What is a telecommunication network

Telecommunication network refers to the construction and management of the former Ministry of Telecommunications network, such as the traditional telephone exchange network (PSTN), digital data Network (DDN), Frame Relay Network (FR), ATM network.

In the PSTN network, some of the main communications backbone has been achieved optical fiber, while the user network is mostly copper wire, Generally used only for transmission of 4kHZ analog voice signal or 9.6kbit/s offset data, even with the modem, the highest can only transmit 34kbit/s data signals, but the PSTN network coverage is very wide, connecting the country's cities and towns. It is a low speed, analog, large scale network. The largest asset of this network is the copper access network, but its value and daily decline in the adaptation of broadband multimedia services.

In the DDN network, DDN can provide a fixed or semi-permanent connection of the telephone switching service rate of NX64KBIT/S, its transmission channel to the user data is completely transparent, it can easily through the network Management center to complete the establishment of a multiple-point connection. DDN is suitable for the transmission of real-time multimedia communications services.

In the FR net, it is based on the statistic multiplexing technology and carries on the packet transmission, the packet exchange, the rate is generally in the 64kbit/s-2.048mbit/s, it may make the multiple connection multiplexing the same letter to realize the resource sharing Frame Relay network suitable for the transmission Non-real time Multimedia communication Service.

In ATM networks, ATM is a support for high-speed data network construction, to run the critical equipment, ATM uses a short, fixed-length (53-byte) packet as a unit for transmitting information, 53 bytes with 48 bytes of information load, and 5 bytes used to identify control and error-correcting information such as virtual circuits and virtual channels. ATM supports 25MBIT/S-24GBID/S rate transmission, and the network composed of ATM can not only transmit voice but also transmit data and images, including high-speed data and active images. People used to want to use ATM networks to be compatible or replace traditional telephone networks, but they ended in failure.

At present, in addition to the above several networks, there are X.25 nets, ISDN nets, chinaet nets and so on.