HCIA (Computer Network Concept-Meaning of Network Protocol Model)
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Preface
This section describes the basic concepts of the network and the significance of the network protocol model
Tip: The following is the content of this article
1. Computer network concept
With the advent of the 5G era and the rapid development of the Internet of Things, more and more terminals are connected to the Internet.
In order for these devices to work in high coordination and communicate with each other, we must use a rule or standard to connect these terminal devices, so who is responsible for connecting them together? It is our computer network that is responsible for the connection.
First of all, we have to define a computer network : a computer network is a combination of multiple computers that are distributed in different geographical locations and have independent functions. They are connected through communication equipment and lines. The function of the network software (network protocol and network operating system, etc. ) Supported by a system aimed at realizing network resource sharing and data transmission.
(For example, now you are using the win10 system to open the browser and read my article written with the win10 Google browser, which shows that we are in a computer network.)
Second, the significance of the network protocol model
When the network just came out, only devices produced by one manufacturer could communicate; this also led users to preferentially choose a large number of customers when choosing, and the same company would either adopt the A solution or the B solution. The two vendors It is impossible to communicate with each other.
In the 1970s, in order to solve this problem, ISO (International Organization for Standardization, International Organization for Standardization) developed OSI (Open System Interconnection). The purpose of the OSI seven-layer reference model is to help manufacturers produce network equipment and software that can communicate with each other, so that the networks of different manufacturers can work together.
The OSI model describes how data and network information are transmitted from one computer application to another computer application through the network medium .
For example: I bought a water bottle in Pinduoduo, and the manufacturer will hand it over to the courier company to deliver it. From the origin of the water bottle to my hand, it will pass through many courier points of the courier company to finally deliver the water bottle to me. It cannot be A courier delivered it directly to me.
(You should know that you often visit Pinduoduo to buy things, such as Shanghai to Hunan, and stop at various courier points in other cities in the middle. It is impossible for Shanghai to go directly to Hunan)
According to the above example, the courier point is equivalent to the layer in the model. In order to ensure that the kettle can be delivered on time, each layer must completely trust the other layers, and each layer will do its own work. The express company The entire process of transporting the kettle will be monitored, and a series of operating standards will be formulated to standardize the process. This standard is the reference model .