TCP/IP、Http、Socket的区别
http://jingyan.baidu.com/article/08b6a591e07ecc14a80922f1.html
多播
http://li-sir.iteye.com/blog/837344
心跳检测
http://weixiaolu.iteye.com/blog/1544860
http://weixiaolu.iteye.com/blog/1504898
http://weixiaolu.iteye.com/blog/1479656
traceroute详解
http://www.exit109.com/~jeremy/news/providers/traceroute.html