Problem
Suppose nodes A, B, C and D are connected on an 800 kbps link in a line A---B---C---D. The propagation delay between the neighboring nodes (A and B, B and C and C and D) is 5 ms. Assume nodes use CSMA/CD and exponential backoff is disabled. Consider the following cases and answer if they are possible or not. Explain your answer and show calculations. Note that each of the following cases are independent (not occurring one after the other) and frame size is 1000 bytes.
A. Assume that node A starts transmitting a frame at t=0ms. Now, node D wants to transmit a frame at t = 14ms. Will node D be able to start the transmission of the frame? Will there be a collision?
B. Assume that node A starts transmitting a frame at t=5ms. Node D starts transmitting a frame at t=19ms. Will there be a collision? If yes, who will (A or D) will detect the collision first and when will they detect the collision respectively?
C. Assume that node A starts transmitting a frame to node B at t=6ms and node D starts transmitting a frame to node C at t=0ms. Can these two frames be received at their intended receivers without collision? Why?