Presentation On Integrated Services Digital Network

(ISDN)

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ISDN: Definition

• Integrated Services Digital Network (ISDN) is a circuit-switched telephone network system, designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in better quality and higher speeds than that available with the PSTN system.

• Was developed by International Telecommunication Union in 1976.

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ISDN: Definition

• Integrated Services Digital Network (ISDN) is a circuit-switched telephone network system, designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in better quality and higher speeds than that available with the PSTN system.

• Was developed by International Telecommunication Union in 1976.

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ISDN: Overview

• Primary idea is to digitize the telephone network to allow the transmission on audio, video and text over existing telephone lines.

• Goal of ISDN is to form a WAN that provides global end to end connectivity over digital media.

• So it supports wider integration and standardization.

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ISDN: Overview 2

• ISDN incorporates all communication connections in a home or building into a single interface.

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ISDN: Subscriber Access

• For flexibility digital pipes between customer and ISDN office are organized into multiple channels of different sizes.

• The three standard ones are– Bearer (B Channel)– Data (D Channel)– Hybrid (H Channel)

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ISDN Channels/Types

Channel Data Rate Application

Bearer (B) 64 Kbps Normal at full duplex.

Data (D) 16 or 64 Kbps Carry control signals for B.

Hybrid (H) 384 Kbps(H0), 1536 Kbps (H11) or 1920 Kbps (H12)

Used in high data-rate applications.

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ISDN Interfaces

• Basic Rate Interface (BRI) specifies pipe consisting of two B channels, each with bandwidth of 64 kbps, and one D channel with a bandwidth of 16 kbps.

• Together these three channels can be designated as 2B+D.

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ISDN Interfaces (Contd..)

• PRI: Primary Rate Interface• Contains a greater number of B channels

and a D channel with a bandwidth of 64 kbps. The number of B channels for PRI varies according to the nation: in North America and Japan it is 23B+1D, with an aggregate bit rate of 1.544 Mbps; in Europe and Australia it is 30B+1D, with an aggregate bit rate of 2.048 Mbps.

• Primary 23 B and 1 D channel 1.544 Mbps

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Features of ISDN

• Speed: allows multiple digital channels to be operated simultaneously through the same regular phone wiring used for analog lines which can support digital connections.

• Supports an uncompressed data transfer speed of 128 kb/s, plus bandwidth for overhead and signaling.

• Also the latency, or the amount of time it takes for a communication to begin, on an ISDN line is typically about half that of an analog line. This improves response for interactive applications, such as games.

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Features (Contd..)

• Multiple Devices: Transferring a file to someone while talking on the phone or seeing their live picture on a video screen would require several potentially expensive phone lines.

• ISDN allows multiple devices to share a single line. It is possible to combine many different digital data sources and have the information routed to the proper destination.

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Features (Contd..)• Signaling: Instead of the phone company sending a

ring voltage signal to ring the bell in your phone ("In-Band signal"), it sends a digital packet on a separate channel ("Out-of-Band signal").

• The Out-of-Band signal does not disturb established connections, no bandwidth is taken from the data channels, and call setup time is very fast. For example, a V.90 or V.92 modem typically takes 30-60 seconds to establish a connection; an ISDN call setup usually takes less than 2 seconds.

• The signaling also indicates who is calling, what type of call it is (data/voice), and what number was dialed.

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Advantages (ISDN)• It is an integrated systems.• It is widely available a new wide area networking

alternative.• It provides better quality and high digital data rates

than PSTN systems.• Some of the principles of ISDN:-

Support of voice and non voice applications. Support for switched and non switched applications.Reliance on 64-kbps connections.Intelligence in the network.Layered protocol architecture.

Variety of configurations.

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Future of ISDN

• ISDN is intended to be a worldwide public telecommunications network.

• The impact of ISDN on users and vendors is significant.

• Some of the points that brings forth its future are as follows:-

National ISDN.Applications.Broadband ISDN.The real world.

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