Audio/Video Transport Working Group R. Brandenburg Internet-Draft TNO Intended status: Standards Track K. Gross Expires: January 4, 2013 AVA Networks Q. Wu Huawei F. Boronat M. Montagud UPVLC July 3, 2012 RTCP XR Report Block for One Way Delay metric Reporting draft-wu-xrblock-rtcp-xr-one-way-delay-01.txt Abstract This document defines an RTCP XR Report Block that allows the reporting of One Way Delay metrics for use in a range of RTP applications. 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 January 4, 2013. Copyright Notice Copyright (c) 2012 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 Brandenburg, et al. Expires January 4, 2013 [Page 1] Internet-Draft One Way Delay July 2012 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. Packet One Way Delay Metrics Block . . . . . . . . . . . . 3 1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . . 3 1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3 1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 4 3. One Way Delay Block . . . . . . . . . . . . . . . . . . . . . 5 3.1. Report Block Structure . . . . . . . . . . . . . . . . . . 5 3.2. Definition of Fields in One Way Delay Metrics Report Block . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Clock synchronization for one way delay metrics . . . . . . . 7 5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 8 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6.1. New RTCP XR Block Type value . . . . . . . . . . . . . . . 9 6.2. New RTCP XR SDP Parameter . . . . . . . . . . . . . . . . 9 6.3. Contact information for registrations . . . . . . . . . . 9 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 8.1. Normative References . . . . . . . . . . . . . . . . . . . 11 8.2. Informative References . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 Brandenburg, et al. Expires January 4, 2013 [Page 2] Internet-Draft One Way Delay July 2012 1. Introduction 1.1. Packet One Way Delay Metrics Block [I-D.ietf-xrblock-rtcp-xr-delay] defines the new block type supporting the reporting of the mean, minimum and maximum values of the network round-trip delay between media source(source) and media receiver(destination). However none of these metrics allow a receiver to report one way delay from source to destination or the other way around. As described in [RFC2679], the path from a source to a destination may be different than the path from the destination back to the source. Even when the two paths are symmetric, they may have radically different performance characteristics. Therefore the measurement of one-way delay can not be roughly estimated by the round-trip delay for many applications in the asymmetric network or symmetric network. This draft defines a new block type to augment those defined in [RFC3611] for use in a range of RTP applications. The new block type supports the reporting of the mean, minimum, maximum values of one way delay between RTP interfaces in peer RTP end systems, as measured, for example, using the method described in [RFC2679]. This metrics belong to the class of transport metrics defined in [MONARCH] (work in progress). 1.2. RTCP and RTCP XR Reports The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] defined an extensible structure for reporting using an RTCP Extended Report (XR). This draft defines a new Extended Report block. The use of Extended Report blocks is defined by [RFC3611]. 1.3. Performance Metrics Framework The Performance Metrics Framework [RFC6390] provides guidance on the definition and specification of performance metrics. The RTP Monitoring Architectures [MONARCH] provides guideline for reporting block format using RTCP XR. The Metrics Block described in this document are in accordance with the guidelines in [RFC6390] and [MONARCH]. 1.4. Applicability These metrics are applicable to a range of delay-sensitive RTP applications in which this report block would be useful, such as some IDMS use cases (e.g., video wall, network games, networked loudspeakers, etc., see Draft IDMS [IDMS]). Brandenburg, et al. Expires January 4, 2013 [Page 3] Internet-Draft One Way Delay July 2012 2. Terminology 2.1. Standards 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]. Brandenburg, et al. Expires January 4, 2013 [Page 4] Internet-Draft One Way Delay July 2012 3. One Way Delay Block Metrics in this block report on one way packet delay in the stream arriving at the RTP system. 3.1. Report Block Structure One Way Delay metrics block 0 1 2 3 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BT=OWD | I | resv. | block length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SSRC of Source | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | One-way-Delay-Median | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Max-One-way-Delay | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Min-One-way-Delay | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Report Block Structure 3.2. Definition of Fields in One Way Delay Metrics Report Block Block type (BT): 8 bits A One way Delay Report Block is identified by the constant OWD. [Note to RFC Editor: please replace OWD with the IANA provided RTCP XR block type for this block.] Interval Metric flag (I): 2 bit This field is used to indicate whether the One Way Metrics are Sampled, Interval or Cumulative metrics [MONARCH], that is, whether the reported values applies to the most recent measurement interval duration between successive metrics reports (I=10) (the Interval Duration), to the accumulation period characteristic of cumulative measurements (I=11) (the Cumulative Duration) or is a sampled instantaneous value (I=01). Brandenburg, et