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Lecture 1 -_overview_of_the_internet-1

Nov 01, 2014



Chapter 1 Internet Technology



  • Introduction to the Internet Infrastructure
  • Common Internet Access Method
  • Internet Service Providers (ISPs)
  • Uniform Resource Locators
  • Internet, Intranet and Extranet
  • Internet Organization
  • Internet Documents

3. Introduction to the Internet Infrastructure 4. Internet Infrastructure US Scenario local ISP campus network corporate network IXP Regional Network Regional Network local ISP local ISP IXP IXP Backbone Network Backbone Network Regional Network Regional Network 5. Internet Infrastructure Malaysia Scenario Backbone Network Backbone Network local ISP local ISP corporate IXP Regional Network local ISP Campus network corporate IXP Regional Network Campus network 6. 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 (calledAS 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)

7. 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, calledInternet Exchange Points(IXPs)
  • ii) Private peering:Two networks establish a direct link to each other.

8. Common Internet Access Method 9. 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

10. 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.

11. Internet Access Methods (Continued)

  • T-1/DS-1
    • A T-1 is a veryspecialized telecommunications circuitthatdoes 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.

12. Internet Access Methods (Continued) Cable Modem DSL 13. Internet Service Providers (ISPs) 14. Introduction

  • Internet Service Provider(ISP)? A business that provides connectivity to the Internet.
  • ISPscan 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

15. 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 connectionto the ISP,(2) software to communicateover the Internet, and(3) an addressso others on the Internet can identify the computer.
  • To connect to an ISP , a computermust be using an operating system that supportsthe communication protocol of the Internet, which isTCP/IP .
  • All latest Windows, Linux, and the Macintosh OS support TCP/IP.

16. Ways to Connect to an ISP

  • 1990s:Regular telephone lines are the most common wayfor 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 areDSL linesandcable modems .

17. How an Internet Service Provider Works

  • After you connect to an ISPby cable modem, DSL, or telephone line, theISP connects you to the Internet .
  • The ISPs equipment can be very simple or complex, depending on the ISPs size.
  • Figure 1 shows an example of how a small ISP might connect to the Internet.

18. Example of how a small ISP might connect to the Internet Figure 1 19. How an Internet Service Provider Works (Continued)

  • Arouteris a device thatconnects 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 ISPs LAN and the regional ISPs network.
  • This regional network is an example of awide area network (WAN) , anetwork that covers a large geographical areaand might use a number of communications technologies.

20. How an Internet Service Provider Works (Continued)

  • Before data gets onto a T1 line, it must be cleaned and formatted by a device called aCSU/DSU , which is really two devices in one.
  • TheChannel Service Unit (CSU)acts as asafe electrical bufferbetween the LAN and a public network accessed by the T1 line.
  • ADigital Service UnitorData Service Unit (DSU) ensures that the data is formatted correctlybefore its allowed on the T1 line.

21. How an Internet Service Provider Works (Continued) Figure 2 22. What You Can Expect from an ISP

  • AnISPis expected tooffer access totheWorld Wide Web ,e-mailservices, and possiblyFTPservices.
  • Some offerchatroom andnewsgroupservices, as well as some space for apersonal Web site .

23. 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.
  • APOP (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) .

24. Uniform Resource Locators 25. Introduction

  • URL is a syntactic form used to identify a page of information on the World Wide Web
  • AURL (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 ishttp , which stands forHypertext Transfer Protocol .

Figure 3 26. 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 27. How URL Works 28. Getting Online

  • Connecting
    • traditional modem (modulator/demodulator)
    • ISDN-Integrated Services Digital Network
    • Cable Modems

29. 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 anIP address (Internet Protocol