Although IPv6 protocols are reaching maturing,the transition from IPv4 to IPv6 is doomed to be a long process. The NAT technology is used very propularly in IPv4 network to make up the shortage of network address.

• IPv6协议已经逐步走向成熟,但IPv4向IPv6的过渡注定是一个漫长的过程,现有IPv4网络中广泛使用NAT(network address translation)技术来缓解地址短缺的问题。