Chapter 8: Communications and Networks Flashcards
Computer communications are
The process of sharing data, programs, and information between two or more computers
Numerous applications depend on
Communication systems, including:
1. Email
2. Texting
3. Videoconferencing
4. Electronic commerce
Connectivity uses a computer network to
Link people and resources
Connects your personal computer to
Other computers and resources on a network and the Internet
The Wireless Revolution:
1) Single most dramatic change in connectivity in the past decade
2) Allows individuals to connect to the Internet and share information from almost anywhere in the world
Electronic systems that
Transmit data from one location to another
Four basic elements of communication systems
1) Sending and receiving devices
2) Connection devices
3) Data transmission specifications
4) Communication channel
Sending and receiving devices
Computer or a specialized communication device
Connection devices
The interface between sending and receiving device
Data transmission specifications
Rules and procedures that coordinate the devices
Communication channel
Carries the message
Communication channels carry the data from
One computer to another, essential element of every communication system
Two categories of communication channels
1) Physical connections using wire or cable
2) Wireless connections
The physical connection between sending and receiving device include:
1) Twisted pair cable: two pairs of copper wire twisted together
2) Coaxial cable: single solid copper core
3) Fiber-optic cable: tiny glass tubes
Twisted pair cable: two pairs of copper wire twisted together
- Telephone lines
- Ethernet cables
Coaxial cable:
Sinble solid copper core and cable TV
Fiber-optic cable:
Tiny glass tubes
1. Faster and more reliable than coax
2. Speed as high as 1 petabit per second
Wireless connections do not use
A solid substance to connect, use the air itself, and most use radio wave to communicate
Primary Wireless Technology
1) Bluetooth (short-range)
2) Wifi (wireless fidelity)
3) Microwave
4) WiMax (extends Wifi)
5) Cellular
6) Satellite
7) Infrared
8) GPS
1) Bluetooth (short-range)
Radio communication standard
2) Wifi (wireless fidelity)
Uses high frequency radio
3) Microwave
Uses high-frequency radio wave signals
4) WiMax (extends Wi-fi)
The new standard that uses microwave to extend Wifi range
Cellular
Use multiple antennae to communication
Satellite
Uses satellites as microwave relay stations
Infrared
Use infrared light wants to communication over short distance
GPS
Determine geographic location of the devices
Types of signals
1) Analog (telephone)
2) Digital (computer)
Transfer rates
1) Mbps: million bits per second
2) Gbps: billion bits per second
3) Tbps: trillion bits per second
Modem
Modulator or demodulator
Modulation is
The process of converting from digital to analog
Demodulation is
The process of converting from analog to digital
Transfer rate (continued)
Speed in which modems transfer data, and usually measured in megabits per second (Mbps)
Types of modems
1) Digital subscriber line (DSL)
2) Cable
3) Wireless
Digital subscriber line (DSL)
High speed telephone lines
Cable
Uses coaxial cable
Wireless
Also known as WWAN
Leased lines
1) T1 combined to form T3 and DS3
2) Have been replaced by OC lines: Faster optical carrier lines
3) Higher capacity: Not affordable for individuals
Digital subscriber line (DSL)
1) Uses phone lines
2) ADSL is most widely used type of DSL
Cable
1) Uses an existing TV cable
2) Faster than DSL
Fiber Optic Service (FiOS)
New technology: Google and Verizon
Satellite connection service
Use almost anywhere
Cellular Services
3G and 4G cellular network connectivity
The Mobile Office
1) Can telecommute from anywhere
2) Become a one-man workforce
The data transmission bandwidth is
How much information can move across the communication channel in a given amount of time.
The data transmission measurement is
Of the width or capacity of the communication channel
Categories of bandwidth
1) Voiceband (or low bandwidth)
2) Medium band-leased lines for high-speed
3) Broadband for DSL, cable, and satellite connection to the Internet
4) Baseband for individual connections for computers in close range
Protocol
Communication rules for exchange data between computers
HTTPS
Hypertext Transfer Protocol Secure: 1) Widely used to protect the transfer of sensitive data
TCP/IP
Transmission control protocol/Internet protocol
1) Most widely used protocol
2) Each computer is identified with unique IP (Internet Protocol) address
3) DNS: Domain name service resolves IP addresses to names
4) Packetization: Information is broken down into small parts (packets) and then reassembled
Network
A communication system that connects two or more computers so they can exchange information and share resources
Nodes
Any device connected to a network
Client
A node that requests and uses resource from other nodes
Server
A node that share resources with other nodes
Directory Server
Specialized server that managers resource
Host
Computer system that can be accessed over a network
Router
Node that forwards or routes data packets
Switch
Central node that coordinates the flow of data
Network Interface Cards (NIC)
Expansion card that connects a computer to a network
Network Operating System
Control activities of all computers on the network
Network Administrator
Computer specialists responsible for network operations
LAN
Local area network, located within close proximity
Home
Local area network for home use, typically wireless
WLAN
Wireless local area network, all communication passes through an access point
PAN
Personal area network, connects digital devices, such as PDAs
MAN
Metropolitan are network, typically spans cities with coverage up to 100 miles
WAN
Wide are network for countrywide or worldwide coverage
How the network is
Arranged and resources are shared
Network Topology
Physical arrangement of the network
Network Strategy
How the information and resources are shared
Network Strategies
1) Client/Server Network
2) Peer-to-Peer (P2P) Network
Client/Server Network
1) Central computers coordinate and supply services to other nodes on the network
2) Server provides access
Peer-to-Peer (P2P) Network
1) All nodes have equal authority
2) Can act as both client and server
Internet technologies support effective communication within and between organizations.
1) Intranet
2) Extranet
Intranet
1) Private network within an organization
2) Works like the Internet
Extranet
1) Private network that connects more than one organization
2) Works like the Internet, but provides suppliers and other trusted partners with limited access to the organization’s networks
Commonly used technologies to ensure network security
1) Firewall
2) Intrusion detection system (IDS)
3) Virtual private network (VPN)
Firewall
1) Hardware and software that controls access to the network
2) Proxy server provides pass-through access
3) Protects against external threats
An intrusion detection system (IDS)
1) Works with the firewall to protect the organization’s network
2) Analyze all incoming and outgoing network traffic
Virtual private network (VPN)
Creates a secure private network connection between your computer and the organization
Telepresence
1) Seeks to create the illusion that you are actually at a remote location
2) Early implementations mainly focus on an extension of video conferencing
