1 stage: The late 1960s and early 1970s were the embryonic stages of computer network development. Its main feature is to connect small computers into an experimental network in order to increase the computing power and resources of the system. ARPANET, the first long-distance packet switching network, was built by the US Department of Defense in 1969, and a computer network system consisting of a communication network and a resource network was realized for the first time. ARPANET is a typical representative of this stage, which marks the real emergence of computer networks.
The second stage: The middle and late 1970s is an important stage for the development of local area network. Its main feature is that as a new computer architecture, local area network began to enter the industry. LAN technology originates from remote packet-switched communication networks and computer systems with I/O bus structure. 1976, the Palo Alto Research Center of Xerox Company of the United States launched Ethernet, which successfully adopted the basic principles of the ALOHA wireless network system of the University of Hawaii and became the first local area network with bus competition. From 65438 to 0974, the Computer Research Institute of Cambridge University developed the famous Cambridge Ring. The successful realization of these networks, on the one hand, marks the emergence of local area networks, on the other hand, their Ethernet and ring networks play a navigation role in the future development of local area networks.
The third stage: the whole 80' s is the development period of computer local area network. Its main feature is the ability of LAN to realize ISO open system interconnection communication mode protocol completely on hardware. The integration of computer local area network and its interconnection products makes the technology of local area network interconnection, local area network interconnection with various hosts and local area network interconnection with wide area network more and more mature. The development of integrated service data communication network (ISDN) and intelligent network (IN) indicates the rapid development of local area network. 1980 In February, the 802 LAN standard committee under IEEE (American Institute of Electrical and Electronics Engineers) was announced, and some drafts of LAN standards such as IEEE80 1.5~802.6 were put forward one after another, most of which have been officially recognized by the International Organization for Standardization (ISO). As an international standard of LAN, it marks the determination of LAN protocol and its standardization, and lays the foundation for the further development of LAN.
The fourth stage: from the early 1990s to the present, it is a stage of rapid development of computer networks, characterized by the development of computer networking, collaborative computing capacity and the popularization of the global Internet. The development of computer has been completely integrated with the network, which embodies the slogan of "network is computer". At present, the computer network has really entered all walks of life and has been adopted by all walks of life. In addition, the application of virtual network FDDI and ATM technology makes the network technology develop vigorously, quickly enter the market and enter the lives of ordinary people.
Function:
This is the problem that must be solved first, and it is definitely the core concept. The computer network we are talking about is actually a system that uses communication equipment and lines to interconnect multiple computer systems with different geographical locations and independent functions, and realizes resource sharing and information transmission in the network with well-functioning network software (i.e. network communication protocol, information exchange mode and network operating system, etc.). ). Its function is mainly manifested in two aspects: one is to realize the enjoyment of resources (including hardware resources and software resources); The second is the information exchange between users. The function of computer network is not only to let computers scattered around the network enjoy all the resources on the network, but also to provide users with powerful communication means and perfect services as much as possible, thus greatly facilitating users. From the perspective of network management, to put it bluntly, it is to use technical means to realize information transmission between networks and provide services for users at the same time.
★ What parts does a computer network consist of?
Computer network usually consists of three parts, namely, resource subnet, communication subnet and communication protocol. Resource subnet is the user-oriented part of computer network, which is responsible for the application-oriented data processing of the whole network; The rules and conventions that communication parties must abide by are called communication protocols, and their existence is the fundamental difference between computer networks and general computer interconnection systems. So from this perspective, we should better understand why the computer network is the product of the development of computer technology and communication technology.
★ How to classify the types of computer networks?
At present, the most common division method is: according to the size of the geographical scope covered by computer networks, it is generally divided into wide area network (WAN) and local area network (LAN) (some are divided by adding a metropolitan area network (MAN)). As the name implies, the so-called WAN is nothing more than a geographically distant network connection form, such as the famous Internet, and Chinanet is a typical WAN. However, the scope of a LAN is usually less than 10 km, and it is often limited to a single building or a group of buildings that are close together. Novell network is the most popular computer local area network at present.
