composition structure
ChinaNet is China's largest Internet service provider. ChinaNet is a part of the Internet in China. It adopts the TCP/IP protocol structure and is connected to the international Internet through a high-speed digital dedicated line.
ChinaNet is a veritable backbone network of the domestic computer Internet. The topological structure of ChinaNet backbone network is divided into core layer and regional layer. The core layer is composed of core nodes in 8 cities: Beijing, Shanghai, Guangzhou, Shenyang, Nanjing, Wuhan, Chengdu and Xi'an, and provides interconnection with the international Internet and information exchange channels between regions. Each of the three core nodes in Beijing, Shanghai and Guangzhou has two international export routers connected to the Internet.
ChinaNet has now opened international export circuits to the United States, European countries, and Asian countries. ChinaNet provides all services on the Internet. Among them, E-Mail and WWW browsing are widely used by users. ChinaNet provides Telnet, FTP, FINGER, USENET, TALK, CHAT and other services.
ChinaNet is based on modern China Telecom. All cities with access to telecommunication networks (China Public Digital Data Network, China Public Switched Data Network, China Public Frame Relay Broadband Service Network and Telephone Network) can pass ChinaNet connects to the Internet and enjoys Internet services. ChinaNet's services include: Internet access services, apply for IP addresses and domain names on behalf of users, rent routers and supporting transmission equipment, provide domain name backup services, technical services and application training.
Network structure
ChinaNet's network structure is divided into backbone layer and access layer.
1. Backbone layer
The backbone layer of ChinaNet is composed of backbone layer nodes and communication lines. The basic requirements for the backbone layer are: provide connection with international and domestic Internet; provide ChinaNet's high-speed bone thousand data channel; provide connections between ChinaNet's various access networks; ensure high reliability, high speed, and low latency requirements; Depending on business needs, it can directly provide connections to large user networks.
The basic principle of connection between backbone layer nodes is: there are at least 3 reachable routes between any pair of backbone layer nodes; depending on business needs, the density of connections between backbone layer nodes can be reasonably adjusted until Full mesh connection; the connection between the backbone layer nodes uses high-speed, high-quality communication lines as far as possible, and the transmission rate is determined by business needs; multiple backup communication lines can be set between any pair of backbone layer nodes.
2. Access layer
The basic requirements for the connection between the nodes in the human network and the connection with the backbone layer are: in principle, any node in an access network at least Connect to at least two other nodes in the network through two direct routes; at least two nodes in an access network are connected to at least two nodes in the underlying layer through direct routes;'connections with higher transmission quality should be used as much as possible For communication lines, the transmission rate depends on business needs; any connection can be appropriately configured with a backup communication line depending on business needs.
Network features
1. The network is safe and reliable. Any node of the ChinaNet network has more than two relay lines, and the main node equipment adopts dual backup equipment, so as to ensure that any network business will not be interrupted when some equipment or lines in the network fail. At the same time, in order to ensure the security of the network, ChinaNet adopts advanced security techniques to prevent various online attacks.
2. The network provides high-speed circuits to ensure the demand for opening up various services on the Internet. For example, services such as multimedia and video conferencing.
3. ChinaNet has achieved nationwide user roaming and has become a leader in this technical field. In order to fully reflect the characteristics of ChinaNet as a national public service data network, and to adapt to the requirements of dial-up users to access the network in different places, ChinaNet adopts the transparent roaming technology of national network users, so that ChinaNet users can use network resources through ChinaNet's local nodes in any province.
4. ChinaNet will provide users with a friendly Chinese interface, which is convenient for users to use various network resources, especially for users who are new to the Internet.
5. Rich online information. Since the opening of ChinaNet, various information sources have been online, and there are more and more Chinese information, such as news, tourism, economy, education, sports, etc., users can check all kinds of information online at any time. Now many users have inquired about stock information through ChinaNet and conducted online transactions.
6. High-quality service. The operation and maintenance of ChinaNet network adopts a 24-hour work system to solve network problems at any time. At the same time, ChinaNet also provides various technical support to solve various problems encountered by users on the Internet.
Provide services
1. E-mail
ChinaNet provides users with SMTP-compliant e-mail services through MAIL SERVER. Through e-mail, you can communicate with all users on the Internet. Users carry out E-MAIL communication; carry out E-MAL communication with users on public e-mail systems of various countries that have been connected to the Internet; query the E-MAIL information query server equipped on the Internet; join through the mailing list (MAILING LIST) Go to relevant announcements, discussions, debates, and get interested information.
