Networks classification

TOPOLOGY

NETWORK

STAR

RING

BUS

PEER TO PEER

CLIENT-SERVER

PYSHICAL / WIRELESS

TWISTED PAIR, COAXIAL, FIBRE OPTIC

INFRARED, RADIOWAVE, SATELLITE

NIC

HUB

ROUTER

MODEM

ACCESS

POINT

LAN

MAN

WAN

INTRANET

EXTRANET

INTERNET

TCP/IP

NETWORK OPERATING SYSTEM

CLIENT SOFTWARE

ARCHITECTURE TYPES

TECHNOLOGY

PROTOCOL

SOFTWAREMEDIUM

DEVICES

192.168.1.3

Mukesh Chinta, Asst Prof, CSE2

Classification of Networks

There is no generally accepted taxonomy into which all computer networks fit,

but two dimensions stand out as important:

Transmission Technology and Scale.


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Based on Transmission Technology

Broadcast Networks: All stations share a single communicationchannel

Point-to-Point Networks: Pairs of hosts (or routers) are directlyconnected

Typically, local area networks (LANs) are broadcast and wide area networks (WANs) are point-to-point

Broadcast Network Point-to-Point Network

Mukesh Chinta, Asst Prof, CSE

Links

(a)

(b)

point-to-point

multiple-access

Geographical coverage and scalability are limited.

Each node needs one interface for each link.


Broadcast Networks

A Single communication link is shared by all the machines

on that network

When a message is transmitted, it can be received &

processed by every machine on that network. This is

called broadcasting

The address field within the message specifies the

intended recipient. Only if its for the host, it process the

message or it ignores it.

Two popular topologies of broadcast LAN are Bus and

Ring

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A variant of broadcasting called multicasting in which

transmission is done to a subset of machines.

Advantages

Network is easy to build- Only one cable is needed

Cost of construction is cheaper when compared to other

networks

Disadvantages

Not very scalable and flexible

An Arbitration mechanism is needed to resolve conflicts

Broadcast Networks

Mukesh Chinta, Asst Prof,

CSE7

Point-to-Point Networks

Consists of many connections between individual pair of nodes.

Often multiple routes of different lengths are possible

Point-to-point transmission with one sender and one receiver is

sometimes called unicasting

End devices that wish to communicate are called stations and

the switching devices are called nodes.


Advantages

Greater aggregate bandwidth- can have more than one

sender

Can add capacity incrementally- add more links/switches

Better fault tolerance

Lower Latency- No arbitration needed to send

Disadvantages

More expensive as it requires lots of transmission lines

and switching elements to connect remote hosts

Point-to-Point Networks


Switched Networks

Circuit Switched

■ ■ ■

Packet Switched

store-and-forward


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Sharing a Link

L2

L3

R2

R3

L1 R1

Switch 1 Switch 2

multiplex demultiplex


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Networks Based on Scale

Classification of network

Local Area Network

(LAN)

Metropolitan Area Network

(MAN)

Wide Area Network

(WAN)

The main differentiation among these classifications is their area

of coverage.

LAN, MAN and WAN compared Mukesh Chinta, Asst Prof,

CSE12

LOCAL AREA NETWORK {LAN}

A LAN is a private network that connects computers and devices in a limited

geographically area such as a home, school computer laboratory, office building.

LAN’s are used to share resources and to exchange information.

LAN’s are restricted in size having a bounded worst-case transmission time, which

simplifies networks management

Traditional LAN’s run

at 10-100Mbps

Common Topologies

used are bus, ring and

star

High data rates with

less errorsMukesh Chinta, Asst Prof,

CSE13

Headphone

PDA

PrinterMouse

Laptop

Smartphone

LOCAL AREA NETWORK {LAN}

Types of LAN

Personal Area Network

(PAN)

House Area Network

(HAN)

A Personal area network (PAN) is a computer network used for communication

among computer and different information technological devices close to one

person. Common Technologies used are Bluetooth and Infrared. Range is ~10m

A House area network (HAN) is a type of local area network that develops from

the need to facilitate communication and interoperability among digital devices

present inside or within the close vicinity of a home.

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Covers a larger geographical area than is a LAN, ranging from

several blocks of buildings to entire cities.

It may be a single network as a cable TV network or it may be means

of connecting a number of LANs into a larger network so that

resources may be shared.

MAN is wholly owned and operated by a private company or may be

a service provided by a public company

A metropolitan area network based on cable TV

METROPOLITAN AREA NETWORK {MAN}


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The main reason for distinguishing MANs as a special category is

that a standard has been adopted for them. It is DQDB

(Distributed Queue Dual Bus) or IEEE 802.6.

METROPOLITAN AREA NETWORK {MAN}

Using DQDB, networks can be up to 20 miles (30 km) long and operate at

speeds of 34 to 155 Mbits/s.

It consists of two unidirectional buses (cables) to which all the computers are

connected. Each bus has a head-end, which initiates transmission activity.

