NTP server systems and the timing of network
The Network Time Protocol, better known as NTP, is a widely used Internet protocol for transmission of time on a network. NTP is widely used to synchronize network time clients a precise time source.
This article describes the Network Time Protocol, and provides an overview of NTP servers to use in order to provide a definite source in each network client.
A Brief History
The NTP is one ofoldest Internet protocols still in use today. E 'in continuous use for over 25 years. The protocol was originally designed to synchronize computer and time-critical processes on the Internet. Originally developed for the Linux operating system, the protocol has been recently partially converted to the operating system Microsoft Windows. NTP is the default in many Linux and Unix Free BSD distributions installed. Most of the NTP server systems using the Linux operating system because of itstime kernel specialized algorithms.
The protocol
NTP is a client-server protocol. NTP protocol offers its customers 3 main products: clock offset, round-trip delay and network reference clock dispersion. The clock offset is the difference between the local system clock and an external clock reference. The round-trip delay is to measure latency in the transmission of data packets on the network. And time wastedthe maximum error associated with the information received from the external reference clock timing.
The NTP has a hierarchical structure. A stratum 1 time server is the primary reference servers and sits at the top of heirachy. The primary server reference is followed by secondary reference servers and clients. Primary NTP server reference is usually from an external reference time, such as a radio or GPS clock sync. At the highest level is a primary reference NTPAround a server for a turn. Each sub-level NTP servers and clients is a level that is larger than the previous level. With increasing level, decreases the precision of timing inconsistencies in network path.
Network Time Protocol uses UDP, which is part of the TCP / IP. Each NTP message consists of a number of areas: Leap Indicator, the version number, Mode, Stratum, Poll, precision, Delay Root, Root dispersion, reference materialsIdentification Code Timestamp, Timestamp, Receive Timestamp; Transmit Timestamp; Key Identifier and Message Digest. The fields are used to identify messages and timestamp information and round-trip delay.
The current version of NTP Version 4 of the Protocol all versions are backward compatible with earlier versions. The only significant change to the protocol between versions 3 and 4 pm heading is a re-interpretation of light to accommodate IPv6.
NTPServer mode
A stratum 1 NTP server has three operating modes: Unicast, Anycast and Multicast. The client initiates the unicast and anycast modes, the server responds with a message using the NTP client to synchronize. Multicast is a transmission mode to transmit at regular intervals of time messages to the entire subdomain.
Accurate Clocks
The distribution of labor standard NTP can use a number of external actionsReferences, or "Clocks". The Global Positioning System (GPS) is a popular choice because they provide a reference point in time in the world is available. A number of national terms and radio frequency are also available, such as WWVB (U.S.), DCF-77 (Germany) and MSF (UK).
The Simple Network Time Protocol (SNTP)
SNTP is a simplified version of an adult Network Time Protocol. SNTP is generally used for the complexity and high precision of the NTP protocolrequired. The SNTP protocol is often used in microcontrollers and computer SBC. The NTP and SNTP protocols are fully interchangeable. Each SNTP clients can synchronize with a real NTP server.
Computer-network 