2. USENET News
USENET is a worldwide electronic bulletin board for publishing announcements, news and various articles for everyone to use. Each forum of USENET is called a newsgroup. Just like a newspaper, every manuscript is regarded as an article. Everyone can read it, or not read articles that are not of interest to everyone. Everyone who has read the article can. Comment or answer or add new content based on your own point of view.
3. Telnet login TELNET
Tele login refers to the process in which the user's computer becomes a remote computer terminal through the Internet with the support of the network communication protocol. To log in on a remote computer, you must first become a legal user of the system and have a corresponding account and password. Once the login is successful, the user can use all the resources opened to the outside world by the remote computer in real time.
Many foreign university libraries provide TELNET external online search services. Some governments and research institutions also open their databases to the outside world, providing various menu-driven user interfaces and even full-text search interfaces for users Query through remote login. When performing remote login, the user should first give the communication domain name or IP address of the remote computer in the TELNET command, and then accept the inquiry from the other party's system, and type in their user name and password correctly. Sometimes, you have to answer the type of emulation terminal you are using. Some databases on the INTERNET provide open remote login services. To query this type of database, you do not need to obtain an account and password first, but use public users disclosed by the system.
4. File transfer-FTP
The file transfer service allows users on the Internet to transfer files from one computer to another. File transfer is similar to remote login, both are real-time online services. Log in to the other party’s computer when working. Unlike remote login, users can only perform file search-related operations after logging in, such as coup working directory, listing file directories, setting transmission parameters, and transferring files. Using FTP can transfer almost all types of files: text files, Binary executable files, image files, sound files, data compression files, etc. INTERNET also provides an "anonymous file transfer service" (Anonymous FTP). When users log in, they can use Anonymous as the user name and their own email address as the password, and then they can log in to the system for file transfer.
5, GOPHER
GOPHER is a menu-driven information query software, which organizes online information into an on-line menu system to facilitate users' browsing and interest It can automatically convert the user’s instructions into FTP or TELNET commands. Under the guidance of the menu, the user can access the remote online information system on the INTERNET in real time without knowing the address of the machine it is visiting.
6, WWW (World Wide Web)
WWW is-a hypertext-based information detection tool, which provides a friendly information query interface, WWW It seamlessly integrates the existing information resources (such as images, text, sound and video) on the Internet, and provides quick search under the graphical interface mode. The same graphical interface can also be used to connect with other servers on the Internet.
7, Archie
Archie can automatically and regularly query the INTERNETFTP server, and store the files in it in a single, searchable database, which is Archie The index of the file directory data in all the servers that can be found. As long as the user gives the file type and file name he wants to find, the Archie server will point out which FTP server stores such files. Many Arcbie servers also accept queries from users’ e-mails.
8. WAIS (Wide Area Information Server)
WAIS is called the database of the database, a general interface software for users to query various databases distributed on the Internet. As long as the user selects the desired database with the cursor in the database list and key in the query Guan Jianyu, the system can automatically perform a remote query to help read out all the records containing the query term in the corresponding database, and according to the query keyword in The frequency of occurrence in each record is scored, and the highest score is 1000 points. The user can further choose whether to read the recorded content of interest.
Network access method
1. Dial-up access
(1) Access to the network through the UNIX host on ChinaNet (TELNET)
Dial-up access fee Less, suitable for small business units or individuals. Dial-up users need to meet the following conditions: a PC, communication software, a MODEM and a telephone line, and apply for a network account at the local telecommunication bureau to use it. For each communication, first log in to the host on ChinaNet via telephone dial-up, run the IP software, and then enter the Internet through the software provided by the UNIX host. E-mail, TELNET, GOPHER and FTP services can be used to access the network in this way.
(2) Access to the network through the SLIP/PPP protocol
Through the SLIP/PPP, the telephone dialing method achieves exactly the same function as the dedicated line access to the network (only the communication rate is subject to certain restrictions). This method is suitable for users who have a small business but want to access the network as a host. The hardware required by users who access the network through SLIP/PPP is exactly the same as that of ordinary dial-up access, but the difference is that they need to be equipped with SLIP/PPP software. Through SLIP/PPP access to the network, users can enjoy all services on the Internet.
