RTP Clock Source Signalling
draft-ietf-avtcore-clksrc-05

The information below is for an old version of the document
Document Type Active Internet-Draft (avtcore WG)
Last updated 2013-07-14
Replaces draft-williams-avtcore-clksrc
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Audio/Video Transport Core                                   A. Williams
Maintenance                                                     Audinate
Internet-Draft                                                  K. Gross
Intended status: Standards Track                            AVA Networks
Expires: January 15, 2014                             R. van Brandenburg
                                                             H. Stokking
                                                                     TNO
                                                           July 14, 2013

                      RTP Clock Source Signalling
                      draft-ietf-avtcore-clksrc-05

Abstract

   NTP format timestamps are used by several RTP protocols for
   synchronisation and statistical measurements.  This memo specifies
   SDP signalling identifying timestamp reference clock sources and SDP
   signalling identifying the media clock sources in a multimedia
   session.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

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
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   This Internet-Draft will expire on January 15, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Williams, et al.        Expires January 15, 2014                [Page 1]
Internet-Draft         RTP Clock Source Signalling             July 2013

   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
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   described in the Simplified BSD License.

Williams, et al.        Expires January 15, 2014                [Page 2]
Internet-Draft         RTP Clock Source Signalling             July 2013

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Applications . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   4.  Timestamp Reference Clock Source Signalling  . . . . . . . . .  6
     4.1.  Clock synchronization  . . . . . . . . . . . . . . . . . .  6
     4.2.  Identifying NTP Reference Clocks . . . . . . . . . . . . .  7
     4.3.  Identifying PTP Reference Clocks . . . . . . . . . . . . .  7
     4.4.  Identifying Global Reference Clocks  . . . . . . . . . . .  9
     4.5.  Private Reference Clocks . . . . . . . . . . . . . . . . .  9
     4.6.  Local Reference Clocks . . . . . . . . . . . . . . . . . .  9
     4.7.  Traceable Reference Clocks . . . . . . . . . . . . . . . .  9
     4.8.  SDP Signalling of Timestamp Reference Clock Source . . . .  9
       4.8.1.  Examples . . . . . . . . . . . . . . . . . . . . . . . 12
   5.  Media Clock Source Signalling  . . . . . . . . . . . . . . . . 13
     5.1.  Asynchronously Generated Media Clock . . . . . . . . . . . 13
     5.2.  Direct-Referenced Media Clock  . . . . . . . . . . . . . . 14
     5.3.  Stream-Referenced Media Clock  . . . . . . . . . . . . . . 14
     5.4.  SDP Signalling of Media Clock Source . . . . . . . . . . . 15
     5.5.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . 17
   6.  Signalling Considerations  . . . . . . . . . . . . . . . . . . 19
     6.1.  Usage in Offer/Answer  . . . . . . . . . . . . . . . . . . 19
       6.1.1.  Indicating Support for Clock Source Signalling . . . . 20
       6.1.2.  Timestamp Reference Clock  . . . . . . . . . . . . . . 20
       6.1.3.  Media Clock  . . . . . . . . . . . . . . . . . . . . . 20
     6.2.  Usage Outside of Offer/Answer  . . . . . . . . . . . . . . 21
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 21
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 21
     8.1.  Reference Clock SDP Parameter  . . . . . . . . . . . . . . 22
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