Network Time Protocol Version 5
draft-mlichvar-ntp-ntpv5-01
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Miroslav Lichvar
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2020-12-09
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Internet Engineering Task Force M. Lichvar
Internet-Draft Red Hat
Intended status: Standards Track Dec 9, 2020
Expires: June 12, 2021
Network Time Protocol Version 5
draft-mlichvar-ntp-ntpv5-01
Abstract
This document describes the version 5 of the Network Time Protocol
(NTP).
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 12, 2021.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Basic Concepts . . . . . . . . . . . . . . . . . . . . . . . 3
3. Data Types . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Message Format . . . . . . . . . . . . . . . . . . . . . . . 4
5. Extension Fields . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Padding Extension Field . . . . . . . . . . . . . . . . . 9
5.2. MAC Extension Field . . . . . . . . . . . . . . . . . . . 9
5.3. Reference IDs Extension Field . . . . . . . . . . . . . . 9
5.4. Server Information Extension Field . . . . . . . . . . . 9
5.5. Correction Extension Field . . . . . . . . . . . . . . . 10
5.6. Reference Timestamp Extension Field . . . . . . . . . . . 10
5.7. Monotonic Timestamp Extension Field . . . . . . . . . . . 10
6. Client Operation . . . . . . . . . . . . . . . . . . . . . . 11
7. Server Operation . . . . . . . . . . . . . . . . . . . . . . 13
8. NTPv5 Negotiation in NTPv4 . . . . . . . . . . . . . . . . . 15
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
11. Security Considerations . . . . . . . . . . . . . . . . . . . 16
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
12.1. Normative References . . . . . . . . . . . . . . . . . . 16
12.2. Informative References . . . . . . . . . . . . . . . . . 16
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
Network Time Protocol (NTP) is a protocol which enables computers to
synchronize their clocks over network. Time is distributed from
primary time servers to clients, which can be servers for other
clients, and so on. Clients can use multiple servers simultaneously.
NTPv5 is similar to NTPv4 [RFC5905]. The main differences are:
1. The protocol specification (this document) describes only the
on-wire protocol. Filtering of measurements, security
mechanisms, source selection, clock control, and other
algorithms, are out of scope.
2. NTPv5 drops support for the symmetric active, symmetric passive,
broadcast, control, and private modes. Only the client and
server modes are supported.
3. Timestamps are clearly separated from values used as cookies.
4. NTPv5 messages can be extended only with extension fields. The
MAC field is wrapped in an extension field.
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5. Extension fields can be of any length, even indivisible by 4,
but are padded to a multiple of 4 octets. Extension fields
specified for NTPv4 are compatible with NTPv5.
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