UDP Checksum Complement in the Network Time Protocol (NTP)
draft-ietf-ntp-checksum-trailer-04

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Document Type Active Internet-Draft (ntp WG)
Last updated 2016-03-01 (latest revision 2016-02-15)
Replaces draft-mizrahi-ntp-checksum-trailer
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Intended RFC status Experimental
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NTP Working Group                                             T. Mizrahi
Internet Draft                                                   Marvell
Intended status: Experimental
Expires: August 2016                                   February 15, 2016

        UDP Checksum Complement in the Network Time Protocol (NTP)
                  draft-ietf-ntp-checksum-trailer-04.txt

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 Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on August 15, 2016.

Mizrahi, T.            Expires August 15, 2016                 [Page 1]
Internet-Draft         NTP Checksum Complement            February 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
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   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...................................................2
      1.1. Intermediate Entities.....................................3
      1.2. Updating the UDP Checksum.................................5
   2. Conventions used in this document..............................6
      2.1. Terminology...............................................6
      2.2. Abbreviations.............................................6
   3. Using UDP Checksum Complements in NTP..........................6
      3.1. Overview..................................................6
      3.2. Checksum Complement in NTP Packets........................7
         3.2.1. Transmission of NTP with Checksum Complement.........8
         3.2.2. Intermediate Updates of NTP with Checksum Complement.9
         3.2.3. Reception of NTP with Checksum Complement............9
      3.3. Interoperability with Existing Implementations............9
      3.4. The Checksum Complement and Authentication................9
   4. Security Considerations........................................9
   5. IANA Considerations...........................................10
   6. Acknowledgments...............................................10
   7. References....................................................10
      7.1. Normative References.....................................10
      7.2. Informative References...................................11
   Appendix A. Checksum Complement Usage Example....................11

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
   implementations that provide accurate timestamping.

Mizrahi, T.            Expires August 15, 2016                 [Page 2]
Internet-Draft         NTP Checksum Complement            February 2016

1.1. Intermediate Entities

   In this document we use the term 'intermediate entity', referring to
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