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LBSC 690 Session 3 Networking
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Analog to Digital We live in an analog world: Sound, temperature, light, etc. Sensory inputs. Are continuous signals. Can assume all (essentially infinite) values in a given interval. Basis for analog computers: Uses electrical voltage/current to variables. to represent.
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Digital Discrete representation: assumes a finite number of values in a given interval. Basis for digital computers: Use 2 discrete values to represent data, & instructions. (Binary system). Analog signals converted to digital by Pulse Code Modulation (PCM).
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PCM Three step process: Analog signal is sampled: Nyquist’s Theorem. Samples are quantized. Quantized samples are encoded into binary digits, called “bits” for short. See handout.
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Evolution Computers initially stand alone. Need to communicate. Transmit data at a distance. Communications: Data communication. Telecommunication: Provides electrical communications at a distance. Service provided by a number of companies internationally. The “telecommunications industry.”
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Telecommunications Industry Carriers: LECs (RBOCs: 7 to 4); CLECs. IXCs. Internet Service Providers (ISPs). Vendors/Consultants & Manufacturers. Judicial/Political/Legislative: Regulatory agencies. Standards Making Organizations. Customers: business & residential. Technology and research.
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Networking Simplest form: Directly connect two communicating devices. Not practical solution. Problem of topology: How to deal with fully connected mesh. Need network. Nodes and segments.
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The Universal Seven Part Data Model DTE DCE DTE DTE: Data Terminal Equipment DCE: Data Communication Equipment DTE/DCE Interface Transmission Channel DCE/DTE Interface
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Network (Cont’d.) NETWORK N N N N S S S S S: Network Station N: Network Node “Local loop”
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Network Types Switched Communication Network: Circuit-switched. Packet–-switched. Broadcast communication Network: Packet radio network. Satellite network. Local area network.
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Generic Switching Network Reference handout.
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Concepts: Bandwidth Measure of channel capacity: frequency range Radio Spectrum (Next Slide) Frequencies available for telecommunications Modulation Process of embedding intelligence in a carrier wave Multiplexing Process that combines multiple calls or messages on a single channel Examples; TDMA (Time Division Multiple Access), CDMA (Code Division Multiple Access)
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Spectrum A limited resource Government controlled: FCC & ITU, e.g. Some assigned frequencies: Am radio: 535-1635 KHz Analog cordless phones: 44-49 MHz TV channels 2-6: 54-88 MHz FM radio: 88-108 MHz TV channels 7-13: 174-216 MHz Cellular phones: 806-890 MHz PCS: 900-929 MHz Satellite TV (small dish): 11.7-12.7 GHz
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Cell Phones More than 115 million users in US 46,000 people subscribing every day Based on concept of cells 10 sq. mi. in area with a Base Station in it Low power: 0.3 & 6 watts Mobile Telephone Switching Office (MTSO). Special codes: electronic serial no. (ESN), mobile identif. no.(MIN, system ident, code (SID). Analog vs. digital. American vs. European approaches GSM (Global System For Mobile communication) TDMA vs. CDMA
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LANs What are they? Need & functions. Hardware/software components. Concept of packets. Ethernet and token ring. ANSI/ IEEE 802.3 (ISO 8802-3) Need to interconnect LANs.
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LANs Data communication facilities designed to provide high-speed switched connections between processors peripherals and terminals within a local area, e.g., buildings or a campus.
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LAN Functions File sharing Printer sharing CD ROM sharing On-line databases Groupware OPAC access Dial in & out Fax in & out Voice-video-multi- media E-mail Internet access
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LAN Benefits Shared access Increased security Application and data highway Adding new applications is done once (on server) Support services more effective and lower cost
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LAN Installation Network Operating System (NOS). Network Interface Cards (NIC). Cabling and connectors. Hubs/ Switches. Network Servers: File, Print, Communication, etc. Clients
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TRAINING Network Management: Network Administrator & Support Personnel. Certification. Continuing education. User training.
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Ethernet Developed in 1973 at Xerox Corporation’s Palo Alto Research Center (PARC). Developed by Bob Metcalfe. Uses the Ethernet Protocol. Protocol: A code prescribing strict adherence to correct etiquette and precedence. Communication protocols: symbols (Character set), rules for sequence and timing of messages, and procedures for error detection and handling. Messages broken into frames (packets). With source and destination addresses.
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Ethernet Broadcast network Carrier Sense Multiple Access/Collision Detection (CSMA/CD) Collision retry (random wait) Need for repeaters Hubs Basic, Smart, Intelligent, Switches Bridges Routers (internetting)
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Network Topology Bus Star Ring Mesh Hybrid
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Transmission Channels (Media) 4-wire phone 3Kbps 200 ft. UTP100Mbps100 ft. STP 16Mbps100 ft. Coax 10Mbps500 ft. Fiber optic 10Gbps2-5 km.
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The Internet Historical development. TCP/IP Protocol Suite. Transmission Control Protocol/Internet Protocol Telnet. FTP. E-mail. Assignment 1: Two exercises. Packet switching. IP Addressing
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Packet Switched Networks General Switching Diagram: Reference Handout
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What is my IP Address? Go to “Start” menu Click on “Run” In window type WINIPCFG When gray window appears, lick on “More Info”
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Tracing a Message Click on MS-DOS prompt At the C:\WINDOWS> prompt type: tracert www.loc.gov
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Modems Function: Modulation – demodulation. Types and speeds: Standard ISDN. Cable TV. xDSL. Satellite
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World Wide Web (WWW) Historical development. HTTP. HTML. Multimedia.
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Trends Convergence. Voice over IP (VIP). Wireless. 3G (Third Generation) PCS (Personal Communication Services) Ubiquitous networking Remote device control.
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