If a frame fails to be acknowledged before its timeout, what is typically performed?

• A. Nothing, since deadlines are soft.
• B. Trigger a retransmission or retry after timeout.
• C. Terminate the connection immediately.
• D. Discard all subsequent frames.

Answer: (B)

In reliable communication, after sending a frame the sender waits for its acknowledgment. If that acknowledgment doesn’t arrive before the timeout, it signals that the frame (or its acknowledgment) may have been lost, so the standard response is to retransmit the frame. This retry mechanism, often part of ARQ strategies, helps ensure the data eventually gets through despite occasional losses or delays.

Why the other options don’t fit: doing nothing would ignore the loss indicator the timeout provides, risking missing data. terminating the connection is overly drastic and disrupts communication unnecessarily. discarding all subsequent frames would break the sequence and reliability of the data stream; instead, only the unacknowledged frame is resent, maintaining order and integrity.