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B-ISDN

B-ISDN Services

Interactive Services

• Conversational Services
  • Real time dialogue between user/application or user/server e.g. teleconferencing, remote CAD/CAM

  • Great demand on network, high throughput and short response times

• Messaging
  • Communication between users via storage units

  • Less demanding of the network

• Retrieval
  • Information retrieval e.g. databases, TV & film libraries, video on demand

  • High throughput and short response times in one direction

Distribution services

• Without Presentation Control
  • Continuous distribution from a central source to an unlimited number of users, e.g. broadcast TV

  • Capability for HDTV

• With Presentation Control
  • Similar distribution mechanism to above

  • Information is presented in cyclic sequences (frames)

  • Users control the start and order of presentations

Service Characteristics

• Services may be classified by characteristics such as data speed, network holding time etc.

• Classifying by speed:
  • Low
    • telemetry, telecontrol, tele-alarm, voice, telefax, low-speed data

  • Medium
    • Hi-fi Sound, video telephony, high-speed data

  • High/very high
    • Quality video distribution, video library, video education

• Services have different tolerances for delay and packet loss - some of which are indicated below

• Note that data transmission might be delay sensitive and at a constant or variable rate

B-ISDN Protocol

Reference Model