Consider sending 6 Kbyte from host A to host B using Stop and Wait, Go-Back-N, and Selective Repeat. Assume packet size

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Consider sending 6 Kbyte from host A to host B using Stop and
Wait, Go-Back-N, and Selective Repeat. Assume packet size (L) is 2
Kbyte, data rate (R) is 8Mbps, RTT=18ms, window size (W) is 4
packets, and the Timeout=30 ms.
Case 1: Assume all packets and ACKs are received correctly, what
is the sender utilization (Usender) when using:
Case 2: Now suppose ACK2 is missed and all other packets and
ACKs are received correctly. The first packet and ACK are P0 and
ACK0 respectively. Neglect the transmission time of ACK
packets.
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