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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

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Chapter 11 internet technology l.jpg

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


11 1 historical development of the internet 1 l.jpg

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


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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”


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    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


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    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


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    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


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    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


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    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


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    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


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    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.


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    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


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    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


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    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.


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    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


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    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


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    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


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    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


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    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


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    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.


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    11.3 How Does the Internet work?

    11.3.4 Internet address (3)

    • 3. e-mail address

      • Format :

        • [email protected]_name

      • No space between any of the words

      • User names in the same domain are unique


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    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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