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Arab Open University - AOU
T209
Information and Communication
Technologies: People and Interactions
Eleventh Session
Prepared by: Eng. Ali H. Elaywe
1
Reference Material
 This session is based on the following
references:
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1- Module 3 (Managing Network)
Companion
2- Book M: Networks for business
3- Part 1 of Book N: Networks
Prepared by: Eng. Ali H. Elaywe
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Topic 1: Brief introduction to Module 3
 This module deals with the study of
Networks and Network Management.
It consists of the following five books:
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1- Book M: Networks for business
2- Book N: Networks
3- Book NM: Network Management
4- Book E: Experiments
5- Book W: Writing Reports
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Topic 2: Book M ( Networks for business )
 Convergence, one aspect of which has resulted in the
combining of an organization’s computing and
telecommunications facilities into a unified network
concept, has brought about many changes in the way
organizations conduct their day-to-day activities

There has also been a transformation in the way organizations
deal with each other and with their clients
 Nicholas Negroponte (Director of MIT Media Laboratory)
places into context the effects he thinks computer networks
will have on organizations:

‘Being digital has three physiological effects on the shape of
our world. It decentralizes, flattens and makes things bigger
and smaller at the same time’
Continue
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 In book M, we will see how and why some of
these changes have taken place. We will do so
by studying the following sub-topics:
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1- Data, information and knowledge
2- Networks and communication
3- The principles of management
4- The structure of business organizations
5- The basics of interworking
6- Computer network management
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Sub-Topic 2.1: Organizational Information
 Orgnization:
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The term organization can be applied to any of the following:
business, charity, company, corporation, enterprise, firm,
institution, multinational, office, shop or store
Within this module the organization consist of people (no more
than a hundred people), artefacts and procedures, integrated
in such a way as to achieve the organizational goals
In order for any organization to function gainfully and
efficiently, it is necessary for it to have a source of reliable
information

Access to information will be vital in determining how well the
organization performs in the outside world
Continue
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 Data:

The British Computer Society’s Glossary of Computing
Terms (1988) defines data in computing as:
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‘data is the coded representation of information, which may
be stored, retrieved, transferred and processed by
computers’
The binary code can use the digits 0 and 1 to represent the
data:
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Binary code is used to store data within computers and
transfer data over computer networks
Whilst data was being transferred you would see endless
sequence of binary digits (0 and 1) this is called binary bitstream
 For example: 1100010000000000001000000101011011111111011
Continue
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 Information:
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Information is the interpretation or meaning attached to
data, i.e. words, figures, pictures, etc
 Knowledge:
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Knowledge is associated with people and expresses what
they know and understand
Knowledge and information often appear as
interchangeable terms
All organizations have valuable knowledge about their
commercial activities locked away in people’s minds
The key to organizational success is to share this knowledge
by providing the appropriate processes and technology
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Sub-Topic 2.2: Networks for communication
 Here we are going to look at what constitutes a
communications network and see how organizations
are able to use networks for communicating and
sharing data, information and knowledge
 A network is made up from elements which have
similar characteristics, although they do not
necessarily have to be identical
 The elements of the network are nodes, which may be
thought of as either a meeting-place of links or a point of
interconnection
 Links connect nodes as illustrated in Figure 1
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Link
Node
Figure1 An example of a network
Continue
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 Networking
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Networking supports the dissemination of
knowledge and information between individuals,
who are able to co-operate to make the most of their
experiences for the benefit of themselves and their
organizations. This is a most important feature of
networking within today’s organizations
Today, much of what we think of as business
networking uses telephone and voice-mail, e-mail
and computer conferencing, although many of us
still prefer and. enjoy face-to-face meetings
Continue
Prepared by: Eng. Ali H. Elaywe
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 Computer Networks
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A group of computers, along with other associated
network elements, can be connected together to
form a computer network
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This makes the exchange of information easier, faster and
generally more reliable
Furthermore, we have the opportunity to share the
resources that are connected to the network
including an opportunity to backup our personal
information onto a server
Server is a fast computer that holds applications,
and data files shared by the users on a network
Continue
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
Activity 5 (exploratory)

