Sliding window protocol

Question

Consider three nodes $ A,B,C$ connected in series. Node $A$ is connected to Node B via $ 3 \text{Gbps}$ link, $500 \text{km}$ length. The links are full duplex, but no other traffic on the links. A large file is to be sent from node $A$ to node $C$. Packets are $1024 \text{bytes}$.Assume velocity of propagation as $2 \times  10^{8} \text{m/sec}$.

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Q1). What is the round trip time?

(a). $5.23 \text{m sec}$                  (b). $7.24 \text{m sec}$

(c). $1.28\text{m sec}$                   (d). $8.98 \text{m sec}$

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Q2). Suppose an end to end sliding window protocol is used what is the optimal value of sender’s window

(a). $28$                                                (b). $38$

(c). $54$                                                (d). $72$

Answer 1

1. a, 2. b

Comments

yes i considered

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@Abhisek Tiwari 4 logically that should be the RTT, even i got the same

In general, for two hosts it will be 2*Tp + Tt(ack), but we ignore the transmission time for ack because size of it is negligible.

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i think such thing should be mentioned. I got this Q in Virtual gate Test and their ans was 5.23 not even range.So i tried to verify the method and RTT definition.

Answer 2

for 1 I got 5.15 ms