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

[Greg Daley <Greg.Daley@eng.monash.edu.au>]

Hi Erik, 

----- Original Message -----
[cut]
> > I'd guess it's tied to DNA initiation, rather than the Link-Up
> > explicitly.
> 
> Things wouldn't work safely from a DAD perspective if there is no 
> link-up notification.
> 
> Take an example:
> 1. Host moves and attaches to link B (no link-up notification)
> 2. Host receives a NS for it's link-local address. It responds 
> since it
>    isn't aware that it might have moved to a different link.
> 3. Host receives an unsolicited RA, which has some 'unexpected' things
>    in it (e.g., only unknown prefixes). This triggers DNA; move
>    addresses to optimistic state and send RS.
> 
> The issue is that if the link-local address is a duplicate on the 
> new 
> link, then at #2 the host would mess up things for the existing 
> user of 
> that link-local address on the new link.
> 
> So things can't be very robust without a link-up notification.

Yes, I agree with your point, that link-indications are required.

That's not what I was trying to get at though.

The DAD doesn't need to be done _directly_ due to the link-indication.
It needs to be done because the host thinks it should be doing DNA.

The link-indications pass to the DNA module which then (processing the 
hint)
initializes DNA procedures, including marking of the optimistic flag.

Perhaps it is a minor nit, but I guess it's not a requirement from
the link-indication, rather it is a DNA requirement which also requires
link-indications to function correctly.

Greg