Problems of IPv4

Exhaustion of IPv4 addresses
4 bytes = 4.3 billion
Much less than the human population (6.1 billion)
Will be exhausted in around 2008
Registries are allocating IPv4 addresses by severe policy
Nobody can obtain enough IPv4 addresses

Increment of routing information
Routing information cannot be aggregated effectively
Unaggregatable address assignments
80,000 entries at present
Burden for backbone routers
Unstability, accidents

Proliferation of NAT
Breaking the Internet architecture
Enclosure of users