TAILIEUCHUNG - Internet Time Synchronization: the Network Time Protocol

In the wake of the global financial crisis, there has been strong, renewed interest in the behavior of public debt, especially in advanced economies. However, empirical work on debt cycles and debt sustainability has been constrained in the past by lack of public debt datasets covering long time periods and a wide group of countries. The most widely used sources of cross-country public debt data are the International Financial Statistics (IFS) and Government Finance Statistics (GFS) databases published by the IMF; and the Global Development Finance (GDF) dataset of the World Bank. Other regional and institutional bodies, such as the. | Internet Time Synchronization the Network Time Protocol1 2 3 David L. Mills Electrical Engineering Department University of Delaware Abstract This paper describes the Network Time Protocol NTP which is designed to distribute time information in a large diverse internet system operating at speeds from mundane to lightwave. It uses a symmetric architecture in which a distributed subnet of time servers operating in a self-organizing hierarchical configuration synchronizes local clocks within the subnet and to national time standards via wire radio or calibrated atomic clock. The servers can also redistribute time information within a network via local routing algorithms and time daemons. This paper also discusses the architecture protocol and algorithms which were developed over several years of implementation refinement and resulted in the designation of NTP as an Internet Standard protocol. The NTP synchronization system which has been in regular operation in the Internet for the last several years is described along with performance data which shows that timekeeping accuracy throughout most portions of the Internet can be ordinarily maintained to within a few milliseconds even in cases of failure or disruption of clocks time servers or networks. Keywords network clock synchronization standard time distribution fault-tolerant architecture maximumlikelihood principles disciplined oscillator internet protocol. 1. Introduction Accurate reliable time is necessary for financial and legal transactions transportation and distribution systems and many other applications involving widely distributed resources. How do hosts in a large dispersed networking community know what time it is How accurate are their clocks In a recent survey involving 94 260 hosts of the Internet system 20 758 provided local time using three time-transfer protocols 24 . About half of the replies had errors greater than two minutes while ten percent had errors greater than four hours. A few had errors

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