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INFS 211:
Introduction to Information
Technology
Session 4 – Computer networking
Lecturer: Dr. Ebenezer Ankrah, Dept. of Information Studies
Contact Information: [email protected]
College of Education
School of Continuing and Distance Education
2014/2015 – 2016/2017
Session Overview
• Computer networks are everywhere. Actually, the internet is a
large network of networks. A network is a group of two or
more computer systems that are configured to share
information and resources such as printers, files and
databases. Essentially, a network enables computer systems
and other devices to communicate with each other. This
session provides direction to students on the categories of
networks, types of networks, and network topology.
Slide 2
Session Overview
• At the end of the session, the student will
– Understand how client/server network differs from peerto-peer network
– Understand the types of networks.
– Understand the various network topologies
– Understand the various bandwidths.
Slide 3
Session Outline
The key topics to be covered in the session are as follows:
• Network Categories
• Types of Networks
• Network Topology
• Bandwidth
Slide 4
Reading List
• Lucas, H. C. (1997). Information Technology for Management
(6th ed.). R. R. Donnelly & Sons Company. (Chapter 12)
• Williams, B. K., & Sawyer, S. C. (2014). Using Information
Technology: A practical introduction to computers and
communications (11th ed.). McGraw-Hill Education. (Chapter
7)
Slide 5
Topic One
NETWORK CATEGORIES
Slide 6
Network Categories
• A network is a logical extension of a telecommunications
system. Networks link computers and computer devices to
provide for flexible processing. Each computer is supported
by network software that provides the server or client
functionality.
• There are two main types of network categories
which are:
– Server based
– Peer-to-peer
Slide 7
Network Categories
• In a server based network, there are computers set
up to be primary providers of services such as file
service or mail service. The computers providing the
service are called servers and the computers that
request and use the service are called client
computers.
Slide 8
Network Categories
• In a peer-to-peer network, various computers on the
network can act both as clients and servers. For instance,
many Microsoft Windows based computers will allow file
and print sharing. Many networks are combination of
peer-to-peer and server based networks.
• The network operating system uses a network data
protocol to communicate on the network to other
computers. The network operating system supports the
applications on that computer. A Network Operating
System (NOS) includes Windows NT, Novell Netware,
Linux, Unix and others.
Slide 9
Topic Two
TYPES OF NETWORKS
Slide 10
Types of Networks
• A network consists of multiple computers connected using
some type of interface, each having one or more interface
devices such as a Network Interface Card (NIC) and/or a
serial device for PPP networking.
• Networks can be characterized using one or more technical
or operational attributes (e.g., type of technology or
number of connected users and devices).
Slide 11
Types of Networks
• One common attribute used to categorize networks
is geographic area or span, where a network is
labeled on the basis of the physical area it covers.
The five most common types of networks in terms of
geographic area from the smallest to the largest are:
•
•
•
•
•
Personal area networks (PANs).
Local area networks (LANs).
Campus area networks (CANs).
Metropolitan area networks (MANs).
Wide area networks (WANs).
Slide 12
Types of Networks
• Personal Area Networks (PANs)
• PANs cover areas generally associated with individual
workspaces (e.g., a home, office or an office cubicle).
Within these spaces, individual networks connecting
two or more devices may be enabled using wireless
technologies.
Slide 13
Types of Networks
PAN
Slide 14
Types of Networks
• Local Area Networks (LANs)
• A local area network (LAN) is designed to connect
personal computers and other digital devices within
a half-mile or 500-meter radius. LANs typically
connect a few computers in a small office.
• LANs cover areas generally associated with some or
all of the space within a building. In most cases,
multiple workspace devices are connected to shared
devices (e.g., switches, servers) to form a LAN.
Slide 15
Types of Networks
One LAN can serve a single
department, multiple groups, or
all users within a building.
Cabling, wireless, or a
combination of both can be used
to link LAN devices.
Slide 16
Types of Networks
• Campus Area Networks (CANs)
• CANs are created by linking the LANs located in two
or more buildings that are in close proximity to each
other. Connections between the buildings can be
made using cabling or wireless technologies. Note
that the term campus LAN is also used to describe a
CAN.
