Data Link Layer Overview Quiz

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Questions and Answers

What is the main purpose of flow control in data communication?

To introduce additional errors for testing purposes

To transmit data faster than the receiver can process it

To ensure a fixed size of data packets

To manage the rate of data transmission between sender and receiver (correct)

How does byte stuffing operate in data communication?

By removing flags from the data stream

By encoding the data into a three-byte sequence

By adding an extra byte whenever five consecutive 1s are detected

By inserting an extra byte when a flag or escape character is present (correct)

What triggers the need for flow control mechanisms?

The sender's capacity to send data rapidly

The delays caused by network congestion

The receiver's memory limit and processing speed (correct)

The complexity of the data format being transmitted

In bit-oriented framing, what condition leads to bit stuffing?

Five consecutive 1s following a 0 Signup and view all the answers

What does error control in the data link layer primarily rely on?

Retransmission of lost or corrupted data Signup and view all the answers

What is the correct function of character-oriented framing?

To send data as a sequence of bytes using an 8-bit coding system Signup and view all the answers

Which statement correctly describes the sender-site algorithm of the simplest protocol?

It continuously sends frames without waiting for a receiver's response Signup and view all the answers

What does bit stuffing help to prevent during data transmission?

Misinterpretation of flag patterns in the data stream Signup and view all the answers

What is the main action the sender takes in the Stop-and-Wait Protocol after sending a frame?

Waits for an acknowledgment Signup and view all the answers

What happens in Stop-and-Wait ARQ if the acknowledgment is lost?

The sender resends the last frame Signup and view all the answers

In Go-Back-N ARQ, what happens if an acknowledgment for the first frame is not received?

All frames in the current window are retransmitted Signup and view all the answers

What characteristic distinguishes Selective Repeat ARQ from other ARQ protocols?

Resends only the lost or damaged frames Signup and view all the answers

How are frames numbered in the Stop-and-Wait Protocol and its variations?

Based on modulo-2 arithmetic Signup and view all the answers

In Go Back 3 with a scenario where every 5th packet is lost while sending 10 packets, how does this affect the total number of transmissions?

More than 10 transmissions occur due to packet loss Signup and view all the answers

Which protocol allows sending multiple frames before receiving the acknowledgment of the first frame?

Go-Back-N ARQ Signup and view all the answers

What mechanism is used for error correction in Stop-and-Wait ARQ?

Retransmission based on time-out Signup and view all the answers

Study Notes

Data Link Layer Overview

Character-oriented framing transmits data as sequences of bytes using 8-bit coding systems like ASCII.
Bit-oriented framing sends data as sequences of bits suitable for interpreting text and multimedia at higher layers.

Framing Techniques

Byte Stuffing: Adds one extra byte when a flag or escape character appears in the data to avoid misinterpretation.
Bit Stuffing: Inserts an extra 0 after five consecutive 1s to prevent confusion with flag patterns like 0111110.

Flow Control Mechanism

Flow control ensures data transmission pacing is matched between sender and receiver, preventing data overload.
Procedures inform the sender of the receiver's capacity to manage incoming data and request reductions or pauses in transmission.

Error Control

Relies on Automatic Repeat reQuest (ARQ) methods for data retransmission when errors are detected.

Simplest Protocol

Demonstrates basic communication where the sender sends frames without awaiting receiver feedback.
Involves sequential events for transmission at both sender and receiver sites.

Stop-and-Wait Protocol

The sender transmits one frame and waits for an acknowledgment (ACK) before proceeding.
If the ACK is not received within a specific timeframe, the sender retransmits the last frame, using sequence numbers based on modulo-2 arithmetic.

Sliding Window Protocol

Facilitates sending multiple frames before receiving acknowledgments based on a defined window size.
Enhances efficiency in data transmission by allowing overlapping of send and receive operations.

Go-Back-N ARQ

Utilizes a sender's window size (N) to permit multiple frame transmissions prior to acknowledgment.
Relies on sequential frame numbering, requiring retransmission of all frames in the window if an ACK is not received in time.

Selective Repeat ARQ

Only retransmits damaged or lost frames upon receiving a negative acknowledgment (NACK) from the receiver.
Ensures efficient handling of errors by acknowledging correctly received frames (ACK), minimizing unnecessary data retransmissions.

Example Scenario for Go Back 3

In a network with every 5th packet lost while sending 10 packets:
- The sender will have to retransmit frames 1 to 3 repeatedly until the acknowledgment for frame 1 is received, implying a higher number of total transmissions.

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Description

Test your knowledge on the Data Link Layer with this quiz that covers key concepts such as framing techniques, flow control mechanisms, and error control. Understand the differences between byte-oriented and bit-oriented framing, along with basic protocols for data transmission.