Difference Between CSMA CA and CSMA CD

In this article, we will learn the Difference Between CSMA CA and CSMA CD. Let’s start!!!

What is CSMA?

CSMA is a method that detects the condition of a shared channel in order to prevent or recover data packets from collisions. It is also used to manage the flow of data packets over the network, ensuring that packets are not lost and data integrity is preserved.

When two or more data packets are sent on a shared channel at the same time in CSMA, there is a probability of collision. Because of the collision, the receiver receives no information about the sender’s data packets. And the lost data must be transmitted so that the receiver may receive it. As a result, before delivering data packets through a network, we must detect the channel. It is separated into two sections: CSMA CA (Collision Avoidance) and CSMA CD (Collision Detection).

CSMA/CD:

To identify a collision at the media access control (MAC) layer, the Carrier Sense Multiple Access/ Collision Detection protocol is employed. When a collision is detected, the CSMA CD instantly stops the transmission by issuing a signal, ensuring that the sender does not lose time delivering the data packet.

Assume that each station detects a collision while transmitting the packets. When a collision is detected, the protocol sends a jam signal in order to stop the transmission and waits for a random amount of time before sending another data packet. If the channel is discovered to be free, it instantly sends and returns the data.

Advantages of CSMA/CD:

1. It is used to identify collisions on a shared channel in a relatively short period of time.
2. For collision detection, CSMA CD outperforms CSMA.
3. To avoid waste transmission, CSMA CD is employed.
4. It is used when it is essential to consume or share the same amount of bandwidth at each station.
5. It has a lower CSMA CD overhead than the CSMA CA.

Disadvantages of CSMA/CD:

1. It is unsuitable for long-distance networks since CSMA CD’s efficiency declines with distance.
2. It can detect collisions only up to 2500 meters away, and it cannot detect collisions beyond this distance.
3. Collision detection performance suffers when numerous devices are added to a CSMA CD.

CSMA/CA:

It is a network protocol that avoids collisions rather than allowing them to occur, and it does not deal with packet recovery after a collision. It is analogous to the CSMA CD protocol, which operates on the media access control layer. When a station delivers a data frame to a channel in CSMA/CA, it checks to see if the channel is in use. If the shared channel is busy, the station will wait until it enters idle mode. As a result, it decreases the likelihood of collisions and makes better use of the channel to transport data packets more effectively.

Advantages of CSMA/CA:

1. When data packets are big in size, the possibilities of collision in CSMA CA are reduced.
2. It manages the data packets and sends them when the recipient requests them.
3. On the shared channel, it is utilized to prevent collisions rather than detect them.
4. CSMA CA prevents data transmission across the channel from being wasted.
5. It is ideally suited for wireless network transmission.
6. It uses the RTS/CTS extension to prevent needless data traffic on the network.

Disadvantages of CSMA/CA:

1. Sometimes CSMA/CA takes twice as long as usual to send a data packet.
2. Each station consumes greater bandwidth.
3. Its efficiency is lower than that of CSMA CD.

Comparison of CSMA/CD and CSMA/CA:

Summary:

In this article, we explored the concepts of CSMA/CD and CSMA/CA protocols, and also looked at the advantages and disadvantages of each. Lastly, we also looked at a direct tabular comparison between CSMA/CD and CSMA/CA.