Consider the evolution of a TCP connection with the following characteristics. Assume that all the following algorithms are implemented in TCP congestion control: slow start, congestion avoidance, fast retransmit and fast recovery, and retransmission upon timeout. If ssthresh equals to cwnd, use the slow start algorithm in your calculation. • The receiver acknowledges every segment, and the sender always has data available for transmission. All TCP segments have the same size (say, 1 unit).
• The network latency in sending a segment (header and payload) from the sender to the receiver is 30ms and the network latency in sending an acknowledgment (header only) from the receiver to the sender is 20ms. Ignore packet processing delays at the sender and the receiver.
• Initially ssthresh at the sender is set to 4. Assume cwnd and ssthresh are measured in segments. Retransmission timeout (RTO) is initially set to 500ms at the sender and updated to 150 ms during the connection lifetime.
• The connection starts to transmit data at time t = 0, and the initial sequence number starts from 1. Segment with sequence number 5 is lost once. No other segments are lost.
How long does it take, in milliseconds, for the sender to receive the ack for the segment with the sequence number 12?