Computer Networking A Top Down Approach, James F. Curose

Question

Suppose Host A wants to send a large file to Host B. The path from Host A to Host B has three links, of rates R1 =500 kbps, R2 = 2 Mbps, and R3 = 1 Mbps.

a. Assuming no other traffic in the network, what is the throughput for the file transfer.
b. Suppose the file is 4 Million bytes. Roughly, how long will it take to transfer the file to Host B.
c. Repeat (a) and (b), but now with R2 reduced to 100 Kbps.

Answer 1

From R1, R2 and R3, R1 has the lowest bandwidth. Because of this bottleneck the overall bandwidth of the whole network will be 500kbps. So,

a) throughput = 500kbps

b) Transmission time = (4 million bytes)/500kbps  =  64 sec

c) Now since R2 has the lowest bandwidth. Throughput will be 100kbps and transmission time will be 320 sec (Calculation is similar to a and b part)

Comments

Sir I have a doubt about when to use the concept of {4 million byes(*(1/500kbps)+(1/2Mbps)+(1/Mbps))} instead of (4 million bytes/500kbps)??