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Chapter 8 Wide Are Networking (WAN)
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Chapter 8 Wide Are Networking (WAN)

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  • 1. Chapter 8 Wide Are Networking (WAN)
    • Concepts
      • Packetizing
      • Multiplexing
    • Switching
    • Transmissions
    • Services
    • Selection
  • 2. Packetizing
    • Organize a group of bits in a predetermined & structure format
    • Include user’s data, overhead or management information for error-free transmission
    • Packets, frames, cells, blocks, data units
  • 3. Multiplexing
    • Frequency division multiplexing (FDM)
    • Time division multiplexing (TDM)
    • Statistical time division multiplexing (STDM)
    • Wavelength division multiplexing (WDM)
    • No interoperation between different manufacturers
  • 4. Frequency Division Multiplexing
    • Use different frequencies for multiple input signals
    • Use guardbands (take space, not efficiency)
    • Transmit data and voice simultaneously over phone line
    • Data over voice (DOV) unit with PBX for college campus, not for PSTN
  • 5. Time Division Multiplexing
    • 100% bandwidth available for a portion of the time
    • Use buffer memory & central clock for flow control (polling)
    • Composite message frame
    • Simple, not efficiency
  • 6. Statistical Time Division Multiplexing
    • Efficiency
      • No idle time
      • No padded blanks or null characters in composite message blocks
      • Dynamically allocating time to terminals
    • Higher cost
      • Buffer
      • Processing power for control information (source terminal, bytes of data, & data compression)
  • 7. Wavelength Division Multiplexing
    • Use different wavelengths of light
    • Long-distance fiber optic network
  • 8. WAN Switching
    • Packet switching network
    • Circuit switching network
  • 9. Packet Switching
    • Packet-switched network
    • Public data network (PDN)
    • Packet assembler/disassembler (PAD)
      • Stand-alone devices
      • Combined with modems or multiplexers
      • Location: end-user or entry point of packet switched data network
    • Equipment: DSEs (data-switching exchanges) or PSEs (packet-switching exchanges)
    • Every user having the same transmission rate
  • 10. Packet Switched Services
    • Connectionless
      • Global address (source & destination)
      • Datagram (address with user data)
      • Unreliable (no error detection or flow control)
    • Connection-oriented: virtual circuits
      • Reliable packet network (ACK/NAK)
      • Call set-up packets, message-bearing packets, & clear request packet
  • 11. Circuit Switching
    • Circuit switched network
    • Use circuit without source & destination address
  • 12. WAN Networking Transmission
    • Local Loop
      • Plain old telephone service (POTS)
      • Integrated service digital network (ISDN)
      • Asymmetric digital subscriber line (ADSL)
      • Cable TV
    • Boradband
      • T1
      • SONET
  • 13. ISDN
    • A switched digital services for delivering voice, video, and data at same time
    • Types
      • Basic rate interface (BRI): 2B+D ( 2 Bearer channels of 64 kbps & 1 Delta or Data channel of 16 kbps)
      • Primary rate interface (PRI): 23B+D
    • Applications use ISDN terminal adapter
      • Single user-to-office or Internet connection
      • Office-to-office connection
  • 14. ADSL
    • Use POTS at higher frequencies
    • Use frequency division multiplexing: (upstream & downstream)
    • Internet & voice at same time
    • Types
      • Very high speed digital subscriber line (VDSL)
      • Rate-adaptive digital subscriber line (RADSL)
      • Symmetric digital subscriber line (SDSL)
    • Application: access Internet using POTS & ADSL units
  • 15. Cable TV Problems for WAN
    • Downstream only infrastructure
    • Remedy methods
      • Upstream using POTS
      • Modify cable architecture to upstream & downstream
  • 16. T-1
    • High-capacity digital transmission over voice channel
    • 1.544 Mbps bandwidth
    • 24 64-Kbps channels (DS-0 circuit)
    • T1 multiplexers
    • Application
      • Leased line or private line for business
  • 17. T-1 Digital Services
    • Digital service hierarchy or DS standards
    • DS-0 : 64Kbps
    • DS-1: T-1uses four copper wires (two twisted pair)
    • DS-2: T-2
    • DS-3: T-3 uses optical fiber media
    • DS-4: T-4
  • 18. SONET
    • Optical transmission services:
      • For failure tolerance & reliable data delivery
      • Metropolitan area only
      • Expensive
    • Applications
      • Broadband ISDN
      • High-definition television
  • 19. WAN Services
    • X.25
    • Frame relay
    • Switched multimegabit data service (SMDS)
    • Cell relay - ATM
    • Broadband ISDN
  • 20. X.25
    • CCITT standard for the interface between DTE and packet-switched network
    • Point-to-point error checking or hop-by-hop error checking
    • Technology
      • Packet assembler/disassembler (PAD)
      • X.25 switches
  • 21. Frame Relay
    • Error detection & correction
      • Point-to-point error detection (discard )
      • End-to-end error correction
    • Frame: variable length
    • Pro: high through put with low delay for data only
    • Con: no guaranteed time delivery (not for voice & video)
  • 22. Frame Relay
    • Technology
      • Frame relay or frame assembler/disassembler (FRAD or FAD) or frame relay access devices
      • Frame relay switch
    • Application: inter-LAN traffic
  • 23. Switched Multimegabit Data Service - SMDS
    • Connectionless network service
    • Use SONET (T-3)
    • Fixed-length cells of data
    • Broadcast
    • Only MCI for long distance
  • 24. Cell Relay - ATM
    • Cell
      • fixed length (53 octects)
      • 48 for data and 5 for control information
    • Predictable delivery time for voice and video
    • Technology
      • ATM network interface cards
      • ATM hub
      • ATM enterprise switch
      • ATM gateway switches or ATM access switches
      • ATM LAM emulation
  • 25. WAN Selection Criteria
    • Data traffic patterns
    • Business objectives
  • 26. Assignment
    • Review chapter 8
    • Read chapter 9

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