1. Chapter 3
Telecommunications and
Computer Networks for
Business

2. 
Data Transmission Unit





Data Transmission Technology



KBPS
MBPS
GBPS
etc.
Broadcast Networks
Point-to-Point Networks
Network Devices

3. Types of Networks
•A network is defined by:
- physical topology
- network protocols
• Local Area Networks (LANs)
• Wide Area Networks (WANs)
• Internetworking
• Intranet
• Extranet
• Internet

4. 


Limited distance (usually within 10 KM)
Privately Owned
Usually use a broadcast medium



e.g. Coaxial cable, Fiber Optics, Virtual
LANs defined by Physical technology:
- defines physical and data link layer
 type and wiring of broadcast medium
 protocol for sharing broadcast medium
LANs Topology:
- Bus
- Ring
- Star
- Mesh

5.  Circuit Switching
 Telephone Exchange
 ISDN
 Packet Switching
 X.25
 SMDS
 Frame Relay
 ATM

6. Switching
• Circuit switching
- sets up dedicated end-to-end channel for
duration of connection
- used for phone network
• Packet switching
- divides data messages into small packets
- each packet is "message switched“
- packets can take different routes
- if one is lost, does not resend whole
message

7. 
In addition to the previous functionality...
 break messages into packets
 attaches destination address, other admin info
to packets
 finds next node in path for each packet
 routes packets to next node
 reassembles packets into messages at receiver’s
end
A
B
S
R
C
D

8. 
7: Application layer


6: Presentation layer


Finds routes for packets; transmits them to next node
2: Link layer


Divides messages into packets;assembles packets into
messages
3: Network layer


Establishes and terminates connections between
applications
4: Transport layer


Handles encryption, compression, other translation of
messages
5: Session layer


E.g., terminal emulation, file transfer
Breaks packets into frames; sends frames between nodes
1: Physical layer

Sends bits over wires

10. TCP/IP
• IP is lowest layer (equivalent to the OSI network
layer)
- moves a packet from one host to another
- connectionless protocol (no guarantee of reliable
delivery)
- each packet contains a 32-bit address of the
destination host
- each host has its own unique address
- Internet is running out of addresses
- partly because addresses allocated inefficiently
- eventually move to more than 32-bit addresses
• TCP (equivalent to OSI transport layer)
-establishes a reliable connection between processes
on
two hosts

11. Internet Evolution
1962-80: The Internet is first conceived in the early 60s in the Dept of
Defence Advace Research Project (ARPA) of USA. In 1969 Researchers at
US created the first host of ARPANET which grows to 213 hosts
international by 1981.
1982-90: In 1982 the term “Internet” is used for the first time with the
creation of TCP/IP. In 1984 William Gibson coins the term
“Cyberspace” in his novel “ Neuromancer”. The number of hosts
exceeds 300,000 by 1990
1991-96: In 1991 a group of particle physicists working at CERN in
Switzerland created World Wide Web. In 1992 number of hosts exceeds
1,000,000.
In 1993 the first graphics-based Web Browser called MOSAIC became
available. In 1994 NETSCAPE Browser was released and in 1995
SUN Microsystems Corp. release an Internet Programming language
called JAVA.
By January 1998 users in almost 210 countries around the world are now
connected to the Internet and number of hosts approaches to 25 million.
(No of users 300 million people (approx)

12. Internet Applications Services
• E-Mail/ Bulletin Boards/ Discussion &
Newsgroups/ Internet Relay Chat (IRC)
• FTP (File Transfer Protocol) to download
information from various ftp sites of Internet
• Telnet to Login into a Remote System in
Internet
Archie to locate files in Internet
• Gopher to retrieve Menu / Indexed
information
from Internet
• WAIS to retrieve Indexed information from
Net
• World Wide Web (WWW)

13. Intranet and Extranet
• The use of Internet Technology to build
a
private corporate network - Intranet
• The extension of Intranet to cover the
Business partners of an Corporation –
Extranet
• Use of high security and access control
such as firewalls

14. How the Intranet Works
Acts as a reservoir
of company info like
provident fund
rules, HR policies etc.
Are an interaction
platform for the
employees to
discuss projects,
share ideas
Intranets are internal
networks that let you
access information
by simple browsing
as on the
World Wide Web
Enhances project
Management
and reporting
systems
Lets you share
Information with
colleagues spread
over various
locations,
simultaneously
Helps improve
workflow and
increase
productivity

15. Intranet Applications
Publishing
Corporate
Documents
Mail
Workgroup
Collaboration
Software
Distribution
Access Into
Searchable
Directories
User
Interface
Corporate/
Department/
Individual
Pages
Other
Information
and
Uses
Intranet
Application

16. Internal Applications on
Intranet
•Product Information
•Project Information
•Access to Data
Warehouse
•Product Support
Databases
•Training and
Registration
•Newswire Clippings
•Software Libraries
•Phone Directory
•Conference Room
Reservations
•Libraries
•Subscription Services
• Policies and Procedures
• Engineering Groups
Information
• Historical Information
• Employee and Group
Information
• Sharing Design Drawings
• Technology Centers
• Sales Support Centers
• Competitive Analysis
• Strategies
• Financial-Management
Query
• Corporate Newsletters

17. Internal Applications on Intranet
•Knowledge
Preservation
•Official Travel Guide
•Manufacturing
Information
•Employee Info-bases
•Employee Property
Management
•Policies and Procedures
•Jobs
•Benefits
•Literature Ordering
•Stock Quote
•Information Catalogs
• Performance Tracking
• Surveillance
• Application Front-end
• Whiteboard
• Conferencing
• Travel Plans
• Art Libraries
• Directions
• Maps
• Indexing Engines

18. What are extranets?
• An extranet is a private network that uses the Internet
protocols and the public telecommunication system to securely
share part of a business's information or operations with
suppliers, vendors, partners, customers, or other businesses
• An extranet can be viewed as part of a company's intranet that
is extended to users outside the company
Company A
Intranet
Extranet
Company B
Company C

19. Applications of Extranets
• Exchange large volumes of data using Electronic Data
Interchange (EDI)
• Share product catalogs exclusively with wholesalers or
those "in the trade"
• Share inventory status, order status and such other
business information
• Collaborate with other companies on joint development
efforts
• Jointly develop and use training programs with other
companies
• Provide or access services provided by one company to a
group of other companies, such as an online banking
application managed by one company on behalf of
affiliated banks
• Share news of common interest exclusively with partner
companies

20. Internet Addressing Systems
• It follows 32 bit IP systems and divided
in 4 Octals and classified into 3 Classes at
present:
- A Class begins with 0 -127
- B Class begins with 128 -191
- C Class begins with 192 - 223
0-255
8
0-255
16
0-255
24
0-255
32