>*** tcpdump -i ifn -evv -n icmp6, when at drifter the follwoing is performed:
>	ifconfig tlp0 inet6 3ffe:2a00:100:3001::2 prefixlen 64 alias
># tcpdump at drifter (3ffe:2a00:100:3001:210:a4ff:fead:43c0):
>17:13:43.026939 0:10:a4:ad:43:c0 33:33:ff:0:0:2 86dd 78: :: > ff02::1:ff00:2: icmp6: neighbor sol: who has 3ffe:2a00:100:3001::2 (len 24, hlim 255)

># tcpdump at server (3ffe:2a00:100:3001::2)
>17:13:41.588065 0:50:4:ec:b1:49 0:50:4:ca:89:4e 86dd 86: 3ffe:2a00:100:3001::2 > 3ffe:2a00:100:3001::3: icmp6: neighbor sol: who has 3ffe:2a00:100:3001::3(src lladdr: 0:50:4:ec:b1:49) (len 32, hlim 255)
>17:13:41.589416 0:50:4:ca:89:4e 0:50:4:ec:b1:49 86dd 78: 3ffe:2a00:100:3001::3 > 3ffe:2a00:100:3001::2: icmp6: neighbor adv: tgt is 3ffe:2a00:100:3001::3(RS) (len 24, hlim 255)
>17:13:46.588372 0:50:4:ec:b1:49 0:10:a4:ad:43:c0 86dd 86: 3ffe:2a00:100:3001::2 > 3ffe:2a00:100:3001:210:a4ff:fead:43c0: icmp6: neighbor sol: who has 3ffe:2a00:100:3001:210:a4ff:fead:43c0(src lladdr: 0:50:4:ec:b1:49) (len 32, hlim 255)

	"server" is not seeing the neighbor solicitation packet from "drifter",
	and that is the very reason DAD is not working.
	I guess you have either:
	- broken switch/hub inbetween (try putting 10Base-T cross cable)
	- broken ethernet card on either side
	- ethernet card with broken driver
		try using non-ex0 card on "server", or equivalent machine.

itojun