Question 4 - TCP Error Control (24 points): Assume that a client has opened a TCP connection with a server to download a file. During setting up the connection, the following connection parameters are set: - The client receive window is set to 5000 bytes (rwnd =5000). - The server Initial Sequence Number (ISN) is set to 0 . - The MSS size is set to 1000 bytes. - The error-control algorithm for this connection is set to GBN with Fast-Transmission feature enabled (re-sending a segment upon receiving three duplicate ACK without waiting for the timer to expire). Once the connection is opened, the server sent four TCP segments, each one carries MSS bytes. Assume that the 2 nd segment got lost during the transmission and never reached the client. (a) (4 points) From the start of the connection until the reception of the 4th segment, how many ACKs the client will send to the server (including the handshake ACK )? (b) (4 points) Assume the server received all ACKs of the successfully delivered segments, what is the ACK number of the last ACK sent by the client to the server? (c) (4 points) Assume that the lost packet timer has NOT expired yet, what are the sequence numbers of the next TCP segments that the server is going to send until exhausting the receive window (rwnd)? (Hint: you might want to draw the exchange of segments between the client and the server to help you visualize the traffic flow. Review the discussion slide number 21 and 22 for flow diagrams example). Now let's assume that the client has closed the TCP connection and opened another TCP connection with the server. This time, the client and the server has the same connection parameters except for the last one where the error-control algorithm is set to SR instead of GBN. Once the connection is opened. the server sent four TCP segments, each one carries MSS bytes. Assume that the 2 nd segment got lost during the transmission and never reached the client. (d) (4 points) From the start of the connection until the reception of the 4 th segment, how many ACKs the client will send to the server (including the handshake ACK)? (e) (4 points) Assume the server received all ACKs of the successfully delivered segments, what is the ACK number of the last ACK sent by the client to the server? (f) (4 points) Assume that the lost packet timer has expired, what are the sequence numbers of the next TCP segments that the server is going to send until exhausting the receive window (rwnd)? Hint 1: SR has no Fast-Transmission feature. Hint 2: don't forget to take into account the 3-way TCP handshake when calculating the acknowledgements and sequence numbers