Solicited Nodes' for DAD (was Re: [DNA-BOF] DAD Optimization ProblemStatement)

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

Hi Youn-Hee.

Youn-Hee Han wrote:
[snip]
>   [Possible subjects 2]   
> 
>    In order to process DAD, all nodes have to send solicited-node 
>    multicast address using NS message, whenever IPv6 addresses are 
>    composed of its interface identifier.  This procedure may reduce 
>    the network performance especially within the low bandwidth 
>    networks.

I think that solicited nodes' addresses are _not_ inefficient
for DAD.  In realistic scenarios, solicited nodes' group
membership is likely only to be those hosts which
have those addresses configured (a very small group).

Also, having a multicast group means that only those
people who are members of the group will process the
packet.

There is no other way to ensure that only those
interested are required to process the packet, except
through unicast either to a host (only works if the host is not
tentative), or a DAD server (with stateful DAD).

The real issue is using multicast on networks which do
not distinguish between multicast and broadcast.

If the packet is only forwarded to group members, this
is not a problem, so this issue is link-layer dependent.

Greg