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Understanding ISDN: Integrated Services Digital Network Overview and Applications

This chapter explores the Integrated Services Digital Network (ISDN) in depth, covering its history, subscriber access methods, and service layers. It describes how ISDN utilizes both bearer (B) and data (D) channels for various applications, including voice and video. The evolution from narrowband to broadband ISDN is discussed, highlighting the importance of different network termination points (NT1 and NT2) and terminal equipment types (TE1 and TE2). The chapter also examines ISDN's signaling techniques, data rates, and functional grouping of layers.

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Understanding ISDN: Integrated Services Digital Network Overview and Applications

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  1. Chapter 16Homework • 24, 25, 26, 27, 31, 41, 58

  2. Chapter 16Integrated Services Digital NetworkISDN • Services • History • Subscriber Access • Layers • BISDN

  3. Review • Using modem over a POTS (plain old telephone system) to connect to Internet through ISP: • The home dialup modem converts digital signal from computer to analog signal. • A modem in the ISP converts the signal back to digital form for input to ISP router. • Data transmission is limited to 56kbps.

  4. Voice over Analog Network

  5. Voice and Data over Analog Network

  6. Analog and Digital Services

  7. Integrated Digital Network

  8. Integrated Services Digital Network

  9. Signaling Techniques (review) • Inchannel • Inband • Control signals are transmitted in the same band of frequencies used by the voice signals. • Out-of-band • Control signals are transmitted over the same facilities as the voice signal but a different part of the frequency band. • Provides continuous supervision during transmission • Common Channel • Control signals are transmitted over dedicated signaling channels.

  10. ISDN • ISDN allows the transmission ofdigital datafrom a home end system over ISDN lines to a phone company’s home office. • It provides a set of channels at a single interface. • The Bearer (B) channels used for data signals (64 kbps). • The Data (D) channel, used primarily for control signals (16, 64 kbps). • The Hybrid (H) used for high data rate applications such as video, teleconferencing. • H0 384 kbps • H11 1536 kbps • H12 1920 kbps

  11. ISDN (continued) • Support voice and non-voice applications • Supports switched and non-switched applications (i.e. circuit switching, packet switching, dedicated (leased )circuits).

  12. ISDN (continued) • ISDN Evolution: • First generation (narrowband) ISDN • Second generation (broadband) ISDN • First-generation (narrowband) ISDN specifications: • Uses 64-kbps channels as a basic unit of switching. • Has circuit switching orientation

  13. ISDN (continued) • Two types of services provided through narrowband ISDN: 1. The basic rate interface (BRI): • is made of two B channels and 1 D channel, suitable for small businesses and residential. • The primary rate interface (PRI): • is made of either 23 B channels or 30 B channels and one D channel, is suitable for businesses with digital PBX or LAN.

  14. ISDN (continued) The primary rate interface (PRI): • 23 B channels at 64kbps each and one D channel at 64 kbps • Data rate=1.544 Mbps • (used in USA, Canada, and Japan) • 30 B channels at 64kbps each and one D channel at 64 kbps • Data rate=2.048 Mbps • (used in Europe)

  15. Basic Rate Interface A digital pipe of 192 kbps is required for BRI since there is 48 kbps operating overhead

  16. Primary Rate Interface

  17. User Access to ISDN • Network termination 1 (NT1) • Network termination 2 (NT2), also called PBX, (Private Branch eXchange)

  18. User Access to ISDN • Network termination 1 (NT1) • Includes functions associated with physical layer of the OSI model. • It is a terminating device placed on customer’s premises and connects it to the ISDN exchange in the carrier’s office

  19. User Access to ISDN • Network termination 2 (NT2 or PBX) • An intelligent device that includes functions associated with first three layers of the OSI model. • Used in larger organizations • It is connected to NT1 • Provides interface for telephones, terminals, gateways

  20. User Access to ISDN • Terminal equipment type 1 (TE1) • Refers to devices that support the standard ISDN interface. ( digital phones, digital facsimile, integrated voice/data terminals) • Terminal equipment type 2(TE2) • Includes existing non-ISDN equipment (host computers with X.25 interface. Terminals with EIA-232-F interface) • Terminal adapter (TA) is needed to connect to ISDN interface.

  21. Functional Grouping

  22. ISDN Layers for B and D Channels

  23. Reference Points • Reference points: • Refers to specifications for connecting two network elements. • R reference point, defines connection between a TE2 and TA. • S reference point, defines connection between a TE1 and TA. • U reference point, defines connection between a NT1 and ISDN office.

  24. BRI Interfaces

  25. Is there a need for higher data rates?

  26. Bit Rates for Different Applications

  27. Broadband ISDN Second generation (broadband) ISDN • Supports very high data rate (600 Mbps) • It uses fiber optic cable at all levels • Has packet switching orientation • It uses ATM to move data from one end point to another.

  28. Broadband ISDN Services Interactive services: • Conversational • Services that support real time data exchange ( phone class, video conferencing, real time data transfer) • Messaging • These services are store-and-forward services (voice mail, data mail, video mail) • Retrieval: • Information are retrieved from a central source (libraries, shared resources)

  29. Broadband ISDN Services Distributive services: are unidirectional • Without user control • Commercial TV, programming contents and times are decided by provider. • With user control • Pay TV • Educational broadcasting

  30. Broadband ISDN Access Methods • Symmetrical: • 155.52 Mbps full-duplex • Suitable for residential and small businesses subscribers • 622 .08 Mbps full-duplex • Suitable for businesses subscribers that provide and receive distributive services • Asymmetrical: • 155.52 Mbps output/622.08 Mbps input full-duplex

  31. B-ISDN Access Methods

  32. Addressing in ISDN NC: National code, refers to ISDN networks in each country

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