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ER/CORP/CRS/OS41/003 Ver. No.: 4.0 Copyright 2008, Infosys Technologies Ltd.

Education and ResearchWe enable you to leverage knowledge anytime, anywhere!

Introduction to Web Technologies

Day 1


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Copyright 2008, Infosys Technologies Ltd. 2

Course Objectives

To introduce the general concepts of computernetworks, internetworking, network architectureand network security.

To introduce the Client Server concepts, WWW,

and Web application development

To provide the overview of Web applicationperformance, Securing the web application and

mobile web application.


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Course Agenda

Day1

Basics of Computer Networks

Network Architecture

OSI-ISO reference Model

Network Components

Internetworking

IP addressing

Concept of Sub-Networking

Day2

Client Server Concepts

Introduction to World Wide Web

Web Application

Day3

Network Security

Proxy server

Firewall VPN

Security of Web Applications

Web Application Performance


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Session Plan - Day1


Network Architecture OSI-ISO reference Model

Network Components

Internetworking-Internet

IP addressing



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References

James F. Kurose, Keith W. Ross, Computer Networking: A Top-down Approach Featuring the Internet, Pearson International, 3rdEdition, 2005.

William Stallings, Business Data Communications, 5/E, PrenticeHall, 2005.

Douglas E Comer, Internet Book, The: Everything You Need toKnow About Computer Networking and How the Internet Works, 4/E,Prentice Hall, 2007

William Stallings, Network Security Essentials: Applications andStandards, Prentice Hall, 3rd Edition, 2007

Raymond Panko, Corporate Computer and Network Security,Prentice Hall, 2004

Jeffrey C. Jackson, Web Technologies: A Computer SciencePerspective, Prentice Hall, 2007

http://www.ietf.org/ http://www.w3.org/ http://www.vpnc.org/vpn-standards.html


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Computer Network

A collection of computers interconnected to exchange information

Need for computer networks Intrinsically distributed information Resource sharing Computational power (load sharing) Reliability


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Types of Computer Networks

Computer Networks are classified based on thecommunication methods and size

Based on communication methods

Broadcast communication networks Point-to-Point networks

Based on the size (scale) Local Area Networks (LAN)

Metropolitan Area Networks (MAN)

Wide Area Networks (WAN)


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Network Topology

Network Topology Refers to how the computers are connected in a network

either physically or logically

Geometric representation of relationship of all the computerand interconnecting devices

Most frequently used topologies are,

Mesh, Star, Ring, Bus

Topologies are evaluated based on communication cost,installation cost, reliability.


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Mesh/Completely connectedTopology

Each node (computer/device) has a dedicated point-to-point link toevery other node

One node can choose any path to another node based on the datatraffic

To connect one node, in a network of n nodes, n-1 links arerequired


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Star Topology

Each node (computer/device) has a dedicated point-to-point link to

the central node If one node wants to send packet to another, it sends the packet to

the controller/switch, which then relays the packet to the otherconnected node

switch


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Ring Topology

Each node (computer/device) has a dedicated point-to-point link withthe two nodes on either side of it

Data packet is passed along the ring in one direction, from one nodeto node, until it reaches its destination


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Bus Topology

One long cable run as a backbone (bus) to link all the nodes in thenetwork

Nodes (computer/device) are connected to the bus by drop lines

TerminatorBackbone

Drop line


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Network Architecture

Defines the design and implementation of computer networks

Has a layered approach which helps in

Reducing the design complexity

Shielding the implementation details of the services

Each layer provides services to the layer above

Different protocols are followed between corresponding layers inSender and Receiver

Two popularly referenced architectures are

ISO-OSI model

TCP/IP model


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Why OSI Model ?


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Application

Presentation

Session

Transport

Network

Data link

Physical

Application

Presentation

Session

Transport

Network

Data link

Physical

Node A Node B

Packet

Frame

Bit

Application protocol

Presentation protocol

Session protocol

Transport protocol

Network protocol

Data link protocol

Physical link protocol

Segment

ISO-OSI Reference Model

OSI M d l L F i


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OSI Model Layer FunctionsOverview

Layer Name Functions

Application Allow access to network for communication

Presentation Translation, encryption, compression,data/address format

Session Synchronization, dialog control

Transport Deals with messages, end-to-end tomessage delivery

Network Deals with packets, routing, congestioncontrol

Data Link Deals with frames, node-to-node delivery,error and flow control

Physical Physical Deals with bits, electricalspecifications


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Application Layer

Top most layer which gives services to the application

Provides a means for the application process to accessthe environment

Contains a variety of protocols that are commonlyneeded

Examples FTP

EMAIL (SMTP) RLOGIN (Telnet)

WWW (HTTP)

Newsgroups


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Presentation Layer

Basically concerned with the syntax andsemantics of the information transmitted

Resolves common data formats

Big Endian versus small Endian

Deals with data compression, encryption &

decryption


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Session Layer

Allows users of different machines to establishsessions between them

Manages dialogue control

Provides synchronization


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Transport Layer

The primary function of this layer is to accept data from the sessionlayer, split it into smaller units if required and then pass these to thenetwork layer.

