Chapter 3 The Basics of Networking Fluency Chapter 3 The Basics of Networking

What is the Internet? What’s your address? The totality of all wires, fibers, switches, routers, satellite links, and other hardware for transporting information between addressed computers. What’s your address?

How have computers changed our lives? For the better? For the worse? What effect has it had on the influence of the English language?

Communication Categories Synchronous Asynchronous Broadcast Multicast Point-to-point So what category does the Internet fit into? Synchronous – both sender and receiver are active at the same time – e.g. telephone Asynchronous – sending and receiving occur at different times – e.g. letter Broadcast – single sender & many receivers – e.g. television & radio Multicast – many receivers but specialized – e.g. car racing magazine Point-to-point: opposite of broadcast & multicast

Computer addresses Each computer connected to the Internet is given a unique IP (Internet Protocol) address IP address – currently series of 4 numbers separated by dots: e.g. 213.43.1.156 Each # can be in range of 0-255 Internet protocol moving to Version 6 (IPv6) with a 16-byte address system.

Domain Names Domain – related group of networked computers A more human-friendly way of addressing computers based on a hierarchy of domains. Domain – related group of networked computers markel.faculty.msmc.edu Domain Name System (DNS) translates the domain name into its 4-number IP address DNS server – a computer that keeps a list of the symbolic names and the corresponding IP addresses

Top Level Domains .com .org .mil .net .gov .edu In addition there’s a 2-letter country code: .uk, .au, .fr etc. that identifies countries There is a US code - .us

TCP/IP Transmission Control Protocol/Internet Protocol TCP – breaks a transmission up into small fixed-size packets Each packet contains the following: Data being sent Destination IP address Sequence # IP - re-orders the packets at the destination to assemble the information Vincent Cerf, one of the IP pioneers, used a postcard analogy to describe the TCP/IP process

Characteristics of TCP/IP Packets are independent Packets are transmitted over the Internet using whatever route is available Transmissions often rely on multiple technologies to move the packets through the Internet: Telephone lines Fiber optics Dedicated lines

Networks WAN – wide-area networks: networks designed to send information between two locations not directly connected. Packets take several “hops” before delivery LAN – local-area network. Computers are directly cabled or “channeled” together. Most LANs use Ethernet technology.

Connecting to the Internet ISP – Internet Service Provider Examples? Connection method: Modem DSL (digital subscriber line) Network connections LANs connect to the Internet via a gateway. Information from a remote Web computer is sent across the Internet, through the gateway to the organization’s intranet, and across the LAN to the user’s computer.

The World Wide Web Web servers – computers programmed to send files to browsers running on other computers connected to the Internet. Subset of the Internet Each web page has a unique address called a Universal Resource Locator or URL Built on a client-server relationship When you request a page, your browser is a client of the web server.

The URL The URL consists of three parts: Protocol: http:// - stands for Hypertext Transfer Ptococol Server computer’s name Pathname of the particular page http://domain.address/pathname http://faculty.msmc.edu/markel/cit1100/outline.html

Structure of emails and URLs Email: receiver@domain.address The receiver can have dots, dashes, and underscores. URL: http://domain.address/pathname The domain address has one or more dots, no @, no slashes. Spaces are not allowed in email or URLs.

Describing a Web Page Web pages stored as a description of how they should appear Description file is called the source file Written in HTML (hypertext markup language) Markup languages describe document layout Hypertext – breaks linear sequence of text through links: non-linear and dynamic HTML was invented by Tim Berners-Lee in 1990 when he was working for CERN, the European Laboratory for Particle Physics.

Directory Organization root page folder folder

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Th . . .th . . . that’s all, folks!