Lecture 1 -_overview_of_the_internet-1-

BITS 2513 – INTERNET TECHNOLOGY

LECTURE 1: OVERVIEW OF THE INTERNET

TOPICS

• Introduction to the Internet Infrastructure

• Common Internet Access Method

• Internet Service Providers (ISPs)• Uniform Resource Locators• Internet, Intranet and Extranet• Internet Organization• Internet Documents

Introduction to the Internet Infrastructure

Internet Infrastructure – US Scenario

local ISP

campusnetwork

corporatenetwork

IXP

RegionalNetwork

RegionalNetwork

local ISP

local ISP

IXP

IXP

Backbone Network

Backbone Network

RegionalNetwork

RegionalNetwork

Internet Infrastructure – Malaysia Scenario

Backbone NetworkBackbone Network

local ISP

local ISP

corporate

IXP

Regional Network

local ISP

Campus network

corporate

IXP

Regional Network

Campus network

Internet Infrastructure (continued)• Autonomous System?

- The infrastructure of the Internet consists of a federation of connected networks that are each independently managed - Note: Each “autonomous system may consist of multiple IP networks- Each AS have a number (called AS number)

• Hierarchy of network service providers (NSPs)– Tier-1: Nation or Worldwide network

(US: less than 20)– Tier-2: Regional Networks Provider(in

US: less than 100)– Tier-3: Local Internet Service Provider

(in US: several thousand)

Internet Infrastructure (continued)• Point-of-Presence (POP)?

- Location where a network (ISP, corporate network, or regional network, etc) gets access to the Internet

• Peering Points?- Locations (Tier-1 or Tier-2) networks are connected for the purpose of exchanging traffic

i) Public peering: Traffic is swapped in a specific location, called Internet Exchange Points (IXPs)

ii) Private peering: Two networks establish a direct link to each other.

Common Internet Access Method

Internet Access Methods

• Dial-Up– Use a modem and standard

telephone line.– The connection is made as

necessary and the maximum speed does not exceed 56Kbps

• ISDN (Integrated Services Digital Network)– Use existing telephone lines, ISDN

allows 64Kbps on a single channel.

– Two channels can be combined for a maximum of 128Kbps

Internet Access Methods (Continued)• DSL (Digital Subscriber Line)

– Use existing telephone lines, DSL integrates regular phone service and Internet access by using a DSL hub.

– “Always Connected" situation. – Speeds between 256Kbps and 640Kbps. Now,

up to 4Mbps– A factor that may limit your maximum speed is

the physical distance from a telephone company central office (CO) to the computer.

• Cable Modem – Use existing cable TV coaxial cables, this service

is provided by cable TV provider. – A cable modem device connects just like a TV or

cable box. – The computer is connected to the cable modem

via a network card (NIC) and an Ethernet cable.– Speeds can exceed 1.5Mbps, but as more people

in your area join the cable access network, speeds may diminish as everyone is sharing the same maximum bandwidth.

Internet Access Methods (Continued)

• T-1/DS-1– A T-1 is a very specialized

telecommunications circuit that does not work over normal telephone lines.

– It has been popular in many businesses for many years.

– It is divided into 24 channels that can be used for many different purposes, but can be combined to achieve a maximum speed of 1.54Mbps.

Internet Access Methods (Continued)

Cable Modem

DSL

Internet Service Providers (ISPs)

Introduction

• Internet Service Provider (ISP)? A

business that provides connectivity to the

Internet.

• ISPs can be a small business that

provides connectivity in only one city,

or a large company with access points

in many cities and countries.

• Some popular ISPs are:– TMNet– Jaring– Regional and local networks– School and college networks– Other small ISPs

Services Offered by an ISP

• The primary purpose of an ISP is to provide access to the Internet.

• To connect to the Internet, a computer needs (1)a physical connection to the ISP, (2) software to communicate over the Internet, and (3) an address so others on the Internet can identify the computer.

• To connect to an ISP, a computer must be using an operating system that supports the communication protocol of the Internet, which is TCP/IP.

• All latest Windows, Linux, and the Macintosh OS support TCP/IP.

Ways to Connect to an ISP• 1990s: Regular telephone

lines are the most common way for an individual to connect to an ISP.

• Nowadays: two competing high-speed methods are available.

• Both were introduced to the marketplace at about the same time, cost about the same, and attain about the same speeds.

• These two methods are DSL lines and cable modems.

