A computer network is a collection of independent computers that are interconnected.Bentley ProjectWise Here "interconnected" means that two or more interconnected computers can exchange information to share resources.

Independence" means that each computer works independently and no one computer can interfere with the work of the others.Bentley BIM Such as start and stop, there is no master-slave relationship between any two computers.

Second, computer network classification

1. According to the geographical location of the network classification

Computer information network according to its geographic location and distribution of classification methods can be divided into three categories of local area networks (LANs), wide area networks (WANs) and metropolitan area networks (MANs).

(1) Local Area Network (LAN)

Local Area Network (LAN) is a network consisting of computers interconnected in close proximity in a localized area, usually with wired connections,BIM Viewer and the distribution range is generally between a few meters and a few kilometers (less than 10 kilometers). Examples include networks interconnected within a building or between several neighboring buildings. Most networking within a unit is a LAN.

(2) Wide Area Network (Ring Network)

A WAN is a network consisting of computers interconnected over long distances, which can reach thousands or even tens of thousands of kilometers, and even cross national borders and continents, all over the world. The Internet is a typical WAN.

(3) metropolitan area network (MAN)

The scale of development of metropolitan area network (MAN) is mainly studied confined to the management of a Chinese city, is a kind of network between the WAN and LAN, the distribution of the scope of influence to carry out generally between a dozen kilometers to hundreds of kilometers.

2. Classification by transmission medium

Computer network according to its transmission medium can be divided into wired network and wireless network.

(1) wired network

There are two kinds of wired networks, one is coaxial cable and twisted pair connection network; the second is the network with optical fiber as the transmission medium. The latter is also called fiber optic network.

The use of coaxial cable and twisted-pair cable connected to the development of the network is more China's economy, easy to install and use, but the transmission security distance can be relatively short, the transmission rate and the ability to engage in interference problems analysis in general; fiber optic network is a long distance, high transmission rate (up to thousands of megabits of bps), and anti-jamming ability, security, but the price level is high, and the need for a high level of installation of engineering technology, has not yet been popularized in our country. Popularization.

(2) wireless network

Air as a medium, electromagnetic waves as a transmission carrier network. The network mode is flexible and convenient, but the cost of the network is high, currently under development, with good prospects.

3. According to the topology of the network.

The topology of the network refers to the geometric arrangement of communication lines and stations (computers or devices) in the network. Computer networks can be categorized into star networks, ring networks and bus networks according to their topology.

(1) Star network

Sites on the network can be connected to the center for sites through point-to-point links. Characterized by the ability to add new sites easily, data security and priority is easy to manage and control, network security monitoring is easy to achieve, but if the central site failure will cause the entire enterprise social network system paralysis.

(2) Ring network

The sites on the network are connected into a closed loop through the communication medium. It is easy to install and monitor, but the capacity is limited and it is difficult to add new sites.

(3) Bus type network

All sites on the Internet share a single data channel. It is characterized by the shortest cable laying, low cost and easy installation; however, it is difficult to monitor and low security. If the medium fails, the network will be paralyzed, and adding new sites is not as easy as the star network.

Third, the function is well: it should be two or more computer technology connected to each other in order to constitute a network, to achieve the purpose of enterprise resource information sharing.