計(jì)算機(jī)網(wǎng)絡(luò)第一周作業(yè)(參考版)
2025-06-21 00:12本頁面
【正文】 拼一個(gè)春夏秋冬！贏一個(gè)無悔人生！早安！—————獻(xiàn)給所有努力的人.學(xué)習(xí)好幫手。不奮斗就是每天都很容易，可一年一年越來越難。是狼就要練好牙，是羊就要練好腿。25. Consider sending a large file of F bits from Host A to Host B. There are three links (and two switches消息分割導(dǎo)致許多更小的數(shù)據(jù)包。10 meters/sec.a. What is the propagation delay of the link? b. What is the bandwidthdelay product, ? c. Let x denote the size of the photo. What is the minimum value of x for the microwave link to be continuously transmitting.答：*103/*108 = 150msb. R16. A packet switch receives a packet and determines the outbound link to which the packet should be forwarded. When the packet arrives, one other packet is halfway done being transmitted on this outbound link and four other packets are waiting to be transmitted. Packets are transmitted in order of arrival. Suppose all packets are 1,500 bytes and the link rate is 2 Mbps. What is the queuing delay for the packet? More generally, what is the queuing delay when all packets have length L, the transmission rate is R, x bits of the currentlybeingtransmitted packet have been transmitted, and n packets are already in the queue?答：Delay1=500bits/(1mbits/s)+4*1000bit/ (1mbits/s)Delay = (Lx)/R + (n+1)*L/R17. Consider the throughput example corresponding to Figure (b). Now suppose that there are M clientserver pairs rather than 10. Denote Rs, Rc, and R for the rates of the server links, client links, and network link. Assume all other links have abundant capacity and that there is no other traffic in the network besides the traffic generated by the M clientserver pairs. Derive a general expression for throughput in terms of Rs, Rc, R, and M.答：Throughput = min{Rs, Rc, R/M}18. Consider problem P23 but now with a link of R = 1 Gbps.a. Calculate the bandwidthdelay product, R它們應(yīng)該被認(rèn)為是同一ISP的一部分。 that is, I = La/R. Suppose that the queuing delay takes the form IL/R (1 – I) for I 1. a. Plot the total delay as a function of L/R.b. Provide a formula for the total delay, that is, the queuing delay plus the 答：令x=L/R, Total delay = x/(1ax)Total delay = IL/R(1I) + L/R = L/R(1I)；14. a. Generalize Equation in Section for heterogeneous processing rates, transmission rates, and propagation delays. b. Repeat (a), but now also suppose that there is an average queuing delay of dqueue at each node.答:a. dendend =N( dproc + dtrans + dprop)b.dendend =N( dproc + dtrans + dprop)+dqueue(ILR(1I))15. Perform a Traceroute between source and destination on the same continent at three different hours of the day.a).第一次實(shí)驗(yàn)的路由器數(shù):24第二次實(shí)驗(yàn)中的路由器數(shù):23第三次實(shí)驗(yàn)中的路由器數(shù):25Ip地址不會(huì)改變。代入方程，得到8 + 8 + 16 + 4+ 1 = 37msec。 for the third packet 2L/ Nth packet has already been transmitted when the second batch of packets arrives.)答：總延遲=(0+1+…+ n 1) L/R平均延遲= (n 1)L/2R11. Suppose N packets arrive simultaneously to a link at which no packets are currently being transmitted or queued. Each packet is of length L and the link has transmission rate R. What is the average queuing delay for the N packets?答 (L/R + 2L/R + ....... + (N1)L/R)/N = L/(RN) * (1 + 2 + ..... + (N1)) = L/(RN) *
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