These slides cover a topic on ISDN(integrated services digital network) part 2 in Data Communication. All the slides are explained in a very simple manner. It is useful for engineering students & also for the candidates who want to master data communication & computer networking.

1. Introduction to Data communication
Topic :ISDN Contd.
Lecture # 10
Dr Rajiv Srivastava
Director
Sagar Institute of Research & Technology (SIRT)
Sagar Group of Institutions, Bhopal
http://www.sirtbhopal.ac.in

2. Unit 2
Lecture 10
Course Lecture 27
ISDN Contd.

3. ISDN Services
ISDN has three types of services :
– Bearer Services
– Teleservices, &
– Supplementary services

4. ISDN Services

5. Bearer Services
Bearer services provide means to transfer
information (voice, data & video) between users
without network manipulating the content of
information.
Network does not process the information
These services belong to first three layers of the
OSI model
These services can be provided using circuit
switched, packet switched, frame switched or
cell switched networks

6. Teleservices
• Network may change or process the contents
of the data
• These services correspond to layer 4-7 of OSI
model
• Teleservices include telephony, teletex, telefax,
videotex, telex & teleconferening

7. Supplementary Services
• Supplementary services are those services that
provide additional functionality to the bearer
services & teleservices
• Examples are reverse charging, call waiting,
and message handling, all familiar from
today’s telephone company

8. ISDN Services
• ISDN Services
• The ISDN will provide a variety of services,
supporting existing voice and data applications
as well as providing for applications now
being developed.
• Some of the most important applications are as
follows.
– Facsimile:
• Transmit the page of data at 64 kbps in 5 seconds.
• Service for the transmission and reproduction of
graphics and handwritten and printed material.

9. Teletex
• Transmission is at the rate of one page in 2 seconds at
9.6 kbps
• Fast exchange of correspondences between terminals.
• Communicating terminals are used to prepare, edit,
transmit and print message.
Videotext:
• A page of data can be transmitted in 1 second at 9.6
kbps.
• An interactive information retrieval service.
Most of the services can be provided with a transmission
rate of 64 kbps or less. For higher rates B-ISDN will be
used.

10. ISDN CHANNELS

11. Subscriber Access to The ISDN
Channel Rates
Channel Data Rates
Bearer (B) 64 Kbps
Data (D) 16, 64 Kbps
Hybrid (H) 384 Kbps(H0),
1.536 Mbps(H11),
1.92 Mbps(H12)

12. B Channels
• A bearer channel (B channel) is defined at a rate
of 64 kbps
• Its a basic user channel & carry any type of
digital information(e.g. digital data, digital voice,
digitized video) in full duplex mode as long as
transmission rate doesn’t cross 64 kbps data rate
• Several multiplxed signal can also travel on it but
it cant demultiplex them in the way
• B channel carries end-to-end transmission

13. D Channels
• A Data channel( D channel) can be either 16 or
64 kbps depending on the need of the user
• Although the name says data, but the primary
function of a D channel is to carry control
signaling for B channel
• Control information such as call establishment,
ringing, call interrupt or synchronization is
carried by this channel
• D channel may be used for packet switching or
low speed telemetry at times when no
signalling information is waiting

14. H Channels
• Hybrid channels (H channels) are provided for
high data transmission rate
• Hybrid channels (H channels) are available
with data rates of 384 kbps(H0),
1536Kbps(H11) or 1920 Kbps(H12)
• These rates suit H channels for high data rate
applications such as video, teleconferencing &
so on

15. ISDN User Interface
• Digital subscriber loops are of two types
Basic Rate Interface (BRI)
Primary Rate Interface (PRI)
• Each type of services suits to different types of
users
• Both include one D channel & some number
of B or H channels

16. Basic Rate Interface (BRI)
• Basic rate interface (BRI) specifies a digital
pipe consisting of 2 B channels & one D
channel
• The BRI requires a digital pipe of 192 kbps
: B1(64)+ B2(64) + 16(D)+ 48 (operating overhead)
= 192 kbps
• It meets the requirement of residential & small
office customers
• Same earlier used twisted pair local loop can
be used in BRI, no need to replace local loop

17. BRI
Digital pipe can be assumed to contain 3 pipes
inside: 2 pipes for B channels & 1 pipe for D
channel, remaining portion can be assumed to
carry overhead bits

18. Primary Rate Interface(PRI)
• A usual PRI specifies one D & 23 B channels
• 23 B channels of 64k + 1 D channel of 64 K =
1.536 Mbps
• Overhead = 8 kbps
• Therefore, PRI requires a Digital pipe of
1.536+ 8 = 1.544 Mbps

19. PRI

20. • Transmission speed of PRI exactly matches
DS-1of American telephone services
• E-1 standard of Europe transmission is met by
30B + 2D channels = 2.048 Mbps
• Some other standards are:
• 3H0+D,
• 4H0+D &
• H12+D

21. ISDN Architecture
In the ISDN standard, the devices that enable users to
access the services of the BRI or PRI are described by
their functional duties and collected in functional
groupings. Subscribers choose the specific devices
best suited to their needs from these groupings. Each
functional grouping is a model that can be
implemented using devices or equipment chosen by
the subscriber. Functional groupings used at the
subscriber’s premises include network terminations
(types 1 and 2), terminal equipment (types 1 and 2),
and terminal adapters.

