ABSTRACT
At the heart of the Network Time Protocol (NTP) design are the algorithms that synchronize the computer clock to NTP servers elsewhere in the Internet or an external source. These include the mitigation algorithms that select the best time values from each server and the best combination of servers, together with the clock discipline algorithm that synchronizes the computer clock with respect to this time. The clock discipline algorithm, shortened to
discipline
, is the main topic of this chapter. It has evolved from humble beginnings to a sophisticated design that automatically adapts to changes in the operating environment without manual configuration or real-time management functions. The discipline has been implemented both in the NTP software daemon and, for the highest accuracy, in the operating system kernel. However, the discipline could be used in principle with any protocol that provides periodic time corrections.
