CSMA/CD and Channel Persistence Methods Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the inefficiency of CSMA before the implementation of CSMA/CD?

Unstable channel until all packets are transmitted (correct)

Channel congestion due to multiple access

Constant channel idle time

Low data transmission rate

How does CSMA/CD overcome the inefficiency of CSMA?

By increasing the data transmission rate

By listening to the medium continuously

By reducing channel wastage during collisions

By aborting transmission after a collision (correct)

In CSMA/CD, what action should a station take if a collision is detected during transmission?

Abort transmission and send a jam signal (correct)

Broadcast a retransmission request to other stations

Continue transmission at a higher power

Increase the data packet size

How does a node detect a collision in CSMA/CD?

By listening to the medium for its own signal Signup and view all the answers

What should a station do after sending a jam signal in CSMA/CD?

Back off and wait for a random amount of time Signup and view all the answers

What role does the CSMA persistence algorithm play in the CSMA/CD protocol?

Manages the detection and handling of collisions Signup and view all the answers

What is the maximum throughput for Pure Aloha according to the text?

1.5 Signup and view all the answers

In CSMA, what is considered the vulnerable time that affects protocol performance?

Maximum propagation time Signup and view all the answers

Which CSMA protocol involves a station waiting a random amount of time after the medium is detected busy to re-attempt transmission?

Non-Persistent CSMA Signup and view all the answers

What is the impact of longer propagation delay on CSMA protocol performance?

Worse performance Signup and view all the answers

What factor in local area networks can help reduce the possibility of collisions in CSMA?

Immediate knowledge of frame transmission Signup and view all the answers

Which type of CSMA protocol specifies that a station should transmit immediately after the medium becomes idle?

1-Persistent CSMA Signup and view all the answers

What is the main difference between 1-persistent and p-persistent CSMA protocols?

1-persistent protocol waits until the medium becomes idle, while p-persistent protocol transmits immediately with a probability of p. Signup and view all the answers

How does non-persistent CSMA handle idle medium?

Back off and wait a random amount of time Signup and view all the answers

Why is bandwidth wasted if waiting time (back off) is large in non-persistent CSMA?

Medium remains idle following the end of transmission Signup and view all the answers

What characteristic describes 1-persistent stations in CSMA?

Transmit immediately with probability 1 Signup and view all the answers

In p-persistent CSMA, what does a station do if the medium is idle?

Transmit immediately Signup and view all the answers

What does 1-persistent CSMA guarantee when two or more stations become ready to transmit simultaneously?

Collision will occur Signup and view all the answers

Study Notes

CSMA Inefficiencies

CSMA (Carrier Sense Multiple Access) can lead to collisions when multiple stations transmit simultaneously without coordination.
Before CSMA/CD, collisions resulted in packet loss without any mechanism to manage or detect them.

CSMA/CD Improvements

CSMA/CD (Carrier Sense Multiple Access with Collision Detection) introduces a method for detecting collisions during transmission.
It allows stations to recognize when a collision occurs and stop transmitting, reducing wasted bandwidth.

Actions During Collision in CSMA/CD

Upon detecting a collision, a station should immediately cease transmission and send a jam signal to inform all other stations of the collision.

Collision Detection in CSMA/CD

Nodes detect collisions by monitoring the channel while transmitting. If the signal observed differs from the transmitted signal, a collision is confirmed.

Post-Jam Signal Actions in CSMA/CD

After sending a jam signal, stations enter a back-off period, during which they wait before attempting to retransmit.

Role of CSMA Persistence Algorithm

The CSMA persistence algorithm determines how stations behave when the medium is busy, influencing the timing of retransmissions following a back-off.

Maximum Throughput of Pure Aloha

Pure Aloha achieves a maximum throughput of about 18.4%, which is significantly lower than more efficient protocols due to its high collision rates.

Vulnerable Time in CSMA

The vulnerable time in CSMA refers to the duration during which collisions can occur, significantly affecting protocol performance, especially during busy network conditions.

Random Wait in CSMA Protocols

Non-persistent CSMA involves stations waiting a random period before reattempting transmission once the medium is busy, reducing collision chances.

Impact of Longer Propagation Delay

Longer propagation delays can degrade CSMA performance by increasing the likelihood of collisions since stations may not detect transmissions in time.

Reducing Collisions in Local Area Networks

Implementing techniques like segmenting networks or introducing switches can reduce collision occurrences in local area networks using CSMA protocols.

Immediate Transmission in CSMA Protocol

In 1-persistent CSMA, a station transmits instantaneously when the medium becomes idle, prioritizing immediacy over consideration for ongoing traffic.

1-Persistent vs. P-Persistent CSMA

The main difference is that 1-persistent CSMA guarantees immediate transmission upon the medium's availability, while p-persistent CSMA has a probability-based approach for transmission, introducing delays.

Non-Persistent CSMA Idle Medium Handling

Non-persistent CSMA requires stations to sense the medium and, if busy, wait a random duration before checking again, improving efficiency but possibly wasting time.

Bandwidth Wastage in Non-Persistent CSMA

Large waiting times in back-off periods can lead to significant bandwidth wastage, as stations spend extended periods not transmitting while waiting for the medium to become free.

Characteristics of 1-Persistent CSMA Stations

1-persistent CSMA stations always attempt to transmit immediately upon detecting an idle medium, which can lead to increased collisions when multiple stations act simultaneously.

Actions in P-Persistent CSMA

In p-persistent CSMA, if the medium is idle, a station transmits with a predefined probability, introducing randomness into the process to mitigate collisions.

Guarantee of 1-Persistent CSMA during Simultaneous Ready States

1-persistent CSMA guarantees that when multiple stations are ready to transmit, at least one will successfully get through, potentially resulting in collisions.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on CSMA/CD (Carrier Sense Multiple Access with Collision Detection) and different channel persistence methods in networking. Topics include reducing collisions, channel idle time, and the inefficiencies of CSMA.