Current / Future Items

Mobile IPv6
Multicasting
Copy "ipv4/ipmr.c" is not good, I think.
Advanced API
new API overrides the definition...
probably we allocate new sockopt and provide old sockopt for compatibility
Introduce u64 counters
update unsigned long internally, and update u64 periodically
everything-over-ipv{4,6} tunnel
ipv{4,6} over ipv4 (tunl), replaces sitX (and greX?)
ipv{4,6} over ipv6 (ip6tnl)