UDP Checksum Complement in the Network Time Protocol (NTP)
RFC 7821
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Type |
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RFC - Experimental
(March 2016; No errata)
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Last updated |
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2016-03-30
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Replaces |
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draft-mizrahi-ntp-checksum-trailer
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IETF
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plain text
pdf
html
bibtex
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WG state
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Submitted to IESG for Publication
Apr 2016
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Document shepherd |
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Karen O'Donoghue
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Shepherd write-up |
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Show
(last changed 2016-03-02)
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| IESG |
IESG state |
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RFC 7821 (Experimental)
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Consensus Boilerplate |
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Yes
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Telechat date |
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Responsible AD |
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Brian Haberman
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Send notices to |
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"Karen O'Donoghue" <odonoghue@isoc.org>
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| IANA |
IANA review state |
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Version Changed - Review Needed
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IANA action state |
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RFC-Ed-Ack
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Internet Engineering Task Force (IETF) T. Mizrahi
Request for Comments: 7821 Marvell
Category: Experimental March 2016
ISSN: 2070-1721
UDP Checksum Complement in the Network Time Protocol (NTP)
Abstract
The Network Time Protocol (NTP) allows clients to synchronize to a
time server using timestamped protocol messages. To facilitate
accurate timestamping, some implementations use hardware-based
timestamping engines that integrate the accurate transmission time
into every outgoing NTP packet during transmission. Since these
packets are transported over UDP, the UDP Checksum field is then
updated to reflect this modification. This document proposes an
extension field that includes a 2-octet Checksum Complement, allowing
timestamping engines to reflect the checksum modification in the last
2 octets of the packet rather than in the UDP Checksum field. The
behavior defined in this document is interoperable with existing NTP
implementations.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for examination, experimental implementation, and
evaluation.
This document defines an Experimental Protocol for the Internet
community. This document is a product of the Internet Engineering
Task Force (IETF). It represents the consensus of the IETF
community. It has received public review and has been approved for
publication by the Internet Engineering Steering Group (IESG). Not
all documents approved by the IESG are a candidate for any level of
Internet Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7821.
Mizrahi Experimental [Page 1]
RFC 7821 NTP Checksum Complement March 2016
Copyright Notice
Copyright (c) 2016 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
(http://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.
Table of Contents
1. Introduction ....................................................3
1.1. Intermediate Entities ......................................3
1.2. Updating the UDP Checksum ..................................4
2. Conventions Used in This Document ...............................5
2.1. Terminology ................................................5
2.2. Abbreviations ..............................................6
3. Using the UDP Checksum Complement in NTP ........................6
3.1. Overview ...................................................6
3.2. Checksum Complement in NTP Packets .........................7
3.2.1. Using the Checksum Complement .......................7
3.2.2. Transmission of NTP with Checksum Complement ........8
3.2.3. Updates of NTP with Checksum Complement .............8
3.2.4. Reception of NTP with Checksum Complement ...........8
3.3. Interoperability with Existing Implementations .............9
3.4. The Checksum Complement and Authentication .................9
4. Security Considerations ........................................10
5. IANA Considerations ............................................10
6. References .....................................................11
6.1. Normative References ......................................11
6.2. Informative References ....................................11
Appendix A. Checksum Complement Usage Example .....................13
Acknowledgments ...................................................14
Author's Address ..................................................14
Mizrahi Experimental [Page 2]
RFC 7821 NTP Checksum Complement March 2016
1. Introduction
The Network Time Protocol [NTPv4] allows clients to synchronize their
clocks to a time server by exchanging NTP packets. The increasing
demand for highly accurate clock synchronization motivates
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