Traffic destined for a computer to the right of the sender uses the upper bus

and to the left uses the lower one. Mukesh Chinta, Asst Prof,

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Wide area networks are the oldest type of data communicationsnetwork that provide relatively slow-speed, long-distance transmissionof data, voice and video information over relatively large and widelydispersed geographical areas, such as country or entire continent.

WAN spans a large geographical area: a country or a continent

It contains a collection of machines intended for running userprograms called hosts. The hosts are connected by a communicationsubnet, or just subnet for short.

In most WAN’s, the subnet consists of two distinct components:transmission lines and switching elements. Transmission lines movebits between machines. Switching elements (Routers) are specializedcomputers that connect three or more transmission lines. When dataarrive on an incoming line, the switching element must choose anoutgoing line on which to forward them.

WIDE AREA NETWORK {WAN}


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WIDE AREA NETWORK {WAN}

When a packet is sent from one router to another via one or more intermediate

routers, the packet is received at each intermediate router in its entirety, stored there

until the required output line is free, and then forwarded. A subnet organized

according to this principle is called a store-and-forward or packet-switched

subnet. Routing decisions are made locally according to a routing algorithm.


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A Quick Comparison


Internetwork {Internet}

It is a Global network of computers which may be server or client that

exchanges information.

It can be defined as a "network of networks" which can be linked

through copper wires, wireless connections, and other technologies.

This is the world-wide network of computers accessible to anyone who

knows their Internet Protocol (IP) address

Such interconnection of networks requires that different, and frequently

incompatible networks, be connected, sometimes by means of machines

called gateways to make the connection and provide the necessary

translation, both in terms of hardware and software.


The term Intranet is derived from two words: ‘Intra’ which means

within and ‘net’which means group of interconnected computers.

It is a private computer network that uses Internet protocols and

network connectivity to securely share any part of an organization's

information or operational systems with its employees.

In short, an intranet is private network, similar to the Internet and

using the same protocols and technology, contained within an

enterprise or not-for-profit organization.

Intranet


Extranet

is an intranet for outside authorized users using same internet technologies.The outside users are trusted partners of the organization who have access toinformation of their interest & concern.

extends the intranet concept to provide a network that connects a company’snetwork to the networks of its business partners, selected customers, orsuppliers.


Relationship between Intranet &

Extranet

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Client-Server Vs Peer-to-peer A network server is a computer designed to process requests and deliver

data to other (client) computers over a local network or the Internet.

A Client is a computer that retrieves information from or uses resources

provided by a server or main computer.

A peer-to-peer network is a network where the computers act as bothworkstations and servers. It is great for small, simple, and inexpensivenetworks. In a strict peer-to-peer networking setup, every computer is anequal, a peer in the network. Each machine can have resources that are sharedwith any other machine.



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Network topology

A topology is a way of “laying out” the network.

Topologies can be either physical or logical.

A topology describes the configuration of a network

and influences the networks cost and performance.

Various topologies are possible for broadcast LAN’s.

Physical topologies describe how the cables are run.

Logical topologies describe how the network

messages travel

Bus (can be both logical and physical)

Star (physical only)

Ring (can be both logical and physical)

Mesh (can be both logical and physical)


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Bus Topology Bus networks use a common backbone to connect all devices. A single cable,

(the backbone) functions as a shared communication medium that devices

attach or tap into with an interface connector.

The bus topology is the simplest and most common method of

interconnecting computers. The two ends of the transmission line never

touch to form a complete loop. A bus topology is also known as multidrop or

linear bus or a horizontal bus.

A device wanting to communicate with another device on the network sends

a broadcast message onto the wire that all other devices see, but only the

intended recipient actually accepts and processes the message.


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Ring Topology In a ring network (sometimes called a loop), every device has exactly two

neighbors for communication purposes.

All messages travel through a ring in the same direction (either "clockwise" or

"counter clockwise"). All the stations are interconnected in tandem (series) to

form a closed loop or circle.

All the stations are interconnected in tandem (series) to form a closed loop or

circle. Transmissions are unidirectional and must propagate through all the

stations in the loop.


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A star topology is designed with each node (file server,

workstations, and peripherals) connected directly to a central

network hub, switch, or concentrator. Data on a star network

passes through the hub, switch, or concentrator before

continuing to its destination.

The hub, switch, or concentrator manages and controls all

functions of the network. It also acts as a repeater for the data

flow.

Star Topology


The mesh topology incorporates a unique network design inwhich each computer on the network connects to every other,creating a point-to-point connection between every device onthe network.

Unlike each of the previous topologies, messages sent on amesh network can take any of several possible paths fromsource to destination.

A disadvantage is that, a mesh network with n nodes must haven(n-1)/2 links and each node must have n-1 I/O ports (links).

Mesh Topology


Hybrid Topology

This topology (sometimes called mixed topology) is simply

combining two or more of the traditional topologies to form a larger,

more complex topology. Main aim is being able to share the

advantages of different topologies.


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Engineering

Networks classification