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CHAPTER 8: COMMUNICATIONS AND NETWORK - Coggle Diagram
CHAPTER 8:
COMMUNICATIONS AND NETWORK
COMMUNICATIONS:
-Computer communications is the process of
sharing data, programs, and information between two or more computers.
-Numerous applications depend on communication systems, including:
-E-mail – sending and receiving electronic documents
-Texting – short electronic messages
-Video Conferencing – low cost alternative to long distance
-Electronic commerce – buying and selling goods
electronically
CONNECTIVITY:
-Connectivity uses computer networks to link
people and resources
-Connects your personal computer to other
computers and resources on a network and the Internet.
COMMUNICATION SYSTEM:
-Communication systems are electronic systems that transmit data from one location to another
-Communication systems can be wired or wireless
BASIC ELEMENTS OF COMMUNICATION:
Sending and receiving devices
-Computer or a specialized communication device
2.Connection devices
-Interface between sending and receiving device
3.Data transmission specifications
-Rules and procedures that coordinate the devices
4.Communication channel
-Carries the message
COMMUNICATION CHANNELS:
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
physical connection between sending and receiving device include:
-Twisted pair cable:
-Coaxial cable:
-Fiber-optic cable:
2.Wireless Connections
-Wireless Connections do not use a solid substance to connect.
-uses the air itself.
-Most use radio waves to communicate
Connection Services - Individuals
Dial up:
-original service using
existing telephones and telephone modems to
connect to the Internet.
has been replaced by higher-speed connection
services including DSL, cable, satellite, and cellular services.
Connection Device Signals:
Types of signals:
-Analog – telephone signals; continuous electronic wave
-Digital – computer signals; presence or absence of an electronic pulse; on/off
Transfer rates -the speed in which modems transmit data
-Mbps – million bits per
second
-Gbps – billion bits per second
-Tbps – trillion bits per second
CONNECTION DEVICES:
Devices need to convert digital signal to analog
modem - modulator-demodulator
-Modulation is the process of converting from digital to analog
-Demodulation is the process of converting from
analog to digital
Transfer rate
-Speed in which modems transfer data
-Usually measured in megabits per second (Mbps)
types of modem:
Digital subscriber line (DSL)
2.cable
3.wireless
DATA TRANSMISSION:
Factors that affect data transmission include bandwidth and protocols.
-Bandwidth is how much information can move across the communication channel in a given amount of time
-Measurement of the width or capacity of the communication channel
-Categories of bandwidth:
-voiceband
-medium band
-broadband
PROTOCOLS:
Protocols are communication rules for
exchanging data between computers
TYPES:
-HTTPS – Hypertext Transfer Protocol
Secure
-TCP/IP (Transmission control
protocol/Internet protocol)
-Each computer is identified with unique IP
(Internet Protocol) address
-Essential features of protocol:
-Identification,Domain Name Server (DNS),Packetization
NETWORKS:
A communication system that connects two or more computers so they can exchange information and share resources.
Specialized Terms in a Network:
-Nodes
-Client
-Server
-Directory server
-Host
-Router
-Switch
-Network Interface Cards (NIC)
-Network operating system
-Network administrator
Star Network:
-Topology where each device
connected directly to a
central network switch.
-All communications pass
through the switch; each
connecting device is asked (“polled”) whether it has a message to send and then each devices is in turn allowed to send its message
Ring Network:
-Topology where each device connected directly to a central network switch.
-Each device is
connected to two other devices forming a ring.
-When a message is sent it passes through each device until it reaches its destination.
NETWORK ARCHITECTURE:
How the network is arranged and resources are shared:
Network Topology
-Physical arrangement of the network
-Bus network
-Ring Network
-Star Network
Network Strategy
-How the information and resources are shared
NETWORK TYPES:
-LAN -local area network: located within close proximity
-Home- Local area network for home and apartment use
-WLAN- Wireless local area network
-PAN- Personal area network
-MAN-Metropolitan area network
-WAN- Wide area network for countrywide
NETWORK TYPES:
Communications networks differ in geographical size.
Three important types are:
-Local area networks - LANs
-Home Networks
-Wireless LAN
-Personal Area networks
-MANs (metropolitan area network)
-WANs (wide area networks)
Mesh Network:
-Topology that does not use
a specific physical layout, but requires that each node have more than one connection to other nodes.
-wireless technologies are frequently used to build mesh network.
Organizational Networks:
-Internet technologies support effective communication
within and between organizations
-Intranet
-Private network within an organization
-Works like the Internet
Extranet
-Private network that connects more than one organization
-Works like the Internet, but provides suppliers and other trusted partners with limited access to the organization’s networks
Tree Network:
-Topology where each
device connected to a
central node either directly or through
subordinate nodes
-Also called hierarchical
Network Strategies:
Client/Server Network- Central computers coordinate and supply services to other nodes on
the network
Advantages:
-handle large networks efficiently
-availability of powerful network management software to monitor and
control network activities
Disadvantages:
-Cost of installation and maintenance
Network Security:
Commonly used technologies to ensure network security:
Firewall
-Hardware and software that controls access to network
-Proxy server provides pass-through access
-Protects against external threats
2.Intrusion detection system (IDS)
-Works with firewall to protect organization's network
-Analyzes all incoming and outgoing network traffic
3.Virtual private network (VPN)
-Creates a secure private network connection between your
computer and the organization
Careers In IT:
Network Administrator:
-Manages a company’s LAN and WAN
networks
-Maintains networking hardware and
software,diagnosing and repairing
problems that arise
-Candidates usually have
a bachelor’s or associate’s degree in computer science, computer technology or
information systems
-Practical networking experience
-Annual salary is typically
between $47,000 and
$64,000