Network Media Quiz (Transmission Media)

2.2 Network Media (Transmission Media) For data to be transmitted from one location to another, a physical pathway or medium must be used. These pathways are called transmissions media and can be either physical or wireless. The physical transmission use wire, cable, and other tangible materials; wireless transmission media send communications signals through the air or space. The physical transmission media are generally referred to as cable media (example, twisted pair wire, coaxial cable, and fiber optic cable). Wireless media include cellular radio, microwave transmission, satellite transmission, radio and infrared media. Modern networks primarily use three types of media to interconnect devices and to provide the pathway over which data can be transmitted. These media are: ◾ Copper cables ◾ Glass or plastic fibers (fiber optic cable) ◾ Wireless transmission Figure 2.2 Network media On metallic wires, the data is encoded into electrical impulses that match specific patterns. Fiber optic transmissions rely on pulses of light, within either infrared or visible light ranges or in wireless transmission, and patterns of electromagnetic waves depict the various bit values. Different types of network media have different features and benefits. All network media do not have the same characteristics and are appropriate for the same purpose. KEY CONCEPTS Signal is an electric or electromagnetic form of data that passes over transmission media. A wire is a long thin piece of metal that is used to fasten things or to carry electric 2 current. Categories of Network Media (Transmission Media) The transmission medium can be divided into two broad categories: wired or guided media and wireless or unguided media Classification of transmission media 2.2.1 Guided (Wired) Media Guided media are those that provide a conduit from one device to another. These include twisted-pair cable, coaxial cable and fiber-optic cable A signal traveling along any of these media is directed and contained by the physical limits of the medium. Twisted-pair and coaxial cables use metallic (copper) conductors that accept and transport signals in the form of electric current. Optical fiber is a cable that accepts and transports signals in the form of light. A) Twisted-pair Cable A twisted pair consists of two conductors (normally copper), each with its plastic insulation, twisted together Twisted-pair cable Fundamentally, twisted pairs are classified as unshielded twisted-pair (UTP) and shielded twisted-pair (STP). B) Unshielded Twisted-Pair (UTP) Unshielded twisted-pair (UTP) is the most common form of network cable. This 3 cable format is used for the Ethernet wiring standards which are managed by the Institute of Electrical and Electronics Engineers (IEEE). These wiring standards are referred by code 802.3 Parts of the UTP cable In modern networks, UTP cables are considered in different categories starting from cat1 to cat7 and so on. C) UTP Cable Connectors The most common UTP connector is RJ45. RJ stands for registered jack, implying that the connector follows a standard borrowed from the telephone industry UTP cables are wired according to different wiring conventions. The individual wires in the cable have to be connected in different orders to different sets of pins in the RJ45 connectors. Ethernet straight-through and Ethernet crossover are the main cable types that are obtained by using specific wiring conventions see Figure. Ethernet cable color coding a) cross-over b) Straight-through The straight-through is the most common type and is used to connect computers to hubs or switches (connect different network devices). Crossover Ethernet cable is more commonly used to connect a computer to a computer 4 (connect similar network devices) and may be a little harder to find since they are not used nearly as much as a straight-through Ethernet cable