1. National informatization in China
There is no reference to national information infrastructure in China, but the idea of national informatization is adopted instead. Under the unified planning and organization of the state, China's national informatization applies modern information technology in agriculture, industry, science and technology, national defense and social life, deeply develops and widely uses information resources, and accelerates the process of national modernization.
the goal of national informatization construction is: by the year 2, a certain scale and relatively complete national informatization system will be initially formed; By 2l, a sound, large-scale and advanced national information system will be established. The national informatization system consists of the following six elements, namely, information resources, national information network, information technology application, information technology and industry, informatization talents, informatization policies, regulations and standards.
It can be seen that China's informatization is different from foreign information superhighway and national information infrastructure. China emphasizes the close relationship between the six elements of the information system and puts the development and utilization of information resources at the core. In recent years, the development speed of information industry in China has exceeded the growth speed of national economy. During the Eighth Five-Year Plan period, the electronic industry increased by an average of 3% annually, and the telecommunications industry increased by an average of more than 4%. China's communication network has basically realized digitalization and program control. The whole country has initially established a network with optical cables as the mainstay, supplemented by digital microwave and satellite communication, and using various means.
at the end of p>l993, the relevant state departments decided to build the "Golden Bridge", "Golden Card" and "Golden Pass" projects, referred to as "Three Gold Projects" for short. "Golden Bridge" project is based on satellite integrated digital network, and forms a network structure integrating air and ground by means of optical fiber, microwave and wireless mobile. It is a national public economic information communication network connecting the State Council, ministries and commissions, provinces and cities, large and medium-sized enterprises and national key projects, which can transmit data, voice, images, etc. E-mail and electronic data interchange (EDI) are used as information exchange platforms to provide physics for the circulation of all kinds of information. At present, Jinqiao Project has established a satellite integrated information network with VSAT technology as the main body and optical fiber as the supplement in 24 central cities in China, such as Beijing, Tianjin, Shenyang, Dalian, Changchun, Harbin and Shanghai.
"gold card" means electronic money project. Its goal is to popularize financial transaction cards and credit cards among 3 million urban population in more than 1 years. The "Golden Gate" project is to use EDI to realize the informationization of international trade and further integrate with international trade.
At present, 114 information centers have been established by ministries (commissions and offices) all over the country, and 5% of them have established computer networks, of which 15% have established computer networks covering the whole country. Provinces (cities, districts) have established 32 information centers, 4% of which have established networks, of which 1% have established computer networks covering the whole province (cities, districts); 1, large state-owned enterprises have established their own information centers, and 5% have established enterprise computer networks. The connection ratio between these networks and public networks is less than 1%. Judging from the development of INTEIWET in China, by June 1999, four Internet networks in China had been interconnected. Among them, there are more than 4 million users, more than 1,6 access units, more than 15, computers connected, and 12,643 third-level domain names registered under CN. It is predicted that in l, the installed capacity of computers in China will exceed 1 million, of which 3% will be connected to various computer networks, mainly public computer networks. At the same time, with the establishment of high-speed internet exchange center and regional exchange center, it will greatly promote the information sharing of the internet. By the year of 2l, there will be more than 1 computer networks in China, 3% of families will have access to network services, and the network with multiple information media will make significant progress.
2. public data networks, China
In recent years, the construction of public data communication network in China is very fast. Telecom departments have established digital communication networks such as CHINAPAC, CHINADDN and CHIANFRN, forming a public data communication network in China.
China Public Packet Switched Data Network (China PAC) was opened in September 1993. By the end of l996, it had covered cities above the county level and some towns in developed areas, and was interconnected with 44 data networks in 23 countries and regions around the world.
(1) network status
packet-switched network is the earliest basic data communication network built and developed by post and telecommunications departments. Based on the recommendation of CITTX.25, packet switching network can meet the communication between terminals and computers, computers and computer LANs with different rates and models. Packet switching network is a basic data communication network, and various value-added services can be built on its network platform, such as e-mail, electronic data exchange, fax storage and forwarding, etc.
