ISDN Slides1

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  • 7/31/2019 ISDN Slides1


  • 7/31/2019 ISDN Slides1



    Narrowband ISDN has been designed tooperate over the current communicationsinfrastructure, which is heavily dependent onthe copper cable. B-ISDN however, reliesmainly on the evolution of fibre optics.

    Broadband ISDN allows its users to communicate

    over high speed, high quality digital channels. Themedia is supports include Telex, fax, voice telephone,video telephone, audio, high definition TV andcomputer networking.

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    Services category examples



    Messaging services Retrieval services


    Tv confernce

    Video mail


    Tv broadcast Videography.

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    What are the features of isdnand why is narrow band ISDN isnot so popular ? Advantage ofBISDN over other networks?

    Explain ISDN swiching servicesand their 4 refernce points?

    ISDN switching. what are the

    interfaces available and explainreference points and its uasage.

    Explain ISDN concept?

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    ISDN Introduction The Integrated Services Digital Network

    (ISDN) is a set of international standards foraccess to advanced, all-digital publictelecommunications networks.

    ISDN provides all of its services over an entirelydigital transmission system

    When ISDN is referred to as a network it is tobe considered a telephone network, not a

    computer network

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    Introduction:-The key elements of this definition are: Video

    Image Data

    Mixed media at a number of standarddata rates

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    Components of ISDN





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    ISDN Channels

    A CHANNEL is the basic unit of ISDNservice. The ISDN Standards define

    three basic types of channels: Bearer channels (B channels)

    Delta (or "Demand") channels (D

    channels) High-capacity channels (H channels)

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    ISDN Access Types

    ISDN offers two general types ofaccess:


    These differ from one another by

    the amount of information they cancarry.

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    ISDN Devices

    Terminal Equipment (TE)

    Terminal Adapter (TA)

    Network Termination 1 (NT1) Network Termination 2 (NT2)

    Exchange Termination (ET)

    Terminal Equipment (TE)

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    ISDN Reference Points

    U - Two wire cable that connects thecustomers equipment to thetelecommunications provider

    R - Point between non-ISDNequipment (TE2) and the TA

    S - Four-wire cable from TE1 or TA

    to the NT1 or NT2 T - Point between NT1 and NT2

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    ISDN Function Devices Terminal Adapter (TA) - A converter device that

    allows non-ISDN devices to operate on an ISDNnetwork.

    Terminal Equipment Type 1 (TE1) - A device thatsupports ISDN standards and that can be connecteddirectly to an ISDN network connection. Forexample, routers with integrated ISDN interfaces,ISDN telephones, personal computers, orvideophones could function as TE1s..

    Terminal Equipment Type 2 (TE2) - A non-ISDN device,

    such as a router, analog phone or modem, whichrequires a TA in order to connect to an ISDNnetwork.

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    ISDN Function Devices

    Network termination type 1 & 2 (NT1)-A smallconnection box that is attached to ISDN BRI lines. This

    device terminates the connection . Network termination type 1 & 2 (NT2)- A device that provides switching services for the internal

    network. This type of interface is typically used with PRI

    lines, when they need to be divided for several functions.

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    ISDN Components and

    Reference Points

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    ISDN Protocols

    E-series protocolsTelephonenetwork standards for ISDN.

    I-series protocolsSpecify ISDN

    concepts and interfaces. Q-series protocolsStandards forISDN switching and signaling.

    Operate at the physical, data link,

    and network layers of the OSIreference model

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    ISDN Services BRI Basic Rate Interface (BRI)

    Two 64 Kbps B channels, one 16 Kbps D channel, and 48 Kbps worth offraming and synchronization.

