Unit 1, Encapsulation

Encapsulation unifies layering and packet switching. It is how we take protocal layers and assemble them into packets in a way that’s flwxible and maintains the separation of conerns.

• Encapsulation is the principle by which you organize information in packets so that you can maintain layers. 把不同layers的放在一个packet里面. It allows the different layers to easily share the storage within a packet.
• Each layer is self-contained, it can provide service to the layer above as long as it is provided with data expected of it.

Makes something the payload of it. 封装，不用管里面是什么，是tcp, udp还是其他协议。

封装的一种应用：V PN
A computer accepts connections from permitted clients, and forwartds the traffic into the private network.

那么VPN和rVPN的区别是？

让外地员工访问到内网资源，利用VPN的解决方法就是在内网中架设一台VPN服务器。外地员工在当地连上互联网后，通过互联网连接VPN服务器，然后通过VPN服务器进入企业内网。为了保证数据安全，VPN服务器和客户机之间的通讯数据都进行了加密处理。有了数据加密，就可以认为数据是在一条专用的数据链路上进行安全传输，就如同专门架设了一个专用网络一样，但实际上VPN使用的是互联网上的公用链路，因此VPN称为虚拟专用网络，其实质上就是利用加密技术在公网上封装出一个数据通讯隧道。（来自百度百科）