GATE CS 2016 Set 2 Q24 — Data Link Layer: Framing, Error Detection, MAC, Ethernet Bridging

In an Ethernet local area network using the CSMA/CD (Carrier Sense Multiple Access with Collision Detection) protocol, let's analyze each statement:

• Option A is FALSE: In CSMA/CD, a station must continuously sense the channel during transmission to detect if a collision occurs. If it stopped sensing, it would not be able to detect collisions.
• Option B is FALSE: The purpose of the jamming signal is to alert all other stations on the network that a collision has occurred, ensuring they discard the damaged frame. Padding fields (not jamming signals) are used to meet the minimum frame size requirement of 64 bytes.
• Option C is FALSE: As soon as a collision is detected, the station immediately stops transmitting the frame and sends a jamming signal to minimize bandwidth wastage.
• Option D is TRUE: The exponential backoff algorithm increases the contention window size exponentially ($2^k$) with each consecutive collision. By spreading the retransmission times of competing stations over a wider range, it effectively reduces the probability of another collision on subsequent attempts.