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This article shows you how to understand the computer network OSI reference model, the content is concise and easy to understand, it can definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

OSI reference Model and layered thought

The process of network transmission is a very complex process, so the idea of layering should be established first. Hierarchical model is a design method for developing network protocols. In essence, the idea of layering is to divide the complex problem of communication between nodes into several relatively simple problems one by one to solve each problem corresponding to one layer. Each layer implements certain functions, and the complex task of data communication can be realized by cooperating with each other.

When we use network transmission, we can only see two aspects: the sender and the receiver, but the intermediate process from the sender to the receiver is not well understood.

The above picture is the hierarchical schematic diagram of the OSI reference model. The network transmission is divided into seven layers. Each layer has its own function and completes the data transmission under mutual cooperation. Let me introduce to you the function and function of each layer.

(1) physical layer: establish, maintain, and disconnect physical connections

From a computer point of view, the physical layer is equivalent to network cables, network cards, and optical fibers.

(2) data link layer: functions such as establishing logical connection, hardware address addressing, error checking, etc.

This is a process like data repackaging and packaging, confirming that the data is sent to the correct address.

(3) Network layer: logical address addressing to realize path selection between different networks.

This is a process of selecting a network transmission path to ensure real-time and efficient data transmission.

(4) Transport layer: defines the protocol port number for transmitting data, as well as flow control and error checking

Determine the transmission of data from one port to another to ensure the accuracy of the data transmission location

(5) session layer: establish, manage, and abort calls

Establish a connection session between ports

(6) presentation layer: data representation, security, compression

This is a process of translating, encrypting and compressing data.

(7) Application layer: an interface between network services and end users

It can be understood as all the APP that we use now.

Application layer, presentation layer and session layer belong to software layer; transport layer, network layer, data link layer and physical layer belong to network layer. This explanation is not easy to understand, and it is easy to understand it with an example that happens around us every day in life.

The transmission of data is like the logistics transmission of express parcels, so we can use examples of express delivery to understand data transmission!

The logistics of express parcels is based on some basic factors, such as roads extending in all directions, cars carrying people and goods, which are precisely the physical layer. When we place an order for an item, the express company's treatment of our goods is to pack up and paste a unique delivery order to ensure that your delivery can be safely delivered to your hand, this is the data link layer. After the express package is completed, it is delivered by the truck, and the first thing of distribution is to choose an optimal route, which is the role of the network layer. When the route selection is completed, the delivery truck will contact the delivery station in your city, and when your package will arrive at the nearest site, from the express company to the station set up by the secondary delivery company around you, is a port-to-port connection, instant transport layer. The connection established by the truck to the express delivery station is supported by the session layer. When the express delivery arrives at the site, you receive a text message to get the express delivery, if it is too time-consuming and laborious to find your own package through the QR code and bar code of the package, so you need to number each package so that you can understand the meaning at a glance is the function of the presentation layer. In this way, the express delivery will be safely delivered to your hands! Such a process of express delivery is the same as the process of data transmission on our network. After reading this example, we should be able to understand the process of data transmission.

Therefore, data transmission is a very complex process, we adopt the idea of layering, simplify the process, and better understand the meaning of it.

The above content is how to understand the computer network OSI reference model. Have you learned the knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

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