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  • 1. Networking: Computer Connections CIS 105 2005
  • 2. Objectives
    • Describe the basic components of a network
    • Explain the methods of data transmission, including types of signals, modulation, and choices among transmission nodes
    • Differentiate among the various kinds of communications links and explain the need for protocols
    • Describe various network configurations
    • List the components, types, and protocols of a local area network
    • Describe the complexity of networking
    • Describe some examples of networking
  • 3. Data Communications Systems
    • Definition: Computer systems that transmit data over communications lines such as telephone lines or cables
    • Network is a computer system that uses communications equipment to connect two or more computers and their resources
  • 4. Networks: Why Use Them?
    • Networking Benefits in a Nutshell
        • Reducing Hardware Costs
        • Enabling Shared Applications
        • Building Massive Information Resources
        • Connecting People
  • 5. Data Communications/ Telecommunications Model
    • Basic Components
      • Sending device
      • Communications link
      • Receiving device
    Initiates instruction Converts data Signal path Converts data Receives Instruction
  • 6. Digital and Analog Transmission
    • Digital transmission
      • Sends data as distinct pulses, either on or off
      • Similar to how data travels through computer
    • Analog transmission
      • Continuous electrical signal in the form of a wave (carrier wave)
      • Many communications media already in place for analog (voice) transmission – (Phone lines are most common)
      • Digital signal from computer must be converted to analog form to be transmitted over analog lines
    • Modem
      • Converts digital signal to analog and vice versa
  • 7. Data Transmission
    • Modems
    • ISDN – integrated services digital network (digital transmission)
    • DSL (digital subscriber line)
      • analog, but uses larger range of frequencies (faster)
      • live connection – no dial-up
      • Varieties: ADSL, RADSL, others
    • Cable Modems (coaxial cable – same as TV cable)
    • Cellular Modem (uses cellular system to transfer data)
    • Network Interface Card (NIC)
      • aka LAN Adapter
      • Attachment point for specific type of cables
  • 8.
    • Signal Type
      • Analog (continuous)
      • Digital (individual electrical pulses)
    • Broadband vs. Baseband
    Transmission Characteristics
    • Direction:
      • Simplex
        • (security/fire alarms)
      • Half-Duplex
        • (CB/fax/atm)
      • Full-Duplex
        • (intensive computing required)
    • Transmission Modes
      • Asynchronous
      • Synchronous
    • Transfer Rates
      • BPS (Bits per second)
      • Bandwidth
        • Analog (Hz) hertz
        • Digital BPS
    Click Here to View Bandwidth Demo
  • 9. Transmission Media:
    • Twisted Pair Cable
      • Shielded (STP)
      • Unshielded (UTP)
    • Coaxial Cable
      • Copper + 3 layers insulation
    • Fiber Optic Cable
      • Glass/plastic – uses light to transmit
        • Faster; more signals
        • Less interference
        • Security
        • Smaller size
    • WAP (Wireless Application Protocol)
    • Broadcast Radio
    • Bluetooth
      • Radio frequency
      • Transceiver chip
    • Cellular Radio
    • Microwaves (line of site)
    • Communications Satellite
    • Infrared
    Wireless Physical
  • 10. Setting Standards
    • Protocol - a set of rules for the exchange of data between a terminal and a computer or two computers
      • Agreement on how data is to be sent and receipt acknowledged
      • Needed to allow computers from different vendors to communicate
      • Transmission Control Protocol/Internet Protocol (TCP/IP)
        • Permits any computer to communicate with the Internet
        • Uses packet switching
  • 11. Packet Switching
  • 12. Local Area Network (LAN)
    • A collection of computers that share hardware, software, and data
      • Typically personal computers
      • Typically within an office or building
    • LAN Hardware
      • Network cable
      • Network interface card (NIC)
      • Router
      • Gateway
  • 13. Network Topology
    • The physical layout of a network
    • Node - each computer, printer, or server on network
    • Three common topologies
      • Star
      • Ring
      • Bus
    Ring Network Star Network Bus Network
  • 14. Wide Area Network (WAN)
    • Can span the world or link computers across town
    • Components
      • Communications services
      • WAN hardware
      • WAN software
  • 15. WAN Communication
      • Provided by common carriers
        • Companies licensed by FCC to provide these services
      • Switched
        • Also called a dial-up connection
        • Most common is public telephone system
      • Dedicated
        • Provides permanent connection between two or more locations
          • Companies can build their own (microwave, fiber, etc.)
