Computer Network Types

A computer network is a group of computers linked to each other that enables the computer to communicate with
another computer and share their resources, data, and applications.

A computer network is mainly of four types:

LAN(Local Area Network)

o Local Area Network is a group of computers connected to each other in a
small area such as building, office.
o LAN is used for connecting two or more personal computers through a
communication medium such as twisted pair, coaxial cable, etc.
o It is less costly as it is built with inexpensive hardware such as hubs,
network adapters, and ethernet cables.
o The data is transferred at an extremely faster rate in Local Area Network.
o Local Area Network provides higher security.

PAN(Personal Area Network)

o Personal Area Network is a network arranged within an individual person,
typically within a range of 10 meters.
o Personal Area Network is used for connecting the computer devices of
personal use is known as Personal Area Network.
o Thomas Zimmerman was the first research scientist to bring the idea of the
Personal Area Network.
o Personal Area Network covers an area of 30 feet.
o Personal computer devices that are used to develop the personal area
network are the laptop, mobile phones, media player and play stations.

There are two types of Personal Area Network:

o Wired Personal Area Network

o Wireless Personal Area Network

Wireless Personal Area Network: Wireless Personal Area Network is developed by

simply using wireless technologies such as WiFi, Bluetooth. It is a low range network.
Wired Personal Area Network: Wired Personal Area Network is created by using the
USB.

Examples Of Personal Area Network:

o Body Area Network: Body Area Network is a network that moves with a person. For example, a mobile network
moves with a person. Suppose a person establishes a network connection and then creates a connection with
another device to share the information.
o Offline Network: An offline network can be created inside the home, so it is also known as a home network. A
home network is designed to integrate the devices such as printers, computer, television but they are not
connected to the internet.
o Small Home Office: It is used to connect a variety of devices to the internet and to a corporate network using
a VPN
MAN(Metropolitan Area Network)

o A metropolitan area network is a network that covers a larger

geographic area by interconnecting a different LAN to form a
larger network.
o Government agencies use MAN to connect to the citizens and
private industries.
o In MAN, various LANs are connected to each other through a
telephone exchange line.
o The most widely used protocols in MAN are RS-232, Frame
Relay, ATM, ISDN, OC-3, ADSL, etc.
o It has a higher range than Local Area Network(LAN).

Uses Of Metropolitan Area Network:

o MAN is used in communication between the banks in a city.

o It can be used in an Airline Reservation.
o It can be used in a college within a city.
o It can also be used for communication in the military.

WAN(Wide Area Network)

o A Wide Area Network is a network that extends over a large

geographical area such as states or countries.
o A Wide Area Network is quite bigger network than the LAN.
o A Wide Area Network is not limited to a single location, but it spans
over a large geographical area through a telephone line, fibre optic
cable or satellite links.
o The internet is one of the biggest WAN in the world.
o A Wide Area Network is widely used in the field of Business, government, and education.

Examples Of Wide Area Network:

o Mobile Broadband: A 4G network is widely used across a region or country.

o Last mile: A telecom company is used to provide the internet services to the customers in hundreds of cities
by connecting their home with fiber.
o Private network: A bank provides a private network that connects the 44 offices. This network is made by using
the telephone leased line provided by the telecom company.

Advantages Of Wide Area Network:

Following are the advantages of the Wide Area Network:

o Geographical area: A Wide Area Network provides a large geographical area. Suppose if the branch of our
office is in a different city then we can connect with them through WAN. The internet provides a leased line
through which we can connect with another branch.
o Centralized data: In case of WAN network, data is centralized. Therefore, we do not need to buy the emails,
files or back up servers.
o Get updated files: Software companies work on the live server. Therefore, the programmers get the updated
files within seconds.
 o Exchange messages: In a WAN network, messages are transmitted fast. The web application like Facebook,
Whatsapp, Skype allows you to communicate with friends.
o Sharing of software and resources: In WAN network, we can share the software and other resources like a
hard drive, RAM.
o Global business: We can do the business over the internet globally.
o High bandwidth: If we use the leased lines for our company then this gives the high bandwidth. The high
bandwidth increases the data transfer rate which in turn increases the productivity of our company.

Disadvantages of Wide Area Network:

The following are the disadvantages of the Wide Area Network:

o Security issue: A WAN network has more security issues as compared to LAN and MAN network as all the
technologies are combined together that creates the security problem.
o Needs Firewall & antivirus software: The data is transferred on the internet which can be changed or hacked
by the hackers, so the firewall needs to be used. Some people can inject the virus in our system so antivirus is
needed to protect from such a virus.
o High Setup cost: An installation cost of the WAN network is high as it involves the purchasing of routers,
switches.
o Troubleshooting problems: It covers a large area so fixing the problem is difficult.

Computer Network Topologies

A Network Topology is the arrangement with which computer systems or network devices are connected to each other.
Topologies may define both physical and logical aspect of the network. Both logical and physical topologies could be
same or different in a same network.

Point-to-Point
Point-to-point networks contain exactly two hosts such as computer,
switches or routers, servers connected back to back using a single piece of
cable. Often, the receiving end of one host is connected to sending end of the
other and vice-versa.