22. Functional Grouping
TE – Terminal Equipment
NT – Network Termination
TA - Terminal Adapter

23. Network Termination 1 (NT1)
• A network termination 1 (NT1) device controls
the physical and electrical termination of the
ISDN at the user’s premises and connects the
user’s internal system to the digital subscriber
loop.
• NT1 can also be called as ISDN switch.
• NT1 forms the boundary to the network and is
owned by the service provider;

24. Network Termination 2 (NT2)
• A network termination 2 (NT2) device performs
functions at the physical, data link, and network layers of
the OSI model (layers 1, 2, and 3). NT2s provide:
• multiplexing (layer 1),
• flow control (layer 2), and
• packetizing (layer 3)
• An NT2 provides intermediate signal processing between
the data-generating devices and an NT1.
• NT2s can be implemented by a variety of equipment types.
For example,
1) Private Branch Exchange (digital PBX) can be an NT2
2) A LAN also can function as an NT2.

25. Terminal Equipment 1 (TE1)
• The term terminal equipment is used by the
ISDN standard to mean the same thing as DTE
in other protocols. It refers to digital
subscriber equipment. Terminal equipment 1
(TE1) is any device that supports the ISDN
standards. Examples of TE1s are digital
telephones, integrated voice/data terminals,
and digital facsimiles.

26. Terminal Equipment 2 (TE2)
• To provide backward compatibility with a customer’s
existing equipment, the ISDN standard defines a second
level of terminal equipment called terminal equipment 2
(TE2). TE2 equipment is any non-ISDN device, such as a
terminal, workstation, host computer, or regular
telephone. TE2 devices are not immediately compatible
with an ISDN network but can be used with the help of
another device called a terminal adapter (TA).
Terminal Adapter (TA)
• A terminal adapter (TA) converts information received in
non-ISDN format from a TE2 into a format capable of being
carried by the ISDN.

27. ISDN Layers
• ITU-T has devised to expand an expanded
model for the ISDN layers.
• Instead of a single seven layers architecture
like OSI, the ISDN is defined in three separate
planes
1. User Plane
2. Control Plane
3. Management Plane
• All these three planes are divided into seven
layers that corresponds to the OSI model.

28. ISDN Layers

29. Simplified Layers of ISDN
Physical Layer is
identical for B & D
channel both.

30. 2B/1Q Encoding

31. ISDN Architecture
• Figure shown next is an architectural description of
ISDN.
• The ISDN will support completely physical
connector for users, a digital subscriber line and a
variety transmission services.
• Physical interface provides a standardized means of
attaching to the network.
• The interface supports a basic service consisting of
three time multiplexed channels, two at 64 kbps and
one at 16 kbps.
• In addition, there is a primary service that provides
multiple 64 kbps channels.

32. • For both basic and primary service, an
interface is defined between the customer
equipment (TE) and a device on the
customer’s premises, known as a Network
Termination (NT).
• The subscriber line is the physical path from
subscriber’s NT to the ISDN central office.
This line must support full duplex digital
transmission for both basic and primary data
rates.

33. • ISDN central office connects subscriber lines to the digital
network, providing access to lower layer transmission
facilities.
 Circuit-switched capabilities: Same facility provided by other
digital-switched telecommunications network. Data rate is 64
kbps.
 Non-switched capabilities: A 64 kbps dedicated link, higher
rates in B-ISDN by using ATM transmission.
 Switched capabilities: This refers to high speed switched
connections using ATM as part of B-ISDN.
 Packet-switched capabilities: This facility resembles packet-
switched service provided by other data networks.
 Frame mode capabilities: A service that supports frame relay.
 Common-channel signaling capabilities: Used to control the
network and provide call management internal to network, SS7 is
used.

34. Packet-
switching
Capabilities
Frame
mode
Capabilities
Common
channel
signaling
Capabilities
ISDN
switch
ISDN
switch
Subscriber
site or service
provider
Network
termination
(NT)
Terminal
equipment
(TE)
Subscriber
interface to
ISDN
Digital
subscriber
loop to
central
office
User-network signaling
User-User signaling
Subscriber
premises

35. ISDN Standards
• The ISDN is governed by recommendations from
ITU-T. these recommendations are called as I-series
of recommendations. They were first issued in 1984.
• These recommendations are as follows:
– I.100 series: General concepts
– I.200 series: Service capabilities
– I.300 series: Network aspects
– I.400 series: User-network interface
– I.500 series: Internetwork interfaces
– I.600 series: Maintenance principles
– I.700 series: B-ISDN equipment aspects.

36. Thank You
Dr Rajiv Srivastava
Director
Sagar Institute of Research & Technology (SIRT)
Sagar Group of Institutions, Bhopal
http://www.sirtbhopal.ac.in