Basic Design

Designed by
USAGI and HUT (Helsinki Univ. of Tech.)
Packet modifications, such as Bi-Tunnel, RO and IPsec, are done inside kernel
XFRM framework
Build XFRM state respectively
it manages packet mangling.
like Binding Cache, but it is not the same.
Standard IPv6-IPv6 tunnel
for link-local protocol
Signaling is handled in userspace daemon
manages binding cache and XFRM policy/state