Network,Time,Protocol,Explaini computer Network Time Protocol: Explaining NTP and Network Time Synch
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
NTP isalmost as old as the Internet itself. It was devised and developed by Dr DavidMills of the University of Delaware and has been in constant use and continuallyupdated since 1985. NTP is an internet protocol designed to synchronise clockson a computer network. In a modernglobal economy time synchronisation is essential for carrying out timesensitive transactions such as booking an airline ticket to bidding on Ebay. Ifclocks were not synchronised to the same time you may find your airline seatsold after you had bought it and Ebays administrators would not be able todiscover whose bid was the latest. NTP cansynchronise networks across the Internet or a Local/Wide Area Network (LAN/WAN)it synchronisestime with reference to a reliable clock source. This source could be relative suchas a computers internal clock or the time on a wrist-watch or absolute such astime from an atomic clock. Most network administrators prefer to use an external absolutesource, mainly because specialist NTP servers are available that can easilyreceive an atomic clock timing reference either through specialist radio transmissions(usually from national physics laboratories) or the GPS network.A universal timescale called UTC (Coordinated UniversalTime) has been developed allowing networks all around the world to be synchronizedto the same timescale and supports such features as leapseconds - added to compensate for the slowing of the Earths rotationNTP uses analgorithm (a complex sequence of instructions) to keep time by constantlychecking the time source and matching it to the time on its clocks on thenetwork and instructs each device to alter if it becomes out ofsynchronisation. NTP uses timestamps to represent the current time of the dayeach. As time is linear each timestamp is always greater than the previous one.NTP timestamps are in two formats but they relay the seconds from a set pointin time (known as the prime epoch, set at 00:00 1 January 1900) The NTPalgorithm then uses this timestamp to determine the amount to advance orretreat the system or network clock.NTP analyses the timestamp values including the frequency of errors and the stability.A NTP server will maintain an estimate of thequality of both its referenceclocks and itself.The NTP program (daemon on UNIX, service on Windows) runs inthe background. NTP receives exchanges time information by packets (a block ofdata) but refuses to believe the time it is told until several exchanges havetaken place, each passing a set of tests or protocol specifications. Only ifthe replies from a server satisfy these tests does the NTP utilizes thisinformation. It usually takes about five minutes (five good samples) until a NTPserver is accepted as a timing source. Microsoft,who has installed a version of NTP in their operating systems since Windows2000, strongly recommends that a hardware source is used as a timing referenceas Internet sources cant be authenticated.Authenticationverifies that each timestamp has come from the intended time reference byanalysing a set of agreed encryption keys that are sent along with the timeinformation. NTP, using Message Digest encryption (MD5) to un-encrypt the key,analyses it and confirms whether it has come from the trusted time source byverifying it against a set of trusted keys.The best solution is to use a specialist NTP server and receivean authoritative time reference via either the GPS network or radiotransmissions (known as MSF in the UK or WWVB in the US). NTP servers judge the distance of each network device from atiming source and organisesthem into Strata. These Stratum levels exist to prevent cycles and guaranteeaccuracy. Stratum 0 are devices such as reference clocks connected directly toa computer. Stratum 1 are computers attached to stratum 0 devices, whileStratum 2 are computers further out.NTP is free to download via NTP.org and is continuallysupported and updated. The current version is v 4. A simplified version of NTP (SNTP)exists has less functions and is used insome devices and applications (and also included in older versions of Windows) wherehigh accuracy timing is not as important.
Network,Time,Protocol,Explaini