Simple Network Time Protocol (SNTP) (RFC1769)
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2019-Feb-12
Internet Society Requests For Comment (RFCs)
This memorandum describes the Simple Network Time Protocol (SNTP), which is an adaptation of the Network Time Protocol (NTP) used to synchronize computer clocks in the Internet. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind.
Network Working Group D. Mills Request for Comments: 1769 University of Delaware Obsoletes: 1361 March 1995 Category: Informational
Simple Network Time Protocol (SNTP)
Status of this Memo
This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
This memorandum describes the Simple Network Time Protocol (SNTP), which is an adaptation of the Network Time Protocol (NTP) used to synchronize computer clocks in the Internet. SNTP can be used when the ultimate performance of the full NTP implementation described in RFC-1305 is not needed or justified. It can operate in both unicast modes (point to point) and broadcast modes (point to multipoint). It can also operate in IP multicast mode where this service is available. SNTP involves no change to the current or previous NTP specification versions or known implementations, but rather a clarification of certain design features of NTP which allow operation in a simple, stateless remote-procedure call (RPC) mode with accuracy and reliability expectations similar to the UDP/TIME protocol described in RFC-868.
This memorandum obsoletes RFC-1361 of the same title. Its purpose is to explain the protocol model for operation in broadcast mode, to provide additional clarification in some places and to correct a few typographical errors. A working knowledge of the NTP Version 3 specification RFC-1305 is not required for an implementation of SNTP. Distribution of this memorandum is unlimited.
The Network Time Protocol (NTP) specified in RFC-1305 [MIL92] is used to synchronize computer clocks in the global Internet. It provides comprehensive mechanisms to access national time and frequency dissemination services, organize the time-synchronization subnet and adjust the local clock in each participating subnet peer. In most places of the Internet of today, NTP provides accuracies of 1-50 ms, depending on the characteristics of the synchronization source and network paths.
Mills [Page 1]
RFC 1769 SNTP March 1995
RFC-1305 specifies the NTP protocol machine in terms of events, states, transition functions and actions and, in addition, optional algorithms to improve the timekeeping quality and mitigate among several, possibly faulty, synchronization sources. To achieve accuracies in the low milliseconds over paths spanning major portions of the Internet of today, these intricate algorithms, or their functional equivalents, are necessary. However, in many cases accuracies of this order are not required and something less, perhaps in the order of large fractions of the second, is sufficient. In such cases simpler protocols such as the Time Protocol [POS83], have been used for this purpose. These protocols usually involve an RPC exchange where the client requests the time of day and the server returns it in seconds past some known reference epoch.
NTP is designed for use by clients and servers wit...