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LBSC 690

LBSC 690. Session 3 Networking. 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:

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LBSC 690

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  1. LBSC 690 Session 3 Networking

  2. 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.

  3. 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).

  4. 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.

  5. 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.”

  6. 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.

  7. 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.

  8. The Universal Seven Part Data Model DTE DTE DCE DCE DTE/DCE Interface DCE/DTE Interface Transmission Channel DTE: Data Terminal Equipment DCE: Data Communication Equipment

  9. Network (Cont’d.) S N NETWORK “Local loop” N S N S S: Network Station N N: Network Node S

  10. Network Types • Switched Communication Network: • Circuit-switched. • Packet–-switched. • Broadcast communication Network: • Packet radio network. • Satellite network. • Local area network.

  11. Generic Switching Network • Reference handout.

  12. 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)

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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 LAN Functions

  18. 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

  19. LAN Installation • Network Operating System (NOS). • Network Interface Cards (NIC). • Cabling and connectors. • Hubs/ Switches. • Network Servers: • File, Print, Communication, etc. • Clients

  20. TRAINING • Network Management: • Network Administrator & Support Personnel. • Certification. • Continuing education. • User training.

  21. 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.

  22. 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)

  23. Network Topology • Bus • Star • Ring • Mesh • Hybrid

  24. Transmission Channels (Media) • 4-wire phone 3Kbps 200 ft. • UTP 100Mbps 100 ft. • STP 16Mbps 100 ft. • Coax 10Mbps 500 ft. • Fiber optic 10Gbps 2-5 km.

  25. The Internet • Historical development. • TCP/IP Protocol Suite. • Telnet. • FTP. • E-mail. • Assignment 1: • Two exercises. • Packet switching. • Addressing: URLs.

  26. Packet Switched Networks • General Switching Diagram: • Reference Handout

  27. Modems • Function: • Modulation – demodulation. • Types and speeds: • Standard • ISDN. • Cable TV. • xDSL. • Satellite

  28. World Wide Web (WWW) • Historical development. • HTTP. • HTML. • XML. • Multimedia.

  29. Trends • Convergence. • Voice over IP (VIP). • Wireless. • 3G (Third Generation) • PCS (Personal Communication Services) • Ubiquitous networking • Remote device control.

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