1. Communications and Networks
Chapter 9
Communications and Networks

2. Competencies (Page 1 of 2)
Discuss connectivity, the wireless revolution, and communication systems
Describe physical and wireless communications channels
Discuss connection devices, including modems, T1, DSL, cable modem, and satellite and cellular connections
Describe data transmission factors, including bandwidths and protocols
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3. Competencies (Page 2 of 2)
Discuss network and key network terminology
Describe different types of networks, including local area, metropolitan area, and wide area networks
Describe network architectures, including configurations and strategies
Describe organizational uses of Internet technologies, including intranets, extranets, and firewalls
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4. Communications
Ask students to give examples of communication devices (key term) that they use daily
The process of sharing data, programs, and information between two or more computers
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5. Communications Today
Numerous applications depend on communication systems— , Instant messaging (IM), Internet telephone, and Electronic commerce
Connectivity uses computer networks to link people and resources
Going wireless has been the most dramatic change
Connectivity is a concept related to using computer networks to link people and resources
Microcomputers. minicomputers, and mainframes can all be connected
Wireless revolution
Use of mobile or wireless devices
The revolution is the support of more than just the wireless telephone
Many devices can and will connect to one another without any physical connection
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6. Communication Systems
Four basic elements
Sending and receiving devices
Communication channel
Connection devices
Data transmission specifications
Electronic systems that transmit data from one location to another
Communication systems can be wired or wireless
Basic elements
Sending and receiving devices – computer or a specialized communication device
Communication channel – carries the message
Connection devices – act as an interface between sending and receiving devices
Data transmission specifications – rules and procedures that coordinate the sending and receiving devices
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7. Communication Channels
Channels carry data from one computer to another
Two categories of communication channels
Physical connection
Wireless connection
Channels are essential to a communication system
They carry data
Types of channels
Telephone lines (key term)
Coaxial cables
Fiber-optic cable (key term)
Infrared (key term)
Broadcast radio (key term)
Microwave (key term)
Satellite
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8. Communication Channels Summary

9. Connection Device Signals
Types of signals
Analog
Digital
Signals
Sent analog – telephone signals; continuous electronic wave
Sent digital – computer signals; presence or absence of an electronic pulse; on/off
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10. Connection Device Types and Transfer Speeds
Types of modems
External
Internal
PC Card
Wireless
Modem – modulator-demodulator
External – stands apart from the computer is typically connected with a cable
Internal – built into the computer system unit already
PC card – credit card-size expansion board that is inserted into portable computers; telephone cable connects the modem to the telephone wall jack
Wireless modem (key term) may be external, internal, or a PC card
Does not use cables
Signals are sent through the air
Transfer Speed (key term) or transfer rate (key term)-measured in bits per second; the higher the speed the faster the transfer rate
Transfer Speeds
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11. Connection Services Dial-Up services Leased lines – T1, T2, T3 and T4
Digital subscriber line (DSL)
Uses existing phone lines
One type widely used is ADSL
Cable modems
Uses existing TV cable
Provides speeds as fast as DSL at a lower cost
Satellite/air connection services
Seven times faster than dial-up
Slower than DSL & cable modem
Standard telephone lines and conventional modems use a dial-up service
Slow
Still popular, but many are using other types of connections
T1, T2, T3, and T4 leased lines – do not require conventional modems and provide very high capacity and is expensive—mainly used by corporations not typical end user; T1 lines provide a speed of 1.5 mbps (mega bits per second)(key term) which is over 26 times as fast as a conventional modem
DSL – uses existing telephone lines to provide high-speed connections; uses DSL modems
Cable modems – Cable connections reach 90% of homes in America but not all cable companies support cable modems presently
Satellite/air connection services – Uses just what it says—satellite and air connections; older satellites couldn’t upload and dial up was still used for the process; but newer satellites are two-way satellites capable of handling both uploading and downloading; available almost anywhere but slower than DSL
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12. Typical User Connection Costs & Speeds
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13. Bandwidth Measurement of the capacity of the channel Categories
Voiceband also known as voice grade/low bandwidth
Medium band
Broadband
Used for high capacity transmission
Used by DSL, cable, and satellite
Several technical matters affect data communications
One is bandwidth – bits-per-second (bps) transmission capability of a channel
Three types:
Voiceband – also known as voice grade or low bandwidth; standard phone line; too slow for many types of transmissions – especially high-quality video; typical speeds are 56 to 96 kbps
Medium band – with special leased lines to connect minicomputers and mainframes as well as to transmit data over long distances (for larger computer systems); not typically used by individuals
Broadband – used for high-capacity transmissions (DSL, cable, satellite connections); (key term) specialized high-speed devices; effectively transmits high-quality video and other communication needs; typically 1.5 mbps; higher speeds possible
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14. Protocols Set of communication rules
Standard for Internet: TCP/IP (Transmission control protocol/Internet protocol)
Identification
Reformatting
Rules for exchanging data between computers
Essential features of protocol
Identifying sending and receiving devices (IP address); (key term) Internet unique number address
Reformatting – allows message to be broken into (key term) so easier to transmit over Internet through various interconnected networks; allows message to be reassembled at destination
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15. Networks A computer network is a communication system
Connects two or more computers
Allows information exchange
A computer network is a communication system that connects two or more computers so that they can exchange information and share resources
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16. Computer Networks Connect Computers
Common network terms
Node
Client
Server
Hub
Network interface cards (NIC)
Network operating system (NOS)
Distributed processing
Host computer
Network manager
Node – any device connected to a network
Client – a node that requests and uses resources available from other nodes
Server – a node that shares resources with other nodes; dedicated servers (key term) specialize in performing specific tasks—could be an application server (key term), communication server, database server, file server, (key term) printer server, (key term) or Web server (key term)
Hub – the center or central node for other nodes
Network interface cards (NIC) – connects the computer to a network
Network operating system (NOS) – software to control and coordinate activities between computers on a network
Distributed processing - computing power located and shared at different locations
Host computer – large centralized computer
Network manager – a computer specialist; network administrator (key term)
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17. Network Types Local area networks Home networks
WLAN
Metropolitan area networks
Wide area networks
Communications networks differ in geographical size. Three important types are:
1)LANs
Computers and devices linked in close proximity to each other
Linked by cable
Typically use a bus (key term) form of organization
With gateways, LANs can be connected to other LANs or any other type of network
Home Networks – LANs are now being commonly used by individuals in home/apartments; allow different computers to share resources including a common Internet connection; can be connected by various means including a wireless LAN (key term) (WLAN) that uses radio frequencies to connect computers
Home networking includes the following:
Radio frequency, telephone lines, electric wiring, cables, NIC/adapter cards
2)MANs (metropolitan area network)– also known as a regional network; (key term) span distances up to 100 miles
Network linking nodes and resources within the geographical bounds of a city
Cellular phones can extend the reach of a MAN
3)WANs (wide area networks)
Countrywide and worldwide networks
Use microwave relays and satellites to reach users
Internet is the widest WAN
LAN
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18. Network Architecture Architecture describes how a network is arranged
Arrangement is called topology
Types of network topology
Star
Bus
Ring
Hierarchical
Networks are connections of two or more computers that work together to exchange information and share resources
The network architecture describes how the network is arranged and how the resources are coordinated and shared
Network architecture also describes how a computer network is configured and what strategies are used
 Topology – network arrangement or configuration
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19. Principal Network Configurations
No instructor notes

