what is a network? wireless/mobile computing need for networking cloud computing evolution of...

Communication

& Network Concepts

Objectives What is a network? Wireless/Mobile Computing Need for networking Cloud Computing Evolution of Networking Switching Techniques Transmission media Data Communication Technologies Types of Networks Network Topologies Network Devices Communication Protocols

What is a network ??

A network is an

interconnected collection

of autonomous computers.

Need for networking

To share computer filesTo share computer peripheralsTo enable different computers

(different platforms) to communicate with each other

To improve communication speed and accuracy.

To reduce cost of data transfer

ARPANET1969

INTERNET1990

NSFNET1980

ARPANET Advanced

Research

Projects

Agency

Network

National Science Foundation Network

NSFNET

INTERNET

WORLD WIDE NETWORK OF COMPUTER NETWORKS

GATEWAYDevice that connects dissimilar networksBACKBONECentral interconnecting structure that connects one or more networks

RING BUS

TREE

STAR

BACKBONE

G

G G

G

Few terms related to Network

Workstation or Node refers to a computer

that are attached to a network.

Server The master comp is

called server. Facilitates the sharing of

data, s/w and h/w.

NODES - WORK STATIONS

SERVER

Dedicated Non-dedicated

DEDICATED servers - used in

Master - Slave ( large) networks

NON -DEDICATED servers - used in

Peer - to - Peer (small )networks

DEDICATED servers –a computer (server)reserved for server’s job and its only job is to help workstations access data, software and hardware.

NON -DEDICATED servers –the computer (server) works as a workstation as well as a server

NIU NETWORK INTERFACE UNIT

NIU / NIC

.WORK

STATION SERVERNIU

Network Interface Unit (NIU) It is a device attached to each workstation to establish

communication b/w the server and the workstation. Helps to make connections within the network. Each NIU has a unique number identifying it called

node address. (given by the router or parent node) NIU is also called terminal access point (TAP). Also called Network Interface Card (NIC) Each NIC is given a unique physical address (by the

manufacturer )called MAC address (Media Access Control).

SWITCHING TECHNIQUES

CIRCUIT SWITCHING

MESSAGE SWITCHING

PACKET SWITCHING

CIRCUIT SWITCHING· in telecommunications· old and expensive· more reliable than packet-switching· two network nodes establish a dedicated communications channel (circuit) connecting them for the duration of the communication session before the nodes may communicate. ·functions as if the nodes were physically connected with an electrical circuit.

MESSAGE SWITCHING

store-and-forward switching

transmission of messages from node to

node through a network.

message is stored at each node until such

time as a forwarding path is available.

PACKET SWITCHING

Paul Baran in - 1960's (

· dividing of messages into packets before they are

sent, transmitting each packet individually, and then

reassembling them into the original message once all

of them have arrived at the intended destination.

TRANSMISSION MEDIA

( Connecting media / Connecting

cables )

1. GUIDED - Twisted pair, Coaxial, Optic fibre

2. UNGUIDED - Microwaves ,Radio waves,

Satellites , Infra red, Laser

Cables

Following types of cables are used in networks

Unshielded Twisted Pair (UTP) Cable

Shielded Twisted Pair (STP) Cable

Coaxial Cable

Fiber Optic Cable

Wireless LANs

TWISTED PAIR CABLE(GUIDED)

COAXIAL CABLE( GUIDED )

THICKNET -- max 500 M longTHINNET -- max 185 M long

OPTIC FIBRE

OPTIC FIBRE ( GUIDED )

•Light weight

•High

transmission rate

•No interference

Multimode - 2kms - 100Mbps Singlemode - 100 kms - 2Gbps

**** No interference. High transmission capacity.

Wireless LAN

WIRELESS / MOBILE COMPUTINGWIRELESS

communication without landlines

radio,cellphone device -continuously

connected to the n/w

MOBILE

laptop,PDA ,smartphonesdevice - not continuously

connected to the n/w

Wireless LANs

Not all networks are connected with cabling some networks are wireless .Wireless LANs use high frequency radio signals,infrared light beams, or lasers to communicate

between the workstations and the file server or hubs .

Each workstation and file server on a wireless network has some sort of transceiver/antenna to send and receive the data.

Wireless LAN contd.

For longer distance, wireless communications can also take place through cellular telephone technology, microwave transmission, or by satellite.

Wireless networks are great for allowing laptop computers or remote computers to connect to the LAN.

Wireless networks are also beneficial in older buildings where it may be difficult or

impossible to install cables.

