Question

Suppose Host A wants to send a large file to Host B. The path from Host A to Host B has three links, or rates R1 = 1 Mbps, R2 = 3Mbps, and R3 = 5 Mbps.

Now assume R3 reduced to 500 kbps.

(2 pt.) What is the throughput?

(3 pt.) What is the file transfer time?

Answer 1

Consider givend data:R1 = 1 Mbps , R2 = 3 Mbps, and R3 = 5  Mbps

The throughput for the file transfer=min{R1,R2,R3}

=min{ 1 Mbps, 3 Mbps, 5  Mbps}

   = 1 Mbps

So, the throughput for the file transfer= 1 Mbps

The file size= 4 million bytes

Convert million bytes to bits

=32000000 bits.

From (a), Throughput for the file transfer=1 Mbps

=1024000 bps

Dividing the file size by the throughput,roughly how long will it take to transfer the file to Host B:

=file size/hroughput for the file transfer

=32000000 bits/1024000 bps

=31.25 seconds

now with R3 reduced to 500 kbps.

That means R3=500 kbps, R1 = 1 Mbps , R2 = 3 Mbps

The throughput for the file transfer=min{R1,R2, R3}

=min{1Mbps , 3Mbps, 500kbps}

   =500 kbps

So, the throughput for the file transfer=500 kbps

Dividing the file size by the throughput,roughly how long will it take to transfer the file to Host B:

=file size/hroughput for the file transfer

=32000000 bits/500000 bps

=64 seconds