NETWORKNETWORKByBy

Bhupendra Ratha, LecturerBhupendra Ratha, LecturerSchool of Library and Information Science School of Library and Information Science

Devi Ahilya University, IndoreDevi Ahilya University, IndoreEmail: Email: bhu261@gmail.combhu261@gmail.com

NetworkNetworkA network is a group of devices (Nodes) connected by media links. A node can be a computer, printer or any other device capable of sending and receiving data generated by other nodes on the network.

In other words, a group of computer and associated peripherals connected by a communication channel capable of sharing files and other resources between several users is called network.

Types of NetworkTypes of Network

Types of Network

LAN(Local Area Network)

MAN(Metropolitan Area Network)

WAN(Wide Area Network)

It is a campus, office or

organizationNetwork extended over

An entire cityNetwork extended over

entire globe

LANLAN

A LAN can be as simple as two PCs and A LAN can be as simple as two PCs and printer in ones home, office or it can be printer in ones home, office or it can be throughout a company and include voice, and throughout a company and include voice, and video peripherals. At present LAN size is video peripherals. At present LAN size is restricted to one kilometers.restricted to one kilometers.

LANLAN

A office

Features of LANFeatures of LAN LAN uses NOS (Networking Operating System) , which LAN uses NOS (Networking Operating System) , which

ties all the components together and makes operations ties all the components together and makes operations transparent to user.transparent to user.

LANs are wholly owned by an organization.LANs are wholly owned by an organization.

LAN is a system of interlinked personal computers.LAN is a system of interlinked personal computers.

A LAN works on the principle of load sharing because the A LAN works on the principle of load sharing because the program to be executed is down loaded into the personal program to be executed is down loaded into the personal computer memory.computer memory.

LAN has a very limited geographic range normally less LAN has a very limited geographic range normally less than than 1 1 km.km.

Advantage of LANAdvantage of LAN It permits sharing of expensive hardware'sIt permits sharing of expensive hardware's LAN improves the productivity, because information storage, LAN improves the productivity, because information storage,

processing and retrieval and other functionally can be processing and retrieval and other functionally can be improved.improved.

It provide cost effective multiIt provide cost effective multi--user computer environment.user computer environment. It provide high transmission rate to accommodate the needs of It provide high transmission rate to accommodate the needs of

both user and equipment.both user and equipment. Error rate is very less because inError rate is very less because in--built method of detecting and built method of detecting and

compensating for systems error is implied.compensating for systems error is implied. It allows file/record locking.It allows file/record locking.

Disadvantage of LANDisadvantage of LAN

Installation and reconfiguration always Installation and reconfiguration always requires technical & skilled man power.requires technical & skilled man power.

Due to sharing of resources, sometime Due to sharing of resources, sometime operational speed may be slow down.operational speed may be slow down.

Insufficient knowledge of network Insufficient knowledge of network administrator creates improper authorization administrator creates improper authorization and security problem.and security problem.

Problem of password hacking.Problem of password hacking.

MANMAN

A network is bigger than LAN but smaller than A network is bigger than LAN but smaller than WAN, “Multiple LANs that are connected WAN, “Multiple LANs that are connected within the same city to form a citywide within the same city to form a citywide network for a specific government or industry network for a specific government or industry using a high speed backbone” It is known as using a high speed backbone” It is known as MAN.MAN.

MANMAN

IndoreNetwork operatedBy Public/Private

company

Features of MANFeatures of MAN

MAN is a network designed to extend over an MAN is a network designed to extend over an entire city.entire city.

MAN includes different private LANs MAN includes different private LANs connected through cable and router or connected through cable and router or gateway.gateway.

It is bigger than LAN but smaller than WAN.It is bigger than LAN but smaller than WAN. FDDI technology is the best suited for MAN.FDDI technology is the best suited for MAN.

Advantage of MANAdvantage of MAN

Any company can connect all its branches Any company can connect all its branches existing in the same city.existing in the same city.

It is economical because sharing of costly It is economical because sharing of costly resources for all branches of a company.resources for all branches of a company.

Disadvantage of MANDisadvantage of MAN

Network installation is difficult and required Network installation is difficult and required skilled persons.skilled persons.

Installation cost is very much.Installation cost is very much.

WANWAN

A WAN is a network that connect users across A WAN is a network that connect users across large distances, often crossing the geographical large distances, often crossing the geographical boundaries of cities, states or Nations.boundaries of cities, states or Nations.

