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RTP Clock Source Signalling
draft-ietf-avtcore-clksrc-11

Document type: Active Internet-Draft (avtcore WG)
Document stream: IETF
Last updated: 2014-04-12 (latest revision 2014-03-24)
Intended RFC status: Proposed Standard
Other versions: plain text, xml, pdf, html

IETF State: Submitted to IESG for Publication Oct 2013
Consensus: Unknown
Document shepherd: Roni Even
Shepherd Write-Up: Last changed 2013-12-06

IESG State: RFC Ed Queue
IANA Action State: RFC-Ed-Ack
RFC Editor State: EDIT
Responsible AD: Alissa Cooper
Send notices to: avtcore-chairs@tools.ietf.org, draft-ietf-avtcore-clksrc@tools.ietf.org

Audio/Video Transport Core                                   A. Williams
Maintenance                                                     Audinate
Internet-Draft                                                  K. Gross
Intended status: Standards Track                            AVA Networks
Expires: September 26, 2014                           R. van Brandenburg
                                                             H. Stokking
                                                                     TNO
                                                          March 25, 2014

                      RTP Clock Source Signalling
                      draft-ietf-avtcore-clksrc-11

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://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 September 26, 2014.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Williams, et al.       Expires September 26, 2014               [Page 1]
Internet-Draft         RTP Clock Source Signalling            March 2014

   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.

Williams, et al.       Expires September 26, 2014               [Page 2]
Internet-Draft         RTP Clock Source Signalling            March 2014

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 . . . . 10
       4.8.1.  Examples . . . . . . . . . . . . . . . . . . . . . . . 12
   5.  Media Clock Source Signalling  . . . . . . . . . . . . . . . . 13
     5.1.  Asynchronously Generated Media Clock . . . . . . . . . . . 13
     5.2.  Direct-Referenced Media Clock  . . . . . . . . . . . . . . 13
     5.3.  Stream-Referenced Media Clock  . . . . . . . . . . . . . . 15
     5.4.  SDP Signalling of Media Clock Source . . . . . . . . . . . 16
     5.5.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . 18
   6.  Signalling Considerations  . . . . . . . . . . . . . . . . . . 20
     6.1.  Usage in Offer/Answer  . . . . . . . . . . . . . . . . . . 20
       6.1.1.  Indicating Support for Clock Source Signalling . . . . 21
       6.1.2.  Timestamp Reference Clock  . . . . . . . . . . . . . . 21
       6.1.3.  Media Clock  . . . . . . . . . . . . . . . . . . . . . 21

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