10,000 bytes of Transport PDU (including the TCP header) are to be transmitted over the three hops described below when the MTU is 1000 bytes and 802.3 at 200Mbps is used with a TCP/IP stack. The LLC-control uses 1 byte and no options are required for the IP.

a) How many 802.3 frames must be sent?

b) Calculate the overhead in bytes, excluding the TCP Header, for the entire transmission assuming no errors.

c) The four stations use sliding windows, the three hops use optical fiber with 20km between the nodes. The Go Back N ARQ is in use at all nodes and the sequence number length is 3 bits. Assume no transmission errors and each node ACKS the first frame received and at least every 4th frame thereafter. Assume each node retransmits a frame with no delay. Is the transmission line between the first two nodes 100% utilized at any time or not? Explain why or why not..