Suppose two nodes, A and B, are attached to opposite ends of an 800 m cable, and that they each have one frame of I,SOO bits (including all headers and preambles) to send to each other. Both nodes attempt to transmit at time t =O. Suppose there are four repeaters between A and B, each inserting a 20-bit delay. Assume the transmission rate is 100 Mbps, and CSMA/CD with back off intervals of multiples of SI2 bits is used. After the first collision, A draws K =0 and B draws K =I in the exponential back off protocol. Ignore the jam signal and the 96-bit time delay.
a. What is the one-way propagation delay (including repeater delays) between A and B in seconds? Assume that the signal propagation speed is 2 . 108 m/sec.
b. At what time (in seconds) is A's packet completely delivered at B?
c. Now suppose that only A has a packet to send and that the repeaters are replaced with switches. Suppose that each switch has a 20-bit processing delay in addition to a store-and forward delay. At what time, in seconds, is A's packet delivered at B?