Question

Suppose the round-trip propagation delay for Ethernet is 46.4 μs. This yields a minimum packet size of 512 bits (464 bits corresponding to propagation delay +48 bits of jam signal).(a) What happens to the minimum packet size if the delay time is held constant and the signaling rate rises to 100 Mbps?(b) What are the drawbacks to so large a minimum packet size?(c) If compatibilitywere not an issue, howmight the specifications be written so as to permit a smallerminimum packet size?

Answer 1

With a constant round-trip propagation delay and an increased signaling rate to 100 Mbps, the minimum packet size in bits stays the same but takes less time to transmit. Large minimum packet sizes lead to inefficiency and increased network overhead. If compatibility weren't a concern, specifications could allow for variable packet sizes.

Step-by-step explanation:

When the round-trip propagation delay is held constant and the signaling rate is increased to 100 Mbps, the minimum packet size remains the same in bits since the physical distance the signal must travel doesn't change. However, because the bitrate is higher, the minimum packet size will take less time to transmit. If the bitrate increases, the amount of time to transmit 512 bits is reduced.

The drawbacks of a large minimum packet size include potentially increased network overhead, inefficiency for small messages due to padding, and more time required for error detection and correction on larger packets. Moreover, it consumes more bandwidth to send small amounts of data which could be sent with smaller packets.

If compatibility were not an issue, the specifications could allow for variable packet sizes with the use of additional header information to manage smaller packets efficiently or a dynamic minimum packet size scheme based on the actual network conditions.

Answer 2

(a) If the signaling rate increases to 100 Mbps while keeping the delay constant, the minimum packet size would decrease.

(b) Larger minimum packet sizes can lead to increased latency and inefficient use of network bandwidth,

(c) To allow for a smaller minimum packet size, specifications could be revised

How to explain

If the signaling rate increases to 100 Mbps while keeping the delay constant, the minimum packet size would decrease.

This is due to the reduction in the time needed to transmit data, allowing for shorter packets.

(b) Larger minimum packet sizes can lead to increased latency and inefficient use of network bandwidth, as smaller packets might not fully utilize available capacity, resulting in slower communication for small data exchanges.

(c) To allow for a smaller minimum packet size, specifications could be revised by considering a more efficient error detection or correction mechanism, reducing the jam signal size, or introducing a different synchronization method to avoid collisions.