SDN课程阅读作业（2）

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？

(1) active networks

　　• introduced programmable functions in the network to enable greater to innovation;

　　• Programmable functions in the network to lower the barrier to innovation;

　　• Network virtualization, and the ability to demultiplex to software programs based on packet headers；;

　　• The vision of a unified architecture for middlebox orchestration.

(2) control and data plane separation

　　• developed open interfaces between the control and data planes;

　　• Logically centralized control using an open interface to the data plane;

　　• Distributed state management;

(3) the OpenFlow API and network operating systems

　　• represented the first instance of widespread adoption of an open interface and developed ways to make control-data plane separation scalable and practical.

　　• Generalizing network devices and functions

　　• The vision of a network operating system

　　• Distributed state management techniques

2.网络虚拟化与SDN的关系？

　• represented the first instance of widespread adoption of an open interface and developed ways to make control-data plane separation scalable and practical.

　　• Generalizing network devices and functions

　　• The vision of a network operating system

　　• Distributed state management techniques