They can be parted into these classes as follow according to the principle to realize it: 1. Double Stack(RFC 2893 obsolete RFC 1933):The node adopting the technique runs both IPv4 and IPv6 protocol stacks.

• 按工作原理可划分为：双协议栈（RFC 2893 obsolete RFC1933）：采用该技术的节点上同时运行IPv4和IPv6两套协议栈。