[DNA] Re: IPv6 WG Last Call:draft-ietf-ipv6-optimistic-dad-01.txt

[Erik Nordmark <Erik.Nordmark@sun.com>]

> 1. remove the following bullet of Section 3.1:
> 
>    * (adds to 7.2.6)  The Optimistic node MAY send an unsolicited
>         Neighbour Advertisement to All Nodes when it first configures an
>         address. The Override flag on this advertisement MUST be cleared
>         (O=0).

ok

> And then (optionally)
> 
> 2. add the following somewhere (perhaps not in Section 3, since it's
>    not a modification to the existing specifications):
> 
>    * The Optimistic node MUST NOT send an unsolicited Neighbor
>      Advertisement containing an Optimistic address in the target
>      address field.
> 
> This is to prohibit new implementations that have seen existing one
> using the obsolete behavior from doing the same thing without
> considering the real reason for it.  I prefer 'MUST NOT', but this
> might be too strong and I can live with 'SHOULD NOT'.

While we don't think sending unsolicited NAs is useful hence they would
consume resources if sent for no reason, this isn't a strong enough
reason to use "MUST NOT" (using "MUST NOT" for things that would cause
interoperability problems, or cause the network to melt would be
appropriate).
So I think this should be a "SHOULD NOT".

> And then (optionally)
> 
> 3. add the following somewhere (perhaps not in Section 3, since it's
>    not a modification to the existing specifications):
> 
>    * The Optimistic node MUST NOT send any Neighbor Advertisement
>      containing an Optimistic address in the target address field,
>      unless the Override flag on the advertisement is zero.
> 
> if we really want to avoid an NA that happens to set the override flag
> ON.

If we do a "SHOULD NOT" in 2 as I suggest, I think it would be useful
to have #3 in the document as well to make it clear that
the override flag must always be zero for optimistic addresses.

   Erik