          • Can also lease circuits from common carrier (leased lines)
            • T1 and T3 high-capacity digital lines
            • DSL or ISDN lines
  • 16. WAN Hardware
    • Normally controlled by one or more host processors (typically mainframe computers)
    • Host connectors connect to WAN through front-end processor
      • Relieves host computer of some communications tasks, freeing it for processing
    • Multiplexer combines data from several slow-speed devices into a single data stream for transmission
  • 17. WAN Software
    • Terminal emulation software
      • allows PC to emulate mainframe terminal
    • File transfer (FTP) software
      • Allows users to upload/download files
      • Download - to retrieve a file from another computer
      • Upload - to send a file to another computer
  • 18. Connecting Networks Multiplexer combines data streams into a single data stream for transmission MUX Wireless access point connects to a wired network and provides wireless transmit/receive over radius of several hundred feet Base Station Connects multiple networks (including those w/different protocols). Can redirect traffic to another route if needed. Router Wide Area Network. Covers large geographical area WAN Local Area Network. Connects computers in limited geo area LAN Collections of computers/devices connects that allows users to share data, information, and hardware, software Network used in place of router when networks use the Internet protocol IP switch Hardware/software combo connecting networks that use different protocols Gateway Connects 2 LANS using same protocol Bridge Accepts signal, amplifies it, retransmits Repeater aka concentrator or MAU (multistation access unit): central point for cables in a network. Hub
  • 19. Client/Server Network
    • Server computer controls network
      • Often has several hard drives, fastest printer
    • Client computer requests services from server
      • Thin client has little or no storage
    • Processing approaches
      • Client/server
      • File server
  • 20.
    • Client/Server
      • Client requests data from server
      • Server passes only the requested data
    • File Server
      • Client requests data from server
      • Server sends entire file
        • Client performs all data entry and processing
        • File retransmitted to server
  • 21. Peer-to-Peer Networks
    • All computers have equal status
    • Users share each other’s files, printers, etc. as needed
    • Common in small offices
    • Networks tend to be slow
  • 22. Communications Protocol
    • Ethernet (IBM 1976)
    • Token Ring (access through password)
    • TCP/IP
      • (Transmission control protocol/Internet protocol)
      • Break into packets
    • Intranet/Extranet
    • Firewalls
    • Home Network
    • Client/Server Network
    • Bus Network
  • 23. Firewall Click Here to See Firewall Demo
  • 24. Terms to Know: Networking
    • Asynchronous communication
    • Bandwidth
    • Base station
    • Bridge
    • Broadband
    • Cable modems
    • Client/server network
    • Coaxial cable
    • Digital Subscriber Line (DSL)
    • Ethernet
    • Fiber-optic cable
    • File server
    • Gateway
    • Hub
    • Integrated Services Digital Network (ISDN)
    • IP Switch
    • Local Area Network (LAN)
    • MUX
    • Network interface card (NIC)
    • Node
    • Packet switching (packets)
    • Protocols
    • Router
    • Synchronous communication
    • T1; T3
    • TCP/IP
    • Topologies (bus, ring, star)
    • Twisted Pair Cable
    • Wide Area Network (WAN)
    • Wireless
  • 25. If Asked, Could You….
    • Describe the basic components of a network?
    • Explain the methods of data transmission, including types of signals, modulation, and choices among transmission nodes?
    • Differentiate among the various kinds of communications links and explain the need for protocols?
    • Describe various network configurations?
    • List the components, types, and protocols of a local area network?
    • Describe the complexity of networking?
    • Describe some examples of networking?
  • 26. Sources
    • Capron; Computers: Tools for An Information Age, 8 th Ed. 2003
    • Pfaffenberger; Computers in Your Future 2003
    • Microsoft Clipart
    • HowStuffWorks -Firewalls