Question

Questions: R19: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

Solution AL RiR2 R3 Ri = 500kbps ; R2 = 2Mbps ; R3 = 1 Mbps It should be equivalent to slowest link which is 500 kbps. Because they are connected in series. Even through R2 has got the fastest transfer rate of 2 Mbps, but it has to wait for the Ri link to mansfer the data with a speed of 500. klops for the work to complete Hence the through put is sookbps Total file size = 4 million tbyte = 8 bits an communication channel data is transfered is form of bit File size = 4x108x8 bit = 64 sec Throughput 5008 103 bits by - Seconds Delay transfer of of 64 seconds will occur size 4 million bytes for a from file A to B Now Ri 2500 kbps R2 = 100 Mbps R3 = 1 Mbps link is R2 = 100 kbps in Throughput = 100 kbps Slowest Delay = File size The Throughput a 4x100 x 8 bits 100x103 bits Sec Sec = 320 sec

So the delay got increased to 320 seconds a af one of the links transfer rāte falls from 10 1 oo kbps hom Soo kbps At to the sending host begins to transmit At ti = 1 Il tile size), the sending host Completes transmission and the entire packet is received @ the router (no propagation delcy counted as it is not mentioned ). Recause the router has the entire packet at time t, can begin to transmit the packet to the receiving host at time to A time to it can bogin ta ta th the most packet R2 arrives at the second router of whole. procedure repeats finally t3 z tz ttita tl IL 9 The 2nd router completes transmission in R3 i and entire packet is received at the recierin end (no propagation delay) -> End - to-end delay = x + 1 2 + 1 the [=> File size (For E as mentioned) in prob 1) е as in