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Chapter 6. By Frankie, K. F. Yip MSN: Facebook:

Chapter 6 The Internet By Frankie, K. F. Yip MSN: Facebook: 6 Background The ARPANET, created in 1969, connected computers at
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Chapter 6 The Internet By Frankie, K. F. Yip MSN: Facebook: 6 Background The ARPANET, created in 1969, connected computers at UCLA, Stanford Research Institute, University of Utah, and University of California at Santa Barbara Today, the Internet connects computers all over the globe and supplies information to people of all ages and interests With an estimated 500 million nodes and more than 1.5 billion users, the Internet is huge Chapter 6: The Internet 2 6 Internet Infrastructure The Internet is not owned or operated by any single corporation or government The Internet backbone is a network of high-capacity communications links (e.g., optic fiber) that provides the main routes for data traffic across the Internet Backbone links and routers are maintained by network service providers (NSPs) E.g., PCCW of Hong Kong NSP equipment and links are tied together by network access points (NAPs) Chapter 6: The Internet 3 6 Internet Infrastructure (Hong Kong) Chapter 6: The Internet 6 Internet Service Providers (ISP) An Internet service provider (ISP) is a company that offers Internet access to individuals, businesses, and smaller ISPs E.g. of Hong Kong ISP: PCCW, HKBN, HGC, i-cable An ISP operates routers, communication equipment, and other network devices that handle the physical aspects of transmitting and receiving data between their subscribers and the Internet Extra services include service and Web hostage Chapter 6: The Internet 5 6 Connecting to the Internet To communicate with an ISP, your computer uses some type of communications device, such as a modem Chapter 6: The Internet 6 6 Hong Kong Internet Exchange (HKIX) HKIX s main goal is to interconnect the Internet Service Providers (ISPs) in Hong Kong so that we can exchange intra-hong Kong traffic locally without routing through US or other countries HK See ISP-A Global Internet HKIX HK ISP-B Source: Downstream Customers Downstream Customers Chapter 6: The Internet 7 6 Internet Protocols The Internet uses a variety of communications protocols (standards) to support basic data transport and services, such as , Web access, and downloading Chapter 6: The Internet 8 6 Internet Addresses Every device on the Internet has an assigned IP address such as In binary, the addresses are 32 bits long, but they are usually written as decimal numbers and divided into four octets by periods The address can a static address or dynamic address Servers use static IP addresses Most other Internet users have dynamic IP addresses Chapter 6: The Internet 9 6 Internet Domains People find it difficult to remember long strings of numbers Many Internet servers also have an easy-toremember name, such as, which is called a domain name Domain names are case insensitive A domain name is a key component of Web addresses and addresses E.g., in the Web address the domain name is In the address the domain name is also Chapter 6: The Internet 10 6 Internet Addresses and Domains Every domain name corresponds to a unique IP address that has been entered into a huge database called the Domain Name System (DNS) Any computer that hosts this database is a domain name server Domain name must be converted into an IP address before we can access the corresponding computer Chapter 6: The Internet 11 6 Fixed Internet Access Dial-up Connections DSL, ISDN, and Dedicated Lines Cable Internet Service Chapter 6: The Internet 12 6 Dial-up Connections A dial-up connection is a fixed Internet connection that uses a voiceband modem and telephone lines to transport data between your computer and your ISP Chapter 6: The Internet 13 6 Dial-up Connections A voiceband modem converts the signals from your computer into signals that can travel over telephone lines Modem speed is measured in bits per second (bps) Chapter 6: The Internet 14 6 DSL, ISDN, and Dedicated Lines Dedicated lines are leased from the telephone company and are not shared by other customers T1, T3, and T4 lines offer fast, high-capacity data transmission ISDN (Integrated Services Digital Network) is a type of fixed Internet connection that moves data at speeds of 64 Kbps or 128 Kbps over ordinary telephone lines Chapter 6: The Internet 15 6 DSL, ISDN, and Dedicated Lines DSL (digital subscriber line) is a high-speed, digital, always-on Internet access technology that runs over standard phone lines One variation is ADSL (asymmetric DSL), with download speed faster than upload speed Chapter 6: The Internet 16 6 Cable Internet Service Cable Internet service distributes always-on, broadband Internet access over the same infrastructure that offers cable television service Chapter 6: The Internet 17 6 Cable Internet Service Cable modems convert your computer s signal into one that can travel over the TV network Always-on connection Chapter 6: The Internet 18 6 Internet Services Real-Time Messaging Voice over IP Grid Computing File sharing Chapter 6: The Internet 19 6 Real-Time Messaging A networked-based, real-time messaging system allows people to exchange short messages while they are online One-to-one communication: Instant messaging (IM) Group communication: Chat Chapter 6: The Internet 20 6 Voice over IP VoIP (Voice over Internet Protocol) or Voice over IP, is a technology in which a broadband Internet connection is used to place telephone calls instead of the regular phone system To set up a standard VoIP system, you can use an inexpensive ATA (analog telephone adaptor), IP phone, wireless IP phone, or USB phone Chapter 6: The Internet 21 6 Voice over IP Advantages Low cost Flexibility Phone number moves with you Disadvantages Quality can vary Must have power to work Chapter 6: The Internet 22 6 Grid Computing A grid computing system is a network of computers harnessed together to perform processing tasks project Cloud computing depends on a grid of servers and storage devices that offer Internetaccessible computing services Google apps Amazon s Elastic Compute Cloud Chapter 6: The Internet 23 6 File Sharing P2P file sharing uses peer-to-peer (P2P) protocols that allow users to obtain files from other users located anywhere on the Internet BitTorrent is a file sharing protocol that distributes the role of file server across a collection of dispersed computers Chapter 6: The Internet 24
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