What about the sorts of resources you would like to
have the opportunity to access?
 1- High quality printers
 2- Access to database servers
 3- Electronic mail facilities
 4- Secure back-up facilities
Continue
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
What advantages do you see from sharing these
resources?
 1- Sharing high quality, fast printers with a range of
features would generally be more cost-effective than
providing lesser-quality network elements to individual
users
 2- Access to database servers allows the sharing of
information to all those who need it
 3- Electronic mail facilities improve organizational
communication
 4- Networked data storage facilities are usually more
reliable and secure than local storage methods
Continue
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The growth in the use of computer networks means
that more and more organizations are looking to
inter-network with each other
Inter-networking in a business context means
undertaking commerce between organizations, and
with their customers, using both private and public
networks
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The B2B acronym is used to mean business-to-business
commerce, e.g. with suppliers
B2C is used for business to customer commerce, e.g. sales
and support
Continue
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 Types of Computer Networks (used by
Organizations)
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A- Intranet
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Which has been coined to describe a private network that has
the look and feel of the Web. It is accessed through a
browser and can offer similar multimedia facilities, but is
only used within a single organization
B- Extranet

An extranet has similar properties to an intranet but
extends its facilities to a group of related organizations with
business connections
Continue
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 The advantages to organizations of using
computer networks include:
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1- More efficient use of resources through sharing
network elements such as printers and scanners
2- Purchasing networked application software,
which may be more economical than buying
individual software packages
3- Access to multiple sources of information
4- Ability to transfer information across the network
Continue
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5- Opportunity for collaborative work using e-mail
and conferencing facilities and to keep employees
informed of the organization’s business through an
intranet
6- Remote access to the organization by customers,
suppliers and field workers through an extranet
 Now that we have seen the advantages that a
computer network brings to an organization,
we will look at how a networked organization
is managed
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Sub-Topic 2.3: Organizational
management
 A manager is someone who manages things
 Management Role
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Consists of three major tasks: monitoring, planning
and reporting
However, the central function of a manager is to
make and implement decisions
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To do this relevant information, gathered as a result of
communication, combined with appropriate task
procedures enables a decision to be made and
implemented
Figure 2 shows a management role
Continue
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Figure 2 Management role
Continue
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 Activity 7 (self-assessment)
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how the tasks of monitoring, planning and reporting
maybe applied to the management of computer
networks?
I see three tasks of a network manager comprising
the following:
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1- Monitoring – the operation of the network to see where
improvements to the service might be made. This will
include communication with users
2- Planning – enhancements to the network to improve the
service to the users
3- Reporting – to others within the organization on the state
of the network
Continue
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 Decision-making process
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The decision-making process is at the heart of the
management function
Decisions should focus on the well-being and success of the
organization rather than the individual
In order to make successful decisions, access to reliable
information and good communication is necessary and
computer networks help to meet this requirement
However, computer networks also need to provide selfinformation if they, in turn, are to be well managed and
monitoring, planning and reporting are vital to the network
management role
Continue
Prepared by: Eng. Ali H. Elaywe
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
Decision-making is hierarchical in nature

Figure 3 illustrates a hierarchical structure showing
roles within an organization:
 Strategic decisions are made at the top of the
organization
 decisions of a non-routine and non-recurring
nature with inherent uncertainty in the outcome
would be made by middle and upper level
management
 leaving routine day to day decisions to lower
levels of management
Continue
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Figure 3 An example of a managerial structure
Continue
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
Management decisions maybe brought
about through a dynamic and interrelated
process comprising of six decision-making
functions. A model describing these
functions is shown in Figure 4