Deals with delivery of messages (end to end message delivery)

Retransmission in case of failures

Transport Layer protocols,

Transmission Control Protocol (TCP )

Sequence Packet Exchange (SPX)


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Network Layer

Primarily deals with Routing the packets from source to destination

congestion control

Network layer protocols

IP (Internet protocol), IPX (Internet PacketExchange) protocol


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Data link Layer

Deals with sending and receiving frames

Responsible for node to node delivery

Provides error-control and flow-control

Data link layer protocols (MAC protocols) CSMA/CD (Carrier Sense Multiple Access protocol with

Collision Detection)

CSMA/CA (CSMA with Collision Avoidance) Token Passing Algorithms

PPP (point-to-point) protocol

HDLC (High level Data Link Control Protocol)


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Physical Layer

Deals with physical aspects such as raw bit transmission

voltage of each bit

number of bits

physical connectors ( RS-232C, X.21 )

Transmission mode ( simplex, half-duplex, full-duplex)


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Network Components

There are many different devices for interconnectingnetworks.

Repeaters

Bridges

Routers Gateway

Router/Switch

Gateway

Bridge

Repeater

X.25Network

IP network

LAN

LAN LAN

LAN


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Network Components (Contd)

Repeaters

allow to extend the physical length of a network

operates at the physical layer of Network

Bridges

divides a large network into smaller

operates in both the physical and data link layer of network

Routers

interconnects similar or dissimilar networks together

operates in physical, data link and network layer of network

Gateways

interconnects dissimilar networks together

operates in all the layers of network

Ed ti d R h


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Internetworking


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Internet

Internet Huge network of networks

Host/Node Communicating system connected to the network

Millions of hosts hooked on to the Internet

Communication Protocol TCP/IP

Means to connect to Internet Dial-up Line (through telephone): Domestic users

DSL: Digital Subscriber Line (through telephone), ADSL,Cable Modem: Domestic users

ISDN,E1,T1,T3 connections, GPRS, CDMA: Largecorporations


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What is Internetworking?

Interconnection of various heterogeneous/homogeneous networks

Network of Networks


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Who provides Internet services?

ISP a company which provides Internet access for

individuals, organizations, and companies User should get an account from ISPs, that includes

a software package To dial to the ISPs To monitor the access time

username, password access phone number

Laptop

ModemTelephone Line

DSLT1 / T3

ISP Network Internet


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How Internet works?

Packet switching protocol (TCP/IP protocol) Involves breaking down of data into packets or

datagrams

Packets are labeled with origin and destination

address Packets are forwarded from one network to another

network until it reaches the destination

If packets are lost, originator re-sends the packets

Provides interoperability between different typesof nodes on the Internet


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What is packet switching?

192.168.121.40192.168.223.208

1

1100111110111..

192.168.121.40192.168.223.208

2

0111110001000..

192.168.121.40192.168.223.208

11100111110111..

192.168.121.40192.168.223.208

20111110001000..

`

192.168.121.40192.168.223.208

300100100010000..

192.168.121.40192.168.223.208

410100010000111..

192.168.121.40192.168.223.20

300100100010000.

192.168.121.40192.168.223.208

410100010000111. .

11111100000100100011111001000100

10100010000111110010101110010001111011111100000100100100010000111110010101110010001111001111100100010010100010000111110001000111

10011111001000111100111110111001

Data /File Packets

F

192.168.223.208

111111000001001000111110010001001010001000011111001010111001000111101111110000010010010001000011111001010111001000111100111110010001001010001000011111000100011110011111001000111100111110111001

192.168.121.40

Router192.168.121.0

Network

192.168.121.5 192.168.223.6

192.168.223.0Network

G F192.168.223.208

Education and Research


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IP addressing


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Internet Protocol Address

A 4-byte addressing scheme used by the IP layer

Within a private or closed network, one can assign any IP address

Every Internet host must have a distinct IP address

It has two components

Network ID

Host ID

IP address is provided by the Internet service provider

IP addresses are a scarce resource!!


