Consider the figure on the next page, which is similar to Figures 7.22-7.25. Answer the following questions:

a. Assuming FIFO service, indicate the time at which packets 2 through 12 each leave the queue. For each packet, what is the delay between its arrival and the beginning of the slot in which it is transmitted? What is the average of this delay over all 12 packets?
b. Now assume a priority service, and assume that odd-numbered packets are high priority, and even-numbered packets are low priority. Indicate the time at which packets 2 through 12 each leave the queue. For each packet, what is the delay between its arrival and the beginning of the slot in which it is transmitted? What is the average of this delay over all 12 packets?
c. Now assume round robin service. Assume that packets I, 2, 3, 6, II, and 12 are from class I, and packets 4, 5, 7, 8, 9, and 10 are from class 2. Indicate the time at which packets 2 through 12 each leave the queue. For each packet, what is the delay between its arrival and its departure? What is the average delay over all 12 packets?
d. Now assume weighted fair queueing (WFQ) service. Assume that oddnumbered packets are from class I, and even-numbered packets are from class 2. Class I has a WFQ weight of 2, while class 2 has a WFQ weigh~ of . Note that it may not be possible to achieve an idealized WFQ schedule as described in the text, so indicate why you have chosen the particular packet to go into service at each time slot. For each packet what is the delay between its arrival and its departure? What is the average delay over all 12 packets'?
e. What do you notice about the average delay in all four cases (FCFS, RR, priority, and WFQ)?

Transcribed Image Text:

Arrivals Time Packet in service Time Departures