[ppml] Use of HD ratios (esp. 0.94)

Mark Smith ipng at 69706e6720323030352d30312d31340a.nosense.org
Tue Oct 23 06:02:48 EDT 2007

On Fri, 19 Oct 2007 12:53:01 -0400 (EDT)
Jon Lewis <jlewis at lewis.org> wrote:

> On Fri, 19 Oct 2007 michael.dillon at bt.com wrote:
> >> In terms of allocation efficiency, and utilization requirements, using
> >> HD-56 instead of some other kind of HD, unfairly penalizes
> >> those who act as good "Internet citizens", and allocate
> >> longer prefixes to customers.
> >
> > Those are BAD Internet citizens who are not following the basic
> > architecture of IPv6 which attempts to give each level of allocation,
> > more addresses than they could ever need. /48 does that for end user
> > networks, and it can be argued that /56 maintains that for residential
> > end users.
> After years of having to be conservative with IPv4 space, I think its just 
> hard for some of us to wrap our heads around the idea of giving customers 
> such astronomical numbers of IPv6 IPs.  2^64, if you don't do the 
> silly autoconf that wastes half the IPv6 space, is just an insane number 
> of IPs. 18.4 trillion million if I did the math right.

How do you cope with 48 bit MAC addresses! 2^46 unicast MAC
addresses on a on a link! That's absurd! Who'd ever plug in even half
that many devices? Would even plug in 2^16 devices? And they decided
that in 1981! What were they thinking!?

(Plug and play convenience - and that's what's being aimed for with


("48-bit Absolute Internet and Ethernet Host Numbers" is the paper you
want if you're interested in the details)


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