Simple Network Time Protocol (SNTP) Version 4 for IPv4, IPv6 and OSI
RFC 2030
Document | Type |
RFC - Informational
(October 1996; Errata)
Obsoleted by RFC 4330
Obsoletes RFC 1769
Was draft-rfced-info-mills (individual)
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Last updated | 2013-03-02 | ||
Stream | Legacy | ||
Formats | plain text pdf htmlized with errata bibtex | ||
Stream | Legacy state | (None) | |
Consensus Boilerplate | Unknown | ||
RFC Editor Note | (None) | ||
IESG | IESG state | RFC 2030 (Informational) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group D. Mills Request for Comments: 2030 University of Delaware Obsoletes: 1769 October 1996 Category: Informational Simple Network Time Protocol (SNTP) Version 4 for IPv4, IPv6 and OSI 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. Abstract This memorandum describes the Simple Network Time Protocol (SNTP) Version 4, 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. When operating with current and previous NTP and SNTP versions, SNTP Version 4 involves no changes to the NTP specification 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. The only significant protocol change in SNTP Version 4 over previous versions of NTP and SNTP is a modified header interpretation to accommodate Internet Protocol Version 6 (IPv6) [DEE96] and OSI [COL94] addressing. However, SNTP Version 4 includes certain optional extensions to the basic Version 3 model, including an anycast mode and an authentication scheme designed specifically for multicast and anycast modes. While the anycast mode extension is described in this document, the authentication scheme extension will be described in another document to be published later. Until such time that a definitive specification is published, these extensions should be considered provisional. This memorandum obsoletes RFC-1769, which describes SNTP Version 3. Its purpose is to correct certain inconsistencies in the previous document and to clarify header formats and protocol operations for current NTP Version 3 (IPv4) and proposed NTP Version 4 (IPv6 and OSI), which are also used for SNTP. A working knowledge of the NTP Version 3 specification RFC-1305 is not required for an implementation of SNTP. Mills Informational [Page 1] RFC 2030 SNTPv4 for IPv4, IPv6 and OSI October 1996 1. Introduction The Network Time Protocol (NTP) Version 3 specified in RFC-1305 [MIL92] is widely 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. RFC-1305 specifies the NTP Version 3 protocol machine in terms of events, states, transition functions and actions and, in addition, engineered algorithms to improve the timekeeping quality and mitigate among several synchronization sources, some of which may be faulty. 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 in the order of significant fractions of a second are acceptable. 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 with a wide range of capabilities and over a wide range of network delays and jitter characteristics. Most users of the Internet NTP synchronization subnet of today use a software package including the full suite of NTP options and algorithms, which are relatively complex, real-time applications (see http://www.eecis.udel.edu/~ntp). While the software has been ported to a wide variety of hardware platforms ranging from personal computers to supercomputers, its sheer size and complexity is not appropriate for many applications. Accordingly, it is useful to explore alternative access strategies using simpler software appropriate for less stringent accuracy expectations. This document describes the Simple Network Time Protocol (SNTP) Version 4, which is a simplified access strategy for servers and clients using NTP Version 3 as now specified and deployed in the Internet, as well as NTP Version 4 now under development. The accessShow full document text