Help with DHCPv6 client-identifiers

[Ted Lemon]

On Nov 20, 2011, at 5:31 AM, "Simon Hobson" <dhcp1 at thehobsons.co.uk> wrote:
> Personally, it strikes me as short sighted to enforce such a large subnet size. The answer of course is that it still leaves a vast number of possible subnets, bt then I suspect the designers of the IPv4 addressing system probably also considered the address space to be vast.

It's probably true that we should have used a 256-bit address just to make sure, but the 64-bit interface identifier was a deliberate choice, and 2^64 is a _really_ big number.

> And your suggestion for a unique*, invariant**, deterministic***, and always available**** identifier is ?
> * Yes, some manufacturers have cocked it up, but it's mostly unique.
> ** The majority of devices where this is being called for don't change their hardware address frequently (or at all).
> *** MAC addresses survive OS re-installs, "reset to factory default" operations, etc.
> **** Any device with an ethernet like interface will have one.
> 
> I think everyone complaining that hardware address isn't supplied by a DHCPv6 client would be happy if the client always supplied a unique, invariant, and determinable ID. Unfortunately, that was not included in the IPv6/DHCPv6 specs.

Yes, it is in the spec.   Read the spec.   For heaven's sake, the whole *point* of the DUID was to come up with something that was more reliably unique than the MAC address.