Unformatted text preview: objects from the same sender. Would parallel downloads via parallel instances of non persistent HTTP make sense in this case? Now consider persistent HTTP. Do you expect significant gains over the non persistent case? Justify and explain your answer. Solution: Note that each downloaded object can be completely put into one data packet. Let Tp
denote the oneway propagation delay between the client and the server.
First consider parallel downloads using nonpersistent connections. Parallel downloads
would allow 10 connections to share the 150 bits/sec bandwidth, giving each just 15
bits/sec. Thus, the total time needed to receive all objects is given by:
(200/150+Tp + 200/150 +Tp + 200/150+Tp + 100,000/150+ Tp )
+ (200/(150/10)+Tp + 200/(150/10) +Tp + 200/(150/10)+Tp + 100,000/(150/10)+ Tp )
= 7377 + 8*Tp (seconds)
Now consider a persistent HTTP connection. The total time needed is given by:
(200/150+Tp + 200/150 +Tp + 200/150+Tp + 100,000/150+ Tp...
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 Spring '08
 GANZ
 Transmission Control Protocol, HTTP

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