参考文档：
https://wenku.baidu.com/view/076791cea1c7aa00b52acb1f.html
https://zhuanlan.zhihu.com/p/54529607
http://kms2.h3c.com/View.aspx?id=41357
https://wenku.baidu.com/view/c6175be7453610661ed9f4fa.html
https://wenku.baidu.com/view/654537fb33d4b14e852468f2.html
http://www.ruijie.com.cn/fw/wt/3163/
https://www.cnblogs.com/fmhbk/articles/7919271.html