RE: [DNA] High-level overview of DNA, take 2

[Bernard Aboba <bernard_aboba@hotmail.com>]

\>    Are there other messages that can be sent that could help? Like NS
>    queries unicast to known routers?

This is what DNAv4 does (via unicast ARP), because this enables a 
determination of whether the host has connected to a previously encountered 
router, without ambiguity.

>    Note: on some links, like wireless ethernet, multicast is
>    (relatively) "expensive". Would it be better to just send a few
>    immediate unicast NS (or RS) messages to the routers we know about?
>    and send a multicast RS only if the unicast fails? Or do both in
>    parallel?

DNAv4 does both DHCP and DNA in parallel.  DNAv4 is handled solely via 
unicast ARP, because on some links multicast not only is sent to many more 
hosts, but also is sent at much lower  rate.   For example, with IEEE 
802.11n, it would be possible to send *a hundred*  unicast packets at 100 
Mbps at the same cost in expended slots as  one multicast packet at 1 Mbps.  
This means that in practice a single multicast RS will cost more than 
sending unicast RS or NS messages to all previous routers.