Re: [DNA] [Issue 15] [Issue 16] DAD and MLD Interaction

[James Kempf <kempf@docomolabs-usa.com>]

> Sounds like a reasonable assumption.
>
> Should this be tied to the Link-Up indications, or to the DNA reception
> and processing of hints?
>
> For example, if no link-layer indication is received does the
> reception of an 'unexpected' RA and subsequent initiation of
> DNA operations cause Optimistic to be set?
>
> I'd guess it's tied to DNA initiation, rather than the Link-Up
> explicitly.
>

Well, there's a couple cases to consider.

Case 1: Multicast RA

Suppose the host receives a multicast DNA RA, either as a result of failover
to multicast mode due to RS overload on the router or simply as a multicast
beacon. If the host can conclude that it has not moved to a new IP link, no
changes in address state are required. If the host can conclude that it has
moved to a new IP link, the old addresses should be Deprecated, the host
should form a new link local address, set state to Optimistic, oDAD it, and
then form new global unicast addresses, etc., just as if it had moved, even
if it didn't get a link event indicating movement (the link event may have
failed for some reason). But the host doesn't need to do anything "prior" to
sending the RS, because it didn't send one.

Case 2: Unsolicted unicast RA

This case is pretty unlikely and is probably due to an error (or somebody
playing a trick on the host by sending an RS with the victim's link address
in the TSLLAO and the victim's link local address as the source address).
I'd say in this case the host should be cautious and should issue a unicast
DNA RA in order to confirm. But I don't think it should make any changes in
its address state machine in this case, because there is no link event
indicating a link change. If a link change actually did occur, of course,
the addresses need to be reconfigured.

How does that sound?

            jak