1.过去20年中可编程网络的发展可以分为几个阶段？每个阶段的贡献是什么？
- We divide the history into three stages
- 1) active networks (from the mid-1990s to the early 2000s), which introduced programmable functions in the network to enable greater to innovation（引入了可编程功能）
- 2) control and data plane separation (from around 2001 to 2007), which developed open interfaces between the control and data planes（控制层数据层分离）
- 3) the OpenFlow API and network operating systems (from 2007 to around 2010), which represented the first instance of widespread adoption of an open interface and developed ways to make control-data plane separation scalable and practical.（开发了使控制数据平面分离可扩展且实用的方法）
来源：https://www.cnblogs.com/fzu-lzh/p/11966339.html
