(1) Normal dialing mode
(a) Dialing up the Internet in this way requires a device: a modem.
It's the abbreviation of English modem. Chinese is commonly known as "cat". Because the ordinary telephone network transmits analog signals, while the computer processes digital signals. If the process of converting digital signals into analog signals is called modulation, then the opposite process is demodulation. Modems play this role. There are two types: built-in and external. The built-in modem is a card inserted into the computer motherboard; Many brands of computers are pre-installed with built-in modems. If it is added later, many people will choose an external modem. Pre-installed built-in modems usually have drivers installed. Just connect the telephone line connector (commonly known as crystal head, because it is white and transparent) to the interface provided by the modem behind the main chassis. The external modem is to plug the telephone line into the modem, and the accessory comes with the connecting cable between the modem and the computer. One end of the connecting cable is connected to the modem, and the other end is connected to the serial interface on the computer host. You can refer to the instruction manual of the accessories. As for installing drivers, MODEM are all so-called PnP devices (plug and play), and windows will automatically detect the installation. In short, you don't need any professional knowledge, and novices can do it.
(2) Single-wire communication (ISDN)
ISDN (Integrated Services Digital Network), whose Chinese name is Integrated Services Digital Network, is commonly known as "One Line Communication" by China Telecom. It is a new way of communication that rose in the international arena in the late 1980s. Only one telephone can be connected to the same pair of ordinary telephone lines, so the original dial-up internet access means that you can't make a phone call at this time. After applying for ISDN, you can use several terminals at the same time through a conversion box called NT. You can surf the Internet while making phone calls or communicating with other data. Although it is still an ordinary telephone line, NT's converter box provides users with two standard 64KB/S digital channels, namely the so-called 2B+D interface. The TA port is connected to the telephone, and the NT port is connected to the computer. The maximum transmission rate it allows is 128KB/S, which is three to four times that of ordinary MODEM. Therefore, its popularity is, in a sense, a major innovation in the traditional concept of communication. Installation and communication costs are similar to ordinary telephones. It has only been opened in major cities in China in the past year or two. You can also apply at the business outlets of the Telecommunications Bureau. Of course, this has become the first way to dial up the Internet at present.
3.ADSL:
ADSL is the abbreviation of English Asymmetric Digital Subscriber Loop. ADSL technology is a new high-speed broadband technology running on the original ordinary telephone line. It uses a pair of existing telephone copper wires to provide users with asymmetric uplink and downlink transmission rates (bandwidth).
The asymmetry is mainly reflected in the asymmetry between the uplink rate (up to 640Kbps) and the downlink rate (up to 8Mdps). Uplink (from user to network) is a low-speed transmission, which can reach 640Kbps；; Downlink (from network to user) is high-speed transmission, which can reach 8Mbps. At first, it was mainly developed for video-on-demand services. With the development of technology, it has gradually become a more convenient broadband access technology, which has attracted the attention of telecom departments. Through the IPTV set-top box, many network applications that could not be realized at low rate before can be realized.
4.DSL:
DSL (Digital Subscriber Line Digital Subscriber Loop) technology is a broadband access technology based on ordinary telephone lines. It transmits data and voice signals on the same copper wire, and the data signals do not pass through the telephone exchange equipment, thus reducing the load of the telephone exchange. And you don't have to dial, always online. It's a private internet mode. DSL includes ADSL, RADSL, HDSL, VDSL, etc.
5.VDSL:
VDSL (Very High Bit Rate Digital Subscriber Loop) is a high-speed digital subscriber loop. Simply put, VDSL is a fast version of ADSL. Using VDSL, the maximum download rate can reach 55Mbps in a short distance, and the upload rate can reach 19.2Mbps, or even higher.
6. Optical fiber access network:
Optical fiber access network (OAN) is an access network using optical fiber transmission technology, that is, a communication system in which local exchange offices and users use optical fiber transmission in whole or in part. Optical fiber has the advantages of broadband, long-distance transmission ability, good confidentiality and strong anti-interference ability, and is the main implementation technology of future access networks. FTTH mode refers to the direct access of optical fiber to users' homes, generally only one or two subscriber lines are needed, which is not economical in the short term, but it is the long-term development direction and the ultimate access network solution.
7.FTTX+ LAN access mode:
This is a scheme to realize broadband access by using optical fiber and five kinds of network cables, and realize gigabit optical fiber to the central exchange of the community (building). The central switch and the corridor switch are connected by 100-megabit optical fiber or five-class network cables, and the corridor adopts integrated wiring, so that the internet access rate of users can reach 10Mbps, and the network scalability is strong and the investment scale is small. In addition, there are various access modes such as fiber to the office, fiber to the home, and fiber to the desktop to meet the needs of different users. FTTX+LAN adopts star network topology, and users * * * enjoy bandwidth.
8.ISDN:
ISDN integrated services digital network is a digital telephone network composed of digital transmission and digital exchange, which is abbreviated as ISDN in English. It can realize users' digital signal access to the network and provide end-to-end digital connection, so that the same network can carry all kinds of voice and non-voice services. ISDN basic rate interface includes two 64 KB channels that can work independently and one 16Kb D channel. Selecting ISDN 2B+D port and a B-channel to access the Internet can reach 64Kb/s, which is 2.2 times faster than ordinary telephone dialing (if the transmission rate of Modem is 28.8Kb/s). If two B channels are used together by software, the communication rate can reach128kb/s/s. ..