Multicasting Routing

Unfortunately, there is no standardized API for IPv6 multicast routing.

KAME uses its own APIs.
examples of socket options
MRT6_ADD_MIF: add a multicast interface.
MRT6_ADD_MFC: add a multicast forwarding cache entry.
for more details
kame/kame/kame/{pim6dd, pim6sd}
kame/kame/sys/netinet6/ip6_mroute.c