通信协议
OSI七层模型与TCP/IP五层模型
https://www.cnblogs.com/qishui/p/5428938.html
网络分层模型OSI和TCP/IP四层模型
https://blog.csdn.net/andrewgithub/article/details/81603205
socket通信处于网络协议那一层和两种接收发送消息方式
https://blog.csdn.net/jia12216/article/details/82702960
https://www.cnblogs.com/qishui/p/5428938.html
https://blog.csdn.net/andrewgithub/article/details/81603205
https://blog.csdn.net/jia12216/article/details/82702960