The Full Form of CSMA/CD Full Form is Carrier Sense Multiple Access/Collision Detection.
CSMA/CD is a MAC protocol that is widely utilised with features that have been standardised using the IEEE 802.3 standard. Whenever a frame in the CSMA is transferred, the station will sense the channel to verify if it’s free or not. In case of a free channel, the station passes the frame. Sometimes, another station may also transfer the frame, thus resulting in a collision of both. In this scenario, the station will cause a round-trip propagation delay (wait) for an acknowledgement post the transfer for CSMA. However, for CSMA/ CD, time taken for this can also be brought down.
How Does CSMA/CD Work?
- Some stations in Carrier Sense Multiple Access/Collision Detection aim to pass the frame first.
- They will have to confirm that there is a free link.
- Then they can transfer information and listen again.
- The station also observes the line for very high voltages, thus indicating a collision.
- On detecting a collision, the station leaves the transfer, waiting for the back off period of time.
- The stations from where the frame is transferred can also release a jam signal in order to reveal that a collision has taken place.
CSMA/CD Features
- CSMA/ CD with carrier sense can sense the channel for passing the frame, so that they can check it later to know if it is busy or not.
- Upon identifying the collision, stations have to wait for sometime before transferring the frames.
- Meanwhile, they can utilise a jam signal to indicate to the other stations that a collision has occurred, and so these stations have to wait.
- Also, a priority mechanism is applied for a transmission priority that is high.
Pros of CSMA/ CD
- It takes a very short time to identify the collisions
- The entire available bandwidth is used to avoid wasteful transfer of frames
- The overhead is very low
Cons of CSMA/ CD
- Not valid for long distance or big networks
- There is no reduction in the possibility of collisions, thus causing degrading performance
- Performance and number of stations are inversely proportional, so these huge number of stations also rapidly degrade the performance
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