Computer Networks By NADEEM AHMED

NADEEM AHMED
Computer Networks

What is computer network?
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.

Problems in computer network and its solution
Problems
Solution IPAddress and
Network Card Issues
Network Related
Problems
Firewall Restrictions
Simply enough,
changing the IP
address on one
computer will fix this
problem in no time
and network card
issue resolve by
pinging.
A quick inspection
of your router or
hub will tell you if
some machine is
disconnected, or if
the culprit is a
faulty cable.
Change your
computer’s firewall
settings and enable it
for accessing network
sharing and services.

Types of computer network
A computer network can be categorized by their size. A computer network is of Eleven types:
 LAN(Local Area Network)
Local Area Network is a group of computers connected to each other in a small area such as building, office.
 PAN(Personal Area Network)
Personal Area Network is a network arranged within an individual person, typically within a range of 10 meters.
 MAN(Metropolitan Area Network)
A metropolitan area network is a network that covers a larger geographic area by interconnecting a different LAN to
form a larger network.
 WAN(Wide Area Network)
A Wide Area Network is a network that extends over a large geographical area such as states or countries.

 Wireless Local Area Network (WLAN)
Functioning like a LAN, WLANs make use of wireless network technology, such as WIFI.
 Campus Area Network (CAN)
Larger than LANs, but smaller than metropolitan area networks (MANs, explained below), these
types of networks are typically seen in universities, large K-12 school districts or small businesses.
 Storage-Area Network (SAN)
As a dedicated high-speed network that connects shared pools of storage devices to several servers,
these types of networks don’t rely on a LAN or WAN.
 System-Area Network (also known as SAN)
This term is fairly new within the past two decades. It is used to explain a relatively local network
that is designed to provide high-speed connection in server-to-server applications, storage area
networks and processor-to-processor applications.

 Passive Optical Local Area Network (POLAN)
As an alternative to traditional switch-based Ethernet LANs, POLAN technologies can be integrated
into structured cabling to overcome concerns about supporting traditional Ethernet protocols.
 Enterprise Private Network (EPN)
These types of networks are built and owned by businesses that want to securely connect its various
locations to share computer resources.
 Virtual Private Network (VPN)
By extending a private network across the Internet, a VPN lets its users send and receive data as if
their devices were connected to the private network – even if they’re not.

Computer network implementation
Different devices are used for the implementation of computer network.
Name of devices are following:
 Hub
 Switch
 Router
 Repeater
 Bridge

Hub
A hub is basically a multiport repeater. A hub connects multiple wires coming from
different branches, for example, the connector in star topology which connects
different stations.
Types of Hub
1. Active Hub
2. Passive Hub
Switch
A switch is a multi-port bridge with a buffer and a design that can boost its
efficiency (large number of ports imply less traffic) and performance. Switch is data
link layer device.
Routers
A router is a device like a switch that routes data packets based on their IP
addresses. Router is mainly a Network Layer device.

Repeater
A repeater operates at the physical layer. Its job is to regenerate the
signal over the same network before the signal becomes too weak or
corrupted so as to extend the length to which the signal can be
transmitted over the same network.
 Bridge
A bridge operates at data link layer. A bridge is a repeater, with add on
functionality of filtering content by reading the MAC addresses of
source and destination.
Types of Bridge
1. Transparent bridge
2. Source routing bridge

1. Transparent Bridges
These are the bridge in which the stations are completely unaware of the
bridge’s existence. These bridges make use of two processes i.e. bridge
forwarding and bridge learning.
2. Source Routing Bridges
In these bridges, routing operation is performed by source station and the
frame specifies which route to follow. The hot can discover frame by
sending a special frame called discovery frame, which spreads through
the entire network using all possible paths to destination.

Applications of computer network
A network is a collection or set of computing devices connected to one
another to establish communication and also share available resources. A
network will comprise software and hardware devices. You can have a
network even if you are not connected to the internet. Computer networks
make it possible for people to transfer files from one place to another and to
communicate taking the shortest time possible.
There are two types of network applications
 Pure network applications
 Standalone network application

Pure Network Applications
These are applications created to be used in networks; using pure network
applications on a single computer doesn't make sense. They help us to transfer data
and communicate within a network. Such applications have a separate and distinct
user interface that users must learn for instance.
1. Email programs
2. File Transfer Protocol (FTP)
Downloading
Uploading
3. Terminal Emulation (TELNET)
4. Groupware
Video Conferencing
Chatting

Stand Alone Applications
These are applications that run on stand-alone computers
(computers not connected to any other). In order to extend
their activity, they are rebuilt to run on network
environments e.g. word processors, spreadsheets, database
management systems, presentations graphics, project
management etc. They function even when the computer is
offline.

Summary
Computer network is a set of computers connected together for the purpose of
sharing resources. Introduction to
Computing Computer network are mainly eleven types WAN, MAN, LAN, PAN
and so on. In computer network we have to face many problems like hacking or fake
IP address. Computer network plays an important role in the sharing of data and
transferring of data from one place to another place. Computer network can
implement by the following devices like Hub, Router etc. Computer network have
many applications that are very helpful for our daily life for example chatting, video
conferencing and social networking etc.

Computer Networks By NADEEM AHMED

Computer Networks By NADEEM AHMED

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Computer Networks By NADEEM AHMED