Final exam prep Flashcards
7- Layer OSI Protocol
application
Presentation
Session
Transport
Network
Data Link
Physical
5 layer internet stack
Application
Transport
Internet
Network Access
Physical
What does the physical layer do
Responsible for network interfacing: Transmission, Rate, Signaling, and Encoding
What does the Network Access Layer do
Controls Access to Transmission Medium
What Are the Standard Digital Encodings
Non-Return to Zero - level
Non-Return to Zero - Inverted
Bipolar-AMI
Pseudoternary
Manchester
Diff Manchester
B8ZS
HDB3
Analog Econdings - Amplitude
ASK ( Amplitude shift Keying)
QAM ( Quadriture Shift Keying)
Analog Encodings - Frequency
BFSK (Binary Frequency Shift Keying)
MFSK (Multiple Frequency Shift Keying)
Analog Encodings - Phase
BPSK ( Binary Phase shift Keying)
QPSK ( Quadriture phase shift keying)
MPSK ( Multiple Phase shift keying)
Role of a Modem
Digital to analog converter
Role of a Codec
Convert analog to Digital Signals
4 types of Noise
Bandwidth thermal Noise
Intermodulation Noise
Crosstalk Noise
Impulse Noise
Intermodulation Noise
Multiple frequencies on same cable
Crosstalk Noise
Noise caused by nearby signals
Impulse Noise
Noise created by lightning for example
Connection Orientated data Service
Connection and Termination needed to transfer data
Connectionless Orientated Data Service
Does not need to establish connection and terminate in order to transfer between devices.
Frequency Division Multiplexing
Breaks Channels uip into equal frequency bands
Time Division Multiplexing
Round Robin, allows each channel a time slot
Even and Odd parity
Add parity bit to make the number of 1s even or odd
Limitations of parity
Can only find an odd amount of errors
Need for Flow Control
Allows the reciever to finsih processing without concern of overflow
Common Flow Control Algorithms
Stop and Wait
Sliding Window
Stop and Wait Algorithm
Source sends frame and waits for ACK before sending next
Sliding Window
Reciever uses buffer of size W
Transmitter send W frames without ACK
Error Control
Needed to recover lost or damaged Frames
ARQ Methods
Stop and Wait
If no ACK before timer runs out retransmit
Go Back N ARQ
Sliding window, go back N frame Retransmit all
Selective Reject
Only resend frame N
Structure of Twisted Pair Cable
Copper cables sheathed and spiraled around eachother to reduce cross talk
Common name of Twisted pair Jack
RJ45
Structure of Coaxial Cable
Core conductor -> Dielectric->Sheild->Jacket
Structure of Fiber optic cable
Core is bundle of fibers each coated in cladding that reflects light back into the fiber
Contention
Any Computer can transmit data at any time, uses different methods to avoid collisions
IEEE 802.3 CSMA (Carrier Sense multiple Access) Algorithm
Responsible for idle line monitoring
Responsible for playing fair oon a shared medium
IEEE 802.3 CD
Responsible for detecting and announcing collisions
IPv4 Address Length
32 bits
802.3 Mac Addtess Length
48 bits
