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Gauri Kulkarni (28)Namrata Khubchandani (27)

Navneet Kaur (36)

Pooja Saraff (45)

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What is ISDN?

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ISDN - Integrated Services Digital Network

Defined in 1988

Simultaneous transmission of voice,video,data and

other network services.

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Advantages of ISDNy Digital

y reliable connection

y Speedy 128 kb/s (160 kb/s) for BRI

y 1920 kb/s (2048 kb/s) for PRI

y Fast call setup

y 2 seconds

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Advantages of ISDNy Bandwidth onDemand

y adding new channels to the bundle of channels

y Multiple devicesy phone, fax, PC, videoconferencing system, router,

terminal adapter,.. each with its own subaddress.

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Advantages cont..y Signaling

- No disturbance to established connections.

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

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Access interfacesy Basic rate interface (BRI)

y Primary rate interface (PRI)

y Broadband ISDN

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BRIy Provides

Two 64bit/s B channels.

One 16 bit/s D channel.y B channels : Data, Voice and other services

y D channels: Control and Signalling information

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Scenarios of usage ofBRIy One B channel dedicated to voice and other dedicated

to data.

y Both B channels dedicated to data for a total transferrate of 128 kbits/sec.

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Interfacing

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Signal Encoding 2BIQ in North AmericaTwo bits combined to form a symbol.

Can operate up to 5.5km with loss up to 42 dB.Signal rate :80 kbits/s Line rate: 160 kbits/s

Echo cancellation allows full duplex operation.

4B3T in Europe and elsewhere

Group of four bits converted to 3 ternary line signal states.The symbol rate is 3/4ths of the data rate (120 kbits/s).

Can be transmitted up to 4.2 km(0.4 mm cable) or 8.2 km(1.6mm cable).

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PRIy Primary Rate Interface

y PRI consists of:

23 B channels and 1 D channel of 64 kbps each in T1line for North America and Japan.

OR

30 B channels, 1 D channel and a synchronizing

channel in E1 line for the rest of the world. T1 line: 1.544 Mbps data services available

E1 line: 1.920 Mbps data services available.

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Dual PRIy (24 + 23) B channels and 1 D channel or more

commonly 46 B channels and 2 D channels are used

for backup signaling.y Done in both T1 line and E1 line.

y There can be more than 2 stages of PRI i.e. more thanin dual PRI.

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PRI Applicationy Typically used in medium and large enterprises to

provide the digital access to PSTN.

yNumber of B channels can be used and reassignedflexibly for special needs like video conferencing.

y PRI user is directly hooked up to the central office.

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B-ISDNy BRI ISDN lacks the channel capacity required for video

and voice transfer.

yAlso for business applications, ISDNs speed of 64kbps was no match for 10 Mbps of LANs.

y Hence, B-ISDN with a higher speed of few Mbps wasintroduced.

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B-ISDN( contd.)y It uses Asynchronous Transfer Mode technology

which carries both synchronous voice and

asynchronous data services on the same line.y Baseband: The original band of frequencies of signal

before it is modulated for transmission.

e.g. Ethernet LAN

Broadband: A single medium (a wire) can carry severalchannels at a time.

e.g. B-ISDN

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y

Enhanced Voice Services- advanced call management features - multipletelephone numbers, shared telephonenumbers, conferencing, transferring and caller

name and number IDy Branch Office Communications

- provides cost-effective connections fortransferring information, links multiple business

locations, WAN

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y

Video Conferencing- supports high fidelity audio and broadcast-quality, full color, full motion images

y Telemetry Security

- supports central surveillance on numerousremote locations along with monitoring the statusof alarms and access control devices.

(B channels provide connectivity for video andD channel accommodates the other alarm inputs)

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Current Scenarioy ISDN service has been displaced by broadband

internet service, such as xDSL and Cable Modemservice.

y

These services are faster, less expensive, and easierto set up and maintain than ISDN.

y Still, ISDN has its place, as backup to dedicatedlines, and in locations where broadband service isnot yet available

y Optimization- replace copper wire with fiber opticcables

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