Difference between Digital Circuit, DDN, Frame Relay, Fiber?

Frame Relay (Frame Relay) is a standard for interfacing networks with Data Terminal Equipment (DTE). Because the fiber optic network than the early telephone network bit error rate is much lower, therefore, can reduce some of the X.25 error control process, which can reduce the processing time of the node, improve the throughput of the network. Frame Relay was created in this environment. Frame Relay provides the data link layer and physical layer protocol specification, any high-level protocols are independent of the frame relay protocol, therefore, greatly simplifies the implementation of frame relay. At present, one of the main applications of Frame Relay is LAN interconnection, especially in the LAN through the WAN interconnection, the use of Frame Relay can better reflect its low network delay, low equipment costs, high bandwidth utilization and other advantages.

The main characteristics of frame relay are: the use of optical fiber as a transmission medium, so the bit error rate is very low, can achieve approximate error-free transmission, reducing the error checking overhead, improve network throughput; frame relay is a broadband packet switching, the use of multiplexing technology, its transmission rate can be as high as 44.6Mbps. However, frame relay is not suitable for transmitting real-time information, such as voice, television, it is limited to the transmission of information. However, frame relay is not suitable for transmitting real-time information such as voice, television, etc. It is limited to transmitting data

Digital Data Network (DDN), DDN is digital data network. It is the use of optical fiber (digital microwave and satellite) digital transmission channels and digital cross-multiplexing nodes composed of digital data transmission network, which can provide users with a variety of rates of high-quality digital private circuits and other new services in order to meet the user's multimedia communications and the formation of medium and high-speed computer communication network needs. DDN service is different from the traditional analog telephone line is the distinguishing feature of the digital circuit is the high quality of transmission, low delay, communication rate can be selected according to need. Small, the communication rate can be selected according to need; circuit can be automatically roundabout, high reliability; a line can be used for multiple purposes, namely, can talk, fax, transmit data, but also can set up a conference TV system, open frame in the continuation of the business, do multimedia services, or to set up their own virtual network, the establishment of network management centers, their own management of their own network.

Digital circuits are based on binary digital logic, in which the operating signals are discrete digital signals. The electronics in the circuit, such as diodes, triodes (BJTs), and field effect tubes (FETs) are in a switching state, sometimes on and sometimes off.

Optical fiber is shorthand for optical fiber, a light-conducting tool reached by using the principle of total reflection of light in fibers made of glass or plastic. Optical fibers were invented by Charles Kao, former president of the Chinese University of Hong Kong. The microscopic fiber is encapsulated in a plastic sheath that allows it to be bent without breaking. Typically, a transmitting device at one end of the fiber uses a light emitting diode (light emitting diode, LED) or a beam of laser light to transmit light pulses into the fiber, and a receiving device at the other end of the fiber detects the pulses using a photosensitive element. In everyday life, optical fibers are used to transmit information over long distances because the conduction loss of light in optical fibers is much lower than the loss of electricity in electrical wires. As the price of optical fibers is decreasing day by day, optical fibers are also being used for medical and recreational purposes.