Local area network (LAN) Network of computers located close together Wide area networks (WANs) Networks of computers connected over greater distances Based on Chapter 2 of Gary Schneider. (2009). E-Business. E 8th Edition. Course Technology, Cengage Learning Circuit Combination of telephone lines and closed switches that connect them to each other 3 Computer network Any technology that allows people to connect computers to each other The Internet A large system of interconnected computer networks spanning the globe World Wide Web A subset of computers on the Internet 2 Circuit switching Centrally controlled, single-connection model Packets Files and e-mail messages on a packetswitched network are broken down into small pieces, called packets Travel from computer to computer along the interconnected networks until they reach their destinations 4
Routing computers Computers that decide how best to forward packets Routing algorithms Rules contained in programs on router computers that determine the best path on which to send packets Programs apply their routing algorithms to information they have stored in routing tables 5 Protocol Collection of rules for formatting, ordering, and error-checking data sent across a network Rules for message handling include: Independent networks should not require any internal changes to be connected to the network Packets that do not arrive at their destinations must be retransmitted from their source network Router computers act as receive-and-forward devices No global control exists over the network 7 TCP IP Controls disassembly of a message or a file into packets before transmission over the Internet Controls reassembly of packets into their original formats when they reach their destinations Specifies addressing details for each packet 6 8
Internet Protocol version 4 (IPv4) Uses a 32-bit number to identify computers connected to the Internet Base 2 (binary) number system Used by computers to perform internal calculations Subnetting Use of reserved private IP addresses within LANs and WANs to provide additional address space 9 A domain name is a set of words assigned to a specific IP address Top-level domain (or TLD) Rightmost part of a domain name Internet Corporation for Assigned Names and Numbers (ICANN) Responsible for managing domain names and coordinating them with IP address registrars 11 Private IP addresses Series of IP numbers not permitted on packets that travel on the Internet Network Address Translation (NAT) device Used in subnetting to convert private IP addresses into normal IP addresses Internet Protocol version 6 (IPv6) Protocol that will replace IPv4 Uses a 128-bit number for addresses 10 12
Web client computers Run software called Web client software or Web browser software Web server computers Run software called Web server software Client/server architecture Combination of client computers running Web client software and server computers running Web server software 13 Electronic mail (e-mail) Must be formatted according to a common set of rules E-mail server Computer devoted to handling e-mail E-mail client software Used to read and send e-mail Examples include Microsoft Outlook and Netscape Messenger 15 Hypertext Transfer Protocol (HTTP) Set of rules for delivering Web page files over the Internet Uniform Resource Locator (URL) Combination of the protocol name and domain name Allows a user to locate a resource (the Web page) on another computer (the Web server) 14 Simple Mail Transfer Protocol (SMTP) Specifies the format of a mail message Post Office Protocol (POP) POP messages can tell the e-mail server to: Send mail to a user s computer and delete it from the e-mail server Send mail to a user s computer and not delete it Simply ask whether new mail has arrived POP provides support for Multipurpose Internet Mail Extensions (MIME) 16
Text markup language Specifies a set of tags that are inserted into text Standard Generalized Markup Language (SGML) Older and more complex text markup language than HTML A meta language World Wide Web Consortium (W3C) Not-for-profit group that maintains standards for the Web 17 Offers a system of marking up documents that is independent of any software application Nonproprietary and platform independent Offers user-defined tags Costly to set up and maintain 19 18 Prevalent markup language used to create documents on the Web today HTML tags are interpreted by a Web browser and are used by it to format the display of the text HTML links can be structured as: Linear hyperlink structures Hierarchical hyperlink structures 20
The most common scripting languages include JavaScript, JScript, Perl, and VBScript Cascading Style Sheets (CSS) are sets of instructions that give Web developers more control over the format of displayed pages Style sheet is: Usually stored in a separate file Referenced using the HTML style tag 21 23 Intranet XML uses paired start and stop tags It includes data management capabilities that HTML cannot provide Interconnected network that does not extend beyond the organization that created it Differences between XML and HTML: Extranet XML is not a markup language with defined tags Intranet extended to include entities outside the boundaries of an organization XML tags do not specify how text appears on a Web page 22 Connects companies with suppliers, business partners, or other authorized users 24
Public network Any computer network or telecommunications network available to the public Private network A private, leased-line connection between two companies that physically connects their intranets Leased line Permanent telephone connection between two points 25 27 VPN An extranet that uses public networks and their protocols IP tunneling Effectively creates a private passageway through the public Internet Encapsulation Process used by VPN software VPN software Must be installed on the computers at both ends of the transmission 26 Bandwidth Amount of data that can travel through a communication line per unit of time Net bandwidth Actual speed that information travels Symmetric connections Provide the same bandwidth in both directions Asymmetric connections Provide different bandwidths for each direction 28
POTS, or plain old telephone service Uses existing telephone lines and an analog modem Provides bandwidth between 28 and 56 Kbps Digital Subscriber Line (DSL) Connection methods that do not use a modem Integrated Services Digital Network (ISDN) Bandwidths between 128 Kbps and 256 Kbps 29 DS0 (digital signal zero) Telephone line designed to carry one digital signal T1 line (also called a DS1) Carries 24 DS0 lines and operates at 1.544 Mbps Fractional T1 Provides service speeds of 128 Kbps and upward in 128-Kbps increments T3 service (also called DS3) Offers 44.736 Mbps 31 Broadband connections operate at speeds of greater than 200 Kbps Asymmetric digital subscriber line (ADSL) Transmission bandwidth is from 100 to 640 Kbps upstream and from 1.5 to 9 Mbps downstream Cable modems Provide transmission speeds between 300 Kbps and 1 Mbps DSL Private line with no competing traffic 30 Bluetooth Designed for personal use over short distances Low-bandwidth technology, with speeds of up to 722 Kbps Networks are called personal area networks (PANs) or piconets Consumes very little power Devices can discover each other and exchange information automatically 32
Ultra Wideband (UWB) Developed for short-range secure communications in military during the 1960s Are expected to be used in the future personal area networking applications, such as home media centers and linking mobile phone to the Internet 802.11a protocol Capable of transmitting data at speeds up to 54 Mbps 802.11g protocol Has 54 Mbps speed of 802.11a Compatible with 802.11b devices 802.11n Expected to offer speeds up to 320 Mbps 33 35 Wireless Ethernet (Wi-Fi or 802.11b) is the most common wireless connection technology for use on LANs Wireless access point (WAP) Device that transmits network packets between Wi-Fi-equipped computers and other devices Has a potential bandwidth of 11 Mbps and a range of about 300 feet Devices are capable of roaming One version of fixed-point wireless uses a system of repeaters to forward a radio signal from an ISP to customers Repeaters Transmitter-receiver devices (transceivers) Mesh routing Directly transmits Wi-Fi packets through hundreds, or even thousands, of shortrange transceivers 34 36
Third-generation (3G) cell phones Combine the latest technologies available today Short message service (SMS) Protocol used to send and receive short text messages Mobile commerce (m-commerce) Describes the kinds of resources people might want to access using wireless devices 37 Semantic Web Project by Tim Berners-Lee If successful, it would result in words on Web pages being tagged (using XML) with their meanings Resource description framework (RDF) Set of standards for XML syntax Ontology Set of standards that defines relationships among RDF standards and specific XML tags 39 Internet2 Experimental test bed for new networking technologies Has achieved bandwidths of 10 Gbps and more on parts of its network Used by universities to conduct large collaborative research projects 38