    Available data bandwidth: 128 Kbps (2 x 64 Kbps)

    User bandwidth: 144 Kbps (128 Kbps + a 16 Kbps D channel)

    Total line capacity: 192 Kbps (144 Kbps + 48 Kbps framing)

    Each B channel can be used for separate applications Such as Internet and Voice

    Allows individual B channels to be aggregated

    together into a channel

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    ISDN Services PRI Primary Rate Interface (PRI)

    A PRI connection can assign various 64 Kbps channels to both ISDNand analog modem connections

    North America and Japan PRI service has 23 64 Kbps B channels,one 64 Kbps D channel, and 8 Kbps of synchronization and framing

    for a total bit rate of up to 1.544 Mbps (same as T1) Europe, Australia, and other parts of the world PRI service has30 64 Kbps B channels, one 64 Kbps D channel, and 64 Kbps offraming and synchronization for a total bit rate of up to 2.048Mbps (same as E1)

    Each B channel to be used for separate applications

    including voice, data and Internet Multiple B channels can be Multilinked together

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    What Is ISDN?

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    ISDN Benefits

    Carries a variety of user traffic, such asdigital video, data, and telephone networkservices, using the normal phone circuit-switched network

    Offers much faster call setup than

    modems by using out-of-band signaling (Dchannel) Often less than one second

    Provides a faster data transfer rate thanmodems by using the 64-kbps bearer

    channel (B channel) Can combine multiple B channels to bandwidth

    of 128 kbps

    Can negotiate PPP links

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    Analogies NT-1 (Network Terminator-1)

    An NT-1 is an interface box that convertsISDN data into something a PC can understand(and vice versa). It works a little like a cableTV descrambler for ISDN signals, and is oftenbuilt into ISDN adapters.

    TA (Terminal Adapter) This chunk of hardware converts the data it

    receives over ISDN to a form your computercan understand. Sometimes mistakenly called

    an ISDN modem or a digital modem, a terminaladapter handles data digitally and does notneed to modulate or demodulate an analogsignal. Terminal adapters can be an internalboard or an external board that connects to

    the computer through the serial port.

    ISDN C t d

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    ISDN Components andReference Points #2

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    ISDN Reference Points

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    ISDN and the OSI

    Reference Model The ISDN Physical Layer

    The ISDN Data Link Layer The ISDN Network Layer

    ITU T S d d f h

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    ITU-T Standards of theFirst Three Layers of ISDN

    ISDN P t l O ti

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    ISDN Protocol OperatingOSI Layers 1 Through 3

    Physical layer ISDN protocols BRI (ITU-T I.430) / PRI (ITU-T I.431)

    Defines two ISDN physical layer frame formats Inbound (local exchange to ISDN customer)

    Outbound (ISDN customer to local exchange )

    Data link layer ISDN protocols LAPD signaling protocol (ITU-T Q.920 for BRI and Q.921 for PRI) for

    transmitting control and signaling information over the D channel

    LAPD frame format similar to ISO HDLC frame format

    Network layer ISDN protocols

    ITU-T I.930 and ITU-T Q.931 defines switching and signaling methodsusing the D channel.

    Note: With Q.921/Q.931 the second digit indicates the OSI


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    ISDN Physical Layer

    ISDN physical-layer frame formats are 48 bits long, of which 36bits represent data

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    ISDN Data Link Layer

    Frame format is very similar to that of HDLC

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    ISDN Network Layer

    Two Layer 3 specifications are usedfor ISDN signaling: ITU-T I.450 (also known as ITU-T


    ITU-T I.451 (also known as ITU-TQ.931)

    Together, these protocols support: User-to-user circuit-switched connections

    User-to-user packet-switched connections

    A variety of standards for: Call establishment

    Call termination

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    ISDN Encapsulation

    The two most common encapsulations: PPP HDLC

    ISDN defaults to HDLC. PPP is much more robust.

    Open standard specified by RFC 1661

    Supported by most vendors

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    ISDN Uses

    Remote Access (Telecommuters) Remote Nodes (Voice and Data)

    SOHO Connectivity (SmallBranches)

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    Remote Nodes(Voice and Dat