RTP Control Protocol (RTCP) Extended Report (XR) for Post-Repair Loss Count Metrics
RFC 7509
| Document | Type | RFC - Proposed Standard (May 2015; No errata) | |
|---|---|---|---|
| Authors | Rachel Huang , Varun Singh | ||
| Last updated | 2015-10-14 | ||
| Stream | IETF | ||
| Formats | plain text html pdf htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Dan Romascanu | ||
| Shepherd write-up | Show (last changed 2014-12-02) | ||
| IESG | IESG state | RFC 7509 (Proposed Standard) | |
| Action Holders |
(None)
|
||
| Consensus Boilerplate | Yes | ||
| Telechat date | |||
| Responsible AD | Alissa Cooper | ||
| Send notices to | (None) | ||
| IANA | IANA review state | Version Changed - Review Needed | |
| IANA action state | RFC-Ed-Ack | ||
Internet Engineering Task Force (IETF) R. Huang
Request for Comments: 7509 Huawei
Category: Standards Track V. Singh
ISSN: 2070-1721 Aalto University
May 2015
RTP Control Protocol (RTCP) Extended Report (XR)
for Post-Repair Loss Count Metrics
Abstract
This document defines an RTP Control Protocol (RTCP) Extended Report
(XR) block that allows reporting of a post-repair loss count metric
for a range of RTP applications. In addition, another metric,
repaired loss count, is also introduced in this report block for
calculating the pre-repair loss count when needed, so that the RTP
sender or a third-party entity is able to evaluate the effectiveness
of the repair methods used by the system.
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 5741.
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/rfc7509.
Copyright Notice
Copyright (c) 2015 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
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described in the Simplified BSD License.
Singh & Huang Standards Track [Page 1]
RFC 7509 Post-Repair Non-RLE Loss Count May 2015
Table of Contents
1. Introduction ....................................................2
2. Terminology .....................................................3
3. Post-Repair Loss Count Metrics Report Block .....................3
3.1. Report Block Structure .....................................4
3.2. Example Usage ..............................................5
4. SDP Signaling ...................................................6
4.1. SDP rtcp-xr-attrib Attribute Extension .....................6
4.2. Offer/Answer Usage .........................................7
5. Security Considerations .........................................7
6. IANA Considerations .............................................7
6.1. New RTCP XR Block Type Value ...............................7
6.2. New RTCP XR SDP Parameter ..................................7
6.3. Contact Information for Registrations ......................7
7. References ......................................................8
7.1. Normative References .......................................8
7.2. Informative References .....................................9
Appendix A. Metrics Represented Using the Template from RFC 6390 ..10
Acknowledgments ...................................................11
Authors' Addresses ................................................11
1. Introduction
RTCP Sender Reports (SRs) / Receiver Reports (RRs) [RFC3550] contain
some rough statistics about the data received from the particular
source indicated in that block. One of them is the cumulative number
of packets lost, which is called the pre-repair loss metric in this
document. This metric conveys information regarding the total number
of RTP data packets that have been lost since the beginning of the
RTP session.
However, this metric is measured on the media stream before any loss-
repair mechanism, e.g., retransmission [RFC4588] or Forward Error
Correction (FEC) [RFC5109], is applied. Using a repair mechanism
usually results in recovering some or all of the lost packets. The
recovery process does not reduce the values reported by the two loss
metrics in RTCP RR [RFC3550] -- namely, the fraction lost and the
cumulative loss. Hence, the sending endpoint cannot infer the
performance of the repair mechanism based on the aforementioned
metrics in [RFC3550].
Consequently, [RFC5725] specifies a post-repair loss Run-Length
Encoding (RLE) XR report block to address this issue. The sending
endpoint is able to infer which packets were repaired from the RLE
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