WANWAN

Earth

Features of WANFeatures of WAN

In this network, computers and small networks In this network, computers and small networks are interare inter--connected without cables but with the connected without cables but with the help of telephone lines, microwave and help of telephone lines, microwave and satellite links.satellite links.

WAN can be implemented with the help of WAN can be implemented with the help of private networks as well as public networks.private networks as well as public networks.

It is the very longIt is the very long--distance communication distance communication network.network.

Advantage of WANAdvantage of WAN WAN has no limit of area, so it is world wide WAN has no limit of area, so it is world wide

network.network. Multi country’s organizations have facility to form Multi country’s organizations have facility to form

their global integrated network through WAN.their global integrated network through WAN. WAN support global markets and global business.WAN support global markets and global business. For a network database, WAN allows users all over a For a network database, WAN allows users all over a

network to access and update a single, consistent network to access and update a single, consistent view of data.view of data.

Disadvantage of WANDisadvantage of WAN

WAN is very big and complex network.WAN is very big and complex network. It is slow in speed.It is slow in speed. WAN is not very much secured means not WAN is not very much secured means not

reliable.reliable. It is very costly because we have to pay every It is very costly because we have to pay every

time for transferring data.time for transferring data. Very much dependency on the third party Very much dependency on the third party

because it is public network.because it is public network.

Difference between Difference between LAN, MAN & WANLAN, MAN & WAN

Point of viewPoint of view LANLAN MANMAN WANWANRangeRange 1km1km CityCity UnlimitedUnlimited

Authority Authority PersonalPersonal Company or Company or OrganizationsOrganizations

No authorityNo authority

CostCost NormalNormal MediumMedium Very muchVery much

Connectivity Connectivity DeviceDevice

Cable mediaCable media Cable media andCable media andTelephone linesTelephone lines

Telephone lines, Telephone lines, microwave and microwave and SatelliteSatellite

SpeedSpeed 0.1 to 100mbps0.1 to 100mbps 1 to 1mbps1 to 1mbps 1800 to 9600 bits 1800 to 9600 bits per secondper second

AccuracyAccuracy Very GoodVery Good GoodGood MediumMedium

Network TopologyNetwork Topology

A topology defines the arrangement of nodes, A topology defines the arrangement of nodes, cables and connectivity devices that make up cables and connectivity devices that make up the network. the network.

In other words we can say topology is the In other words we can say topology is the geometric arrangement of workstations and the geometric arrangement of workstations and the links among them.links among them.

Parameters to analyses the TopologyParameters to analyses the Topology

There are certain parameters, to help us select the best There are certain parameters, to help us select the best topology for our situation and they are;topology for our situation and they are;

ApplicationApplication ComplexityComplexity PerformancePerformance System overheadSystem overhead VulnerabilityVulnerability ExpandabilityExpandability

ApplicationApplication It shows in what size installation is the topology most It shows in what size installation is the topology most

appropriateappropriate..

ComplexityComplexity

It shows, how technically complex is the topology ? It shows, how technically complex is the topology ?

PerformancePerformance

It shows, how much of a traffic load can the It shows, how much of a traffic load can the system supportsystem support

System overheadSystem overhead It shows, what is the comparative price for It shows, what is the comparative price for

excess capability.excess capability.

VulnerabilityVulnerability

It shows, how susceptible in the topology to It shows, how susceptible in the topology to failure and damage.failure and damage.

ExpandabilityExpandability When we are ready to extend the LAN, how When we are ready to extend the LAN, how

easily can be topology accommodate easily can be topology accommodate additional workstations and cover larger additional workstations and cover larger distances ?distances ?

Types of TopologyTypes of Topology

Topology can be divide in two basic type;Topology can be divide in two basic type;

1.1. Physical topologyPhysical topology

2.2. Logical topologyLogical topology

Physical TopologyPhysical Topology

It describes the actual layout of the network It describes the actual layout of the network transmission media, means the way of transmission media, means the way of networks looks.networks looks.

Logical TopologyLogical Topology

It describes the logical pathway a signal It describes the logical pathway a signal follows as it passes among the network nodes, follows as it passes among the network nodes, means the way the data passes among the means the way the data passes among the nodes.nodes.

