Consider the problem of transferring a bunch of files that are 20GB in size betw

Question

Consider the problem of transferring a bunch of files that are 20GB in size between San Marcos and Austin. You would like to send these files as fast as possible. You can use FedEx service or you could use your Internet connection which you can assume to be 10 Mbps in capacity and has 10 msec propagation delay. You can assume that transferring the files over the Internet connection would incur an extra 5% of overhead due to the headers..

a)  Given that you cannot change your current link’s capacity but you can compress your files, what is the compressed data size of these files so that they can be transferred in 30 mins? (Assume that the headers cannot be compressed (e.g., used for routing) and would still account for 5% overhead of the compressed data size).

b) Do you expect that the propagation delay of the link affect your calculations? Explain why or why not.

Explanation / Answer

a)
if we need to compress the size and the 5% overhead is still applicable then the size which we require to send in 30 minuted will be

10*2^20*1800= 2025 MB,

so 2025 of Megabytes of needs to be the size of the compressed file.

b)
propogation delay is determined as the time taken to propogate one bit from one router to another. numerically it is function of distance between routers, but it does not depend of packets length and the transmission link.
Thus, if there is a propogation delay, it will definitely affect the calculations as routers are in San Marcos and Austin which are far apart.

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