★ What is the architecture of computer network?
In computer network technology, network architecture refers to the overall design of communication system, aiming at providing standards for network hardware, software, protocols, access control and topology. Now the reference model of OSI (Open Systems Interconnection) is widely used. It describes the network structure from seven levels: physical layer, data link layer, network layer, transport layer, dialogue layer, presentation layer and application layer. You should note that the quality of network architecture will directly affect the performance of bus, interface and network, and the key elements of network architecture are protocol and topology. At present, the most common network architectures are FDDI, Ethernet, token ring network and fast Ethernet.
★ What is the protocol of computer network?
Just said that one of the key elements of network architecture is network protocol. The so-called protocol is a formal description of the data format and the rules that must be observed when computers exchange data, and its function is exactly the same as that of Mandarin. According to different networks, Ethernet, NetBEUI, IPX/SPX and TCP/IP protocols are usually used. Ethernet is the most common underlying network protocol among bus protocols, which is simple to install and low in price. NetBEUI can be said to be a network protocol specially designed for small LAN. For those small LANs that don't need to communicate with large hosts through routers, it is enough to install NetBEUI protocol, but if routing to another LAN is needed, IPX/SPX or TCP/IP protocol must be installed. The former is almost synonymous with Novell network, while the latter is adopted by the famous Internet network. Especially TCP/IP (Transmission Control Protocol/Internet Protocol) is one of the earliest protocols in open system interconnection, and it is also the most perfect and complete at present.
★ What is the topological structure of the computer network?
The topological structure of computer network refers to the form that all sites in the network are connected with each other, specifically, the connection form of file servers, workstations and cables in the local area network. At present, the main topological structures are bus topology, star topology, ring topology and their mixture. As the name implies, the bus type actually connects the file server and the workstation on a common cable called bus, and there must be terminators at both ends of the bus; Star topology takes a device as the central connection point, and all workstations are directly connected to it to form a star; Ring topology is to connect all stations in series to form a ring loop like a chain; It is natural to mix these three basic topologies.
★ What hardware is involved in computer network construction?
The hardware system of computer network usually consists of five parts: file server, workstation (including terminal), transmission medium, network connection hardware and external equipment. The general requirement of a file server is a microcomputer equipped with a high-performance CPU system, which acts as the core of the network. In addition to managing the transactions on the whole network, it must also provide various resources and services. The workstation can be said to be an intelligent terminal. After it takes out programs and data from the file server, it can be processed on this workstation. Generally there are disks and diskless ones. Next, let's talk about the transmission medium, which is the physical path between the sender and the receiver in the communication network. In a local area network, it is a cable used to connect servers and workstations. At present, the commonly used network transmission media are twisted pair (mostly used in LAN), coaxial cable and optical cable. Common network connection hardware includes network cards, hubs, repeaters and modems. Any equipment that can be enjoyed by workstations, such as printers, scanners and plotters, can be called external equipment.
★ What operating systems are commonly installed in computer networks?
As we all know, the network operating system is the soul of the whole network, and it is also an important embodiment of the distributed processing system, which determines the functions of the network and thus determines the application fields of different networks. At present, the popular network operating systems mainly include Unix, NetWare, Windows NT and the newly popular Linux. Unix has a long history and is quite mature today, especially known for its security, reliability and wide application. In contrast, NetWare is famous for its file service and print management, and its directory service can be said to be a masterpiece of directory management recognized by the industry; Windows NT is a real 32-bit operating system, which can support a variety of hardware platforms. It maintains the popular Windows user interface and is used by more and more networks. The latest Linux is becoming one of the excellent network operating systems with its advanced design ideas and the status of free software.
★ What is the future development trend of computer network?
There are three basic technical trends in the future network development. One is the development of distributed computing and intelligence brought by low-cost microcomputer, that is, client/server structure; The second is to adapt to the development of multimedia communication and mobile communication structure; Third, the network structure adapts to network interconnection, expands the scale and even establishes a global network.