Network Time Protocol (Version 3) Specification, Implementation and Analysis (RFC1305)
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2019-Feb-11
Internet Society Requests For Comment (RFCs)
This document describes the Network Time Protocol (NTP), specifies its formal structure and summarizes information useful for its implementation. [STANDARDS-TRACK]
Network Working Group David L. Mills Request for Comments: 1305 University of Delaware Obsoletes RFC-1119, RFC-1059, RFC-958 March 1992
Network Time Protocol (Version 3) Specification, Implementation and Analysis
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This document describes the Network Time Protocol (NTP), specifies its formal structure and summarizes information useful for its implementation. NTP provides the mechanisms to synchronize time and coordinate time distribution in a large, diverse internet operating at rates from mundane to lightwave. It uses a returnable-time design in which a distributed subnet of time servers operating in a self- organizing, hierarchical-master-slave configuration synchronizes local clocks within the subnet and to national time standards via wire or radio. The servers can also redistribute reference time via local routing algorithms and time daemons.
Status of this Memo
This RFC specifies an IAB standards track protocol for the Internet community and requests discussion and suggestions for improvements. Please refer to the current edition of the <169>IAB Official Protocol Standards<170> for the standardization state and status of this protocol. Distribution of this memo is unlimited.
Keywords: network clock synchronization, standard time distribution, fault-tolerant architecture, maximum-likelihood estimation, disciplined oscillator, internet protocol, high-speed networks, formal specification.
This document describes Version 3 of the Network Time Protocol (NTP). It supersedes Version 2 of the protocol described in RFC-1119 dated September 1989. However, it neither changes the protocol in any significant way nor obsoletes previous versions or existing implementations. The main motivation for the new version is to refine the analysis and implementation models for new applications at much higher network speeds to the gigabit-per-second regime and to provide for the enhanced stability, accuracy and precision required at such speeds. In particular, the sources of time and frequency errors have been rigorously examined and error bounds established in order to improve performance, provide a model for correctness assertions and indicate timekeeping quality to the user. The revision also incorporates two new optional features, (1) an algorithm to combine the offsets of a number of peer time servers in order to enhance accuracy and (2) improved local-clock algorithms which allow the poll intervals on all synchronization paths to be substantially increased in order to reduce network overhead. An overview of the changes, which are described in detail in Appendix D, follows:
1. In Version 3 The local-clock algorithm has been overhauled to im...