> From: Thomas Narten <[EMAIL PROTECTED]>
> 
> Note: one thing we could all be better about is defining just what
> "DAD vs. DIID" means.

I had my implementation before the term "DIID" was coined. I suppose,
in the effect, if I have the "id defense mode" turned on, it is very
close.

The main fact is that my version is just an implementation based on
the autoconfigure RFC, taking the allowed DAD optimization (= do DAD
on link-local, combine id with announced prefixes without doing DAD on
those combinations).

Some want to disallow the DAD optimization. I would like to present
another proposal:

  ********************************************
  leave autoconfigure basicly RFC as it is now
  ********************************************

Autoconfigururation deals only with an ID that is assigned to host and
is combined with announced prefixes (A=1). If host does this, it must
do DAD on link-local and doing DAD other addresses based on same ID is
not required.

I think autoconfiguration should be the normal mode how IPv6 nodes get
their addresses. Anything else is to be treated *exceptional*, and such
other mechanisms have to define their own ways of avoiding address
collisions. For example,

- if address is not link local, they could do DAD on corresponding
  link local, or

- they could assign the ID from a range that is not used by the
  autoconfigure (put asides id range 1-1024 or somesuch for the
  purpose).

- they guarantee that the prefix part of the address is never
  announced on the link with A=1 (this also guarantees that address
  never going to collide with autoconfigured addresses).

- just hope you are lucky

- etc.

I have explained in other messages, that the "Do DAD on every combined
address" has some unpleasant features, caused by the "delayed fail
mode". This adds complexity, compared to the "optimized DAD", where
you do it once, and if passed, you don't have to worry about it.

Choosing this does not require a change in any stacks that do DAD on
all addresses (KAME, Microsoft). It only affects abnormal address
configurations.





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