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Selective-Reject ARQ Systems

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Consider a selective-reject ARQ system with a window size of 3.

a) Circle (or shade or bold) the sender window after frames 0 through 3 have been sent and ACK 2 has been received

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0

b) Circle (or shade or bold) the sender windows after frames 4 through 6 have been transmitted, ACK 5 and NAK 5 are received.

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0

c) After a) and b) have occurred, which frames need to be resent?

d) After a) and b) have occurred, which frames have been acknowledged?

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[2] Consider a selective- reject ARQ
Posting

Consider a selective-reject ARQ system with a window size of 3.
=============================================
a) Circle (or shade or bold) the sender window after frames 0 through 3 have been sent and ACK 2 has been received

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0

=================================================
Window [0,2] [3-5]
SN
Node A

Node B
RN

Packets
Delivered 0 1 2

b) Circle (or shade or bold) the sender windows after frames 4 through 6 have been transmitted, ACK 5 and NAK 5 are received.

0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0

Window [4,6] [5,7]
SN
Node A

Node B
RN

Packets
Delivered 4

c) After a) and b) have occurred, which frames need to be resent?
5,6,7

d) After a) and b) ...

Solution Summary

This job emphasizes a selective-reject ARQ system with a window size of 3.

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See Also This Related BrainMass Solution

Time Sequence diagrams

Please reference this figure for the question:

55. Draw 3 time sequence diagrams that illustrate the flow of frames between points B and G in Figure 1 using the following information:

a. Stop and Wait ARQ, SENDER sends four frames (F1, F2, F3, and F4). F1, F2 and F4 are received error free, but F3 is lost in the network during its initial transmission. Continue the diagram until all frames are received are error free and properly acknowledged.

b. Go-Back-N ARQ, SENDER sends five frames (F1, F2, F3, F4, and F5). F1 through F2 are received error free but F3 is lost in the network after F4 and F5 are sent. Assume that F4 and F5 are received error free. Continue the diagram until all frames are received error free and properly acknowledged.

c. Selective Reject ARQ, SENDER sends six frames (F1, F2, F3, F4, F5 and F6) but only has a four frame send window. F1,F2 and F4 are received error free but an error is detected in F3 after F4 is received. When sent F5 is received error free while F6 is lost in the network. Continue the diagram until all frames are received error free and properly acknowledged.

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