(From Tanenbaum, Computer Networks, 3rd edition, Chapter 4, Problem 21)
Consider building a CSMA/CD network running at 1 Gbps over a 1-km cable with no repeaters. The signal speed in the cable is 200,000 km/sec. What is the minimum frame size?
HINT: To solve this problem remember that to make CSMA/CD work, it must be impossible to transmit entire frame in one-way propagation time. In other words, the frame must be long enough that that it could not be transmitted in one-way propagation time.