Lecture-3 ISO Model, Network Security, and Protocols

Twisted pair twisted pair cabling is extremely thin

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Unformatted text preview: compared to coaxial cable. It is made up of four pairs of wires that are twisted around each other and then sheathed in a insulator. If there is a metal foil wrapper around the wires underneath the external sheath, the wire is known as shielded twisted-pair (STP). Lecture-3 38 Communications and Network Security …cont. The twisting of the wires provides protection from external radio frequencies and electric and magnetic interference and reduces crosstalk between pairs. Crosstalk occurs when data transmitted over one set of wires is picked up by another set of wires due to radiating electromagnetic fields produced by the electrical current. Each wire pair within the cable is twisted at a different rate (i.e., twists per inch); thus, the signals traveling over one pair of wires cannot cross over onto another pair of wires. The tighter the twist (the more twists per inch), the more the cable is to internal and external interference and crosstalk and thus the capacity for throughput (that is, higher bandwidth) is greater. Lecture-3 39 Communications and Network Security …cont. Lecture-3 40 Communications and Network Security …cont. The following problems are the most common with twisted-pair cabling: Using the wrong category of twistedpair cable for high-throughput networking Deploying a twisted-pair cable longer than its maximum recommended length (i.e., 100 m). Using UTP in environments with significant interference Lecture-3 41 Communications and Network Security …cont. Conductors The distance limitations of conductorbased network cabling is due to the resistance of the metal used as a conductor. Copper, the most popular conductor, is one of the best and least expensive room-temperature conductors available. It is resistant to the flow of electrons. This resistance results in a degradation Lecture-3 42 of signal strength and quality over the Communications and Network Security …cont. Conductors The maximum length defined for each cable type indicates the point at which the level of degradation could begin to interfere with the efficient transmission of data. Lecture-3 43 Communications and Network Security …cont. Wireless Wir...
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This note was uploaded on 01/21/2014 for the course IT 205 taught by Professor Kurts during the Winter '08 term at University of Phoenix.

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