The most common types of Network The most common types of Network TopologyTopology

Bus TopologyBus Topology Ring TopologyRing Topology Star TopologyStar Topology Tree TopologyTree Topology Mesh TopologyMesh Topology Token ring TopologyToken ring Topology

Bus TopologyBus TopologyDrop lines/Interface units

Terminator Terminator

Characteristics of Bus TopologyCharacteristics of Bus Topology

A bus topology is one in which all device A bus topology is one in which all device connect to common shared cable (backbone) connect to common shared cable (backbone) through interface units/drop lines and taps. through interface units/drop lines and taps.

This topology is used in traditional data This topology is used in traditional data communication networks where the host at one communication networks where the host at one end of the bus communicate with several end of the bus communicate with several terminals attached along its length.terminals attached along its length.

Cont…Cont…

Special connector called terminator must be Special connector called terminator must be placed at the end of the backbone cable to placed at the end of the backbone cable to prevent signals from reflecting back on the prevent signals from reflecting back on the cable and causing interference.cable and causing interference.

Bus configuration is known as multiBus configuration is known as multi--drop line.drop line.

Advantage of Bus TopologyAdvantage of Bus Topology

Installation is very easy because it is a single cable Installation is very easy because it is a single cable network.network.

It uses less cabling than any other topology.It uses less cabling than any other topology. Additional nodes can be connected to an existing bus Additional nodes can be connected to an existing bus

network at any point along its length.network at any point along its length. It is a resilient (flexible) architecture means simple It is a resilient (flexible) architecture means simple

and reliable .and reliable . It is very economical.It is very economical.

Disadvantage of Bus TopologyDisadvantage of Bus Topology

Difficult reconfiguration and fault isolation.Difficult reconfiguration and fault isolation. All the nodes are directly connected to central All the nodes are directly connected to central

cable and nodes have to decide which uses the cable and nodes have to decide which uses the network first.network first.

Entire network shutdown if there is a failure in Entire network shutdown if there is a failure in the backbone.the backbone.

The damage area reflects signals back in the The damage area reflects signals back in the direction of origin, creating noise in both direction of origin, creating noise in both directions.directions.

Ring TopologyRing Topology

Features of Ring TopologyFeatures of Ring Topology Ring topology are wired in a circle, each node is connected to Ring topology are wired in a circle, each node is connected to

its neighbors on either side.its neighbors on either side. Data signals passes around the ring in one direction.Data signals passes around the ring in one direction. Each device incorporates a receiver and a transmitter, and Each device incorporates a receiver and a transmitter, and

serves as a repeater that passes the signal on to the next device serves as a repeater that passes the signal on to the next device in the ring.in the ring.

Ring topologies are quite rare.Ring topologies are quite rare. No routing capability is required as messages automatically No routing capability is required as messages automatically

travel to the next workstation on the network.travel to the next workstation on the network.

Advantage of Ring TopologyAdvantage of Ring Topology

A ring relatively easy to install and reconfigure.A ring relatively easy to install and reconfigure. Less cabling involved in a ring topology comparable Less cabling involved in a ring topology comparable

to that of bus and is small relative to other.to that of bus and is small relative to other. Each device is linked only to its immediate neighbors Each device is linked only to its immediate neighbors

so to add or delete a device requires moving only two so to add or delete a device requires moving only two connections.connections.

It is good for small number of workstations operating It is good for small number of workstations operating at high speeds over short distances are to be at high speeds over short distances are to be connected.connected.

Disadvantage of Ring TopologyDisadvantage of Ring Topology

A node failure causes entire network failure.A node failure causes entire network failure. A ring requires relatively complex hardware to A ring requires relatively complex hardware to

implement.implement. The failure of one node will affect all others The failure of one node will affect all others

has serious problem for fault diagnosis.has serious problem for fault diagnosis. Topology affects the access protocol.Topology affects the access protocol.

Star TopologyStar Topology

Features of Star TopologyFeatures of Star Topology It require that all devices connect to a central hub or It require that all devices connect to a central hub or

wiring concentrator through a dedicated point to point.wiring concentrator through a dedicated point to point. The hub receives signals from the other network devices The hub receives signals from the other network devices

and routs the signals to the proper destinations.and routs the signals to the proper destinations. Nodes do not have to make routing decisions, as all Nodes do not have to make routing decisions, as all

communications must pass through the central hub before communications must pass through the central hub before going to their destinations.going to their destinations.

The size and capacity of the network is the depend on the The size and capacity of the network is the depend on the central hub.central hub.

