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Spring 2000 CS 461 Outline Nodes Links (ch2.1) Encoding (ch2.2) Framing (ch2.3) Error Detection (ch2.4) Reliable Transmission (ch2.5) MAC (ch2.6-8) Nodes Links Nodes PC, Routers, Swiches Links Conducted Media Twisted Pair Coaxial Cable Optical Fiber (Table 2.1) Wireless Media Characteristics and quality determined by medium( immunity to interference, bit rate, distance, frequency, signal etc.) For guided, the medium is more important For unguided, the bandwidth produced by the antenna is more important Key concerns are data rate, distance and cost Twisted Pair - Applications Most common medium Telephone network Between house and local exchange (subscriber loop) Within buildings To private branch exchange (PBX) For local area networks (LAN) 10Mbps or 100Mbps Twisted Pair - Pros and Cons Cheap Easy to work with Low data rate Short range Twisted Pair - Transmission Characteristics Analog Amplifiers every 5km to 6km Digital Use either analog or digital signals repeater every 2km or 3km Limited distance Limited bandwidth (1M) Limited data rate (100M) Susceptible to interference and noise Unshielded and Shielded TP Unshielded Twisted Pair (UTP) Ordinary telephone wire Cheapest Easiest to install Suffers from external EM interference Shielded Twisted Pair (STP) Metal braid or sheathing that reduces interference More expensive Harder to handle (thick, heavy) Coaxial Cable Coaxial Cable Applications Most versatile medium Television distribution Cable TV Long distance telephone transmission Can carry 10,000 voice calls simultaneously Being replaced by fiber optic/UTP Short distance computer systems links Local area networks Coaxial Cable - Transmission Characteristics Analog Amplifiers every few km, closer if higher frequency Up to 500MHz Digital Repeater every 1km, closer for higher data rates Coaxial Cable Baseband coaxial technology uses digital signaling in which the cable carries only one channel of digital data Broadband coaxial technology transmits analog