CHINAPAC consists of the national backbone network and the provincial intranet of each province (city, district). At present, the backbone network covers all provincial capitals, and the provincial intranet covers all cities and developed towns with business requirements. Through the interconnection with the telephone network, CHINAPAC can cover all areas reached by telephone netcom. CHINAPAC has a primary exchange center and a secondary exchange center. The primary exchange center adopts an incomplete mesh structure, and the-primary exchange center adopts a star structure from its subordinate secondary exchange center. CHIANIPAC has international entrances and exits in Beijing and Shanghai, and Guangzhou has entrances and exits to Hong Kong and Macao to complete the networking with international data.
(2) network characteristics and service functions
The outstanding advantage of packet-switched network is that it can open multiple virtual circuits on one physical circuit at the same time for multiple users to use at the same time; The network has dynamic routing function and complex and complete error correction function. X.25 protocol was developed under the condition of poor transmission quality of physical links. In order to ensure the reliability of data transmission, it must perform error checking and error retransmission on each link. Although this complicated error checking mechanism limits its transmission efficiency, it does provide a good guarantee for the safe transmission of user data.
the services provided by p>CHINAPAC are as follows:
L. basic business functions
basic business functions refer to the basic business functions provided by any digital terminal equipment (DTE). It can meet the basic requirements of users for communication. There are two basic services, Switched Virtual Circuit (SVC); Permanent virtual circuit (PVC)
2. Optional service function
User-optional service function is a special service function provided to users to meet their special needs, such as incoming call blocking, outgoing call blocking, one-way incoming logical channel, one-way outgoing logical channel, etc.
3. Other business functions
CHINANET also provides other business functions recommended by ITU-T, such as virtual private network (VPN), TCP/IP, packet multicast, call redirection, etc.
(3) User access mode
CHINANET provides two access modes.
1. Private line mode
is suitable for applications with large communication traffic, frequent use, high reliability and no loss, but it needs to be used as a private line and the cost is relatively high. The access rate of private line is 9.6 ~ 64 kbps.
2. Telephone dialing
is suitable for applications with small business volume, long intermittent time and tolerance for call failure. Because it uses the existing telephone line, it does not need additional investment, and the data can share the line with voice, so it greatly saves investment and is an ideal access means for scattered users. It can be divided into x.28 asynchronous dial-up network access or X.32 synchronous dial-up network access, and the dial-up network access rate is l2-96BPS
(4) Tariff policy < P > There are two current charging methods in p>CHINAPAC, namely, time metering charging and monthly charging. Charge by time and measurement.
Wide application field and service positioning
Compared with DDN and Frame Relay, packet service charges are cheaper, and it is the most economical choice for users to construct their internal WAN. In the case of establishing multipoint connection at the same time, the virtual circuit function of packet switching network can replace the expensive multipoint DDN private line. However, due to the complexity of the X.25 protocol itself, packet services are used in low-speed applications where the rate is lower than 64K. For example, at present, with the continuous advancement of the Gold Card Project, the use of POS machines is becoming more and more popular, and the POS business volume is small, but the real-time requirement is high. Non-sub-network interconnection is a very good scheme to realize the communication between POS machines and hosts.
China public digital data network (ChinaDDN)
Digital communication network (DDN) is a digital transmission network that uses digital channels to provide permanent and semi-permanent connection lines and mainly transmits data signals. It can provide various flexible data interfaces to serve the transmission of data signals. Because of its simple protocol and high speed, it has developed rapidly in China in recent years.
DDN consists of digital channels, DDN nodes, network management systems and subscriber loops. It mainly provides point-to-point and point-to-multipoint digital private line services, as well as frame relay and compressed voice /G3 fax services.
The main features of DDN are:
(1) The transmission quality is high, which is greatly improved due to the large number of optical fiber transmission channels used in DDN at present;
(2) The transmission rate is high, ranging from 24BPS to 2MBPS
(3) The protocol is simple, because the DDN mainly uses time division multiplexing and cross-connection technology to transmit user information completely transparently, with less technical requirements for users and flexible application;
(4) In the DDN network, advanced network management technology is adopted, which can realize centralized management of line scheduling and fault monitoring, and can automatically route circuitous lines in case of fault, thus improving the utilization rate of subscriber lines.
