(7) (4 pts) Hosts A and B access the Internet through a router as shown below. Assume A and B each opens one TCP channel and connected to two different servers located inside the Internet. Suppose that all packets are transmitted with a constant packet size (called MTU) and the sender will grow its window linearly according to the following formula: W=W-1 + MTU. This means that the bandwidth of each TCP channel increases in a linear fashion. Assume that ACKS will be lost when the sum of their TCP channels' bandwidths reaches 3M bps. When an ACK is missing, the slow-start of TCP congestion control kicks in and the window sizes of A and B will be reduced to % of their current values. After that, the same window operating procedure will continue. To simplify the discussion, we assume the size of an MTU is small. Assume at to, host A's TCP channel has the bandwidth of 200 Kbps and B's TCP channel has the bandwidth of 800 Kbps. (a) When the sum of the bandwidths of the two TCP channels reaches 3 Mbps, what is the bandwidth of B's TCP channel? (b) Once the total bandwidth reaches 3M bps, both A and B will reduce their sending window sizes according to the description above. When their total capacity reaches 3Mbps again, what is the bandwidth of B's TCP channel? B Router 3M bps Bandwidth 3M Figure b 3M Bandwidth (host A)