http://www.fiber-optic-solutions.com/optical-transponder-o-e-o-wdm-network.html

https://wenku.baidu.com/view/93ef3a1cc281e53a5802ffc5.html

https://www.zhihu.com/question/40583330

http://www.zhihu.com/topic/19676045/top-answers

OpenFlow:Enabling Innovation in Campus Networks