Computer Network | Prepared by: Ashish Kr. Jha
Chapter 1
Introduction to computer Network
The concept of Network is not new. In simple terms it means an interconnected set of some
objects. For decades we are familiar with the Radio, Television, railway, Highway, Bank and
other types of networks. In recent years, the network that is making significant impact in our
day-to-day life is the Computer network. By computer network we mean an interconnected set
of autonomous computers. The term autonomous implies that the computers can function
independent of others. However, these computers can exchange information with each other
through the communication network system. Computer networks have emerged as a result of
the convergence of two technologies of this century- Computer and Communication as shown
in Fig. 1.1. The consequence of this revolutionary merger is the emergence of an integrated
system that transmit all types of data and information. There is no fundamental difference
between data communications and data processing and there are no fundamental differences
among data, voice and video communications.
Figure 1.1: Evolution of Network
1. Definition:
A computer network is a set of connected computers. Computers on a network are
called nodes. The connection between computers can be done via cabling, most
commonly the Ethernet cable, or wirelessly through radio waves. Connected computers
can share resources, like access to the Internet, printers, file servers, and others. A
network is a multipurpose connection, which allows a single computer to do more.
A computer network, or data network, is a digital telecommunications network which
allows nodes to share resources. In computer networks, computing devices exchange
data with each other using connections (data links) between nodes. These data links are
[1]
, Computer Network | Prepared by: Ashish Kr. Jha
Established over cable media such as wires or optic cables, or wireless media such as
WiFi.
Network computer devices that originate, route and terminate the data are called
network nodes. Nodes can include hosts such as personal computers, phones, servers as
well as networking hardware. Two such devices can be said to be networked together
when one device is able to exchange information with the other device, whether or not
they have a direct connection to each other. In most cases, application-specific
communications protocols are layered (i.e. carried as payload) over other more general
communications protocols. This formidable collection of information technology
requires skilled network management to keep it all running reliably.
Computer networks support an enormous number of applications and services such as
access to the World Wide Web, digital video, digital audio, shared use of application
and storage servers, printers, and fax machines, and use of email and instant messaging
applications as well as many others. Computer networks differ in the transmission
medium used to carry their signals, communications protocols to organize network
traffic, the network's size, topology, traffic control mechanism and organizational
intent. The best-known computer network is the Internet.
Advantages of Computer Networking
1. It enhances communication and availability of information.
Networking, especially with full access to the web, allows ways of communication
that would simply be impossible before it was developed. Instant messaging can now
allow users to talk in real time and send files to other people wherever they are in the
world, which is a huge boon for businesses. Also, it allows access to a vast amount
of useful information, including traditional reference materials and timely facts, such
as news and current events.
2. It allows for more convenient resource sharing.
This benefit is very important, particularly for larger companies that really need to
produce huge numbers of resources to be shared to all the people. Since the
technology involves computer-based work, it is assured that the resources they
wanted to get across would be completely shared by connecting to a computer
network which their audience is also using.
3. It makes file sharing easier.
Computer networking allows easier accessibility for people to share their files,
which greatly helps them with saving more time and effort, since they could do file
sharing more accordingly and effectively.
4. It is highly flexible.
This technology is known to be very flexible, as it gives users the opportunity to
explore everything about essential things, such as software without affecting their
functionality. Plus, people will have the accessibility to all information they need to
get and share.
[2]
, Computer Network | Prepared by: Ashish Kr. Jha
5. It is an inexpensive system.
Installing networking software on your device would not cost too much, as you are
assured that it lasts and can effectively share information to your peers. Also, there is
no need to change the software regularly, as mostly it is not required to do so.
6. It increases cost efficiency.
With computer networking, you can use a lot of software products available on the
market which can just be stored or installed in your system or server, and can then be
used by various workstations.
7. It boosts storage capacity.
Since you are going to share information, files and resources to other people, you
have to ensure all data and content are properly stored in the system. With this
networking technology, you can do all of this without any hassle, while having all
the space you need for storage.
Disadvantages of Computer Networking
1. It lacks independence.
Computer networking involves a process that is operated using computers, so people
will be relying more of computer work, instead of exerting an effort for their tasks at
hand. Aside from this, they will be dependent on the main file server, which means
that, if it breaks down, the system would become useless, making users idle.
2. It poses security difficulties.
Because there would be a huge number of people who would be using a computer
network to get and share some of their files and resources, a certain user’s security
would be always at risk. There might even be illegal activities that would occur,
which you need to be careful about and aware of.
3. It lacks robustness.
As previously stated, if a computer network’s main server breaks down, the entire
system would become useless. Also, if it has a bridging device or a central linking
server that fails, the entire network would also come to a standstill. To deal with
these problems, huge networks should have a powerful computer to serve as file
server to make setting up and maintaining the network easier.
4. It allows for more presence of computer viruses and malware.
There would be instances that stored files are corrupt due to computer viruses. Thus,
network administrators should conduct regular check-ups on the system, and the
stored files at the same time.