(1) service application and characteristics of DDN
DDN mainly provides point-to-point digital private line services. Widely used in banking, securities, meteorology, culture and education and other fields, used in the interconnection of LAN7WAN and different networks. For example, the headquarters and branches of a company are located in different places, and the communication between the two points is very frequent. It is necessary not only to keep in touch by telephone, but also to carry out computer networking communication. If we rent a dedicated DDN line and add multiplexing equipment at both ends to connect the telephone system and computer system distributed in the two places, we can communicate conveniently between Egypt and Egypt. This not only saves the long-distance telephone charges between the two places, but also realizes the interconnection of computer systems.
DDN also provides multicast services, mainly including broadcast multicast services, two-way multicast services (polling) and video conferencing services. The characteristic of broadcast multicast service is that data information flow can be transmitted from one point to multiple points, so that multiple points can obtain the same information at the same time. Multicast service is suitable for information release (stock, news, weather forecast, etc.). Two-way multipoint service mainly means that a master station can communicate with a slave station in two directions at a time, and the master station visits a slave station regularly to exchange information with the slave station. Two-way multicast service is suitable for centralized monitoring, credit card verification, data service, reservation system and other fields. Video conference service is to use the multipoint bridging function of DDN to realize the coking of multipoint I, video and voice information. Each station of a video conference system can communicate with other stations as a master station, but there can only be one master station at a time. One of the characteristics of multipoint service is that one point can communicate with multiple points through only one interface, which saves user equipment and network resources and reduces investment. In addition, using the frame relay resource module and voice compression module on DDN network, we can also realize open frame relay service and compressed voice /G3 fax service.
(2) the history, present situation and development of China DDN
public data networks is a data network operated by the post and telecommunications departments and providing services to users nationwide. At the beginning of 199s, it was first developed in several cities. In 1994, CHINADDN first-class trunk network was established. At present, the first-class trunk network has reached all provincial capital cities, and all provinces, municipalities directly under the Central Government and autonomous regions are actively building and operating DDN networks. By the end of 1996, CHINADDN had covered 2,1 cities above the county level, and developed areas had covered towns and villages, with a total of 18, ports. In the near future, it can provide users with nationwide virtual private network (VPN) services.
CHINADDN is divided into three levels: primary trunk network, secondary trunk network and local network according to the geographical area of responsibility for network construction, operation, management and maintenance. The primary trunk network consists of nodes located in provinces, autonomous regions and municipalities directly under the Central Government, which mainly provides inter-provincial long-distance DDN service transfer, and has reached all provincial capital cities except Taiwan Province. The secondary trunk network is composed of nodes located in the province, which provides DDN services for long-distance calls in and out of the province. Intranets have been built in all provinces except Tibet. Local network refers to the network within the city, which mainly provides local and long-distance DDN services for users.
at present, CHINDDN has become the support network of other networks in the post and telecommunications department. A large number of trunk lines of CHINDDN, CHINAFAX and CHINANET are all on CHINADDN. CHINADDN, as a transmission plane of the first phase project of Telephone No.7 signaling network, will play an important role in the construction of telephone network. CHINADDN is also selected as the transmission channel for the DCN project linking the Ministry network management center with the provincial network management centers. Mobile phone signaling roaming and multimedia networks all rely on CHIANDDN to transmit information. The China Financial Data Network established by the Ministry of Posts and Telecommunications and People's Bank of China is a huge frame relay network, all of which use CHIANDDN as the data transmission channel. CHINADDN is increasingly becoming an important support for various telecom services.
In addition, all walks of life have rented CHINADDN special lines to carry out their own business. Specialized banks, securities companies and educational and scientific research departments are all users of CHINADDN.
(3) User access method of CHINADDN
At present, the media connecting users and DDN service providers (telecommunications bureaus) are mainly telephone copper wires, so that users access China DDN mainly by using MODEM, voice multiplexing equipment and 2B+D line terminal equipment, which are connected by telephone copper wires. With the user's demand for high speed, HDSL equipment will also be applied in the network.
China Public Frame Relay Network (ChinaFRN)
China Public Frame Relay Broadband Service Backbone Network (CHINAFRN) is the first broadband data communication network that will provide services to the public in China. Its completion and commissioning will definitely have a positive impact on China's national economic informationization and will become an important part of China's information superhighway.
CHINAFRN mainly provides medium and high-speed data communication services above 64K. Business types can be bursty or real-time.
CHINAFRN can also provide high-speed relay transmission for other data communication networks, which can enhance the performance of each network and improve the line efficiency.
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