Support of the IEEE 1588 Timestamp Format in a Two-Way Active Measurement Protocol (TWAMP)
RFC 8186

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Internet Engineering Task Force (IETF)                         G. Mirsky
Request for Comments: 8186                                     ZTE Corp.
Category: Standards Track                                      I. Meilik
ISSN: 2070-1721                                                 Broadcom
                                                               June 2017

             Support of the IEEE 1588 Timestamp Format in a
              Two-Way Active Measurement Protocol (TWAMP)

Abstract

   This document describes an OPTIONAL feature for active performance
   measurement protocols that allows use of the Precision Time Protocol
   timestamp format defined in IEEE 1588v2, as an alternative to the
   Network Time Protocol that is currently used.

Status of This Memo

   This is an Internet Standards Track document.

   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).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   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/rfc8186.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   described in the Simplified BSD License.

Mirsky & Meilik              Standards Track                    [Page 1]
RFC 8186             1588 Timestamp Format in TWAMP            June 2017

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions Used in This Document . . . . . . . . . . . .   3
       1.1.1.  Terminology . . . . . . . . . . . . . . . . . . . . .   3
       1.1.2.  Requirements Language . . . . . . . . . . . . . . . .   3
   2.  OWAMP and TWAMP Extensions  . . . . . . . . . . . . . . . . .   3
     2.1.  Timestamp Format Negotiation in OWAMP Connection Setup  .   4
     2.2.  Timestamp Format Negotiation in TWAMP Connection Setup  .   5
     2.3.  OWAMP-Test and TWAMP-Test Updates . . . . . . . . . . . .   5
       2.3.1.  Consideration for TWAMP Light Mode  . . . . . . . . .   6
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   5.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   The One-Way Active Measurement Protocol (OWAMP) [RFC4656] defines
   that only the NTP format [RFC5905] of a timestamp can be used in the
   OWAMP-Test protocol.  The Two-Way Active Measurement Protocol (TWAMP)
   [RFC5357] adopted the OWAMP-Test packet format and extended it by
   adding a format for a reflected test packet.  Both the sender's and
   reflector's packets timestamps are expected to follow the 64-bit-long
   NTP format [RFC5905].  NTP, when used over the Internet, typically
   achieves clock accuracy within 5 ms to 100 ms.  Surveys conducted
   recently suggest that 90% of devices achieve accuracy better than 100
   ms and 99% of devices achieve accuracy better than 1 sec.  It should
   be noted that NTP synchronizes clocks on the control plane, not on
   data plane.  Distribution of clock within a node may be supported by
   an independent NTP domain or via interprocess communication in a
   multiprocessor distributed system.  Any of the mentioned solutions
   will be subject to additional queuing delays that negatively affect
   data-plane clock accuracy.

   The Precision Time Protocol (PTP) [IEEE.1588] has gained wide support
   since the development of OWAMP and TWAMP.  PTP, using on-path support
   and other mechanisms, allows sub-microsecond clock accuracy.  PTP is
   now supported in multiple implementations of fast-forwarding engines;
   thus, accuracy achieved by PTP is the accuracy of the clock in the
   data plane.  Having an option to use a more accurate clock as a
   source of timestamps for IP performance measurements is one of the
   advantages of this specification.  Another advantage is realized by
   simplification of hardware in the data plane.  To support OWAMP or
   TWAMP, test protocol timestamps must be converted from PTP to NTP.