5. Its light policing usage promotes negative acts.
It has been observed that providing users with internet connectivity has fostered
undesirable behavior among them. Considering that the web is a minefield of
distractions—online games, humor sites and even porn sites—workers could be
[3]
, Computer Network | Prepared by: Ashish Kr. Jha
tempted during their work hours. The huge network of machines could also
encourage them to engage in illicit practices, such as instant messaging and file
sharing, instead of working on work-related matters. While many organizations draw
up certain policies on this, they have proven difficult to enforce and even engendered
resentment from employees.
6. It requires an efficient handler.
For a computer network to work efficiently and optimally, it requires high technical
skills and know-how of its operations and administration. A person just having basic
skills cannot do this job. Take note that the responsibility to handle such a system is
high, as allotting permissions and passwords can be daunting. Similarly, network
configuration and connection is very tedious and cannot be done by an average
technician who does not have advanced knowledge.
7. It requires an expensive set-up.
Though computer networks are said to be an inexpensive system when it is already
running, its initial set up cost can still be high depending on the number of
computers to be connected. Expensive devices, such as routers, switches, hubs, etc.,
can add up to the cost. Aside from these, it would also need network interface cards
(NICs) for workstations in case they are not built in.
Applications
In a short period of time computer networks have become an indispensable part of
business, industry, entertainment as well as a common-man's life. These applications
have changed tremendously from time and the motivation for building these networks
are all essentially economic and technological.
Initially, computer network was developed for defense purpose, to have a secure
communication network that can even withstand a nuclear attack. After a decade or so,
companies, in various fields, started using computer networks for keeping track of
inventories, monitor productivity, communication between their different branches
offices located at different locations. For example, Railways started using computer
networks by connecting their nationwide reservation counters to provide the facility of
reservation and enquiry from anywhere across the country.
And now after almost two decades, computer networks have entered a new dimension;
they are now an integral part of the society and people. In 1990s, computer network
started delivering services to private individuals at home. These services and
motivation for using them are quite different. Some of the services are access to remote
information, person-person communication, and interactive entertainment. So, some of
the applications of computer networks that we can see around us today are as follows:
Marketing and sales: Computer networks are used extensively in both marketing and
sales organizations. Marketing professionals use them to collect, exchange, and analyze
data related to customer needs and product development cycles. Sales application
includes teleshopping, which uses order-entry computers or telephones connected to
order processing network, and online-reservation services for hotels, airlines and so on.
[4]
Chapter 1
Introduction to computer Network
The concept of Network is not new. In simple terms it means an interconnected set of some
objects. For decades we are familiar with the Radio, Television, railway, Highway, Bank and
other types of networks. In recent years, the network that is making significant impact in our
day-to-day life is the Computer network. By computer network we mean an interconnected set
of autonomous computers. The term autonomous implies that the computers can function
independent of others. However, these computers can exchange information with each other
through the communication network system. Computer networks have emerged as a result of
the convergence of two technologies of this century- Computer and Communication as shown
in Fig. 1.1. The consequence of this revolutionary merger is the emergence of an integrated
system that transmit all types of data and information. There is no fundamental difference
between data communications and data processing and there are no fundamental differences
among data, voice and video communications.
Figure 1.1: Evolution of Network
1. Definition:
A computer network is a set of connected computers. Computers on a network are
called nodes. The connection between computers can be done via cabling, most
commonly the Ethernet cable, or wirelessly through radio waves. Connected computers
can share resources, like access to the Internet, printers, file servers, and others. A
network is a multipurpose connection, which allows a single computer to do more.
A computer network, or data network, is a digital telecommunications network which
allows nodes to share resources. In computer networks, computing devices exchange
data with each other using connections (data links) between nodes. These data links are
[1]
, Computer Network | Prepared by: Ashish Kr. Jha
Established over cable media such as wires or optic cables, or wireless media such as
WiFi.
Network computer devices that originate, route and terminate the data are called
network nodes. Nodes can include hosts such as personal computers, phones, servers as
well as networking hardware. Two such devices can be said to be networked together
when one device is able to exchange information with the other device, whether or not
they have a direct connection to each other. In most cases, application-specific
communications protocols are layered (i.e. carried as payload) over other more general
communications protocols. This formidable collection of information technology
requires skilled network management to keep it all running reliably.
Computer networks support an enormous number of applications and services such as
access to the World Wide Web, digital video, digital audio, shared use of application
and storage servers, printers, and fax machines, and use of email and instant messaging
applications as well as many others. Computer networks differ in the transmission
medium used to carry their signals, communications protocols to organize network
traffic, the network's size, topology, traffic control mechanism and organizational
intent. The best-known computer network is the Internet.
Advantages of Computer Networking
1. It enhances communication and availability of information.
Networking, especially with full access to the web, allows ways of communication
that would simply be impossible before it was developed. Instant messaging can now
allow users to talk in real time and send files to other people wherever they are in the
world, which is a huge boon for businesses. Also, it allows access to a vast amount
of useful information, including traditional reference materials and timely facts, such
as news and current events.
