Shulou(Shulou.com)06/01 Report--

The main predecessor of the Internet is Arpanet. He was led by Robert Strauss-Kahn of the Defense Advanced Research projects Agency (ARPA) of the Defense Department in 1974 and Winton of Stanford University. Cerf developed the TCP/IP protocol, which defines the method of transmitting information between computer networks. On January 1st, 1983, ARPA changed its network core protocol from network control program to TCP/IP protocol. The technologies used by ARPA (such as TCP/IP protocol) have become the core of the Internet in the future.

Tim, who works for CERN. Berners-Lee launched the world's first web browser and first web server at the end of 1990, which promoted the emergence of the World wide Web and led to the rapid development of Internet applications.

The working principle of the Internet is what we need to know in detail. We have the following picture to describe the communication between computers and between people.

From above, we can see that air medium is needed to transmit sound before communication between people. What about the computer? Communication between computers also needs a medium to transmit the sound (protocol) between them, but there are many things in this transmission medium, such as radio waves, optical brazing, coaxial cable, telephone, network cable. Just said the agreement, then what is the agreement? An agreement is a way of communication agreed upon by both parties, and you will reply to me whatever I send. Fixed, if not, report an error. The figure above shows a mode of communication between two computers using the tcp/ip protocol. Shake hands three times, disconnect four times. We can now sum up that the communication between computers is to transmit their call information (protocol) through the optical brazing medium. Now that we're talking about the agreement, let's get to know it in detail. Tcp/ip protocol is the language of computers, so what does it contain?

This agreement is also a large agreement family, it contains a lot of small agreements. It is because these small protocols cooperate with each other that computer communication is barrier-free. Before the birth of this agreement, scientists divided them into different levels, allowing different protocols to do different things at different levels. Let's just look at the picture.

When there is weak electric transmission in the transmission medium, there is our physical layer to receive, the protocol of the physical layer is translated to the network layer, the protocol of the network layer is translated to the transport layer, and the protocol of the transport layer is translated to the session layer. the protocol of the session layer is translated to the presentation layer and translated to the application layer by the protocol of the presentation layer. In this way we saw the data from the remote server. When we want to send the locally written data to the remote end, the protocols of each layer can then translate the data to the lower layer, and eventually become a weak signal to reach the remote end. I don't know if we can understand this explanation. If there is anything we don't understand, we can discuss it with each other.

Finally, let's make a simple summary.

The communication between computers is realized by tcp/ip protocol family. The most basic communication structure is a three-way handshake and four disconnections. Later, we will learn that different services will be implemented using different protocols. That's all for this chapter. In the next chapter, let's take a look at IP addresses and several important protocols.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.