| Help With Some Tute Questions PLEASE! [message #103243] |
Tue, 18 March 2003 19:36 |
SiXey
Messages: 8
Registered: May 2002
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Junior Member |
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Hi, Ive just started a networks subject and i have some questions that i have no idea how to work out. I dont want the answer but i want someone to please tell me how i work it out.
heres the questions:
1)Imagine that you have trained your St. Bernard, Bernie, to carry a box of three 8mm Exabyte tapes instead of brandy. (When your disk fills up, you consider that an emergency.) These tapes each contain 7 gigabytes. The dog can travel to your side, where ever you may be, at 18km/hour. For what range of distances does Bernie have a higher data rate than a 155-Mbps ATM line?
2)Suppose a 100-Mbps point-to-point link is being set up between the earth and a new lunar colony. The distance from the moon to the earth is approximately 384,000 kilometres, and data travels over the link at the speed of light - 300,000 kilometres per second.
a)Calculate the minimum RTT (Round Trip Time) for the link.
b)Using the RTT as a delay, calculate the delay x bandwidth product for the link; What is the significance of this product?
c)A camera on the lunar surface takes pictures of the earth and saves them in digital format to disk. Suppose Mission Control on earth wishes to download the most current image, which is 25MB. What is the minimum amount of time that will elapse between the request for the data goes out and the transfer finished?
3)Consider an application that transmits data at a steady rate (for example, the sender generates an N-bit unit of data evey k time units, where k is small and fixed). Also, when such an application starts, it will continue running for a relatively long period of time. Answer the following questions, briefly justifying your answer:
a)Would a packet-switched network or a circuit-switched network be more appropriate for this application? Why?
b)Suppose that a packet=switched network is used and the only traffic in this network comes from such applications as described above. Furthermore, assume that the sum of the application data rates is less that the capacities of each and every link. is some form of congestion control needed? Why?
4)The president of the Speciality Paint Corp. gets the idea to work together with a local brewer for the purpose of producing an invisible beer can (as an anti-litter measure). The president tells her legal department to look into it, and they in turn ask engineering for help. As a result, the chief engineer calls his counterpart at the other company to discuss the technical aspects of the project. The engineers then report back to their respective legal departments, which then confer by telephone to arrange the legal aspects. Finally, the two corporate presidents discuss the financial side of the deal. Is this an example of a multi-layer protocol in the sense of the OSI model?
Any help would be GREATLY APPRECIATED!
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