Need help with this question if someone could help me step by step 2. Consider a
ID: 3909484 • Letter: N
Question
Need help with this question if someone could help me step by step
2. Consider a short, 10-meter link, over which a sender can transmit at a rate of 150 bits/sec in both directions. Suppose that packets containing data are 100,000 bits long, and packets containing only control (e.g., ACK or hand-shaking) are 200 bits long. Assume that N parallel connections each get 1/N of the link bandwidth. Now consider the HTTP protocol, and suppose that each downloaded object is 100 Kbits long, and that the initial downloaded object contains 10 referenced objects from the same sender. a. What is the total time needed to receive all objects via parallel downloads b. Now consider persistent HTTP without using parallel download, what is c. From the above computing, what conclusion can you get (suppose speed using non-persistent HTTP connections? the total time to receive all the objects? of light is 300*106 m/sec)?Explanation / Answer
Since the size of the packet is the size of the downloaded object, each downloaded objects requires 1 data packet . Let Tp denote the one-way propagation delay between the client and the server.
a)
Consider parallel downloads using non-persistent 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)
b)
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 ) + 10*(200/150+Tp + 100,000/150+ Tp )
=7351 + 24*Tp (seconds)
c)
Assuming the speed of light is 300*106 m/sec, then Tp=10/(300*106 )=0.03 microsec.
Tp is therefore negligible compared with transmission delay.
Thus, we see that persistent HTTP is not significantly faster (less than 1 percent) than the non-persistent case with parallel download.