Solve only 7.3

In Figure 7.10 frames are generated at node A and sent to node C through node B. Determine the minimum data rate required between nodes B and C so that the buffers node B are not flooded, based on the following: The data rate between A and B is 100 kbps. The propagation delay is 5 mu s/km for both lines. There are full-duplex lines between the nodes. All data frames are 1000 bits long; ACK frames are separate frames of negligible length. Between A and B, a sliding-window protocol with a window size of 3is used. Between B and C, stop-and-wait is used. There are no errors. A channel has a data rate of R bps and a propagation delay of t s/km. The distance between the sending and receiving nodes is L kilometers. Nodes exchange fixed-size frames of B bits. Find formula that gives the minimum sequence field size of the frame as function of R, t, B, and L (considering maximum utilization) Assume that ACK frames are negligible in size and the processing at the nodes is instantaneous