4) (25 points) Consider TCP reliable data transfer of letters A, B, C, D, and E, each encoded into five bytes of data and sent in an individual segment from host X to host Y. The user types a new letter every 0.5 seconds. Suppose the first segment carrying letter A has SeqNumb-65 and ACK # 345 . Suppose the regular one-way delay between X and Y (and vice versa) is 0.5 seconds. Suppose all exchanges take the regular delay, but the transmission of letter B from X to Y takes 1.75 seconds. a) Draw the exchanged segments with SeqNumb, ACK, and carried data b) How large does the Timeout need to be to avoid retransmissions? c) When is each letter delivered to the application layer at Y? 4) (25 points) Consider TCP reliable data transfer of letters A, B, C, D, and E, each encoded into five bytes of data and sent in an individual segment from host X to host Y. The user types a new letter every 0.5 seconds. Suppose the first segment carrying letter A has SeqNumb-65 and ACK # 345 . Suppose the regular one-way delay between X and Y (and vice versa) is 0.5 seconds. Suppose all exchanges take the regular delay, but the transmission of letter B from X to Y takes 1.75 seconds. a) Draw the exchanged segments with SeqNumb, ACK, and carried data b) How large does the Timeout need to be to avoid retransmissions? c) When is each letter delivered to the application layer at Y