The decision-making process starts with the
setting of objectives and is completed when these
objectives are achieved
Continue
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Figure 4 A model of the managerial decision-making process
(after Harrison and Peletier)
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Sub-Topic 2.4: Business
Organizations
 Managers and organizations work together in a
shared process
 Organizations consist of people who, with the
aid of technology and procedures, aim to achieve
the objectives of the organization
 In this sub-topic, we are going to see how
organizations are structured
 We will then look at how computer networks
have affected the structure and information
flow within organizations
Continue
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Sub-Sub-Topic 2.4.1: The network
approach
 Activity 10 (self-assessment)
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What do we call a structure that consists of interconnected
nodes?
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The structure is called a network. So, we may think of an
organization as having a network type structure
Within any organization, there will be sub-organizations –
groups or divisions of people, often referred to as departments
or units
A sub-organization may be thought of as a node within the
organization
 For example, the sales, finance and manufacturing groups in
an organization may be thought of as nodes
In order that these nodes may communicate, they are
connected to other nodes that makes a network
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 The action of breaking down a network into individual,
but interconnected, nodes is known as decomposition
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Why the decomposition is important? because an
organization is a complex network. In order to
understand how the sub-organizations interact, the
organization has to be decomposed in order to identify
the managed parts, nodes, links and interfaces
 The rail network may be accessed through railway
stations and the airline networks via airports. Such
places act as interfaces between the individual
networks. Without these interfaces, amalgamation of the
various networks would not be possible and we could not
have an integrated transport network
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Sub-Sub-Topic 2.4.2: Organizational
Structures
 A- Hierarchical Organization
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Historically, the structure of organizations was
hierarchical, as illustrated in Figure 5
Members of the organization were ranked in
authority relative to one another
Ultimate authority and responsibility lies at the top
in the organization, as shown in Figure 5a
Information flows up and down through
successions of layers or levels. Hierarchies can
work well in the absence of plentiful information,
because those of lower rank, without access to
information, merely follow orders Continue
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 B- Flattened Organization
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A computer network makes it easier for information
to flow both within the organization and to the
community in which the organization exists
The ease of distribution of information has caused
relationships within the organization to become
more peer-like, that is of equal rank, with members of
the organization treated alike
This leads to a flattened organization, as illustrated
in Figure 5b, with fewer layers of management but
having a broader span of control than in the
hierarchical structure
Continue
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 C- Network Organization
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However, building on the ideas of networks, it is
quite feasible to consider the organizational
structure as a network, as illustrated in Figure 5c
With the manager allowing situational leadership to
occur based upon which node of the network is best
suited to solve the problem
Information flows between all the nodes within the
network organization
Continue
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
The key to the network organization is one of
employee empowerment
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Here autonomous, self-directed teams make their
own decisions building upon the ready flow of
information provided by the computer networks
which they use as part of their work. As an
organizational programme, empowering
employees means that they have permission to
develop and utilize their skills and knowledge to
their full potential for the good of the organization
and themselves
Continue
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Figure 5 Examples of three different organizational
structures
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Sub-Sub-Topic 2.4.3: Information
flows
 Information flow within an organization is between users.
To aid our understanding of how information flows, we
will develop the concepts of vertical and horizontal flow:
 A- Vertical flow
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Vertical flow will be between different layers within the hierarchy
(see Figure 6)
Information can flow vertically following the lines of the
managerial reporting structure staying within the department or
unit
This notion is illustrated in Figure 7 showing that each node
(manager) is communicating information to and from several
subordinate nodes (lower levels)
This vertical flow is used essentially to manage the suborganization in which the flow of information is active
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Figure 6 Information flow
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Figure 7 Vertical information flow
Continue
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 B- Horizontal information flow:
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Information flow should be horizontally between equivalent
layers of functionally (i.e. managerial, supervisory or
operational) dependant nodes or peer groups, i.e. groups of
similar status or role (see Figure 6)
This leads to cross-functional activities whereby suborganizations interface with each other at their particular layer
For a business to function efficiently and effectively information
must cross departmental boundaries horizontally, as shown in
Figure 8, production to distribution, sales to production to finance,
etc
Continue
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Figure 8 Business processes crossing functional
boundaries (after Messerschmitt)
Continue
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 Important Notes
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The vertical dimension focuses on departmental
specialization, i.e. sales, finance, production, etc. However,
for a business to function efficiently and effectively