20. Strategies
Strategy is a way of coordinating the sharing of information and resources
Common network strategies
Terminal
Client/server
Peer-to-peer
Strategy: ways of coordinating the sharing of information and resources in a network
Terminal network (key term) system
Centralized host, usually a mainframe
Nodes are usually terminals with little or no processing capabilities
Reservation systems
Client/server network systems
Powerful computer coordinates services
This server provides access to centralized resources
Widely used on the Internet
Peer-to-peer network (key term) system -Bus topology
Nodes have equal authority and act as both servers and clients
A node could obtain files from another node and provide files to another node
Gnutella is a widely used peer-to-peer network system for sharing all kinds of files including music files
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21. Organizational Internets
Intranets
Private network within an organization
Provides information to employees
Extranets
Private network that connects organizations
Used to allow suppliers and others access
Firewalls
Security system
Protects against external threats
Intranet – Intranets use browsers, Web sites, and Web pages like the public Internet; typically include , mailing lists, newsgroups, and FTP services
Extranet – Purpose is to increase efficiency and reduce costs
Firewalls – Organizational firewalls include a proxy server (key term) that is a gatekeeper; all communications between the outside world and an organization must pass through the proxy server where the source and content of each communication is evaluated; end users have many of the same concerns regarding security as organizations and can use firewalls as well
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22. Careers In IT Network Administrator
Manage a company’s LAN and WAN networks
Maintain hardware and software
Diagnose and repair problems
Candidates usually have a bachelor’s degree in computer science and practical experience
Annual salary is typically between $40,000 and $50,000

23. A Look to the Future Cars that Monitor and Respond
Pod car (Personalization on Demand)
Predicts and responds
Designed to learn and adapt to an individual's driving needs and habits
Toyota and Sony are collaborating on a "smart" car
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24. Discussion Questions (1 of 2)
Define and discuss connectivity, the wireless revolution, and communications.
Identify and describe the various physical and wireless communication channels.
Identify the standard Internet protocol and discuss its essential features.
Have students turn to the end of Chapter 9 in their textbooks to view the same “Open-Ended” questions/statements
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25. Discussion Questions (2 of 2)
Define and discuss the four principal network topologies.
Define and discuss the three most common network strategies.
Have students turn to the end of Chapter 9 in their textbooks to view the same “Open-Ended” questions/statements
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