Data Communication Protocols Flashcards
Data communication protocols are used in telecom to?
transfer digital data from one location to another
Synchronous Transmissions are handled by what layer of OSI Model
Physical Layer
When choosing a standard certain aspects need to be considered:
-throughput
-environment
-length of run
Transmission Types:
-Synchronous
-Asynchronous
Advantages of Asynchronous
-Synchronization happens for each character
-Cheap
-Simple
Disadvantages of Asynchronous
-Large overhead
-Clock drift and framing errors
Methods of Asynchronous Synch
-Bit Synch
-Character Synch
-Frame Synch
In order for info to flow properly both sending and receiving devices have to determine what aspects/properties
- Bits per second
- Data bits
- Parity
- Stop bits
- Flow Control
What does overhead include
Start bits, stop bits, and parity bits
Problems with Asynchronous Bit Synch
- Clock drift
- Framing error
What is clock drift
Clock on the receiver ≠ clock on transmitter
What is framing error a result of
Clock drift or noise
Characteristics of Synchronous Transmission
-Shared clock
-Multiple Bytes
-Clock is encoded in data or
-Clock provided on a separate line
A separate line for clock is used in short distances TRUE or FALSE
True
4 Types of encoding
- AMI (Alternate Mark Inversion)
-HDB3 (High density Bipolar of order 3)
-Manchester Encoding
-Differential Manchester Encoding
What does DPLL stand for
Digital Phase Lock Loop
Describe DPLL
In order for the receiver to properly recreate the Transmitters clock the receiver places the signal through DPLL. The receiver uses bit transitions in the transmitted signal to transmit.
What are the most reliable types of encoding
- Manchester
- Differential Manchester
What does SDLC stand for
Synchronous Data Link Control
What does HDLC stand for
High-Level Data Link Control
What is the most important data link protocol
HDLC (High-Level Data Link Control)
3 Types of Frames:
Information
Supervisory
Unnumbered
What 3 sequences happen at the HDLC Level
Initialization, Data Transfer, Disconnect
Describe Connection Oriented
Sending a request to open a connection
A protocol example of Connection Oriented
TCP
Describe Connectionless Oriented
No effort is made to setup a dedicated end-to-end connection
A protocol example of Connection Oriented
UDP