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IP Address (IPV4)

1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 0 0 1

w x y z

NETWORK ID HOST ID

EXAMPLE: 130.195.128.25

130 195 128 25


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IP Address (IPV4): Range for each


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IP Address (IPV4): Range for eachclass

Class Range RemarksA 1.0.0.0 to 126.255.255.255B 128.0.0.0 to 191.255.255.255C 192.0.0.0 to 223.255.255.255D 224.0.0.0 to 239.255.255.255 (Multi-Casting)E 240.0.0.0 to 247.255.255.255 (Reserved for

future use)


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Special IP Addresses (IPV4)

Zero Addresses (0.0.0.0 to 0.255.255.255) There is no particular function for this range of IP Address.

Private Addresses IP Standard defines specific address ranges within Class A,

Class B, Class C reserved for use by Private Networks.

Loopbacks Address (127.0.0.0 to 127.255.255.255) Reserved and used for internal testing on a local machine. They should not be used for host address.

Class RangeA 10.0.0.0 to 10.255.255.255

B 172.16.0.0 to 172.31.255.255

C 192.168.0.0 to 192.168.255.255


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Static and Dynamic IP Address

Computer

Boots up(Assumes StaticIP addr set by Admin)

Static and Dynamic IP Address


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Static and Dynamic IP Address(Contd)

User Dials intothe network(Connect)

Modem

ISP's Network

DHCPSERVER

2. Assigns IP Address andother config info

1.Userdialsintothe

network

DYNAMIC IP for Dial up Users

Internet

2.Assig

nsIPA

ddressa

nd

otherco

nfiginfo

LAN

OtherComputerson Network.

Server

IBM Compatible

DHCPSERVER

1. ComputerBoots up

(Broadcasts on theNetwork)

DYNAMIC IP for LAN Users


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Two-layer hierarchy is not appropriate for large networks

with IP addresses Consider Infosys Network as an example

C1 ,C2 are computers in the sub network

Concept of Sub Networking

Infosys

BEF

E&R

C1 C2

Facilities

C1 C2

CCD

IBU

BCMD CSPD


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Domain Name system (DNS) Server

Its too difficult to remember IP Addresses

Each IP Addresses is registered for a Domain Name

Example: 216.251.50.51 = www.infosys.com

Host can also be identified with Name

User submits the request to the Domain Name

Domain Name Server Translates Domain Name to IP Address and vice versa

De-centralized


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Intranet Vs Internet

Internet Not owned by any single entity Have publicly known IP addresses (Unique world-wide)

Information access is open to everyone

Intranet Used by corporations for their own business or operational

needs

Usually accessible only to the members, employees of theorganization

Use the same technology as Internet

Smaller in size Private network Better controlled and more secure

S


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Summary


Network Architecture OSI-ISO reference Model

Network Components

Internetworking

IP addressing



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Thank You

The contents of this document are proprietary and confidential to Infosys Technologies Ltd. and may

not be disclosed in whole or in part at any time, to any third party without the prior written consent ofInfosys Technologies Ltd.

2008 Infosys Technologies Ltd. All rights reserved. Copyright in the whole and any part of this

document belongs to Infosys Technologies Ltd. This work may not be used, sold, transferred, adapted,abridged, copied or reproduced in whole or in part, in any manner or form, or in any media, without theprior written consent of Infosys Technologies Ltd.



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We enable you to leverage knowledge anytime, anywhere!

Appendix 1

Self Study

C i f T l


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Comparison of Topology

Feature Mesh Star Ring Bus

Installation cost High Low Low LowCommunicationcost

Low

(1 hop)

Low

( 2 hops)

Variable

(1 to n-1hops)

Low

Reliability High Poor Low Low

TCP/IP R f M d l


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TCP/IP Reference Model

Application

Transport

Internet

Network Access

HTTP, TFTP, Telnet, FTP, SMTP, DNS

TCP, UDP

IP, ICMP. IGMP, DHCP, RIP, OSPF

MAC Protocols: Ethernet(CSMA/CD) CSMA/CA,Token ring, TokenBus, ARP

routing and delivery of data acrossnetworks.

Combination of data link and physical layers



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We enable you to leverage knowledge anytime, anywhere!

Appendix 2

Self Study (The following slides are notincluded for assessment)

S b N t ki


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Sub-Networking

Creating sub-networks within a given IP address range Extends the network portion of IP address into the Host Part Converts the rigid boundary to arbitrary

Uses the Subnet mask to decide the no. of bitsrepresenting Physical Network ID and host ID

1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 0 0 1

Internet ID Host ID

PhysicalNetwork

Sub-Netting

Default IP Address DefinitionInternet ID Host ID


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