The data link layer used the raw transmission facility and transforms it to an apparently error free facility tobe used inserting appropriate frame boundary, transmit the frames sequentially and process the acknowledgment sent back by the receiving computer. If a frame is completely destroyed by noise burst, it is the duty of data link layer to transmit it from the source machine data link layer also ensures that a fast sender be not allowed to…"The data link layer of network."
The physical layer is responsible for transmitting raw bits over the communication channel. This layer is to ensure how to send a 1 bit from the sending computer as 1 bit to the receiving computer, not as 0 bit. The physical layer also deals with the issue of how many bit per second will be transmitted, what level of voltage will be used to represent 1 and 0 whether transmission will be unidirectional or bidirectional,…"The Physical Layer of Network"
1 . To interchange data between two process running on two computers there must be some addressing technique for communication correctly. 2. The communication may be unidirectional or in both direction alternately one after another or bidirectional 3. Error control is also important issue because physical communication channels are not perfect, rather error pron. Now both communicating parties must agree on which error detecting and correcting code to use. The receiver should also let the…"Different Design Issues of Layer of Network Software"
Many different types of network protocols and standards are required to ensure that a computer can communicate with another computer located on the next desk or any location around the worlds. A network protocol is a set of rules that governs the communications between computers and other devices on a network. This rules include guidelines that regulate the characteristics of a network such as access method, allowed physical topologies, types of cabling, and speed of…"Protocols and Standards of communication"
Transmission modes mean the way in which a communication is achieved between two linked device. The device which sends data or information is called the sender and which receives the information is called the receiver. A channel can support either one way communication or two way communication at a time. Based on the way of communication link, transmission modes can be classified as : simplex, half duplex, and full duplex. Simplex :: A simplex connection…"DATA TRANSMISSION MODES OF COMMUNICATION"
The term synchronous is used to describe a data transfer method in which a continous stream of data signals is accompanied by timing signals to ensure that the transmitter and the receiver are synchronized with one another. These types of connections are used when large amount of data must be transferred very quickly from one location to the other. The speed of the synchronous connection is attained by transferring data in large blocks instead of…"SYNCHRONOUS TRANSMISSION COMMUNICATION"
Communication is called asynchronous if the transmitter and receiver do not need to synchronise before each transmission. A sender can wait arbitrarily long between transmission and receiver must be ready to receive data when it arrives most PC serial devices such as mouse, keyboards and modems are asynchronous. As the name implies, asynchronous communication is performed between two or more devices which operate on independent clocks. Thus there is no guarantee that when Point A…"ASYNCHRONOUS TRANSMISSION OF COMMUNICATION"
Serial transmission sends one bit at atime over a single transmission line. The cost of communication hardware is considerably reduced since only a single wire or channel is require for the serial bit transmission which also slows the speed of transmission. Telephone lines use serial transmission for digital data, thus modems are connected to the computer via a serial port. A serial port is a socket on a computer used to connect the serial interface…"SERIAL TRANSMISSION COMMUNICATION SYSTEM"
Parallel transmission communicates bits simultaneously over multiple lines typically the total consists of one or more bytes at a time. Parallel devices have a wider data bus then serial devices and can therefore transfer data in words of one or more bytes at a time. As a result, there is a speedup in parallel transmission bit rate over serial transmission bit rate. The timing for parallel transmission is provided by a constant clocking signal sent…"Parallel transmission communication system"
Digital transmission is the sending information over a physical communications media in the form of digital signals. Analog signals must therefore be digitized first before being transmitted. However, as digital information cannot be sent directly in the form of 1s and 0s, it must be encoded in the form of a signal with two states, for example:: 1. Two voltage levels with respect to earth 2. The difference in voltage between two wires 3. The…"Digital transmission system of network."