Looking at the figure, we see that A transmits for the duration t4 _ t1; C transmits for the duration t3 - t2.Later we show that, for the protocol to work, the length of any frame divided by the bit rate in this protocol must be more than either of these durations. At time t4, the transmission of A's frame, though incomplete, is aborted; at time 13, the transmission of B,s frame, though incomplete, is aborted