2. It allows for more convenient resource sharing.
This benefit is very important, particularly for larger companies that really need to
produce huge numbers of resources to be shared to all the people. Since the
technology involves computer-based work, it is assured that the resources they
wanted to get across would be completely shared by connecting to a computer
network which their audience is also using.
3. It makes file sharing easier.
Computer networking allows easier accessibility for people to share their files,
which greatly helps them with saving more time and effort, since they could do file
sharing more accordingly and effectively.
4. It is highly flexible.
This technology is known to be very flexible, as it gives users the opportunity to
explore everything about essential things, such as software without affecting their
functionality. Plus, people will have the accessibility to all information they need to
get and share.
[2]
, Computer Network | Prepared by: Ashish Kr. Jha
5. It is an inexpensive system.
Installing networking software on your device would not cost too much, as you are
assured that it lasts and can effectively share information to your peers. Also, there is
no need to change the software regularly, as mostly it is not required to do so.
6. It increases cost efficiency.
With computer networking, you can use a lot of software products available on the
market which can just be stored or installed in your system or server, and can then be
used by various workstations.
7. It boosts storage capacity.
Since you are going to share information, files and resources to other people, you
have to ensure all data and content are properly stored in the system. With this
networking technology, you can do all of this without any hassle, while having all
the space you need for storage.
Disadvantages of Computer Networking
1. It lacks independence.
Computer networking involves a process that is operated using computers, so people
will be relying more of computer work, instead of exerting an effort for their tasks at
hand. Aside from this, they will be dependent on the main file server, which means
that, if it breaks down, the system would become useless, making users idle.
2. It poses security difficulties.
Because there would be a huge number of people who would be using a computer
network to get and share some of their files and resources, a certain user’s security
would be always at risk. There might even be illegal activities that would occur,
which you need to be careful about and aware of.
3. It lacks robustness.
As previously stated, if a computer network’s main server breaks down, the entire
system would become useless. Also, if it has a bridging device or a central linking
server that fails, the entire network would also come to a standstill. To deal with
these problems, huge networks should have a powerful computer to serve as file
server to make setting up and maintaining the network easier.
4. It allows for more presence of computer viruses and malware.
There would be instances that stored files are corrupt due to computer viruses. Thus,
network administrators should conduct regular check-ups on the system, and the
stored files at the same time.
5. Its light policing usage promotes negative acts.
It has been observed that providing users with internet connectivity has fostered
undesirable behavior among them. Considering that the web is a minefield of
distractions—online games, humor sites and even porn sites—workers could be
[3]
, Computer Network | Prepared by: Ashish Kr. Jha
tempted during their work hours. The huge network of machines could also
encourage them to engage in illicit practices, such as instant messaging and file
sharing, instead of working on work-related matters. While many organizations draw
up certain policies on this, they have proven difficult to enforce and even engendered
resentment from employees.
6. It requires an efficient handler.
For a computer network to work efficiently and optimally, it requires high technical
skills and know-how of its operations and administration. A person just having basic
skills cannot do this job. Take note that the responsibility to handle such a system is
high, as allotting permissions and passwords can be daunting. Similarly, network
configuration and connection is very tedious and cannot be done by an average
technician who does not have advanced knowledge.
7. It requires an expensive set-up.
Though computer networks are said to be an inexpensive system when it is already
running, its initial set up cost can still be high depending on the number of
computers to be connected. Expensive devices, such as routers, switches, hubs, etc.,
can add up to the cost. Aside from these, it would also need network interface cards
(NICs) for workstations in case they are not built in.
Applications
In a short period of time computer networks have become an indispensable part of
business, industry, entertainment as well as a common-man's life. These applications
have changed tremendously from time and the motivation for building these networks
are all essentially economic and technological.
Initially, computer network was developed for defense purpose, to have a secure
communication network that can even withstand a nuclear attack. After a decade or so,
companies, in various fields, started using computer networks for keeping track of
inventories, monitor productivity, communication between their different branches
offices located at different locations. For example, Railways started using computer
networks by connecting their nationwide reservation counters to provide the facility of
reservation and enquiry from anywhere across the country.
And now after almost two decades, computer networks have entered a new dimension;
they are now an integral part of the society and people. In 1990s, computer network
started delivering services to private individuals at home. These services and
motivation for using them are quite different. Some of the services are access to remote
information, person-person communication, and interactive entertainment. So, some of
the applications of computer networks that we can see around us today are as follows:
Marketing and sales: Computer networks are used extensively in both marketing and
sales organizations. Marketing professionals use them to collect, exchange, and analyze
data related to customer needs and product development cycles. Sales application
includes teleshopping, which uses order-entry computers or telephones connected to
order processing network, and online-reservation services for hotels, airlines and so on.
[4]
