NTP,Accurate,Network,Time,Sync computer NTP: Accurate Network Time Synchronisation
Gone are those times when the companies and the organisations didn't need a hi-tech system to handle them. Owing to the considerable increase in the business sector and thus, an enormous increase in the complexity of the organisational struc ----------------------------------------------------------Permission is granted for the below article to forward,reprint, distribute, use for ezine, newsletter, website,offer as free bonus or part of a product for sale as longas no changes a
All PCsand networking devices use clocks to maintain an internal system time. Theseclocks, called Real Time Clock chips (RTC) provide time and dateinformation. The chips are battery backed so that even during power outages,they can maintain time. However, personal computers are not designed to beperfect clocks, their design has been optimized for mass production andlow-cost rather than maintaining accurate time.These internal clocks are prone todrift and although formany application this is can be quite adequate, often machinesneed to work together on a network and if the computers drift at differentrates the computers will become out of sync with each other and problems canarise particularly with time sensitive transactions.A timeserver uses the Network Time Protocol (NTP) which was developed over 20 yearsago. It uses analgorithm (Marzullos algorithm) to synchronisetime on a network. NTP (version 4)can maintain time over the public Internet to within 10 milliseconds (1/100thof a second) and can perform even better over LANs with accuracies of 200microseconds (1/5000th of a second) under ideal conditions.NTP uses a single time reference andsynchronises all machines on the network to that time. This time reference canbe either relative (a computers internal clock or the time on awrist-watch perhaps) or absolute such as a UTC (Universal Coordinated Time)clock source like an atomic clock that is as accurate as is humanely possible.Atomic clocks are the most absolute time-keepingdevices. They work on the principle that the atom, caesium-133, has anexact number of cycles of radiation every second (9,192,631,770). This hasproved so accurate the International System of Units (SI) has now defined thesecond as the duration of 9,192,631,770 cycles of radiation of the caesium-133atom.However, atomic clocks are extremely expensive and aregenerally only to be found in large-scale physics laboratories. However, NTPcan synchronise networks to an atomic clock by using either the GlobalPositioning system (GPS) network or specialist radio transmission.Themost widely used is the GPS system which consists of a number of satellitesproviding accurate positioning and location information. Each GPS satellite canonly do this by utilising an atomic clock which in turn can be can be used as atiming reference. Atypical GPS time server can provide timing information to within a fewnanoseconds of UTC as long as there is an antenna situated with a good view ofthe sky.There arealso a number of national time and frequency radio transmissions that can beused to synchronise a NTP server. In Britain the signal (called MSF) isbroadcast by the National.Physics Laboratory in Cumbria which serves as the UnitedKingdom's national time reference, there are also similar systems inColorado, US (WWVB) andin Frankfurt, Germany (DCF-77). These signals provides UTC time to an accuracyof 100 microseconds, however, the radio signal has a finite range and isvulnerable to interference.All Microsoft Windows versions since 2000 includethe Windows Time Service (w32time.exe) which has the ability to synchronise thecomputer clock to an NTP server.
NTP,Accurate,Network,Time,Sync