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71 Cards in this Set
- Front
- Back
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Protocol Stack |
List of protocols used by a system |
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Protocol |
Formal set of conventions governing how communication should take place in a system |
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Channel |
Specific band of frequencies allocated to a particular service of transmission |
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Data Communications Circuit |
Provides transmission path between locations used to transfer digital info from 1 station to another |
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Communications Link |
Path for transmission of signals between devices |
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Station/Node |
Endpoint where subscribers gain access to data communications circuit |
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Baud rate |
-Rate of change of signal in a transmission medium after encoding and modulation -Number of signaling element pet second -1 output signaling element over time |
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Information Capacity |
-Measure of how much info can be propagated through a communication system -Number of independent symbol that can be carried through a system in a given unit of time -Dependent on frequency and bandwidth |
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Bit Rate |
-Rate of change of a digital info signal -Number of bits transmitted per second |
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Block/Frame/Packet |
Group of bits transferred as a unit
Bit-Layer 1 Physical Frame - Layer 2 Data Link Packet - Layer 3 Internet Block - Layer 4 Transport |
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Space |
Binary 0 |
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Mark |
Binary 1 |
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Bit |
-Binary Digit -Most basic digital symbol to represent info |
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Bit Rate = Baud Rate |
ASK modulation |
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DSLAM |
DSL Access Multiplexer |
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Information Theory |
Theoretical study of efficient use of bandwidth to propagate info through electronic communication systems |
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Bandwidth |
-Range of frequencies contained in a spectrum -To define a particular channel in a transmission system -Data rate/Speed Analog: f = cycles/sec or hertz Digital: baud = bits/sec or speed bps/data rate |
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Data Communication Code |
-Represents characters/symbols -Includes character codes, character sets, symbol codes, character languages |
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Data Transmission Code |
Info converted to binary code |
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Data |
Info stored in digital format |
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Information |
-Knowledge/Intelligence -Analog or digital |
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Text, Numbers, Images, Audio, Video |
5 Data Representations |
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Text |
-Alphanumeric characteristics -bit patterns -each set is called a code |
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Numbers |
-bit patterns converted to binary |
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Images |
Bit patterns or matrix of pixels wherein each pixel is a dot |
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Audio |
Continuous form/recording or broadcasting of sound or music |
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Video |
Recording or broadcasting of picture or movie |
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Front End Processor |
-DTE that directs traffic to and from many ckts with different parameters and data formats |
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Line Control Unit |
-DTE that directs traffic between one data comm medium and few terminals which uses same protocols, codes & other parameters |
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Data Terminal Equipment |
End devices used to deliver message in that can be understood end to end |
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Data Communications Equipment |
-aka MODEM or Data Circuit Terminating Equipment -for long distance serial data comm system responsible for diff modulation techniques |
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Message, Sender, Receiver, Transmission Medium, Protocols |
5 Components of Data Communication |
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Message |
Info or Data to be communicated |
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Sender |
Device that sends data message |
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Receiver |
Device that receives message |
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Transmission Medium |
Physical path by which message travels from sender to receives |
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Protocol |
Rules and conventions used in order to exchange info in a Data Comms Network |
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Network |
Set of devices (node/station) interconnected by comms media link |
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Data Comms Network |
Systems of interrelated computers & computer equipment that are interconnected to one another for the purpose of transmitting & receiving info |
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Computer Network |
2 or more computers interconnected with one another for the purpose of sharing resources such as printers, databases, files & backup devices |
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Analog Signal |
Signal whose amplitude continuously varies with time |
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Digital Signal |
Signal which are discrete; amplitude maintains a constant level for a prescribed period of time |
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Analog Communication System |
System where signals are transmitted & received in analog format |
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Digital Communication System |
System which signals are transmitted and received in digital form |
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TELEPHONE |
Analog data (voice sound waves) ====> ❓❓❓ ====> Analog signal |
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MODEM (ask or psk) |
Digital data (binary voltage pulses) ====> ❓❓❓ ====> Analog signal (modulated on carrier frequency) |
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CODEC |
Analog signal ====> ❓❓❓ ====> digital signal |
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Digital Transmitter |
Digital data ====> ❓❓❓ ====> digital signal |
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Transcode |
1 digital format to another digital format |
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Simplex, Half Duplex, Full Duplex |
Data Transmission Modes (Data Flow) |
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Simplex |
Communication is unidirectional; only 1 of 2 devices on a link can transmit while the other can only receive |
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Half Duplex |
only 1 of 2 devices on a link can transmit while the other can only receive at a time; Ethernet or LAN |
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Full Duplex |
Send simultaneously; DSL; both stations can transmit and receive |
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Network |
Set of devices or nodes connected by communication link |
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Node |
Can be a computer, printer, etc. that's capable of sending and/or receiving data generated by others on the network |
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Virtualization |
1 physical device, multiple virtual devices |
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Distributed Processing |
-aka Cloud Computing -task is divided among multiple computers |
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Performance, Reliability, & Security |
Networks are evaluated using these 3: |
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Performance |
Effectiveness of network |
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Throughput & Delay (accuracy of delivery) |
2 metrics to evaluate performance of a network |
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(2) used to measure throughput and delay |
Transit time & Response time |
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Transit Time |
Time required for a message to travel from 1 device to another |
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Response Time |
Time elapsed between inquiry and response (ping) |
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Reliability |
-Based on frequency of failure measurement -Ability of network to recover from a network link failure & the network's robustness in a catastrophe -redundancy = backup link -target is to be 99.9999% |
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Security |
-Protecting data from unauthorized access and damage development -implementing policies and procedures for recovery from breaches and data losses |
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Point-to-Point, Multipoint |
Types of Network Connection |
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Philippine Internet Exchange |
PHIX Ex. PLDT, Globe, Smart |
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Point-to-Point |
Dedicated link between 2 devices |
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Multipoint |
-aka Multidrop -Multiple connection in a single link -ex. Cable TV |
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Mesh, Bus, Star, Ring |
Network Topologies |
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L = n(n-1)/2 |
Full Mesh/Full Redundancy formula |
