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Simple Network Time Protocol (SNTP) (RFC1769)

IP.com Disclosure Number: IPCOM000004020D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2000-Sep-12
Document File: 11 page(s) / 32K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

D. Mills: AUTHOR

Abstract

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.

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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.

Abstract

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.

1. Introduction

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.

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

fu...