Advantage of Star TopologyAdvantage of Star Topology

Each device needs only one link and one I/O Each device needs only one link and one I/O port to connect it to any number of others.port to connect it to any number of others.

It is easy to install and reconfigure.It is easy to install and reconfigure. Robustness of network means if one link fails, Robustness of network means if one link fails,

only that link is affected and all other links only that link is affected and all other links remain active.remain active.

Due to the above fact, fault identification and Due to the above fact, fault identification and fault isolation is very easy.fault isolation is very easy.

Disadvantage of Star TopologyDisadvantage of Star Topology

Cabling is required very much.Cabling is required very much. Difficult to expand the network.Difficult to expand the network. If the central node in a star network fails the If the central node in a star network fails the

entire network is rendered inoperableentire network is rendered inoperable Maintenance and installation problems can Maintenance and installation problems can

increase costs considerably.increase costs considerably.

Tree TopologyTree Topology

Server

Central/Primary node

Secondary hub

Features of Tree TopologyFeatures of Tree Topology

In tree , central hub is used to connect only In tree , central hub is used to connect only secondary hubs, not with all nodes.secondary hubs, not with all nodes.

So nodes & devices are connected through the So nodes & devices are connected through the secondary hubs.secondary hubs.

Normally the central hub of tree is an active Normally the central hub of tree is an active hub so it is able to filter & regenerate the hub so it is able to filter & regenerate the signals signals

Secondary hub may be active or passive.Secondary hub may be active or passive.

Advantage of Tree TopologyAdvantage of Tree Topology

Tree network can be easily extended because Tree network can be easily extended because central hub has so many hubs.central hub has so many hubs.

Network (or subNetwork (or sub--network) can be isolated and network) can be isolated and communication can be prioritized.communication can be prioritized.

Due to the above fact time sensitive data will Due to the above fact time sensitive data will not have to wait for access to the network.not have to wait for access to the network.

Disadvantage of Tree TopologyDisadvantage of Tree Topology

Tree topology has all the disadvantages of star Tree topology has all the disadvantages of star topology . topology .

The subsection has dependence on the root The subsection has dependence on the root section.section.

Bigger branches slow down the speed of Bigger branches slow down the speed of network.network.

Mesh TopologyMesh Topology

Features of Mesh TopologyFeatures of Mesh Topology

Every device has a dedicated point to point Every device has a dedicated point to point link to every other device.link to every other device.

Mesh is really a hybrid model representing an Mesh is really a hybrid model representing an all channels topology.all channels topology.

Every device on the network must have Every device on the network must have nn--1 input/output ports.1 input/output ports.

Advantage of Mesh TopologyAdvantage of Mesh Topology

It is very much fault tolerance capacity.It is very much fault tolerance capacity.

Privacy or security is very high, every message Privacy or security is very high, every message sent travels along a dedicated line only the sent travels along a dedicated line only the intended recipient sees it.intended recipient sees it.

Disadvantage of Mesh TopologyDisadvantage of Mesh Topology

Installation & reconfiguration is very difficult.Installation & reconfiguration is very difficult. Extra workload to network administrator.Extra workload to network administrator. It requires very much cabling & I/O ports.It requires very much cabling & I/O ports. Extra wiring can be greater than the available Extra wiring can be greater than the available

space can accommodate.space can accommodate. It is the most expansive network.It is the most expansive network.

Token Ring TopologyToken Ring Topology

Features of Token Ring TopologyFeatures of Token Ring Topology

In this topology, wired in a circular format but In this topology, wired in a circular format but all the node connected by the drop lines and Tall the node connected by the drop lines and T--shape tokens.shape tokens.

In this topology all the nodes have only In this topology all the nodes have only receiver and transmitter not a repeater.receiver and transmitter not a repeater.

Advantage of Token Ring TopologyAdvantage of Token Ring Topology

A node failure causes entire network are not A node failure causes entire network are not failure.failure.

No problems in fault diagnosis.No problems in fault diagnosis.

Privacy and accuracy in data transmission.Privacy and accuracy in data transmission.

Disadvantage of Token Ring TopologyDisadvantage of Token Ring Topology

A token ring is difficult to install and A token ring is difficult to install and reconfigure.reconfigure.

Cabling is required very much.Cabling is required very much. It does not allow direct traffic between It does not allow direct traffic between

devices.devices.