ObjectivesObjectives (continued)Objectives (continued)Why You Need to Know About…The InternetWhat is the Internet?The Architecture of the InternetProtocolsTCP and IPTCP and IP (continued)TCP and IP (continued)DHCPRoutersHigh-Level ProtocolsSMTPFTPTelnetHTTPURLs and DNSURLS and DNS (continued)Port NumbersNATChecking Your ConfigurationHTMLCreating a Simple Web PageCreating a Simple Web Page (continued)XMLUsing the InternetSearch EnginesOne Last ThoughtSummarySummary (continued)Summary (continued)Connecting with Computer Science2Objectives • Learn what the Internet really is• Become familiar with the architecture of the Internet• Become familiar with Internet-related protocols• Understand how the TCP/IP protocols relate to the Internet• Learn how IP addresses identify devices connected to the InternetConnecting with Computer Science3Objectives (continued)• Learn how DHCP can be used to assign IP addresses• Learn how routers are used throughout the Internet• Learn how a DNS server translates a URL into an IP address• Learn how port numbers are used with IP addresses to expand Internet capabilities• Learn how NAT is used in networkingConnecting with Computer Science4Objectives (continued)• Learn how to determine your own TCP/IP configuration• Learn how HTML and XML are used with the World Wide Web• Learn how to develop a simple Web page using HTML• Learn how search engines make the World Wide Web more usableConnecting with Computer Science5Why You Need to Know About…The Internet• Internet as revolutionary information technology• Impacts most spheres of human thought and action– E-commerce, information exchange, embedded devices • Intersection with computer science– Networks– Protocols– Server and client programsConnecting with Computer Science6What is the Internet?• The Internet: global collection of LANs and WANs• Internet service provider (ISP) connects desktop to the Net• No single entity owns the Internet– Some groups propose rules– Other groups provide maintenance • Sum of Net activities serves the larger social goodConnecting with Computer Science7The Architecture of the Internet• Anatomy of a connection – Desktop linked via modem/transceiver to LAN of ISP– ISP switching center: called a point-of-presence (POP)– POP connected to larger ISP with larger POP – Larger ISP connects to national or international ISPs, called national backbone providers (NBPs) • Network equipment and protocols critical to processConnecting with Computer Science8Connecting with Computer Science9Protocols• Protocol: set of rules that facilitate communication• Many protocols involved with the Internet– HTTP (Hypertext Transfer Protocol)– SMTP (Simple Mail Transfer Protocol)– FTP (File Transfer Protocol)• Protocols especially vital for networkingConnecting with Computer Science10TCP and IP• TCP (Transmission Control Protocol)– Responsible for the reliable delivery of data – Separates data into manageable, fixed-size packets – Establishes virtual circuit for transmission – Manages packet sequencing – Re-transmits packets received in error– Header appended to data segment contains relevant informationConnecting with Computer Science11Connecting with Computer Science12Connecting with Computer Science13TCP and IP (continued)• IP layer adds address header to TCP packets – Most widespread version (IPv4) has 32 bit value– New version of IP (IPv6) has 128-bit addresses• IPv4 address hierarchy – First part identifies network class (A, B, C, D, E)– Middle part identifies the host on the network– Final part identifies the node connected to the hostConnecting with Computer Science14Connecting with Computer Science15TCP and IP (continued)• Class indicates entity size and IP address allocation• IANA (Internet Assigned Numbers Authority) – maintains global high-level registry of IP addresses • ARIN (American Registry for Internet Numbers) – Agency allocates IP addresses to NBPs and ISPs • ISPs allocate addresses to other ISPs and home users• IP supports subnetConnecting with Computer Science16DHCP• DHCP: Dynamic Host Configuration Protocol– Allows for automatic assignment of IP addresses– Computer uses DHCP to get IP address from router• Flexibility for Database Administrator– Sets up server to allocate block of addresses – One time cost to configure computer for DHCPConnecting with Computer Science17Routers• Router– Computer linked to different communication lines – Routes packets on to line closer to destination– Joins networks together, including the Internet– Monitors communication lines for congestion – May send message packets along different paths• Routers work in a manner similar to post officeConnecting with Computer Science18Connecting with Computer Science19High-Level Protocols• Suite of protocols can be compared to OSI layers– TCP/IP spans Session, Transport, Network layers– SMTP, HTTP, FTP “above” TCP/IP in OSI model• High-level protocols use TCP/IP to accomplish tasks– TCP splits messages into packets, if necessary– TCP layer adds header, forwards to IP for address– IP sends packets to Data Link and Physical layersConnecting with Computer Science20Connecting with Computer Science21SMTP• SMTP: Simple Mail Transport Protocol (SMTP) – Used to send e-mail messages over the Internet– Establishes link from e-mail client to e-mail server– Handshaking creates parameters of communication• Receipt of e-mail handled by another protocol – POP3 (Post Office Protocol version 3) – IMAP (Internet Message Access Protocol)Connecting with Computer Science22FTP• FTP: File Transfer Protocol – Provides efficient transmission of data files– Requires client and server programs (like SMTP)– Most OSs include command-line FTP client• Windows: type FTP at the command prompt or• Specify server address in the IE address barConnecting with Computer Science23Connecting with Computer Science24Telnet• Telnet: Internet standard protocol for remote login to a UNIX host– Telnet runs on top of TCP/IP – Allows client computer remote control over host– Most OSs include a command-line Telnet clientConnecting with Computer Science25HTTP• HTTP: Hypertext Transfer Protocol (HTTP) – Developed in 1990 by Tim Berners-Lee– Allows Web browsers and Web servers to communicate– Central to the idea of the World Wide Web – Example,
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