Slide 17
Types of Networks
CAN
Slide 18
Types of Networks
• Metropolitan Area Networks (MANs)
• Metropolitan area network (MAN) is a network that
spans a metropolitan area, usually a city and its major
suburbs. Its geographic scope falls between a WAN and
LAN.
• MANs are created by linking the networks located at two
or more sites within a city. Connections can be made
using cabling or wireless technologies, with optical fiber
cabling often used to link a customer’s buildings to a
facility operated by a telecommunications provider.
Slide 19
Types of Networks
MAN
Slide 20
Types of Networks
• Wide Area Networks (WANs)
• Wide area networks (WANs) span broad geographical
distances; Entire regions, states, continents, or the entire
globe. The most universal and powerful WAN is the
Internet.
• Computers connect to a WAN through systems, such as
telephone systems, cable systems and satellites. WANs
are created by linking the networks located at two or
more sites over geographic distances that extend beyond
the span of a single metropolitan area.
Slide 21
Types of Networks
These include links between
cities, countries, and in the
case of global WANs,
continents.
Telecommunications circuits
link each building to facilities
operated by a
telecommunication provider.
Slide 22
Topic Three
NETWORK TOPOLOGY
Slide 23
Network Topology
• Network topology is a model that describes how a
network is structured or configured. The network
topology describes the method used to carry out
the physical wiring of the network. There are three
major topologies, namely:
– Bus topology
– Ring topology
– Star topology
Slide 24
Network Topology
• Bus Topology
• In a bus topology, one station transmits signals, which
travel in both directions along a single transmission
segment.
• Both ends of the network must be terminated with a
terminator. A barrel connector can be used to extend it.
• All the machines on the network receive the same
signals. Software installed on the clients enables the
client to listen for messages addressed specifically to it.
Slide 25
Network Topology
• Ring Topology
• A ring topology connects network components in a
close loop. Messages pass from computer to
computer in only one direction and around the loop.
Only one station at a time may transmit.
• Devices are connected from one to another, as in a
ring. A data token is used to grant permission for
each computer to communicate.
Slide 26
Network Topology
• Star Topology
• In a star topology, all devices on the network connect
to a single hub. All network traffic flows through the
hub.
Slide 27
Network Topology
Network
Topology
Slide 28
Topic Four
BANDWIDTH
Slide 29
Bandwidth
• The communication speed and capacity of
telecommunications networks can be classified by
bandwidth.
• The bandwidth is the frequency range of a
telecommunication channel. It determines the channel’s
maximum transmission rate.
• The speed and capacity of data transmission rates are
typically measured in bits per second (BPS). The types of
bandwidths are; Narrow-band, Medium-band and
Broadband
Slide 30
Bandwidth
• Narrow-band
– Narrow-band channels typically provide low-speed
transmission rate (64K -2M BPS).
– Usually unshielded twisted-pair lines are used.
– Commonly used for telephone voice communication and
for data communication.
• Medium-band
– Medium-band uses shielded twisted-pair lines for
transmission.
– Speed up to 100MBPS.
Slide 31
Bandwidth
• Broadband
• Broadband channels typically provide high-speed
transmission rates at intervals from 256,000 BPS to
several billion BPS.
• They are use in microwave, fiber optics or satellite
transmissions.
Slide 32
References
• French, C. S. (2001). Data processing and information technology
(10th ed.). London, Continuum: Sage Publications Ltd.
• Hutchinson, S. E., & Sawyer, S. C. (2000). Computers,
communication and information: A user’s introduction (7th ed.).
Boston: Irwin McGraw-Hill.
• O’Leary, T. J. (2004). Computing today. Boston: McGraw Hill.
• O’Leary, T. J., & O’Leary, L. I. (2005). Computing Essentials.
Boston: McGraw Hill.
• Thompson, R. L., & Cats-Bail, W. L. (2003). Information
technology and management (2nd ed.). Boston: Irwin McGrawHill.
• Williams, et al (2003). Using information technology: a practical
introduction of computers and communications. Boston:
McGraw-Hill.
Slide 33