A sample implementaiton set of "L2TP-IPv6PD" client using mpd.
"OCN IPv6", provided by NTT Communications Corp, was the first
commercial tunnel service using "L2TP-IPv6PD".

NOTE: This port runs on FreeBSD 6.3 and later.  If you want to run it
on FreeBSD 6.2, you need to apply following diff to your ng_ksocket:

http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/netgraph/ng_ksocket.c.diff?r1=1.59&r2=1.60

WWW: http://www.ocn.ne.jp/ipv6/service/pdf/ocnipv6uni_ver1.0.pdf