How an Internet Service Provider Works• After you connect to an ISP by

cable modem, DSL, or telephone line, the ISP connects you to the Internet.

• The ISP’s equipment can be very simple or complex, depending on the ISP’s size.

• Figure 1 shows an example of how a small ISP might connect to the Internet.

Example of how a small ISP might connect to the Internet

Figure 1

How an Internet Service Provider Works (Continued)

• A router is a device that connects two or more networks and can intelligently make decisions about the best way to route data over these networks.

• The two networks in Figure 1 are the ISP’s LAN and the regional ISP’s network.

• This regional network is an example of a wide area network (WAN), a network that covers a large geographical area and might use a number of communications technologies.

How an Internet Service Provider Works (Continued)

• Before data gets onto a T1 line, it must be cleaned and formatted by a device called a CSU/DSU, which is really two devices in one.

• The Channel Service Unit (CSU) acts as a safe electrical buffer between the LAN and a public network accessed by the T1 line.

• A Digital Service Unit or Data Service Unit (DSU) ensures that the data is formatted correctly before it’s allowed on the T1 line.

How an Internet Service Provider Works (Continued)

Figure 2

What You Can Expect from an ISP

• An ISP is expected to offer access

to the World Wide Web, e-mail

services, and possibly FTP services.

• Some offer chat room and

newsgroup services, as well as

some space for a personal Web

site.

Point of Presence

• A small ISP might have only local telephone number that you can dial for access, but some larger ISPs have local telephone numbers in many major cities and other countries.

• A POP (point of presence) is a connection point to the Internet, either a telephone number you can call to access your ISP (Dial-Up) or an IP address provided by your ISP (Direct-Connected).

Uniform Resource Locators

Introduction• URL is a syntactic form used to identify a page of

information on the World Wide Web• A URL (Uniform Resource Locator) is an address for a

Web page file or other resource on the Internet.• The first part of the URL shown in Figure 3 is http, which

stands for Hypertext Transfer Protocol.

Figure 3

Introduction (Continued)• As the previous slide, URLs

consist of the following:– Protocol: HTTP, FTP, mailto,

news– Server name: Internet

address of Web server– Port number: default is 80– Path/filename: folder and

filename; default is index.html

– Anchor: bookmark within an HTML file

http://www.course.com:80/myfolder/myfile.htmlhttp://www.course.com/myfolder/myfile.html

How URL Works

Getting Online

• Connecting – traditional modem

(modulator/demodulator) – ISDN-Integrated Services

Digital Network – Cable Modems

Using Web Browsers

• Domain names are easy for humans to remember and use, but the devices on the Internet rely on numeric addresses to identify every host on every network that is connected directly to the Internet.

• Such a numeric address is called an IP address (Internet Protocol address).

• A group of controlling protocols is called TCP/IP (Transmission Control Protocol/Internet Protocol), and sometimes is called a protocol stack.

How a browser works

Internet, Intranet and Extranet

A Brief History of the Internet• The Internet came into existence in

1969 when Advanced Research Projects Agency (ARPA) connected the computers of four major universities in the United States (UCLA, Stanford, UC Santa Barbara, and the University of Utah).

• Until the lately 1980s, it was a loosely organized group of interconnected networks that were used predominantly by major academic institutions in the United States for research and development.

Internet?• The Internet consists of a large

number of computers connected, or networked, to each other.

• There are two types of such networked computers: servers and clients. 

• There is no real difference between these computer types except that servers tend to have greater capacity and be more expensive.

• The different uses of servers and clients means that they tend to be configured differently and run different software.

Intranet• An Intranet is a network that

uses the TCP/IP protocols to provide private services within an organization.– It uses Internet technology within a

private network.• An Intranet is an information

portal designed specifically for the internal communications of small, medium or large businesses, enterprises, governments, industries or financial institutions of any size or complexity.

Intranet• Intranets can be custom-

designed to fit the exact needs of businesses no matter where they are situated.

• Users of intranets consists mainly of:– Members of the executive team.– Accounting and order billing.– Managers and directors.– Sales people and support staff.

– Customer service, help desk, etc..

Extranet

• Extranet refers to Internet resources that are beyondthe reach of the public and require a logon name and password to access.

