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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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