Networks

1
Networks

• CPS120
• Introduction to Computer Programming
• Lecture 4

2
What Is a Network

• A network is a group of connected computers that
  allow people to share information and equipment

3
Types of Networks

• LAN (Local Area Network) connects computers
  within a small geographic area like a building
• WAN (Wide Area Network) connects computers across
  a large geographic area like a city or country
  (often via satellite)
• Internet World-wide network of networks

4
Advantages

• Road warriors
• Eliminate sneakernet
• Share information
• Share equipment

5
Who Runs It?

• A network administrator manages the network and
  makes sure it runs smoothly
• Often called a systems administrator or an IS
  manager

6
Network Applications

• Electronic mail
• Groupware
• Calendaring
• Scheduling
• Video-conferencing
• Requires sound card, speakers, mike camera

7
Physical Networking

• Hubs
• A hub is a device that provides a central
  location where all the cables on a network come
  together
• NICs (Network Interface Card)
• An expansion card that physically connects each
  computer to the network
• Cables
• Coaxial, Unshielded Twisted Pair (UTP), Shielded
  Twisted Pair, Fiber-optic
• Wireless

8
How Information Is Stored

• Client-Server
• Used for large networks
• Files are stored on a central computer and
  everyone who can access the network can be given
  access them
• Easy to create scheme to backup and protect files
• Client a computer that can access information
  stored on the server
• Server Central computer that stores files
• NetWare, UNIX, Windows NT/2000

9
How Information Is Stored

• Peer-to-Peer
• Used for a small number of computes (e.g. 10)
• Files stored on own computers access given to
  them to others on the network
• LANtastic, Windows-98, Windows-ME

10
How Information Is Exchanged

• Ethernet
• Most popular and least expensive solution
• Each computer waits for a pause before sending
  information
• Like polite conversation
• Collisions between information often occur
• Computers wait a moment, then resend
• Ethernet 10 Mbps, Fast Ethernet 100 Mbps,
  Gigabit Ethernet 1000 Mbps

11
How Information Is Exchanged

• Token-ring is a type of network where a token
  that collects and delivers information is passed
  from compute to computer
• Speeds of 4 or 16 Mbps
• Asynchronous Transfer Mode (ATM) is a type of
  network that works by sending information in
  equal-sized pieces called cells
• 25, 155, 622 or 2488 Mbps
• Often networks networks

12
Network Security

• Firewall specialized hardware or software
  package designed to protect a private computer
  network from unauthorized access
• Think Moat
• User name and password
• Used for authentication
• Good passwords

13
Intranet

• Small version of the Internet in a company
• Uses familiar web-browsers and email packages
• Allows hyper-linking
• VPNs (Virtual Private Network)
• End-to-end encryption
• More cost efficient than private lines

14
Internet and WWW

• Chapter 10

15
Internet Fundamentals

• Dates from DARPA in the 1960s
• Consists of thousands of connected networks
  around the world
• Each organization on the Internet is responsible
  for maintaining its own equipment
• These organizations allow you to pass-through
  their nets
• Designed to provide multiple routing to bypass
  disabled computers
• Called cyber-space or the information superhighway

16
Internet Offerings

• Electronic mail (Most popular application)
• Information
• Entertainment
• Discussion Groups
• Chat
• Programs (Shareware)
• Online shopping

17
Connecting

• Computer
• Software
• Modem or high-speed connection
• ISP (Internet Service Provider)
• Access for a fee

18
World Wide Web

• Part of the Internet consisting of a huge
  collection of documents stored on computers
  around the world
• Web server computer that stores and delivers web
  pages
• Web site collection of web pages
• URL (Uniform Resource Locator) unique address
• HTTP, Computer, Directory, Name of Page
• Hyperlinks jump to different web pages

19
Browsers

• A program that lets you view and navigate
  information on the World Wide Web
• Home Page Web page that appears each time you
  start your web browser
• Browser
• Internet Explorer
• Netscape Navigator
• Features
• Bookmark
• History lists

20
Multimedia

• MP3 compressed files containing music or video
• WinAmp
• Streaming video requires player
• RealPlayer, QuickTime
• Enhancements
• Java
• JavaScript
• ActiveX

21
Web Portal

• Central starting point for browsing personalized
  by the individual
• Yahoo, Excite, Go, Lycos
• Info
• Free services like email, shopping, chat, games,
  stock quotes and sports scores

22
Shopping

• Auctions
• Secure web sites i.e. HTTPS

23
Children on the Web

• Inappropriate information
• Pictures
• Documents
• Protection
• Adult supervision
• Browser restrictions
• Restriction programs
• CyberPatrol
• NetNanny

24
Create Publish Web Pages

• HyperText Mark-up Language is a computer code
  used to create Web pages
• There are many programs available, called visual
  editors which can help you create Web pages
  without having to learn HTML
• Publishing your pages loaded to an addressable
  server