2. Learning Objectives
• What are Networks and why one needs them for
business applications?
• What is the different kind of data communications
channels that exists and are there any defined
standards for these channels?
• How many types of networks exist and what are the
different topologies that these networks may follow?
• What are the different components of networks and
how one can select a network?
• What are the roles, Internet, Intranet and Extranet
play for success of the business?
3. Networks
• A Network is interconnection of resources that
organization owns.
• A Network is a technology solution that helps
organization to interconnect its hardware,
software, databases and various media to
achieve interconnectivity between its employees
and stakeholders.
• Data communication or data conferencing allows
two or more users to share the common data
resource either on the common computer server
or their networked computers.
4. Types of Networks
• Local Area Network (LAN)
– A local area network (LAN) interconnects two or more
computers or devices within a relatively small, well-
defined area, such as a room, building, or cluster of
buildings using physical wires, infrared links or
wireless systems.
• Wide Area Network (WAN)
– A wide area network (WAN) interconnects two or
more computers that are geographically dispersed.
• Virtual Private Network (VPN)
5. Network Topologies
• Topology is the process and method of
connecting different nodes in a network. A
network can be arranged as per one of the
four different topologies:
– Star Topology
– Ring Topology
– Bus Topology
– Tree Topology
– Mesh Topology
6. Network Components
• There are two basic components to the backbone
of a network: the network connectivity (cable or
wireless) and the hardware devices that connect
networks to the network backbone.
– Twisted Pairs Cables
– Coaxial Cables
– Fiber Optical Cables
– Microwave Transmission
– Satellite Transmission
– Infrared
– Bluetooth
7. Cellular Technology
• Cellular networks are divided up into cells, each cell being serviced by one
or more radio transceivers (transmitter/receiver). Communication in a
cellular network is full duplex, where communication is attained by
sending and receiving messages on two different frequencies - frequency
division duplexing (FDD).
– First Generation (1G): First generation services were analogue services for cell
phones.
– Second Generation (2G): 2G services were digital. The transition to 2G
provided the ability to store, copy, encrypt and compress data, and allowed
data transmission without loss and with error-correction. There are two kinds
of 2G services
• Global System for Mobility (GSM)
• Code Division Multiple Access (CDMA)
– 2.5 / 3G: The introduction of packet switching for data rather than circuit
switching.
– "True" 3G: Third Generation networks offer users a wider range of more
advanced services while achieving greater network capacity through improved
spectral efficiency. Services include wide-area wireless voice telephony, video
calls, and broadband wireless data, all in a mobile environment.
8. Network Components
• Ethernet
• Hubs - Hubs are very simple devices that pass all traffic in both
directions between the LAN sections they link.
• Bridges - Bridges connect two LAN segments that use the same data
link and network segments.
• Switches - Switches are similar to bridges but connect more that
two LAN segments.
• Routers - Routers connect two or more LANs that use the same or
different data link protocols but employ the same network
protocol.
• Brouters - Brouters are devices that combine the functions of both
bridges and routers; they bridge same data link layer LANs and
route different data link layer LANs.
• Gateways - Gateways connect two or more LANs that use the same
or different data link and network protocols.
9. Communication
• Data Communication: Data communication is the process
of sending data electronically from one point to another.
• Telecommunication, or teleprocessing, is the processing of
using communication facilities, such as the telephone
system, microwave relays, and satellite to send data
between computers.
• Analog Data Transmissions: Analog data transmission is the
transmission of data in a continuous waveform.
• Digital Data Transmission: Digital data transmission is the
transmission of data using distinct on and off electrical
states.
• Modem is a modulation-demodulation device which
converts the digital signal to analog and vice-versa.
10. Communication Channels
• A communication channel is the medium, or pathway, along
which data are transmitted between devices.
Communication channels fall into two basic types: wire
cable and wireless.
• Two methods that are used to regulate the flow of data
from communication channels into a computer are
multiplexing and concentration.
• Multiplexing: Multiplexing is the process of combining the
transmissions from several devices into a single data stream
that can be sent over a single high-seed communication
channel.