al. Expires January 4, 2013 [Page 5] Internet-Draft One Way Delay July 2012 Reserved (resv): 6 bits These bits are reserved. They SHOULD be set to zero by senders and MUST be ignored by receivers. block length: 16 bits The length of this report block in 32-bit words, minus one. For the Delay block, the block length is equal to 4. SSRC of source: 32 bits The SSRC of the media source shall be set to the value of the SSRC identifier carried in the RTP header [RFC3550] of the RTP packet to which the XR relates. One-way-Delay-Median: 32 bits The Mean One way Delay is the mean value of the RTP-to- RTP interface one way delay in units of 1/65536 seconds over the measurement period, typically determined using RTCP SR/RR. This value is calculated according to section 3.6 of [RFC2679]. Max-One-way-Delay: 32 bits The Max One Way Delay is the maximum value of the RTP- to-RTP interface one way delay in units of 1/65536 seconds over the measurement period, typically determined using RTCP SR/RR. This value is calculated according to section 3.6 of [RFC2679]. Min-One-way-Delay: 32 bits The Max One Way Delay is the minimum value of the RTP- to-RTP interface one way delay in units of 1/65536 seconds over the measurement period, typically determined using RTCP SR/RR. This value is calculated according to section 3.6 of [RFC2679]. Brandenburg, et al. Expires January 4, 2013 [Page 6] Internet-Draft One Way Delay July 2012 4. Clock synchronization for one way delay metrics This subsection provides informative guidance on use of methodology for one way delay metrics measurement. As specified in the methodology of [RFC2679], it is important for media source (Src) and media receiver (Dst) to synchronize very closely since one way delay values will often be as low as the 100 usec to 10 msec range. In order to arrange Src and Des synchronized before measurement method is applied, a participant at the Dst can indicate which synchronization source is being used at the moment. A participant can also indicate any other synchronization sources available to it. This allows multiple participants in an RTP session to use the same or a similar clock synchronization source for their session. Brandenburg, et al. Expires January 4, 2013 [Page 7] Internet-Draft One Way Delay July 2012 5. SDP Signaling [RFC3611] defines the use of SDP (Session Description Protocol) [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used without prior signaling. This section augments the SDP [RFC4566] attribute "rtcp-xr" defined in [RFC3611] by providing an additional value of "xr-format" to signal the use of the report block defined in this document. rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)] CRLF (defined in [RFC3611]) xr-format =/ xr-one-way-delay-block xr-one-way-delay-block ="one way delay" Brandenburg, et al. Expires January 4, 2013 [Page 8] Internet-Draft One Way Delay July 2012 6. IANA Considerations New block types for RTCP XR are subject to IANA registration. For general guidelines on IANA considerations for RTCP XR, refer to [RFC3611]. 6.1. New RTCP XR Block Type value This document assigns the block type value OWD in the IANA "RTCP XR Block Type Registry" to the "One Way Delay Metrics Block". [Note to RFC Editor: please replace OWD with the IANA provided RTCP XR block type for this block.] 6.2. New RTCP XR SDP Parameter This document also registers a new parameter "one way delay" in the "RTCP XR SDP Parameters Registry". 6.3. Contact information for registrations The contact information for the registrations is: Qin Wu (sunseawq@huawei.com) 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China Brandenburg, et al. Expires January 4, 2013 [Page 9] Internet-Draft One Way Delay July 2012 7. Security Considerations It is believed that this proposed RTCP XR report block introduces no new security considerations beyond those described in [RFC3611]. This block does not provide per-packet statistics so the risk to confidentiality documented in Section 7, paragraph 3 of [RFC3611] does not apply. Brandenburg, et al. Expires January 4, 2013 [Page 10] Internet-Draft One Way Delay July 2012 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", March 1997. [RFC2679] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way Delay Metric for IPPM", RFC 2679, September 1999. [RFC3550] Schulzrinne, H., "RTP: A Transport Protocol for Real-Time Applications", RFC 3550, July 2003. [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control Protocol Extended Reports (RTCP XR)", November 2003. [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session Description Protocol", July 2006. 8.2. Informative References [I-D.ietf-xrblock-rtcp-xr-delay] Hunt, G., Clark, A., Gross, K., and Q. Wu, "RTCP XR Report Block for Delay metric Reporting", ID draft-ietf-xrblock-rtcp-xr-delay-06, May 2012. [IDMS] Brandenburg, R., Stokking, H., and M. Deventer, "RTCP for inter-destination media synchronization", ID draft-ietf-avtcore-idms-05, June 2012. [MONARCH] Hunt, G., "Monitoring Architectures for RTP", ID draft-ietf-avtcore-monarch-17, June 2012. [RFC6390] Clark, A. and B. Claise, "Framework for Performance Metric Development", RFC 6390, October 2011. Brandenburg, et al. Expires January 4, 2013 [Page 11] Internet-Draft One Way Delay July 2012 Authors' Addresses R.van Brandenburg TNO Email: ray.vanbrandenburg@tno.nl Kevin Gross AVA Networks Email: kevin.gross@avanw.com Qin Wu Huawei 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China Email: sunseawq@huawei.com F.Boronat UPVLC Email: fboronat@dcom.upv.es M. Montagud UPVLC Email: mamontor@posgrado.upv.es Brandenburg, et al. Expires January 4, 2013 [Page 12]