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Re: IPv6 daydreams

  • From: Mark Smith
  • Date: Mon Oct 17 05:06:05 2005

Hi David,

On Sun, 16 Oct 2005 16:49:25 -0700 (PDT)
David Barak <[email protected]> wrote:

> I'd change the allocation approach: rather than give
> every customer a /64, which represents an IPv4
> universe full of IPv4 universes, I'd think that any
> customer can make do with a single IPv4-size universe,
> and make the default end-customer allocation a /96. 
> ISPs could still get gigantic prefixes (like a /23 or
> something), to make sure that an ISP would never need
> more than one prefix.

If we're going to do that, we may as well also start reclaiming those 48
bit MAC addresses that come with ethernet cards. After all, nobody would
need anymore than say 12 to 13 bits to address their LANs.

Hmm, so what do 48 bit addresses give us that 12 bits don't ? How about
convenience. It is convenient to be able to plug in an ethernet card,
and, excepting the very rare occasions when a manufacturer has stuffed
up, be assured that you can just plug it in and it works. No jumpering,
no maintaining a LAN address registry per segment, no address
collisions, or at least extremely rare ones.

>From what I understand, it is considered that 48 bit MAC addresses will
be too small for our convenience needs of the future, so IEEE have
invented 64 bit ones (EUI-64s).

Wouldn't it be nice to the same sort of convenience in a new layer 3
protocol that we've had since 802.3 was first published (and since I
started working in networking 1993) ? I'd like it, and I'm willing to
pay a few bytes in the src and dst addresses in my layer 3 protocol
header for it.

/64s in IPv6 for multi-access segments (i.e. everything other than
single address loopbacks) is convenient and useful, and I think should
be kept.



        The Internet's nature is peer to peer.