Chapter I
1. What is the difference between a host and an end system? List the types of end systems. Is a Web rver an end system?
2. What is a client program? What is a rver program? Does a rver program request and receive rvices from a client program?
3. gre报名流程List six access technologies. Classify each one as residential access, company access, or mobile access.
4. Dial-up modems, HFC, and DSL are all ud for residential access. For each of the access technologies, provide a range of transmission rates and comment on whether the transmission rate is shared or dedicated.
5. Describe the most popular wireless Internet access technologies today. Compare and contrast them.
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shine6. What advantage does a circuit-switched network have over a packet-switched network? What advantages does TDM have over FDM in a circuit-switched network?
7. Consider nding a packet from a source host to a destination host over a fixed route. List the delay components in the end-to-end delay. Which of the delays are constant and which are variable?
8. 展会英语How long does it take a packet of length 2,000 bytes to propagate over a link of distance 2,000 km, propagation speed m/s, and transmission rate 2 Mbps? More generally, how long does it take a packet of length L to propagate over a link of distance d, propagation speed s, and transmission rate R bps? Does this delay depend on packet length? Does this delay depend on transmission rate?
9. What are the five layers in the Internet protocol stack? What are the principal responsibilities of each of the layers?
10. Which layers in the Internet protocol stack does a router process? Which layers does a link-layer switch process? Which layers does a host process?
11. What is an application-layer message? A transport-layer gment? A network-layer datagram? A link-layer frame?
12. This elementary problem begins to explore propagation delay and transmission delay, two central concepts in data networking. Consider two hosts, A and B, connected by a single link of rate R bps. Suppo that the two hosts are parated by m meters, and suppo the propagation speed along the link is s meters/c. Host A is to nd a packet of size L bits to Host B.
a. Express the propagation delay, , in terms of m and s.
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b. Determine the transmission time of the packet, , in terms of L and R.
c. Ignoring processing and queuing delays, obtain an expression for the end-to-end delay.
d. Suppo Host A begins to transmit the packet at time t = 0. At time,where is the last bit of the packet?
e. Suppo is greater than. At time t =,where is the first bit of the packet?
f. Suppo 机械专业大学排名 is less than. At time t =, where is the first bit of the packet?
g. Suppo, L = 100bits, and R = 28 kbps. Find the distance m so that equals英语日记80字.
13. In modern packet-switched networks, the source host gments long, application-layer messages (for example, an image or a music file) into smaller packets and nds the packets into the network. The receiver then reasmbles the packets back into the original message. We refer to this process as message gmentation. Figure 1.24 illustrates the end-to-end transport of a message with and without message gmentation. Consider a message that is bits long that is to be nt from source to destination in Figure 1.24. Suppo each link in the figure is 2 Mbps. Ignore propagation, queuing, and processing delays.decade什么意思
a. Consider nding the message from source to destination without message gmentation. How long does it take to move the message from the source host to the first packet switch? Keeping in mind that each switch us store-and-forward packet switching, what is the total time to move the message from source host to destination host?
b. Now suppo that the message is gmented into 4,000 packets, with each packet being 2,000 bits long. How long does it take to move the first packet from source host to t
he first switch? When the first packet is being nt from the first switch to the cond switch, the cond packet is being nt from the source host to the first switch. At what time will the cond packet be fully received at the first switch?
c. How long does it take to move the file from source host to destination host when message gmentation is ud? Compare this result with your answer in part (a) and comment.
