Lecture Slides on The Internet - Principles of Information Technology | ITEC 110, Study notes of Computer Science

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Objectives

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 theInternet - Learn how IP addresses identify devices connectedto the Internet

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Objectives (continued)

Learn how to determine your own TCP/IPconfiguration

Learn how HTML and XML are used with the WorldWide Web - Learn how to develop a simple Web page usingHTML - Learn how search engines make the World Wide Webmore usable

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Why 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 programs

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The 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 process

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TCP 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 information

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TCP 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 host

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DHCP

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 DHCP

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Routers

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 office

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High-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 layers

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