e.g. same price, same quota/bandwidth,
one ISP giving you 64K more address space. I think customers will say,
"I fully understand what it's for, and I don't really know what I'll
use it for .. but I'll have it if I ever need it."
> >> The current revision of IPv6 introduces a way to nail down the boundary
> >> between network and host. This is fantastic, from an implementation
> >> point of view. It simplifies the design of silicon for forwarding
> >> engines, etc.
> > And it's 150% Wrong Thinking(tm). IPv6 is classless - PERIOD. The
> > instant some idiot wires /64 into silicon, we're right back to not being
> > able to use x.x.x.0 and x.x.x.255. Addresses are 128-bits; you cannot
> > make any assumptions about what people may or may not be doing with those
> > bits. If I don't use SLAAC, then I'm not bound by it's lame rules.
I think it is both "classless" and "classfull" (although it's different
enough that we probably should stop using loaded IPv4 terms ...)
Forwarding is purely "classless" - the best route is the one with the
longest matching prefix length, regardless of where that prefix length
lands within the 128 bits.
For 1/8th of the address space, it's "classful". It's been shown that
humans work best with simplicity, so introducing fixed operational (but
not forwarding) boundaries between node, subnet and global prefixes
makes IPv6 much more operationally simple than dealing with IPv4
classes, subnets or classless addressing. I think anybody who has dealt
operationally with IPX, Appletalk, XNS, DECnet or even Ethernet with
it's single OUI/Node ID boundary would agree.
If the plan for the "classful" 1/8th ends up being wrong, the
"classless" forwarding means that we don't have to deploy new routing
code or hardware to change to a different addressing model, be it
"classless" or something else.
> >> You don't do that. Or at least, you shouldn't do that. :-) We have a
> >> fairly reliable DNS system these days...
> The assumption that IPv6 addresses are harder has not been my
> experience. A server address of 2610:b8:5::1 is just as easy
> for me to remember as 184.108.40.206. Granted, auto configured
> addresses are much harder to remember.
> > And where did DNS get the name/number assignments? In my case, it's
> > either been typed in by ME or automatically updated by DHCP.
> Anything I put in DNS is a server/router, and gets a static address, just
> like with IPv4.
> Dan White
> BTC Broadband