module 6 Flashcards
data communication system
eletronic transfer of data from one location to another
major components of data communication system
sender and receiver devices
modems or routers
a communication channel
bandwidth
the amountof data that can be transferred from one point to another in 1 second
attenuation
loss of power in a signal as it travels from the sending device to the receving device
communication media
connect the sender and receiver devices - can be conducted or radiated
conducted media: provides a physical path (cable) that signals are transmitted on
radiated media: use an antenna for transmitting data through air or water
data transmission are divided in two types
broadband: multiple pieces of data sent simultaneously
narrowband: voice grade transmission that can transfer limited information in a specific period of time
sender and recevier devices
input/output device
smart terminal
personal computer
netbook computer
supercomputer
smartphone
modem
device that connects the user to the internet
three types of processing configurations
centralized
decentralized
distributed
centralized processing
all processing is done at one central computer
decentralized
each user, department, or division has its computer
more responsive that a centralized processing system
high costs due to # of systems and duplication of efforts
distributed processing
solves the problems that centralized and decentralized processing faced
processing is distributed
Open Systems Interconnection model (OSI)
seven layer architecture
defines how data is transmitted from computer to computer
each layer performs a specific task
seven layers an osi model
application
presentation
session
transport
network
data link
physical
three major types of networks
local area networks (LAN)
wide area networks (WAN)
metropolitan area networks (MAN)
LAN
connects workstations and peripheral devices in close proximity
used to integrate services within a limited geographical area
WAN
can span several cities, states or countries
speed determiend by interconnections
MAN
designed to handle data commincation for multiple orgs in a city
five common topologies
star
ring
bus
hierarchal
mesh
star
consists of central computer and nodes
host computer supplies the main processing power
ring
no host computer required
each computer manages its own connectivity
arranged in a circle
bus
connects nodes along a network segment
ends of the cable are not connected
hierarchical
combines computers with different processing strengths
failure of nodes at the bottom level may not have a negative impact on network performance
middle and top nodes are crucial for network operations
mesh
every node is connected to every other node
highly reliable
costly and difficult to maintain
protocols
agreed upon methods and rules to exchange info
applied to hardware connections, data transmission and file transfers
specify the format of message packets
routing
determining the route that data packet is transferred
uses a routing table to determine the best route for the packet
centralized routing
where one node is in charge of selecting the path for all packets
distributed routing.
relies of each node to calculate the best possible route
three levels of logic
presentation: focuses on how data is returned to the client
application: focuses on software processing requests for users
data management: focuses on data management and storage operations
two tier architecture
client (tier 1) communicates. directly with the server (tier 2)
N-tier architecture
works to balance the workload b/w the client and server
removes the application logic from the client and server and places it on a middle-tier server
wireless tech
wireless LANs (WLAN)
wireless WANs (WWAN)
WiMax
worldwide interoperability for microwave access
designed for wireless MANs
mobile networks
three part architecture:
base stations
mobile telephone switching offices
subscribers
techniques to improve security
include a service set identifier (SSID)
use a wired equivalent privacy (WEP)
use an extensible authntication protocol (EAP)
use wifi protected access (WPA)
use WPA2
convergence
integration of voice, video and data to that multimedia info can be used fro decision making
