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30 Cards in this Set
- Front
- Back
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What are the 7 layers of the OSI model
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Application, Presentation, Session, Transport, Network, Data-Link, Physical
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What is the Application Layer?
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end users services such as FTP, EMAIL, VIRTUAL TERMINAL SVCS AND NETWORK MANAGEMENT.
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What is the Presentation Layer?
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Defines the syntax which two network hosts use to communicate, encryption and compression, converts in/outgoing data from one presentation to another
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What is the Session Layer?
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Sets up coordinates and terminates conversations, exchanges and dialogs between applications at each end
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What is the Transport Layer?
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Delivers messages between networked hosts, responsible for fragmentation and reassembly.
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What is the Network Layer?
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Establishes paths for data transfer thru the network (Routers)
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What is the Data-Link Layer?
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Responsible for communications between adjacent network nodes (Hubs and Switches)
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What is the Physical Layer?
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Bit Level transmission between network nodes (connector types, cable types, voltages and pin-outs)
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Data Communication
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Electronic transmission of computer generated data from one point to another point or multipoint
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Point to Point
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No one uses it but you. Private
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Multipoint
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Shared Network (cable)
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Media
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Physical Structure; Fiber, copper, T1, air (wireless) with high enough frequency you can send a signal thru a void (space)
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Analog Signal
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representation of an object that resembles the original, takes more power to send, implies continuous operation.
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Digital Signal
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Uses discrete (discontinous) values to represent information for input, processing, transmission, storage etc. Uniformity can be stored and transmitted w/o loss of integrity, much more accurate.
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Frequency
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Higher the frequency the more frequent waves
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Speed
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How often the waves repeat
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Height of Waves (Sine Waves)
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Deceibels volumne (amplititues)
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Attenuation
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Reduction in amplitude and intensity of a signal. Weakening of the RF signal due to being partially blocked and absorbed.
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Cumulative Distortion
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Use of amplifiers to deal with attenuation of analog signals tend to cause some level of distortion to the newly amplified analog signal; in turn this distortion effect is cumulative when amplifiers amplification processes are required. Use of repeaters to deal with attenuation signals does not introduce the potential of accumulative distortion.
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Modulation
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Addition of information (or the signal) to an electronic or optical signal carrier
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AM
AMPLITUDE MODULATION |
In which the voltage applied to the carrier is varied over time
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FM
FREQUENCY MODULATION |
In which the frequency of the carrier waveform is varied in small but meaningful amounts.
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PM
PHASE MODULATION |
In which the natural flow of the alternating current waveform is delayed temporarily.
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DEDICATED LINE AKA LEASED LINE
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Private, always on. A communications cable or other facility dedicated to a specific application
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FDX - FULL DUPLEX
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Simultaneous transmission in both directions (eg home phone)
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HDX - HALF DUPLEX
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One direction at a time (eg walkie talkie, Nextel chirpers)
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SDX - SINGULAR DUPLEX
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Recieves only (Airport monitor, radio)
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MULTIPLEXING
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(MUXING) Where multiple analog message signals or digital data streams are combine into one signal over a share medium (ie.,
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FDM
FREQUENCY DIVISON MULITIPLEXING |
Form of Signal multiplexing where multiple baseband signals are modulated on different frequency carrier waves and added together to created a composite signal
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TDM
TIME DIVISION MULTIPLEXING |
Transmitting multiple digitized data, voice and video signnal simultaneously over one communciation media by interleaving pulses representing bits from different channels or time slots.
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