2. (18 pts) You are using a Go-Back-N protocol and have determined that a good size of the sender window is 4. Assume that the first packet that is sent is numbered O and that ACKs indicate the next packet expected. You are sending a message of 5 packets. Suppose that sending a packet and getting an ACK take the same time, and the timeout timer is set to be 2 times the round trip delay. Assume the second packet sent is lost and all other packets and ACKs arrive correctly What is the minimum number of bits you can use for the sequence space? Why? a. b. Show the state of the sender and receiver just before the timer first times out c. What first two packets does the sender send after this first timeout? d. How long (as a fraction of the timeout time) after this first timeout does the receiver get the lost packet. Explain