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NTP Server Systems â € "Network Time Protocol
The Network Time Protocol (NTP) is used by NTP Server systems to distribute EBay official information network clients in time. The NTP protocol is widely used in the Internet to facilitate the synchronization process and equipment. This article discusses how NTP server systems using the Network Time Protocol to provide network and a precise time reference.
NTP Overview
NTP was used as an Internet protocol for over 25 years. This is the protocol's oldest Internet runs continuously. The protocol was born through the need for time synchronization of critical processes on the Internet. NTP operates mainly on Linux and UNIX platforms, including Free-BSD, but it was also partly brought on Windows systems. Dedicated systems typically use NTP server the Linux operating system.
NTP
NTP is designed to give customers time network, with three products: clock Offset System, the roundtrip delay and dispersion in relation to a reference clock accurate. Clock offset is the difference time between the local clock and the reference clock. Round-trip delay measures the amount of time, the protocol required for a response from the server. Dispersion is the maximum error of the local clock relative to the specified reference.
NTP stratum
NTP works hierarchical manner, the primary reference, followed by secondary references and clients. At the top of the hierarchy, the primary reference is generally synchronized to an external source, like a radio or GPS clock. The main reference is attributed to a single layer. Each level in the hierarchy is assigned a stratum greater than the previous level. As the stratum increases, the precision of the reference deteriorates slightly due to inconsistencies in the time path network. References secondary layer between two and fifteen years.
NTP Messages
NTP uses UDP (User Data-gram Protocol). The NTP message consists of a number of areas: the jump indicator, the version number; Fashion; stratum; Survey, precision, root delay, after the dispersion, reference code, timestamp reference; Origination timestamp; Receive timestamp; Transmit Timestamp; identification number and a message digest.
The leap warning indicator of impending leap second addition or removal. The version number indicates the version of NTP in use. Fashion NTP mode specified current message. Stratus is a value of eight bits that indicates the level hierarchical reference clock. Interval indicates the maximum interval between messages. The precision specifies the precision the local clock. Delay indicates the round trip delay root reference. Root dispersion indicates the nominal error relative to the primary reference. Reference identifier is a string of 4 ASCII to identify the source of reference such as GPS, DCF or MSF. Specifies the reference date and time where the reference clock was last adjusted. The brand Origination Time specifies the time the NTP message departed the application client to the NTP server. Date and time of receipt specifies the length of the NTP request message was received by the NTP server. Date and time of transmission specifies how long the response message was transmitted by the NTP server to the client. The key identifier field is used when authentication is required and provides authentication code message.
Operation NTP server
A NTP server can operate in three modes: unicast, multicast and anycast. In unicast and anycast modes, the client sends a request message to the NTP server. The server responds with a NTP time message that the client uses for synchronization time. In multicast mode, the NTP time messages are broadcast at regular intervals specified.
NTP reference clocks
Primary NTP servers can synchronize with a number of sources of external time reference. The GPS (Global Positioning System) is often used to provide reference high-precision clock. There are a number of national time and frequency radio broadcasts available. The broadcast time is transmitted from WWVB Colorado and covers most of the United States. The DCF-77 radio signal is broadcast from Frankfurt, Germany covering much of central and western Europe. MSF The radio time signal is broadcast from Rugby, United Kingdom, covering the British Isles and much of Western Europe. Local, other and radio frequency are: TDF, France, and Chu, Canada.
NTP Version
The current version of NTP is version 4. The only change significant in protocol version 3 and 4 head is a little re-interpretation to accommodate IPv6.
SNTP â € "Simple Network Time Protocol
SNTP is a simplified procedure of the Network Time Protocol, where the complexity of the protocol all the rules are not necessary. SNTP can be applied when the high-performance synchronization of NTP is not required. The SNTP message format protocol is almost identical to the NTP. However, sub-programs complex for a time to maintain timing precision has been removed or simplified. Small computers with processing power reduced, such as micro-controllers or monitoring equipment often use SNTP. The SNTP and NTP protocols are completely interchangeable, a SNTP client can synchronize with an NTP server, no problem.
More information: NTP RFCâ € ™ s
The original was introduced Network Time Protocol in RFC 958 (Request for Comments: 958). Version 3 of the full protocol and NTP synchronization algorithms described in RFC 1305. SNTP Version 4 Protocol described in RFC 2030.
About the Author
Dave Evans develops atomic clock time synchronisation systems to ensure accurate time on PC’s and networks. Click here to find out more about SNTP server and NTP Server systems.
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