2. Access the network through the packet network
(1) Access the network through the UNIX host on ChinaNet
This method is suitable for all users on the packet network. The user only needs to apply for an INTERNET account and go through the relevant procedures to change from a group user to an INTERNET user. The INTERNET service that users who access the network in this way can use is exactly the same as that of ordinary dial-in users, but the communication cost has nothing to do with the communication distance.
(2) Access to the network by TCP/IP protocol through the packet network
This method is similar to the dedicated line access to the network, but the difference is that the transmission medium is the virtual circuit (SVC or PVC) of the packet network , Not a physical circuit. In addition to the authorized users of the packet network, the user also needs to be equipped with a router supporting the TCP/IP protocol and a host or network running IP software. At the same time, users also need to apply for IP addresses and domain names for their online devices. In this way, all terminals on the user network can be INTERNET users and can enjoy all INTERNET services.
Through the packet network and router to access the network, users can use one machine for multiple purposes, that is, users can communicate with users on the packet network at the same time in addition to the authorized users of the Internet. Access to the network through the packet network, the network access rate can be 1200~64000bps optional. This method is suitable for users who use e-mails and other users who do not have too much communication.
3. Access to the network through frame relay
The characteristics of frame relay are high communication efficiency and the ability to establish PVCs with multiple points at the same time, and the rental fee is lower than that of dedicated lines (for dedicated lines). 20%), suitable for interconnection between LANs. To access the network through frame relay, users need to apply for the frame relay circuit used when accessing the network, be equipped with a router that supports the TCP/IP protocol, and apply for IP addresses and domain names for online devices. By accessing the network through frame relay, the terminals on the user network can enjoy all the services of the Internet. The frame relay network access rate is optional from 9600bps-2048kbps, which is suitable for all users who require host or network access.
4. Access to the network through a dedicated line
The dedicated line access to the network has a high communication rate, which is suitable for network users with large business volume, but the network access cost is high, and the user needs to have a dedicated line and a router. After entering the network, all terminals and workstations on the Internet can enjoy all INTERNET services. The communication rate of the dedicated line network is 1200bps~2048kbps optional.
Access methods
In order to use the resources on the Internet, users have three basic access methods, namely dial-up, dedicated line and quasi-dedicated line.
1. Dialing method
The telephone dialing method is a simple INTERNET access method. It connects the user's computer and modem to the INTERNET host via a telephone line dial-up. The user's computer can be a PC, Macintosh, or Amiga. Once the connection is completed, the remote communication software will emulate this computer into a terminal, so that the user can communicate with the host computer on the Internet. The dial-up method is more economical and can meet the needs of most users. The user's hardware equipment configuration is simple, just register an account in the "host" at the end of the lNTERNET service provider, and the user's computer can easily enter the host to obtain various network programs on the Internet. Dial-up connection can usually provide Email, Telnet, Gophet and FTP services. But when doing FTP, you need to do something. The download work from the host" to the personal computer.
2. Dedicated line
The user’s local area network or host is directly connected to the local INTERNET service provider’s network with a cable, and the user has his own Host name and address. This kind of connection is generally suitable for some large companies, scientific research institutions and other units. It is a complicated and expensive solution. When connecting, the user and the Internet service provider need to assemble and run the IP Software router. The user’s local area network provides a complete Internet connection for all personal computers and workstations on the local area network through this router. The connection rate of the dedicated line method is higher, and the user can use the computer or workstation to directly connect to the Internet to obtain various network programs For example, the user can run the user-friendly guidance software and graphical www search.
3. Quasi-dedicated line method
The quasi-dedicated line method still uses telephone lines and modems to connect to through dial-up. On the Internet. The difference is that the user’s computer is not used as a terminal. Both it and the host use a special computer program SLIP (Connected Internet Protocol) or PPP (Point-to-Point Protocol). The user’s machine can be considered as physical Internet Part of it, and has its own host name and address. This method is also called SLIP/PPP. This method is more suitable for users who do not have a dedicated line and want to obtain all the network functions and advantages of the Internet. This is a more economical solution. This method is suitable for small companies and families. Its hardware configuration is consistent with the dialing method, but SLIP/PPP software is required to make the standard telephone line present the characteristics of a dedicated line. This method allows users to obtain various network functions, such as www Graphic retrieval. In addition, when doing FTP, the file can be downloaded directly to the user’s personal computer.