Question

Different transport-layer protocols perform differently; this question will show the difference in propagation time between different protocols.

For each question, we will send a message that contains 9 packets. Additionally, assume that the time to send or receive the packet and the ACK (if present) are negligible compared to the propagation time on the medium, and that there is no packet loss in the medium.

Stop-and-Wait

Assume we are using a stop-and-wait protocol with a RTT for a packet is 3 ms. How much time is required to complete the transmission?

Answer 1

Using the stop-and-wait protocol with an RTT of 3 ms per packet, the total time required to transmit 9 packets is 27 ms, as each packet's acknowledgment is needed before the next packet is sent.

Step-by-step explanation:

According to the stop-and-wait protocol, each packet must be acknowledged before the next packet is sent. Given a round-trip time (RTT) of 3 ms for each packet, and knowing that there are 9 packets to send, we can determine the total time required to complete the transmission. The RTT includes the time for a packet to reach its destination and the time for the acknowledgment to return. Since the transmission and acknowledgment times are negligible compared to the propagation time, we only consider the RTT.

To send 9 packets using the stop-and-wait protocol, with an RTT of 3 ms per packet, the total time required would be 9 packets multiplied by 3 ms per packet. Therefore, the total transmission time is 27 ms. This is because each packet must be fully acknowledged before the next one is sent, leading to a straightforward multiplication of the number of packets by the RTT for each packet.