Consider the GBN protocol with a sender window size of 5 and sequence number range of 1024. Suppose at time t, the next in-order packet that the receiver is expecting has the sequence number 40. Assume that the medium does not reorder messages. Answer if the following is possible or not possible, and explain in 2 sentences why it is possible or not possible. a. What are the possible sets of sequence numbers inside the sender's window at rime t?
b. What are the possible values of ACK field in all possible messages currently propagating back to the sender at time t?