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Chapter 11 Internet Technology

Chapter 11 Internet Technology 11.1 Historical Development of the Internet 3 11.2 Connecting to the Internet 4 11.3 How does the Internet work? 10 Chapter 11 Internet Technology 11.1 Historical Development of the Internet (1) A. Development of Internet

JasminFlorian
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Chapter 11 Internet Technology

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  1. Chapter 11 Internet Technology 11.1 Historical Development of the Internet 3 11.2 Connecting to the Internet 4 11.3 How does the Internet work? 10

  2. Chapter 11 Internet Technology 11.1 Historical Development of the Internet (1) • A. Development of Internet • In 1969, the US Defense Department built a network called the ARPANET • Tied together computers of military and universities 1. Allow geographically separated computers to share data 2. Allow communication via e-mails 3. Designed to withstand damage • Data could bypass the damaged part of the network 4. Allow various types of computers to run on it

  3. Chapter 11 Internet Technology 11.1 Historical Development of the Internet (2) • Initially, ARPANET consisted of four main computers • In 1986, US NSF connected its network of supercomputers to ARPANET • Civilian network • NSF allowed anyone to join the network • ARPANET is renamed as “Internet”

  4. Chapter 11 Internet Technology 11.1 Historical Development of the Internet (3) • B. Development of WWW • The popularity of the Internet is due to the World Wide Web (WWW), or the Web • Internet’s fast growing portion • The Web was invented by Dr. Tim Berners-Lee in 1991 • A researcher in CERN • In 1993, Mosaic was developed • The first widely distributed Web browser by Marc Andreessen • Mosaic is the ancestor of today’s Web browsers • e.g. Netscape or Internet Explorer

  5. Chapter 11 Internet Technology 11.2 Connecting to the Internet • 1. Internet Service Provider • 2. Internet Access for Home Users • Dial-up Access • Broadband Access • 3. Internet Access by Network Users • 4. Internet Access by Mobile Users

  6. 11.2 Connecting to the Internet 11.2.1 Internet Service Providers (1) • Internet • Global collection of networks • Collaborative: • Each member network provides • servers • communication devices and • connecting lines etc. • Directs traffic • The Internet is not run by a single organisation • Large organisations provide Backbones • e.g. UUNET and NASAR • High-speed channels that link the networks

  7. 11.2 Connecting to the Internet 11.2.1 Internet Service Providers (2) • Internet service providers (ISP) • Offer Internet access to • individuals, companies and organisations. • Have permanent connection to the Internet backbone • Service may be • charged at an hourly rate • fixed monthly amount for unlimited access • means that there is no limit for duration of connection

  8. 11.2 Connecting to the Internet 11.2.2 Internet Access for Home Users (1) • 1. Dial-up Access • Using regular modem and telephone line • Temporary link to the Internet • Modem is connected to the serial port • Network interface card (NIC) is not necessary • Inexpensive but slow • 56 kbps • In Hong Kong, need to pay for PNETS • Public Non-Exclusive Telecommunications Service • charging per minute use telephone line • Connection may not be successful due to busy phone line

  9. 11.2 Connecting to the Internet 11.2.2 Internet Access for Home Users (2) • 2. Broadband Access (1) Asymmetric Digital Subscriber Line (ADSL) or (2) Cable TV network. • Hardware needed: • NIC and • Special modem • Applying advanced technology over telephone line • very high transfer rate up to 1.5 M to 10 Mbps • Connection is fast and easy because • dial-up is not necessary • Installed by trained technicians

  10. 11.2 Connecting to the Internet 11.2.3 Internet Access for Network Users • Hardware • Router • to connect a LAN to the Internet • Wireless access point, wireless NIC • more convenient • Access to ISP via 1. broadband with telephone line/optical fibre 2. ISDN with dedicated phone line 3. T1 with a digital line 4. Wireless technology with radio waves/satellites • Unlimited access • Fixed monthly payment.

  11. 11.2 Connecting to the Internet 11.2.4 Internet Access by Mobile Users • Wireless Service Provider (WSP) • a type of ISP • that uses radio waves • rather than cable • to provide Internet access to users of wireless devices • e.g. handheld computers and mobile phones

  12. Chapter 11 Internet Technology 11.3 How Does the Internet Work? • A. TCP/IP • B. IP Address • C. Domain Name • D. Internet Address • E. DNS Server

  13. 11.3 How Does the Internet work? 11.3.1 TCP/IP (1) • Transmission Control Protocol (TCP) and Internet Protocol (IP) • Set of rules used in data transmission on the Internet • Data is broken up into small packets by the sender • Each packet is directed by a series of routers • So, different packets use different routes • Finally, recombined by the receiver.

  14. 11.3 How Does the Internet work? 11.3.1 TCP/IP (2) • Advantages of TCP/IP: 1. The load of transmission lines is evenly distributed 2. Unaffected by the failure of any path • More than one path, the packets would be routed round the problem 3. Entire message is guaranteed to be transmitted • If packet is not received properly, request re-transmission 4. Different Computers can communicate • for all OS that support TCP/IP

  15. 11.3 How Does the Internet work? 11.3.2 IP Address • On the Internet, computers have unique IP address • each can be uniquely identified • A series of four numbers separated by a period • Each number between 0 and 255 • e.g. 202.148.153.59 • Combination of IP addresses is • 256 x 256 x 256 x 256. • Large organisations: permanent • Home users: temporary • Each packet carries IP addresses of sender and receiver • Similar to the addresses on an envelope

  16. 11.3 How Does the Internet work? 11.3.3 Domain Name (1) • IP address • Used by computers • difficult for people to remember • May change if it is shared • Domain • A group of computers under the same organization • Domain name • Text version of IP address • of a server of the organisation • using words separated by periods, e.g. • “Radian.com.hk” • More meaningful and easy-to-remember

  17. 11.3 How Does the Internet work? 11.3.3 Domain Name (2) • Top level domains • can be 1. Generic top level domains • e.g. .com, .org, etc. 2. Country-code top level domains • e.g. .hk, .cn, .au, etc. • Second-level domains • under .hk • .com.hk, .org.hk, .net.hk • .edu.hk, .gov.hk, .idv.hk

  18. 11.3 How Does the Internet work? 11.3.4 Internet address (1) • 1. Uniform Resource Locator (URL) • Address of a Web page • e.g. http://www.radian.com.hk/forum/content.html • Defining the route to a file on the Web, including • Protocol prefix e.g. http://, ftp://, news:// • Type of host server e.g. www, mail, ftp • Domain name e.g. gov.hk, radian.com.hk • Subdirectory name e.g. forum • Filename. For example, e.g. content.html

  19. 11.3 How Does the Internet work? 11.3.4 Internet address (2) • 2. Home page • Starting page of a Web site • Stored in the root directory • Filename: • Index or Default • with extension: html, htm, asp, jsp etc.

  20. 11.3 How Does the Internet work? 11.3.4 Internet address (3) • 3. e-mail address • Format : • user@domain_name • No space between any of the words • User names in the same domain are unique

  21. 11.3 How Does the Internet work? 11.3.5 DNS Servers • DNS Servers • Translate domain name into IP address • maintain a table with • Domain names of organisations and their corresponding IP addresses • For each domain name, e.g. e-mail address or URL • DNS server translates into IP address • Kept by major ISP • the table is updated regularly

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