LECTURE#6 - CABLES Asma AlOsaimi

Copper Coaxial Cable - Thick or Thin Unshielded Twisted Pair - CAT 3,4,5,5e&6 Optical Fiber Multimode Singlemode Wireless (later) Short Range Medium Range (Line of Sight) Satellite CABLE TYPES 2

Connectors and Media Converters Connectors: pieces of hardware connecting wire to network device Every networking medium requires specific kind of connector Media converter: hardware enabling networks or segments running on different media to interconnect and exchange signals Type of transceiver Device that transmits and receives signals 3

Coaxial cable, called “coax” for short, was the foundation for Ethernet networks in the 1980s and remained a popular transmission medium for many years. High resistance to noise; expensive Coaxial cable RG-6: This is the cable that delivers broadband cable internet service and cable TV over long distances. RG-8: Also called “thicknet”, an obsolete Ethernet 10Base- 5 standard. You will never find this on a newer network. RG-58: Also called “thinnet”, a Ethernet 10Base-2, easier to handle and install and like thicknet is never installed on newer networks. RG-59: Is used for relatively short connections, for example, when distributing video signals from a central receiver to multiple monitors within a building. 4

Twisted-pair cable consists of color-coded pairs of insulated copper wires. Every two wires are twisted around each other to form pairs, and all the pairs are encased in a plastic sheath. The number of pairs in a cable varies, depending on the cable type. Modern networks typically use cables that contain four wire pairs, in which one pair is dedicated to sending data and another pair is dedicated to receiving data. Twisted-pair cabling is the most common form of cabling found on LAN’s today. All twisted pair cable falls into one of two categories: -STP (Shielded Twisted-Pair) -UTP (Unshielded Twisted-Pair) Twisted-Pair cable 5

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STP consists of twisted-wire pairs that are not only individually insulated, but also surrounded by a shielding made of a metallic substance such as foil. Shielding acts like a barrier to external electromagnetic forces, prevents noise, and contains the electrical energy of the signals inside. The effectiveness of STP depends on: -The level and type of environmental noise -The thickness of the shield material -The grounding mechanism -The symmetry and consistency of the shielding Shielded Twisted-Pair 7

UTP categories Category 1Voice only (Telephone) Category 2Data to 4 Mbps (Localtalk) Category 3Data to 10Mbps (Ethernet) Category 4Data to 20Mbps (Token ring) Category 5 Category 5e Data to 100Mbps (Fast Ethernet) Data to 1000Mbps (Gigabit Ethernet) Category 6 Data to 2500Mbps (Gigabit Ethernet) reduced attenuation and crosstalk 8

Comparing Twisted Pair and Coaxial Cable Twisted Pair -Cheaper -Only effective in short distances -Easily accommodates different topologies Coaxial Cable -Copper core is more expensive -Able to run cable further distances -Signal stays stronger over distance -Less noise interference 9

Comparing STP and UTP STP -Reduces noise UTP -Cheaper Both -Can transmit data at 10 Mbps, 100Mbps, 1Gbps, and 10Gbps -Use RJ-45 modular connectors -Have a maximum segment length of 100 meters -Connector: Both use RJ-45 and RJ-11 -Size and scalability: Max segment length for both is 100 m on 10BASE-T and 100BASE- T networkMaximum of 1024 nodes 10

Fiber-Optic Cable Contains glass or plastic fibers at core surrounded by layer of glass or plastic cladding Reflects light back to core 11 Figure 3-24: A fiber-optic cable

12 Figure Four types of fiber-optic connectors: (a) ST, (b) SC, (c) LC, and (d) MT-RJ

SMF (Single-mode Fiber) Narrow core through which laser-generated light travels over one path, reflecting very little Accommodates high bandwidths and long distances Expensive 13

MMF (Multimode Fiber) Benefits over copper cabling: Nearly unlimited throughput Very high resistance to noise Excellent security Ability to carry signals for much longer distances before requiring repeaters than copper cable Industry standard for high-speed networking 14

MMF (continued) Throughput: transmission rates exceed 10 Gigabits per second Cost: most expensive transmission medium Connector: 10 different types of connectors Typically use ST or SC connectors Noise immunity: unaffected by EMI Size and scalability: segment lengths vary from 150 to 40,000 meters Optical loss: degradation of light signal after it travels a certain distance away from its source 15

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