UNGUIDED

Radiowave Microwave Satellite

300KHz - 3GHz Above 3GHz Microwave signals

10 miles range 100kms range spanning large area (16km)

FACTORS TO SELECT A MEDIUM

COST

DATA RATE

BANDWIDTH

DISTANCE

DATA COMMUNICATION -TERMINOLOGIES

Data Channel

Baud (bps)

Bandwidth -- difference between the highest and the lowest

frequencies ( kHz , MHz , GHz , THz ) Data Transfer rates

BITS / BYTES Bps --- Bytes per second

bps --- bits per second

Kbps --- Kilo bytes per second

kbps --- kilo bits per second

Mbps --- Million bytes per second

mbps --- million(mega) bits per second

TYPES OF NETWORKS

LAN - Local Area Network

MAN - Metropolitan Area Network

WAN - Wide Area Network

LAN

MAN

WAN

LAN - WAN Confined to a

small area( 10km)

Data rate - high

Owned by single organization

Low error rates

Span entire countries

Data rate - low

Owned by multiple organizations

High error rates

NETWORK TOPOLOGIES

Pattern of interconnection of nodes in a network

1. Star 2. Bus

3. Ring 4. Tree 5. Graph6. Mesh

Selection of a topology depends on the following factors:

1. Cost

2. Flexibility

3. Reliability

STAR TOPOLOGY

ثراراالالاالتت Ease of service

One device per connection

Centralized control/

problem diagnosis

simple access protocols long cable length difficult to expand central node dependency

short cable length

no wiring space required

suitable for optical fibres

node failure causes network failuredifficult to diagonise faultsn/w reconfiguration is difficult

RING TOPOLOGY

BUS TOPOLOGY

•short cable length and simple wiring•resilient architecture•easy to extend

•difficulty in fault diagnosis , fault isolation•repeater configuration•nodes must be intelligent

TREE TOPOLOGY MESH TOPOLOGY

Considerations When Choosing a Topology:

Money. A linear bus network may be the least expensive way to install a network; you do not have to purchase concentrators.

Length of cable needed. The linear bus network uses shorter lengths of cable.

Future growth. With a star topology, expanding a network is easily done by adding another concentrator.

Cable type. The most common cable in schools is unshielded twisted pair, which is most often used with star topologies.

NETWORK DEVICES•MODEM• RJ-45•ETHERNET CARD•HUB•SWITCH•REPEATER•BRIDGE•ROUTER•GATEWAY

MODEM

MODEM

INTERNAL MODEMEXTERNAL MODEM

RJ -45REGISTERED JACK - 45

Register Jack 45 is an 8 wire connector which is commonly used to connect computers on LAN.

Looks like RJ-11 telephone connector

ETHERNET CARD

ETHERNET CARD

Developed by XEROX

Data transfer rate- 10Mbps

connections for coaxial/twisted pair/fiber optic

HUB

HUB - ( Concentrator )

central connection point from cables from workstations

forward data packets

active hub -- used as repeaters to extend the length of the network

passive hub -- passes signal from one comp to another

SWITCH

SWITCH VS HUBUSED IN LANS

EXPENSIVE

MORE INTELLIGENT

SWITCHES CAN BE CONNECTED TO EACH OTHER - SO EASY TO ADD MORE DEVICES

REPEATER

electronic device - receives a low level signal - amplifies

– transmits used when the distance exceeds 70m

BRIDGE

- establishes an intelligent connection between 2 n/w of same stds but with

diff cabling

-- sends traffic from one side to the other ( switch sends data from either side )

-- uses physical address

Bridge – connects two LANS having the same protocol – (e.g. Ethernet or Token ring)

LAN A

Bridge

LAN B

Data not destined for other network is

prevented from

passing over the

bridge.

ROUTER

ROUTER

devices that join multiple wired or wireless networks (different protocols)

interfaces multiple networks to copy packets from one network to another.

uses logical (IP) address

Uses of Router

A router can be used to connect

a Local Area Network (LAN) to another LAN,

a Wide Area Network (WAN) to another

WAN,

a LAN to the Internet.

GATEWAY

Gateway

Gateway is a device that connects dissimilar networks.

Establishes intelligent connection between a local network and external networks with completely different structures.

Gateway is the ISP that connects the user to the internet.

small networks --> HUBS

when no of nodes grows ---> SWITCHES

if any protocol related problems arise --->

ROUTERS

COMMUNICATION PROTOCOLS

HTTP - Hyper Text Transfer Protocol (to read a web page)

FTP - File Transfer Protocol (to transfer files from one n/w to another)

TCP/IP - Transmission Control Protocol / Internet protocol

( provides end-to-end connectivity specifying how

data should be formatted, addressed, transmitted)

•SLIP/PPP - Serial Line Internet Protocol / Point to Point Protocol

•SMTP - Simple Mail Transfer Protocol

•POP - Post Office Protocol

•VoIP - Voice over IP

Wireless / Mobile computing Technologies

GSM - Global System for Mobile Communications

CDMA - Code Division Multiple Access

GPRS - General Packet Radio services

WLL - Wireless Local Loop

3G - Third Generation

SMS - Short Message Service

E-Mail - Electronic Mail

Chat

Video Conferencing

Wi Fi Bluetooth

WiMAX(Worldwide Interoperability for Microwave Access)

WiMAX is more similar to Wi-Fi than to 3G cellular technologies

Provides mobile broadband connectivity across cities and countries through a variety of devices.

World Wide Web Consortium

Purpose/focus-- Developing protocols and guidelines that ensure long-term growth for the Web.

Internet Engineering Task Force

Creating standards applying to the internet

Best of Luck!!!!