Let us now turn from the OSI reference model to the reference model used in the grandparent of all wide area computer networks, the ARPANET, and its successor, the worldwide Internet. This architecture later became known as the TCP/IP Reference Model, after its two primary protocols. 现在让我们从 OSI 参考模型转向所有计算机广域网络的鼻祖ARPANET及后来全球互联网Internet中使用的 TCP/IP 参考模型。 这种体系结构后来被称为 TCP/IP 参考模型,以它的两个主要协议命名 ( TCP 、 IP ) 。 TCP/IP 模型有几层?How many layers does the TCP/IP model have?