1. Communications & Networks
Chapter 8
Communications & Networks

2. Overview Identify Various Communication Uses List Network Advantages
Differentiate Network Types
Describe Communications Standards
Describe Communications Devices
Identify Different Transmission Media

3. Communications Two or More Devices Requirements
Transfer Data or Instructions
Requirements
Sending Device
Communications Device
Connects Sending Device to Channel
Connects Channel to Receiving Device
Communications Channel
Media on Which Data Travels
Receiving Device

4. Uses Wireless Messaging Text Messaging Picture Messaging
Send / Receive Text Messages Using Phone
14-17: 60 v. 5
Picture Messaging
Send / Receive Graphics, Pictures, Video
Sexting: 30% of 17-year-olds
Loss of Reaction : Alcohol=12%, Marijuana=21%, Texting=35%
Pew Internet 5/10
Pew Internet 12/09

5. Uses GPS (Global Positioning System) Groupware
Signals Sent by Satellites Orbiting Earth
Signal Sent Every 1/1000 of a Second
Earth-based Receivers Analyze Signals
Determine Receiver’s Geographic Location
Groupware
Assists Groups in Working Together
Share Data Over Network
e.g., Schedule Meetings

6. Uses Web Services Software Applications Mashup
Communicate with Other Remote Computers
Use Internet or Internal Business Network
Mashup
Combines Services from Multiple Sources

7. Uses
Very Hard to Give Up
Pew Internet 3/08

8. Networks Collection of Computers & Devices Connected via Advantages
Communications Devices
Transmission Media
Advantages
Facilitating Communications
Sharing Hardware
Sharing Software
Sharing Data And Information

9. Network Types LAN (Local Area Network) WLAN WAN (Wide Area Network)
Network in Limited Geographical Area
Typically Within a Building
WLAN
Wireless LAN
WAN (Wide Area Network)
Large Geographic Area
Uses Many Types of Media
Internet

10. Network Architectures
Client/Server
Client
Requests Resource Accessed from Server
Server
One or More Computers Controlling Resource
P2P (Peer-to-Peer)
Access Any Other Computer in Network
Internet File Sharing

11. Network Topology Configuration of Devices in a Network Bus
Consists of Single Central Cable
All Devices Connect to it
Inexpensive & Easy to Install

12. Network Topology Ring Star Cable Forms Closed Ring
Data Travels In One Direction
Expensive & Difficult to Install
Star
All Devices Connect to Hub
All Data Passes Through Hub
Bottlenecks Can Occur
Easy to Install

13. Intranet & Extranet Intranet Extranet Internal Corporate Network
Uses Internet
Accessible to Corporate Employees
Facilitates Working in Groups
Extranet
Allows Access to Parts of a Intranet
Customers / Suppliers

14. Protocol Protocol Collection of Procedures Type of Error Checking Used
Establish, Maintain, & Terminate Transmissions
Type of Error Checking Used
Data Compression Method, If Any
Indicate Finished Sending Message
Indicate Message Has Been Received

15. Standards Ethernet TCP/IP For LANs Uses Bus or Star Topology
Widely Implemented
TCP/IP
Used for Internet Transmissions
Packet Switching
Transmits Data by Breaking it Into Packets
Reassembles Data at Destination

16. Standards 802.11 (Wi-Fi) 802.16 (WiMAX) Bluetooth WAP
Family of Standards for Wireless LANs
(WiMAX)
Towers Cover 30-mile Radius
Provides Wireless Broadband Internet
Bluetooth
Short-range Radio Technology
WAP
Wireless Mobile Devices Connect to Internet

17. Standards IrDA RFID Data Transferred via Infrared Light Waves
Radio Signals Communicate with Tags
Failed Legislation
Nevada
Require Retailers to Inform Customers
Rhode Island
Government Agency Cannot Track Individuals
Texas
Prohibit Schools from Using RFID on Students

18. Types & Speeds
Measured in bps (Bits per Second)

19. Devices Modem DSL Modem Cable Modem
Converts Analog to Digital & Vice Versa
Required for Telephone Line Communication
DSL Modem
Cable Modem
Uses Cable TV Network

20. Devices Wireless Modem Network Card Wireless Access Point
Internet Access
Network Card
Connects PC to Network
Wireless Access Point

21. Devices Router Hub / Switch Connects Multiple Computers / Routers
Transmits Data to Network Destination
Uses Fastest Available Path
Many Protected by Hardware Firewall
Hub / Switch
Provides Central Point for Network Cables

22. Channel Communication Path Between Devices Bandwidth Latency
Difference Between Frequencies
Amount of Data that Travel Over Channel
Latency
Time for Signal to Travel
From One Network Location to Another

23. Channel Broadband Transmission Media
Transmit Multiple Signals over Channel
Transmission Media
Materials or Techniques
Capable of Carrying Signals

24. Physical Transmission Media
Twisted-pair
Telephone System
Coaxial Cable
Cable Television
Fiber-optic
Thin Strands of Glass or Plastic
Uses Light to Transmit Signals
Less Susceptible to Interference
More Secure

25. Wireless Transmission Media
Broadcast Radio
Distributes Radio Signals
Long & Short Distances
Cellular Radio
Widely Used for Mobile Communications

26. Wireless Transmission Media
Microwave Station
Earth-based Reflective Dish
Contains Antenna, Transceivers
Uses Line-of-sight Transmission
Satellite
Space Station
Receives Microwave Signals
Amplifies Signals
Broadcasts Signals Back