Chapter 3 The Basics of Networking

Transcription

1 Fluency with Information Technology 7 th Edition Chapter 3 The Basics of Networking

2 HTML Hypertext Markup Language Layout of document (Margin, font, text, image, ) Jump from point to point (non-linear) Dynamic and interconnected Net and Web

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4 People interconnected Social relationships changing English Nowhere is remote software, web pages, science/technology Freedom of speech and assembly Internet use unmediated (wikis), expression, blogs, private topics

5 Communication Types Synchronous: (phone) send/receive - same time Asynchronous: ( ) send/receive - different times Broadcast (multicast): single sender: many receiver - Point-to-point: single sender: single receiver

6 Internet Schematic Diagram

7 Basic Client/Server Interaction

8 Client/Server Relationships

9 Client / Server Server stores web page Client accesses web page Click link, enters client/server relationship with web server Once page is sent, relationship ends Can serve many clients at same time

10 Added to URL +internet&form=edghpc&qs=pf&cv id=3d2711f651a c85fe7d28 016c&cc=US&setlang=en-US

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12 Computer Address Names IP addresses: ( ) Unique numerical address connected to Internet given to each computer IPv4: 4 numbers, one byte each (Range: 0-255) - Range allows for billions of IP addresses IPv6: 128 bit addresses Domain Names: (fast.cs.ucsd.edu) Symbolic names - domain hierarchy

13 Top-level Domains Domains (related group of networked computers).edu.org.net.mil.gov Country designators such as.ca (Canada)

14 Two Views of the.edu Domain Hierarchy spiff.cs.washington.edu Figure 3.8 Two ways to think about the Internet domain hierarchy.

15 DNS translates humanreadable names into IP addresses

16 DNS (Domain Name System) Servers Your computer asks nearest DNS server to translate a name like: That local server asks a root name server for IP address of edu authoritative name server 13 root name servers which load share and backup Next it asks edu server for si authoritative name server Then it asks si server for airandspace server, which it asks for IP address of www

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20 TCP / IP (Transmission Control Protocol/ Internet Protocol) Sequence of small fixed-size units (IP packets) Unit of data, destination IP address, sequence number Sent over Internet one at a time using available route Take a different route, therefore no transmission delay (congestion and service interruptions)

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22 A ping is a please reply message

23 Traceroute

24 WAN (Wide Area Network) and LAN Internet: WAN collection sends information between widely separated locations LAN (Local Area Networks) connect computers linked by single cable or wire pair Ethernet

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27 Channel (wire, wire pair, or optical fiber) winds past set of computers Computer connected to channel, allows signal to be sent detected by all computers connected to channel Decentralized: Ethernet Computer listens to channel, if quiet, then free. Computer transmits unless another starts at same time. - In that case, both stop for a random time and then try again.

28 Enterprise Network Connections (LAN): Large networked organization (school, business, government) Creates a LAN or intranet Intranet (LAN) Intranet connects to Internet by gateway Sent from Web computer across Internet, through gateway, across LAN to user's computer

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30 Wireless Networks Wi-Fi (802.11) is a LAN variation Router physically connected to modem and Internet (wired) Broadcasts and receives radio frequency (rf) signals (wireless) Mobile computers send and receive signals (wireless) Access point hands out temporary IP addresses via DHCP (Dynamic Host Configuration Protocol) Router relays Internet requests for connected wireless computers

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33 LAN Connecting a Computer to Internet ISP (Internet Service Providers) Sell connections to Internet (Verizon, AT&T, ) User plugs into a modem that converts bits into form compatible with ISP Modem connects to Internet via Internet gateway Providers: ADSL or DSL (Digital Subscriber Line) and cable (TV) Smartphone has modem to connect to wireless

34 Web servers: World Wide Web Computers programmed to send files to browsers running on other computers connected to Internet Files: enhance web pages (images/animations) or help web services (audio/video) Web servers and their files make up World Wide Web World Wide Web is a subset of Internet

35 Internet and Web Is "www" required? WWW is a name; web pages optional usage User must give exact domain name for DNS Organizations help users reach them by: 1. Redirection: browser insert "www" 2. Register multiple domain names Museum of Modern Art registered both "moma.org" and " to same IP address

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38 Client/server interaction Uniform Resource Locator (URL) 1. Protocol: Hypertext Transfer Protocol ftp:// File Transfer Protocol 2. Server computer's name (IP address/domain) 3. Page's pathname (Which file (page) and where) If no index.html, lists files Web Page Request

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40 Directory hierarchy in pathname of URL Page given by pathname: /galleries/ga1100/pioneer.html Slash (/), into subdirectory or into file Directory Hierarchy: Can contain subdirectories, File Structure

41 Directory Hierarchy Figure 3.12 The hierarchy of this book, highlighting the path to this figure. Downward-pointing triangles are expanded, right-pointing triangles are not.