What are the layers of network interconnection? What s the difference?

OSI (Open System Interconnect) is an open system interconnection.

It is generally referred to as the OSI reference model.

It is a network interconnection model studied by the ISO (International Organization for Standardization) organization in 1985.

In the early days of the Internet, many large companies had network technology, and the computers within the company could be connected to each other. Yes, but not with other companies. Because there is no one uniform specification.

The information that computers transmit to each other cannot be understood by the other party. So it can't be interconnected.

In order to make network applications more popular, ISO has introduced the OSI reference model. The implication is that it is recommended that all companies use this specification to control the network. So that all companies have the same norms and can be connected.

It reads as follows:

Layer 7 Application Layer—Serves the application directly, and the application can.

changes, but to include electronic messaging.

Layer 6 Presentation Layer—Format data to provide a common connection to the application.

Mouth. This can include cryptographic services.

Layer 5 Session Layer—An end-connect is established between two nodes. This service includes:

Whether the connection is set up in full-duplex or half-duplex.

, although it is possible to handle duplex mode in layer 4.

Layer 4 Transport Layer—Regular Data Delivery Connection-oriented or connectionless. Include.

Full-duplex or half-duplex, flow control, and error recovery services.

Layer 3 Network Layer—This layer establishes the connection between two nodes through addressing, which includes routing and relaying data through the interconnected network.

Layer 2 Data Link Layer—This is where the data is framed and flow control is handled. This layer.

Specify the topology and provide hardware addressing.

Layer 1 Physical Layer—Transmission of the original bit stream, electronic signal transmission, and hardware interfaces.

When data is sent, it is passed from layer 7 to layer 1, and the receiver is reversed.

The upper three layers are collectively called the application layer, which is used to control the software aspect.

The lower four layers are collectively called the data flow layer and are used to manage the hardware.

Data is split when it is sent to the data streaming layer.

The data at the transport layer is called the segment, the network layer is called the packet, the data link layer is called the frame, and the physical layer is called the bitstream

Each layer in OSI has a role for each layer. For example, the network layer needs to manage the IP address of the local IP and the destination IP address. The data link layer needs to manage MAC addresses (media access control) and so on, so the data is encapsulated after splitting at each layer to complete the role of mutual communication between the receiver and the machine.

As such.

The OSI model is quite versatile.

For example, the design of many network devices, such as switches, hubs, and routers, is based on the OSI model.

It is enough to know so much of the Tao. At least that's all CCNA can do.

1. Physical layer: used for the interconnection of network segments within different geographical ranges. Network devices that work at the physical layer are repeaters and hubs.

2. Data link layer: used to interconnect two or more LANs of the same type and transmit frames. The inter-network devices that work at the data link layer are bridges (or bridges) and switches.

3. Network layer: It is mainly used in the interconnection of WAN, and the inter-network equipment working in the network layer is a router and a layer 3 switch.

4. High-level: used for the conversion of different protocols between high-level layers, the inter-network equipment working in the third layer is called a gateway.

Take broadband as an example, there are now types of broadband, one is network cable, and the other is optical fiber! : Computer-Cat-M-Device-Switch-Fiber-Core Router - Network Cable:

Computer-Switch-Fiber-Core Router- Optical Fiber: Computer-Optical Modem-Optical Switch-Optical Fiber-Core Router- The characteristics are all similar,

The hierarchical network explanation is that hierarchical hierarchy refers to the hierarchical order of a system in terms of structure or function. It has diversity and can be divided according to various criteria such as the mass of matter, energy, state of motion, spatial scale, time order, degree of organization, etc.

Different levels have different properties and characteristics, and there are both common and special laws.

The hierarchical network explanation is that hierarchical hierarchy refers to the hierarchical order of a system in terms of structure or function. It has diversity and can be divided according to various criteria such as the quality of matter, the source of energy, the state of movement, the spatial scale, the chronological order, and the degree of organization.

Different levels have different properties and characteristics, and there are both common and special laws. The part of speech is: noun.

The structure is: layer (semi-enclosed structure) secondary (left and right structure). The phonetic pronunciation is:

Pinyin is: céngcì.

