Flow scheduling protocols without real-time clocks

The authors propose replacing the real-time clock, used in scheduling protocols to determine the packet´s arrival time to the multiplexor, by an event-driven, discrete clock. The multiplexor advances its discrete clock, at the start of serving any packet, by a value equal to the service time needed to serve that packet. The discrete clock is implemented in three different timestamping protocols. They prove that using discrete clock preserves the bounds on delay. They also illustrate the relations between the valve of the time-stamp based on a real-time clock, and the corresponding value based on discrete clock