If the hosts are connected point-to-point logically, then may have multiple intermediate devices. But the end hosts are
unaware of underlying network and see each other as if they are connected directly.

Bus Topology

In case of Bus topology, all devices share single communication line or

cable. Bus topology may have problem while multiple hosts sending
data at the same time. Therefore, Bus topology either uses CSMA/CD
technology or recognizes one host as Bus Master to solve the issue. It
is one of the simple forms of networking where a failure of a device
does not affect the other devices. But failure of the shared
communication line can make all other devices stop functioning.

Both ends of the shared channel have line terminator. The data is sent in only one direction and as soon as it reaches
the extreme end, the terminator removes the data from the line.
Star Topology
All hosts in Star topology are connected to a central device, known as hub device, using a point-to-point connection.
That is, there exists a point to point connection between hosts and hub. The hub device can be any of the following:
• Layer-1 device such as hub or repeater
• Layer-2 device such as switch or bridge
• Layer-3 device such as router or gateway

As in Bus topology, hub acts as single point of failure. If hub fails, connectivity of
all hosts to all other hosts fails. Every communication between hosts, takes
place through only the hub.Star topology is not expensive as to connect one
more host, only one cable is required and configuration is simple.

Ring Topology
In ring topology, each host machine connects to exactly two other machines,
creating a circular network structure. When one host tries to communicate or
send message to a host which is not adjacent to it, the data travels through all
intermediate hosts. To connect one more host in the existing structure, the
administrator may need only one more extra cable.

Failure of any host results in failure of the whole ring. Thus, every connection in
the ring is a point of failure. There are methods which employ one more backup
ring.

Mesh Topology

In this type of topology, a host is connected to one or multiple hosts. This

topology has hosts in point-to-point connection with every other host or may
also have hosts which are in point-to-point connection to few hosts only.

Hosts in Mesh topology also work as relay for other hosts which do not have
direct point-to-point links. Mesh technology comes into two types:
• Full Mesh: All hosts have a point-to-point connection to every other host in the network. Thus for every new
host n(n-1)/2 connections are required. It provides the most reliable network structure among all network
topologies.
• Partially Mesh: Not all hosts have point-to-point connection to every other host. Hosts connect to each other
in some arbitrarily fashion. This topology exists where we need to provide reliability to some hosts out of all.

Tree Topology

Also known as Hierarchical Topology, this is the most common form of

network topology in use presently.This topology imitates as extended Star
topology and inherits properties of bus topology.

This topology divides the network in to multiple levels/layers of network.

Mainly in LANs, a network is bifurcated into three types of network devices.
The lowermost is access-layer where computers are attached. The middle
layer is known as distribution layer, which works as mediator between upper layer and lower layer. The highest layer is
known as core layer, and is central point of the network, i.e. root of the tree from which all nodes fork.

All neighboring hosts have point-to-point connection between them. Similar to the Bus topology, if the root goes down,
then the entire network suffers even. though it is not the single point of failure. Every connection serves as point of
failure, failing of which divides the network into unreachable segment.
Hybrid Topology

A network structure whose design contains more than one topology is said to
be hybrid topology. Hybrid topology inherits merits and demerits of all the
incorporating topologies.

The above picture represents an arbitrarily hybrid topology. The combining

topologies may contain attributes of Star, Ring, Bus, and Daisy-chain
topologies. Most WANs are connected by means of Dual-Ring topology and
networks connected to them are mostly Star topology networks. Internet is
the best example of largest Hybrid topology

NETWORK HARDWARE
Network hardware refers to the physical devices that facilitate communication between hardware running
on a computer network.

Network interface card

• A network card, network adapter, network interface card or NIC is a piece of computer hardware
designed to allow computers to communicate over a computer network.
Hubs
• An Ethernet Hub or concentrator is a device for connecting multiple twisted pair or fibre optic
Ethernet devices together, making them act as a single segment. It works at the physical layer of
the OSI model, repeating the signal received at one port out each of the other ports (but not the
original one). The device is thus a form of multiport repeated.
• The availability of low-priced Ethernet switches has largely rendered hubs obsolete but they are still
seen in older installations and more specialist applications.
Switches
• A network switch, or switch for short, is a networking device that performs transparent bridging
(connection of multiple network segments with forwarding based on MAC addresses) at full wire
speed in hardware.
• A network switch, or switch for short, is a networking device that performs transparent bridging
(connection of multiple network segments with forwarding based on MAC addresses) at full wire
speed in hardware
Routers
• A router is computer networking device that forwards data packets across a network toward their
destinations, through a process known as routing.
• A router acts a junction between two or more networks to transfer data packet among them.
• A router is different from a switch, which connects devices to form a Local Area Network (LAN).
Wireless
• A Wireless Access Point (WAP) connects a group of wireless stations to an adjacent wired local
area network (LAN). An access point is similar to an Ethernet hub, but instead of relaying LAN data
only to other LAN stations, an access point can relay wireless data to all other compatible wireless
devices as well as to a single connected LAN device (in most cases an Ethernet hub or switch)
allowing wireless devices to communicate with any other device on the LAN.