计算机网络有那几个方向

视频：

https://mp4.xacisco.net/2019/349-%E8%AE%A1%E7%AE%97%E6%9C%BA%E7%BD%91%E7%BB%9C%E6%9C%89%E9%82%A3%E5%87%A0%E4%B8%AA%E6%96%B9%E5%90%91/%E8%AE%A1%E7%AE%97%E6%9C%BA%E7%BD%91%E7%BB%9C%E6%9C%89%E9%82%A3%E5%87%A0%E4%B8%AA%E6%96%B9%E5%90%91.mp4