• Concentration: Concentration is the process of connecting
and serving the networked devices; a concentrator, often a
computer, provides the concentration.
11. Data Transmission
• Baud Rate: It is the rate at which data are transferred.
Baud is often equated with bits per second (bps).
• Two factors that determine the rate at which data can
be transmitted are the bandwidth of the
communication channel and the method of data
transmission – asynchronous or synchronous.
– Bandwidth of a communication channel determines the
rate, or speed, at which data can be transmitted over that
channel.
– Asynchronous transmission of data is a method that sends
one character at a time.
– In Synchronous transmission, blocks of characters are
transmitted in timed sequences.
12. Application Application
layer layer
Presentation
layer
Presentation
layer
Seven-
Session
layer
Session
layer
layered OSI
Transport
layer
Transport
layer
model for
network
communic
Network Network Network
layer layer layer
Data-link
layer
Data-link
layer Data-link
layer
ations
Physical
Physical layer Physical
layer layer
Host Node Intermediate Nodes User Node
14. Network Architectures
• Broadly there are two types of network
architecture that are being implemented by
most of the organizations.
• Centralized
• Distributed
• Client-Server
15. Network Technologies for Business
• Internet
– Public Network
• Intranet
– Private Network using Internet technologies
• Extranet
– Private-Private Network using Internet
Technologies
16. Summary
• A computer network is created when several computers and other devices, such as printers and secondary
storage devices, are linked together by data communication channels. Each computer or device in a network is
organized as per the topology. Network topologies include a star network, ring network, tree, mesh and bus
network.
• A wide-area network (WAN) consists of two or more computers that are geographically dispersed but are linked
by communication facilities provided by third-party telecommunication service provider, such as the telephone
system or microwave relays.
• A local-area network (LAN) consists of two or more computers directly lined within a small, well-defined area,
such as a room, building, or cluster of buildings.
• There are three basic components to a backbone network; the network cable, wireless and the hardware devices
that connect other network to the backbone. The cable is essentially the same as the one used in LANs, except
that it is usually higher quality to provide higher data rates. The hardware devices include hubs, bridges,
switches, routers, brouters, and gateways.
• Data communication is the process of sending data electronically from one point to another. Using
communication facilities such as the telephone system and microwave relays to send data between computers is
a type of data communication often referred to as telecommunications.
• The transmission of data takes one of the two forms: analog or digital.
• Modulation is the process of converting a digital signal into an analog signal. Demodulation is the process of
converting an analog signal into a digital signal. A modem (modulator-demodulator) is the device that converts
the signals.
• A communication channel is the pathway along which data arc transmitted between devices. The three basic
types of communication channels are wire cable microwave, and fiber optics.
17. Summary
• Multiplexing is the process of combining the transmissions of several computers or other devices so
that the transmissions can share the same communication channel. Concentration allows a
communication chan11el to be connected to and serve more devices than the capacity of that channel
normally allows.
• The baud rate of a communication channel is the number of times per second that the transmitted
signal changes (modulates or demodulates). The bandwidth, or band, of a communication channel
determines the speed at which that channel can transmit data.
• Asynchronous transmission transmits data one character at a time. Synchronous transmission transmits
data as a block of characters in timed sequences. Protocol is the set of rules and procedures defining
the technical details of data transfer between two devices. Data transfer can occur in three modes:
simplex, half-duplex and full-duplex.
• Distributed data processing (DDP) is the concept of dispersing into the areas where the computers,
devices, software, and data are connected through communication channels.
• In C/S architecture, Client is any PC or end-user computer, which is connected using networking
technologies to a Server, which manages the network and also the part of data processing, depending
on how the C/S architecture is configured. C/S architecture can be two-tier, three-tier or n-tier
depending on the size and spread of the organization.
• Internet, Intranet and Extranet are three technological innovations that most of the organization in the
world stared using. Internet is a universal network that allows anyone to everyone a free and easy
access. It is a public network. Intranet is a private internet meant for defined users of an organization.
Extranet is a extended intranet that allows sharing of data across business partners. Both intranet and
extranet uses internet technologies, which means they are created using TCP/IP.