Explanation:
In a computer network, retransmission of packets is a process where a sender sends the same packet again to the receiver if it does not receive an acknowledgment from the receiver within a certain time period. However, retransmission should only be done when it is necessary. Here are the reasons why retransmission should not be done when a packet is error-free:

1. Efficiency: Retransmission of error-free packets consumes network resources and can lead to unnecessary congestion. Since error-free packets do not need any correction, retransmitting them would be a waste of bandwidth.

2. Latency: Retransmitting error-free packets unnecessarily increases the overall latency of the network. This delay can be especially problematic in real-time applications such as video streaming or online gaming.

3. Network Performance: Retransmission of error-free packets can disrupt the flow of data and degrade the overall performance of the network. It can lead to unnecessary reordering of packets and increase the chances of congestion in the network.

4. Reliability: Retransmission of error-free packets can introduce unnecessary redundancy and increase the chances of duplicate packets being received by the receiver. This can cause confusion and affect the reliability of the data being transmitted.

5. Protocol Efficiency: Most network protocols have mechanisms in place to ensure reliable delivery of packets. These protocols use techniques such as checksums, acknowledgments, and sequence numbers to detect and recover from errors. Retransmission of error-free packets bypasses these mechanisms and can lead to inefficiencies in the protocol.

In conclusion, retransmission of packets should only be done when there is an error or loss of data. Retransmitting error-free packets can have negative effects on network efficiency, latency, performance, reliability, and protocol efficiency. Therefore, it is important to avoid retransmission when packets are error-free.