[ppml] IPv6, Vista, and the Popular Press [more]

Tony Hain alh-ietf at tndh.net
Fri Jun 15 03:23:29 EDT 2007

Durand, Alain wrote:
> > >From what I understand from that book, the original IPv6
> > addressing was
> > 64 bits in size. However, to allow for deriving node
> > addresses from IEEE MAC addresses, and allowing for those to
> > be increased from 48 to
> > 64 bits, the decision was made to make the node address
> > portion of the address 64 bites, and then to make the network
> > portion also 64 bits.
> The 64 bit EUI came much later, at about the same time as 8+8...
> Steve Deering always told me that his original design was 64 bits as
> you can read in the original SIP proposal (SIP: Steve's IP)
> There was at the time disagreement between the proponent of variable
> length addresses (NSAP) and fixed length address.
> When SIP and PIP (Paul's IP from Paul Francis) were merged into
> SIPP (SIP Plus), the compromise was to use a 'long' fixed format,
> hence 128 bits.

The problem of the day that caused more than 64 bits was that 'too many bits
were being used by the pesky hosts to allow for the ISP hierarchy that was
expected'. This resulted in giving the entire 64 bits of the original design
to routing. People keep complaining about waste, but the reality is that the
real waste is in giving more bits to the routing system that will never use

IPv6 is not the last protocol known to mankind. It will be replaced long
before the public routing world uses 2^48. Myopic conservatism is the real
source of waste because it precludes the opportunity for others to innovate
with bits that would otherwise sit on the shelf forever.


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