information must cross departmental boundaries horizontally,
as shown in Figure 8, production to distribution, sales to
production to finance, etc
Computer networks sustain horizontal data flow, allowing
information exchange between departmental peers. This has
benefited both the employees, who became empowered by
access to information, and the clients, who get a better
service
We will now see how computer networks are implemented within
organizations
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Sub-Topic 2.5: Internetworking
 Interworking takes place when components and
systems, often from different vendors, work together
to perform some task. Successful interworking
depends crucially on standards
 Standards are ways of working agreed by manufacturers,
institutes and even governmental organizations. Among
many other things, standards define the interfaces and
links between network elements
 standard network protocols are rules governing the
transmission and reception of data. Later on, we will
look at standards as they relate specifically to
networking, and how protocols and layered
architecture have evolved
Continue
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 We shall be involving four aspects of networking
functionality:
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A- Connectivity is the ability of the network to move
information from one point to another, regardless of the
technologies used, by making the links and ensuring the
integrity of the information
B- Interoperability is the ability of network elements, the
generic name given to items of equipment on a network from
any manufacturer, to exchange information
C- Client/server applications are network-wide
applications for users including e-mail, file transfer and
Internet access
D- Manageability provides the network manager with the
support to operate the network
Continue
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 Voice over Internet Protocol
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Today, computer networks are part of an
organization’s communications infrastructure
alongside voice and fax services
In some cases, the computer network has
integrated these functions as well, with services
such as Voice over Internet Protocol (VoIP)
appearing. This is an emerging technology that
allows telephone calls to be transmitted over an
existing computer network
Continue
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 Activity 13 (self-assessment)
 1- What do you think is the benefit to an
organization of implementing VoIP?
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The major benefit to an organization of implementing VoIP is
that of economy, as only one network is being used to supply
both telephony (voice) and computer (information) services
to the users. Many organizations currently have two separate
networks, one for the telephone service, and the other for
computers
Each requires a separate infrastructure to support it and
individual installation and maintenance personnel to maintain
the service, thus duplicating costs
Continue
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2- Can you think of a reason why you
would not want to use VoIP?
A- The failure of the network infrastructure would mean the
organization would have no communication system. This
might occur as a result of fire or vandalism
B- The implementation of leading-edge technology is often
problematic. The existing network infrastructure would be
designed for transfer of data and despite the article’s
confidence about the ability of the network to handle the
voice traffic, more research and experience is needed
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Sub-Sub-Topic 2.5.1: Protocols and
layered architecture
 Network Protocols
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For network elements to communicate with each other they
must use a common set of rules just as we do when talking to
each other. These rules and procedures controlling transmission
across a network are called network protocols
The principal function of protocols on computer networks is
to allow fair access to all users of the network
Other functions of protocols are to identify each element on
the network, to secure the attention of the other device, to
verify the correct receipt of the transmitted information and
to undertake a recovery procedure when an error is detected
Continue
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
Networks typically have hardware and software from
many different manufacturers which must interwork
with each other
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This means that they must ‘speak the same language’ and
follow the same protocols
So the network protocols are international standards
 Layered Architecture
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The idea of layered architecture has been formalized
in the Reference Model of Open Systems
Interconnection (OSI)
The OSI model has seven layers, each of which has
a well-defined function and is illustrated in Figure 9
Continue
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Figure 9 The OSI Reference Model
Continue
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Sub-Sub-Topic 2.5.2: A
communications model
 A summary of the seven layers follows:
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Layer 1: physical layer. Concerned with the transmission
of bits, dealing with the necessary interfacing, providing
mechanical, electrical and functional characteristics to
access the physical medium
Layer 2: data-link layer. Provides reliable means of
transmission of the data across the physical link between
two network elements. It deals with any errors that may
have occurred during the transmission and
acknowledges the receipt of the data
Layer 3: network layer. Establishes, maintains and
terminates the communication of the data between one
network computer and another
Continue
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Layer 4: transport layer. Provides networkindependent end-to-end control of the communication
session once the path has been established. Basically,
this layer acts as the liaison between the user and the
network
Layer 5: session layer. Responsible for establishing,
maintaining and breaking sessions in an orderly manner.
The protocol manages the complete dialogue
between the user applications
Layer 6: presentation layer. Concerned with the
interpretation of the data between the two
corresponding application layer protocols so that the
structure of the data is preserved
Continue
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
Layer 7: application layer. Provides support to the user
applications such as file transfer, remote file access,
print access and e-mail relay. It also manages
communication between applications
 Each layer adds or removes information depending on
whether it is at the sender or the receiver