• An extranet is somewhat very similar to an intranet. Extranets are designed specifically to give external, limited access to certain files of your computer systems to: – Certain large or priviledged customers.– Selected industry partners.– Suppliers and subcontractors... etc.

http://libproxy.utem.edu.my/login

Internet Organization

Organizations That Standardized the Internet

• American National Standards Institute (ANSI)

• American Registry For Internet Numbers (ARIN)

• Asia Pacific Network Information Centre (APNIC)

• Directory Interoperability Forum (DIF)

• Institute of Electrical and Electronic Engineers, Inc. (IEEE)

• International Multimedia Teleconferencing Consortium (IMTC)

• International organization For Standardization (ISO)

Organizations That Standardized the Internet (continued)

• International Telecommunication Union (ITU)

• International Webcasting Association (IWA)

• Internet Architecture Board (IAB)

• Internet Assigned Numbers Authority (IANA)

• Internet Corporation for Assigned names and Numbers (ICANN)

• Internet Engineering Steering Group (IESG)

Organizations That Standardized the Internet (continued)

• Internet Engineering Task Force (IETF)

• Internet Mail Consortium (IMC)• Internet Network Information

Center (InterNIC)• Internet Society (ISOC)• Internet Protocol Multicast

Standards initiative (IPMSI)• International Committee for

Information technology Standards (INCITS)

Organizations That Standardized the Internet (continued)

• National Science Foundation (NSF)

• Organization for The Advancement of Structured Information Standards (OASIS)

• Portable Application Standards Committee (PASC)

• Reseaux IP Europeens Network Coordination Centre (RIPE NCC)

• US Internet Industry Association (USIIA)

• World Wide Web Consortium (W3C)

Internet Standardization Process

• Working groups present their work i of the Internet are published as RFC (Request for Comments). RFCs are the basis for Internet standards.

• Not all RFCs become Internet Standards ! (There are >3000 RFCs and less than 70 Internet standards)

• A typical (but not only) way of standardization is:– Internet Drafts– RFC– Proposed Standard – Draft Standard (requires 2 working

implementation)– Internet Standard (declared by IAB)

Internet Documents

Types of Internet Document

• There are five basic types of files on the Internet:– Text– Graphics– Audio– Video– Software

Text

• Plaintext– End with extension .txt.

• Hypertext– Written in Hypertext

Markup Language and end in .htm or .html.

• Hypertext defines how the text should appear, which words are hyper or linked, and what they link to.

DOC and WPD

• Word processor formats include Microsoft Word files (.doc) and Word Perfect files (.wpd).– Let your browser use its

helper app to display the file, and then use the Save feature in the helper app.

PDF

• Adobe created the Portable Document Format (PDF).

• To view PDF files use the Adobe Acrobat Reader available for free at www.adobe.com.

• PDF files can be viewed on any computer platform.

Graphic File Format• Every Web browser supports GIF (.gif) and JPEG

(.jpg) graphic file formats.

Graphic File Formats (Continued)

• Graphics Interchange Format (GIF)– Compressed but do

not lose any of the original data (lossless)

– Limited to 256 colors– Still patented in a few

countries

• Portable Network Graphics (PNG)– Up to 48 bits worth

of color– New graphic format

• Joint Photographic Experts Group (JPEG)– Compresses the data

but can lose some of the original content (lossy)

– Contains millions of colors

Waveforms• Sound is captured by sampling it at regular

intervals and recording the data.

Sound Formats• WAV (.wav) files are native to Windows.• Sun audio sound formats include .au

and .snd.• RealAudio file names use the extensions .ra

and .ram.– Text file that contains the URL of the real audio file.

• Audio Interchange File Format (AIFF) is an Apple/Macintosh format.

• MP3 uses the MPEG audio codec to encode and decode recorded music.

– Compresses a file to about 10% of its original size without losing quality.

– MP3 files can be created from regular CD using special software called a ripper.

– Patented format, generally okay if personal use• Musical Instrument Digital Interface (MIDI)

is a music synthesizer file format (.mid).– Files contains information on when to turn notes on

or off, how long to maintain them, and what instrument to use.

– Your sound card contains the instrument sounds.

Video Formats• Video files create large files that are compressed

using a video compression scheme.

Video Formats (Continued)

• Microsoft’s AVI (audio/video interleave)– Audio is interleaved with video.– Audio is not interrupted but video

frames may be dropped.

• Apple’s MOV and QT– Used by QuickTime.

• RealNetwork’s RealVideo (.rm)– Provides streaming video and

audio.

Video Formats (Continued)

• MPEG is emerging as the video standard.– Compresses the video.– Uses delta-frame encoding

by encoding only the changes from frame to frame.

– Various standards from MPEG-1 through MPEG-4.