What is the Internet? What isInternet?
To put it simply,The network is to connect two or more computers in a certain area in a certain way.,For users to share files, programs, data and other resources.
Internet,That is, Global Information Network (World Wide Web, abbreviationWWW) is based on hypertext(Hypertext)The information retrieval tool, which uses hyperlinks to different parts of the worldInternetThe relevant information on the node is organically organized. Users only need to issue a search request, and it can automatically locate and find the corresponding search information.
The following is a brief introduction to several common network types and classification methods.
Classified by the geographical location of the network
* local area network(Local Area Network,AbbreviationLAN）
Generally limited to a smaller area, less than10kmThe scope of It is usually connected in a wired manner.
* Metropolitan Area Network (Metropolis Area Network,AbbreviationMAN）
The scale is limited to the scope of a city.10～100kmarea.
* Wide Area Network (Wide Area Network,AbbreviationWAN）
The network spans national boundaries, continental boundaries, and even globally.
Currently, LAN and WAN are hot topics of the network. Local area networks are the basis for forming the other two types of networks, and metropolitan area networks are generally joined to wide area networks. A typical representative of a wide area network isInternetnet.
Classified by network topology
The topology of a network refers to the geometric arrangement of communication lines and sites (computers or devices) in the network.
* Star Network
Each site is connected to the central station through a point-to-point link. The feature is that it is easy to add new sites to the network, the security and priority of data are easy to control, and network monitoring is easy to implement, but the failure of the central node will cause the entire network to be paralyzed.
* Ring network
Each site is connected to a closed ring through a communication medium. The ring network is easy to install and monitor, but its capacity is limited. After the network is built, it is difficult to add new sites.
* Bus network
All sites in the network share a data channel. Bus network installation is simple and convenient, with the shortest cables to be laid and the cost is low. The failure of a certain site generally does not affect the entire network. However, media failure will cause network failure, low security of the bus network, difficult monitoring, and adding new sites is not as easy as Star Network.
Networks with other types of topological structures such as tree networks, cluster star networks, and mesh networks are based on the above three topological structures.
Classified by transmission medium
* Wired network
A computer network that uses coaxial cable and twisted pair cable to connect.
Coaxial cable network is a common way of networking. It is relatively economical, has relatively convenient installation, has average transmission rate and anti-interference ability, and has a short transmission distance.
Twisted pair network is the most common way to connect to the network at present. It is cheap, easy to install, but is susceptible to interference, has a low transmission rate, and has a shorter transmission distance than coaxial cables.
* Fiber Optical Web
Optical fiber network is also a type of wired network, but it is listed separately due to its particularity. Optical fiber network uses optical fibers as the transmission medium. Optical fiber transmission distance is long, transmission rate is high, and can reach several gigabitsbps, strong anti-interference and will not be monitored by electronic monitoring devices, and is ideal for high-security networks. However, due to its high price and requires high-level installation technology, it has not yet been popularized.
* Wireless
Using air as the transmission medium and electromagnetic waves as the carrier to transmit data. At present, wireless networking costs are relatively high and are not very popular. However, because the networking method is flexible and convenient, it is a promising way to connect.
Local Area Networks usually use a single transmission medium, while metropolitan Area Networks and WANs use multiple transmission mediums.
Classified by communication method
* Point-to-point transmission network: Data is transmitted in a point-to-point manner in a computer or communication device. Star networks and ring networks adopt this transmission method.
* Broadcast transmission network: data is transmitted in a shared medium. Wireless networks and bus networks belong to this type.
Classified by purpose of network usage
* Shared Resource Network: Users can share various resources in the network, such as files, scanners, plotters, printers and various services.InternetThe network is a typical shared resource network.
* Data processing network: a network used to process data, such as scientific computing networks and enterprise management networks.
* Data transmission network: a network used to collect, exchange and transmit data, such as intelligence retrieval networks, etc.
Currently, the purpose of network usage is not the only one.
Classified by service method
* Client/Server network
A server refers to a high-performance computer or specialized device that specializes in providing services, and the client is a user's computer. This is a network form in which clients make requests to the server and obtain services. Multiple clients can share various resources provided by the server. This is the most commonly used and important type of network. Not only suitable for networking of similar computers, but also for networking of different types of computers, such asPCmachine,Machybrid networking of machines. This kind of network security is easily guaranteed, computer permissions and priorities are easy to control, monitoring is easy to implement, and network management can be standardized. Network performance depends to a large extent on the performance of the server and the number of clients. Currently, there are many servers that optimize performance for this type of network called dedicated servers. Banks and securities companies all use this type of network.
* Peer-to-peer network
Peer-to-peer networks do not require file servers. Each client can talk to each other and share each other's information resources and hardware resources. The computers that form the network generally have the same type. This network method is flexible and convenient, but it is difficult to achieve centralized management and monitoring, and has low security. It is more suitable for small networks that work collaboratively within the department.
Other classification methods
For example, classified according to the characteristics of the information transmission modeATMThe network data is asynchronously transmitted, and the data is53Byte units are transmitted, providing up to1.2GbpsThe transmission rate has the ability to predict network delay. It can transmit real-time information such as voice and video, and is one of the most promising network types.
There are also some informal classification methods: such as enterprise network and campus network, which can be understood based on the name.
There are different classification methods for networks from different perspectives, and each network name has a special meaning. The characteristics of the network can be seen by combining several names or adding names to the parameters. Gigabit Ethernet represents a bus network with a transmission rate of up to gigabit. Understanding the classification methods and type characteristics of networks is one of the important foundations for being familiar with network technology.
Article entry: csh Editor in charge: csh