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Each layer adds appropriate information to the message
as it is passed from layer 7 down to layer 1 (in sending
process)
Following transmission (sending), this information is
stripped away (in receiving process) as the message is
passed up from layer 1 to layer 7 (in receiving process)
Continue
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 This means that virtual links may be said
to exist between equivalent layers of the
sender and receiver ends providing
complementary services

So that for example in Figure 9 the transport
layer of system A has a virtual
communications link to the transport layer of
system B
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Sub-Topic 2.6: Network
Manageability
 Network management is an engineering discipline
embedded in the development of computer networks and
telecommunications systems
 Network management aims at achieving or balancing the
often-contradictory goals of those involved in using the
systems against those providing the services
 All seven layers of the OSI model are involved in
management aspects of the network. The scope of the OSI
‘Framework for Network Management’ covers the following
five major network management activities:(see Figure 10)
Continue
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Figure 10 Network management functions
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1- Accounting management: provides information
that indicates resource usage by a user or group of
users. This information would be used for planning
purposes rather than for billing the users, although
as most departments within organizations are costcentres, billing may become the norm
2- Configuration management: provides facilities
for setting network parameters, initializing and
changing the system set-up and collecting
information about the network
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3- Fault management: includes the detection, diagnosis
and correction of faults. This includes facilities for error
reporting and recording, setting threshold limits which
determine when problems should be reported, and
observing the use of particular transmission links
4- Performance management: activities are aimed at
providing an indication as to how well the network is
able to perform its intended functions. For example an
indication of how long a message takes to be received
and how much of the network capacity is being used
by active applications are just two of the many statistics
that may be measured
Continue
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
5- Security management: controls access
to the network, and protects both the network
and the management systems from abuse,
either accidental or intentional,
unauthorized access and loss of messages
or information during transfer on the
network
Continue
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 Alongside these five categories, the following
activities also need to be considered:
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1- Planning covers the requirements for installation and
upgrades to the network in response to organizational forecasts
and the requirements of the users
2- Material management involves the procurement, control and
distribution of materials used in the installation, operation and
rectification of the network
3- Personnel management plans and controls the activities of
the operations staff who undertake the day-to-day activities on
the network
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Topic 3: Part1 of Book N: Local Area
Networks
 If you are confident with this subject, you should
be able to work through the book N and T209
CD-ROM separately


Try to run four packages which can be accessed via
the T209 CD-ROM ‘home page’
Try to do the activities associated with each package
as they will use animation to get cross ideas that are
much more difficult to explain using text only
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Sub-Topic 3.1: Introduction
 Activity 3 (self-assessment)
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I want to network two computers. What do I need,
in addition to the two computers, to make this
simple network?
A simple point-to-point connection of 2 computers
requires:
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A network interface card (NIC) needs to be provided in each
computer. The NIC provides an interface via a connector on
the back of the computer. Suitable cables can then be
‘plugged’ into this connector to join the computers together
Software is also necessary to operate the network protocols,
but I have not covered this yet
Continue
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 Reasons for linking computers together:
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1- One reason is to share hardware resources, such
as printers or scanners
2- Currently a more important shared resource is data,
normally stored in a distributed database which is
made up from files stored on different computers
linked via a network
3- A third and very significant reason for installing
computer networks is to allow people to
communicate with each other
Continue
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Sub-Sub-Topic 3.1.1: Measuring data

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1- Data communication
 Is a general term used to describe the sending of data over
communication networks
2- Bit-rate
 The number of bits transferred during a given period of time is
called bit-rate, and is usually expressed in bits per second
(bit/s)
3- Bandwidth
 In the digital system: Bandwidth is the maximum bit-rate
that a channel can handle
 Note that the term bandwidth has a different definition for
analogue systems, where it is defined as the difference
between the highest and lowest frequencies present in a
signal
Continue
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
4- Data Transfer Rate
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

data rate = quantity of data to be transferred
time taken for the transfer
time taken for a transfer = quantity of data to be transferred
data rate
A group of eight bits. Octet is used in communications,
and byte is used in computing
Prepared by: Eng. Ali H. Elaywe
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 Activity 7 (exploratory)

A user of a stand-alone personal computer wishes to transfer a 100
Kbyte file onto another stand-alone personal computer in a nearby
building. She copies the file onto a floppy disk, walks to the other
building and copies the file onto the other computer. If it takes her
five minutes to walk from one computer to the other, what is the
effective data rate in bit/s of the ‘communication’ created by her
journey? Assume that 1 byte = 8 bits


