v6 subnet size for DSL & leased line customers

Mark Smith nanog at 85d5b20a518b8f6864949bd940457dc124746ddc.nosense.org
Fri Dec 28 04:19:46 UTC 2007

On Fri, 28 Dec 2007 12:57:45 +0900
Randy Bush <randy at psg.com> wrote:

> > Ever calculated how many Ethernet nodes you can attach to a single LAN
> > with 2^46 unicast addresses?
> you mean operationally successfully, or just for marketing glossies?

Theoretically. What I find a bit hard to understand is peoples'
seemingly complete acceptance of the 'gross' amount of ethernet address
space there is available with 46 bits available for unicast addressing
on a single LAN segment, yet confusion and struggle over the allocation
of additional IPv6 bits addressing bits for the same purpose - the
operational convenience of having addressing "work out of the box" or
be simpler to understand and easier to work with.

Once I realised that IPv6's fixed sized node addressing model was
similar to Ethernet's, I then started wondering why Ethernet was like
it was - and then found a paper that explains it :

"48-bit Absolute Internet and Ethernet Host Numbers"



        "Sheep are slow and tasty, and therefore must remain constantly
                                   - Bruce Schneier, "Beyond Fear"

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