What is the specific explanation of the hierarchy, we will introduce it to you through the following aspects:

1. Explanation of terms [click here to view the details of the plan].

Hierarchical céngcì. (1) The level of the institution. (2) Sequential, stage crack resistance.

2. Citations and Explanations.

It refers to the order in which things are inherited. Quoting Xu Hongzu's "Xu Xiake's Travels: After Traveling to Yantang Mountain": "Heavy clamping, layering, indistinguishable layers.

Qing Yao Nai's poem "Mi Youren Chujiang Wind and Rain Picture Scroll": "There is no need for a bleak mimetic model, the yuan is clearly out of the level." "Lao She's "Camel Xiangzi" VIII:

It's the same in hell, but at a different level. Refers specifically to the institutions at all levels to which they belong. For example:

Reduce layers and streamline personnel.

3. Chinese dictionary.

Order, order. Such as: the hierarchy is clear.

Synonyms about hierarchy.

The grade is organized. Verses about levels.

And the level has its own shallowness and depth, and its level cannot be counted.

Idioms about levels.

Emerge endlessly, the grass is stacked on top of each other, and the mountains and scales are stacked compared to the layers and platforms, which is too dense and dense, and the layers of mountains and mountains are seen one after another.

Words about levels.

The layers are tired, the layers are endless, the fish are endless, the idle is seen in the pengsu grass, the second layer is seen in the stacked mountains, the scales are distinct, and the layers are distinct.

Sentence formation about levels.

1. The article is well written, the level is clear, and it echoes before and after.

2. The level of this article is unclear, disorganized, and people can't see the center.

3. This work sets off the image of the protagonist from the front and multiple levels.

4. The hierarchical teaching of secondary school English is imminent.

5. Institutional reform should not only reduce personnel, but also reduce levels.

Because a computer network is a complex network system, the hierarchical structure of the method to describe it can be decomposed into many relatively small parts with clear and simple boundaries to deal with.

1 What is the practical significance of network interconnection? What are some common issues that need to be addressed when interconnecting networks?

A: Network interconnection expands the range of shared resources and a larger communication area for users.

When interconnecting networks, common problems need to be solved: different addressing schemes;

different maximum grouping lengths;

different network access mechanisms;

different timeout controls;

different error recovery methods;

different methods of status reporting;

different routing techniques;

different user access control;

different services (connection-oriented and connectionless-oriented);

different management and control styles; Wait a minute.

Are you talking about OSI or something. Layer 2 is a switching LAN based on the broadcast domain, MAC address**. WAN is concerned about the next two layers, such as fr.

A Layer 2 network is a network that is interconnected by switches. The main meaning is to form a LAN of the broadcast domain, which can be used for data frames according to different MAC addresses, and can also be connected to different types of networks.

Network interconnection is actually divided into physical interconnection (hard interconnection) and software level (e.g., between the Internet). It's called a soft interconnect).Hard interconnection is actually a skilled job, and the technical content is slightly lacking.

Soft interconnection is the technical core of network interconnection and the right way to develop your career.

Database system Personally, I think that the career development will be broader, and data mining can be carried out in the later stage (all database application companies need this service) are very open in the computer network system, and the exchange concept is proposed to improve the shared work model.

When interconnecting a network, there are common problems that need to be addressed:

different addressing schemes; different maximum grouping lengths;

different network access mechanisms;

different timeout controls; different error recovery methods;

different methods of status reporting;

different routing techniques;

different user access control;

different services (connection-oriented and connectionless-oriented);

different management and control styles; Wait a minute.

1 What is the practical significance of network interconnection? What are some common issues that need to be addressed when interconnecting networks?

A: Network interconnection expands the range of shared resources and a larger communication area for users.

When interconnecting networks, common problems need to be solved: different addressing schemes;

different maximum grouping lengths;

different network access mechanisms;

different timeout controls;

different error recovery methods;

different methods of status reporting;

different routing techniques;

different user access control;

different services (connection-oriented and connectionless-oriented);

different management and control styles; Wait a minute.