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In a TCP connection, the window size determines how many packets can be sent before waiting for an acknowledgment. Think of it as a buffer space for unacknowledged packets. In our exercise, the window size is 1, which means only one packet is sent at a time and the sender waits for its acknowledgment before sending the next packet.
A small window size, like 1, can slow down the transmission rate since the sender must wait for the acknowledgment after every single packet. This is especially impactful if there are delays, as seen in our scenario where packets are lost every other transmission.

Packet loss occurs when data packets traveling across a network fail to reach their destination. Packet loss can cause transmission delays because lost packets need to be resent. In our exercise, every other packet is lost, causing significant disruption.
The impact of packet loss is pronounced with a small TCP window size. Since only one packet is sent at a time, losing every other packet means frequent resending and waiting, which can drastically reduce effective throughput and increase the overall transmission time.

Round-Trip Time (RTT) is the time it takes for a signal to go from the sender to the receiver and back again. In our problem, the RTT is given as 1 second. This means, under ideal conditions without packet loss, each packet acknowledgment should return within 1 second.
In the context of our scenario, lost packets will increase the effective RTT as the packets need to be resent, and each subsequent retry causes a delay.

Timeout is the duration a sender waits for an acknowledgment before assuming a packet is lost and resending it. Determining the timeout value is crucial and is usually based on RTT and its variations.
In case (a), after a packet is eventually received, the timeout doubles each time a packet is lost, which follows an exponential pattern: 2 seconds, 4 seconds, 8 seconds, and so forth. When a packet is finally received, the timeout resets, but still considers the EstimatedRTT.
In case (b), after a packet is received, the timeout resumes from the last exponentially backed-off value. This means it continuously doubles with each packet loss and carries this timeout value forward post-reception.

Exponential backoff is a strategy employed to manage network congestion by exponentially increasing the waiting time between subsequent attempts following packet loss. This is crucial to prevent overwhelming the network with retries.
In case (a), the exponential backoff is demonstrated through doubling the timeout period after each packet loss. Additionally, the EstimatedRTT is recalibrated to its pre-timeout value upon successful reception.
In case (b), the exponential backoff continues without resetting. This means if the timeout period was 8 seconds after a series of losses and then a packet was successfully received, the timeout retains the 8 seconds and continues to double if packet loss persists.