What is IPv6? (2)

Say a long good-bye to NAT, say hi again to end-to-end model
Has been used as temporary cure for address space issue

NAT breaks bidirectional communication
NAT is a bondage to application protocol designers
NAT does not let multicast/IPsec through
NAT does not work with proprietary protocols
NAT does not improve security
NAT box is a single point of failure
If you reboot NAT box, all connection will be gone
NAT is a barrier to scalability of the Internet as a whole
prevents deployment of peer-to-peer apps