CHAPTER 8

CHAPTER 8

The upper OSI layer protocols such as the Data Link Layer, Network, Transport, Session, Presentation, and Application Layer they prepare data from the human network for transmission to its destination while the physical layer controls how data is placed on the communication media.

The role of OSI physical layer is to encode binary digits that present to Data Link layer frames into signals and to transmit and receive these signals across the physical media such as wireless, copper wire and optical fiber that connect network device.

There are three basic type of network media used for transmitting data such as copper cable, fiber and wireless. Each type of network media have different type of signals use, depending on the media type: in copper cable uses electrical pulses, fiber uses lights and wireless uses radio transmissions.

External Signaling Interference

Noise from the electrical motors, fluorescent lights radio waves and other devices that are sources of noise can actually distort and drop or can corrupt the data that is being carried by the copper media, that is why the UTP is designed for. The Untwisted Shielded Pair, its outer jacket is designed to protect the wire inside against noises and of course physical damage. The twist of the pair wire is to protect the signal from interference, when the two wire are place together in the same position or in a straight form the noise coming from outside will create the same and continuous interference they received equal impact of the noise and that is why the signal will drop and stop sending a data into the destination.

                While if the two wires are twisted together the noise that hits the wire is not stable that would cause the unwanted noise or unwanted signal to lose because not all the part of the wire that the noise penetrate since the wire is twisted and not in a straight direction and the data will be sent successfully to its destination.

                Color coding of the wire inside electrically isolates wires from each other and identifies each pair, the color of the wire is designed to identify what pair is to twist for. (e.g.) The color orange is twisted to white orange and the green is twisted to white green and soon.