The user transfers 100 × 1024 × 8 bits in 5 minutes
So the data transfer rate = 100 × 1024 × 8 bits / 5 × 60 seconds
= 2730 bit/s = 2.73 kbits/s
Prepared by: Eng. Ali H. Elaywe
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 Activity 8 (self-assessment)

How long would it take to transfer the same 100 Kbyte file
over a link with a bandwidth of 10 Mbit/s?

time taken for a transfer = quantity of data to be transferred
data rate
= 100 × 1024 × 8 bits = 0.08192 s
10 × 106 bit/s
= 81.92 ms

This answer makes no allowance for the time taken to send
the header portion of each frame, so in practice the time
taken might be longer, perhaps 90 ms
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Sub-Sub-Topic 3.1.2: Connecting
computers
 Network Types:

1- Local Area Network (LAN)


A collection of computers which are reasonably closely located
(e.g. within a building or a group of buildings on one site) can
be connected together to form a local area network (LAN)
2- Wide Area Network (WAN)


If the computers are far apart, perhaps in different parts of the
country, or in different countries, the network connecting them
is described as a wide area network (WAN)
WANs can also be used to connect a number of
geographically separated LANs
Continue
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
3- The Inter-network (or Internet)


These different kinds of networks – LANs and WANs – can all be
connected together to form a ‘network of networks’, described as
an inter-network
The Internet (with a capital I) is one (very large) internetwork
 Concept of Medium:


Many different types of medium are used to connect computers
We usually think of connections as some kind of ‘wire’, such as:




Optical-fiber
Co-axial cable
Twisted pair
But computers can also be connected using ‘wireless’
communication, for instance microwave or infra-red links
Continue
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 Network Topologies:

1- Star Network


In a network of computers with a star topology, each computer has
its own link to a central point, called a hub (Figure 11a)
2- Mesh Network


If we wished to add more computers we could connect each new
one to each of the others, to form a fully connected mesh (Figure
11b)
As more computers are added, the number of links required can
become very large. But it is not necessary to have point-to-point
connections between all the computers, because communication can
go between two computers via others
Continue
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Figure 11 Network topologies
Prepared by: Eng. Ali H. Elaywe
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69

3- Ring Network


Here each computer is connected to just two neighbours.
Communications are passed from computer to computer
around the ring (Figure 11c). Some local area networks use
a ring topology
4- Tree Network


Another arrangement which relies on communication via
intermediate computers is a tree (Figure 11d). This topology
is usually drawn as an upside-down tree. One computer forms
the ‘root’, and there are links to other computers branching
from it
Communications between computers travel up and down the
branches of the (inverted) tree
Continue
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
5- Bus Network


You can imagine this as a piece of cable with computers
connected to it at intervals. When one computer needs to
communicate with another it sends a signal onto the cable (the
bus) and that signal is then available to all the other
computers (Figure 11e)
The bus topology was originally used on Ethernet LANs,
but is rapidly being replaced by a topology based around
hubs, as you will see shortly
Continue
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 Activity 9 (exploratory)



How many links are required to fully mesh:
(a) 4 computers, 5 computers, 6 computers
(b) 100 computers? (See if you can deduce a
formula)




Suppose that (n) is the number of nodes (computers)
number of links = n(n-1)/2
(a) if n = 4 then the number of links = 4(4-1)/2 = 12/2 = 6
(b) For 100 computers (n = 100), the number of connections is:
100 x (100 – 1)/ 2 = 100 x 99 / 2 = 4950
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 Important Note

Connecting a large number of computers in a
mesh soon becomes impractical. LANs are
designed to support many users, so the idea
of sharing a channel (rather than fully
meshing things) is central to the protocols
used in local area networks
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Topic 4: Preparation for Next Session







1) Read Book M
2) Must read Part1 and Part 2 in Book N
3) See the computer animations in the electronic
version of Part1 and Part 2 in Book N (in T209CD-ROM-1)
4) Do associate activities
5) Complete the associate Journal items
6) Contribute to the your tutor group conference
7) Read the TMA03 and prepare questions to be
addressed in the next meeting or preferably in the
conference
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