12.2 Suppose nodes A and B are attached to opposite ends of a 100 Mbps Ethernet cable segment. Suppose A begins transmitting a frame and, before it finishes, B begins transmitting a frame. In order for A to detect collision with B, what should be the maximum length of the Ethernet cable segment? (Assume that the transmit frame size is 500 bits and signal propagation speed is 2 108 m/sec.