Internet Engineering Task Force (IETF) A. Clark
Request for Comments: 6958 Telchemy
Category: Standards Track S. Zhang
ISSN: 2070-1721 J. Zhao
STTRI
Q. Wu, Ed.
Huawei
May 2013
Internet Engineering Task Force (IETF) A. Clark
Request for Comments: 6958 Telchemy
Category: Standards Track S. Zhang
ISSN: 2070-1721 J. Zhao
STTRI
Q. Wu, Ed.
Huawei
May 2013
RTP Control Protocol (RTCP) Extended Report (XR) Block for Burst/Gap Loss Metric Reporting
用于突发/间隙损失度量报告的RTP控制协议（RTCP）扩展报告（XR）块
Abstract
摘要
This document defines an RTP Control Protocol (RTCP) Extended Report (XR) Block that allows the reporting of burst and gap loss metrics for use in a range of RTP applications.
本文档定义了一个RTP控制协议（RTCP）扩展报告（XR）块，该块允许报告在一系列RTP应用程序中使用的突发和间隙损失指标。
Status of This Memo
关于下段备忘
This is an Internet Standards Track document.
这是一份互联网标准跟踪文件。
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.
本文件是互联网工程任务组（IETF）的产品。它代表了IETF社区的共识。它已经接受了公众审查，并已被互联网工程指导小组（IESG）批准出版。有关互联网标准的更多信息，请参见RFC 5741第2节。
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/rfc6958.
有关本文件当前状态、任何勘误表以及如何提供反馈的信息，请访问http://www.rfc-editor.org/info/rfc6958.
Copyright Notice
版权公告
Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2013 IETF信托基金和确定为文件作者的人员。版权所有。
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.
本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(http://trustee.ietf.org/license-info)自本文件出版之日起生效。请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本，并提供简化BSD许可证中所述的无担保。
Table of Contents
目录
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Burst/Gap Loss Metrics Block . . . . . . . . . . . . . . 2
1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . 3
1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3
1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Burst/Gap Loss Metrics Block . . . . . . . . . . . . . . . . 4
3.1. Report Block Structure . . . . . . . . . . . . . . . . . 5
3.2. Definition of Fields in Burst/Gap Loss Metrics Block . . 5
3.3. Derived Metrics Based on Reported Metrics . . . . . . . . 7
4. Considerations for Voice-over-IP Applications . . . . . . . . 8
5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . 9
5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . 9
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 . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 10
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
10.1. Normative References . . . . . . . . . . . . . . . . . . 11
10.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. Metrics Represented Using the Template from RFC 6390 13
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Burst/Gap Loss Metrics Block . . . . . . . . . . . . . . 2
1.2. RTCP and RTCP XR Reports . . . . . . . . . . . . . . . . 3
1.3. Performance Metrics Framework . . . . . . . . . . . . . . 3
1.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Burst/Gap Loss Metrics Block . . . . . . . . . . . . . . . . 4
3.1. Report Block Structure . . . . . . . . . . . . . . . . . 5
3.2. Definition of Fields in Burst/Gap Loss Metrics Block . . 5
3.3. Derived Metrics Based on Reported Metrics . . . . . . . . 7
4. Considerations for Voice-over-IP Applications . . . . . . . . 8
5. SDP Signaling . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1. SDP rtcp-xr-attrib Attribute Extension . . . . . . . . . 9
5.2. Offer/Answer Usage . . . . . . . . . . . . . . . . . . . 9
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 . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 10
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
10.1. Normative References . . . . . . . . . . . . . . . . . . 11
10.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. Metrics Represented Using the Template from RFC 6390 13
This document 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 proportion of packets lost by the network. The losses during loss bursts are reported, together with the number of bursts and additional data, allowing the calculation of statistical parameters (mean and variance) of the distribution of burst lengths. Some uses of these metrics depend on the availability of the metric "cumulative number of packets lost" from RTCP [RFC3550].
本文件定义了一种新的块类型，以扩充[RFC3611]中定义的块类型，以便在一系列RTP应用中使用。新的块类型支持报告网络丢失的数据包比例。报告损失突发期间的损失，以及突发次数和其他数据，从而计算突发长度分布的统计参数（平均值和方差）。这些指标的某些用途取决于RTCP[RFC3550]中“累计丢失数据包数”指标的可用性。
This block provides information on transient IP problems. Burst/gap metrics are typically used in Cumulative reports; however, they also may be used in Interval reports. The burstiness of packet loss affects user experience, may influence any sender strategies to mitigate the problem, and may also have diagnostic value.
此块提供有关瞬时IP问题的信息。突发/间隙指标通常用于累积报告中；但是，它们也可用于间隔报告中。数据包丢失的突发性会影响用户体验，可能会影响任何发送方缓解问题的策略，还可能具有诊断价值。
The metric belongs to the class of transport-related end system metrics defined in [RFC6792].
该指标属于[RFC6792]中定义的与传输相关的终端系统指标类别。
The definitions of "burst", "gap", "loss", and "discard" are consistent with definitions in [RFC3611]. To accommodate the range of jitter buffer algorithms and packet discard logic that may be used by implementors, the method used to distinguish between bursts and gaps may be an equivalent method to that defined in [RFC3611]. The method used should produce the same result as that defined in [RFC3611] for conditions of burst packet loss but may produce different results for conditions of time-varying jitter.
“突发”、“间隙”、“丢失”和“丢弃”的定义与[RFC3611]中的定义一致。为了适应实施者可能使用的抖动缓冲算法和数据包丢弃逻辑的范围，用于区分突发和间隙的方法可以是[RFC3611]中定义的等效方法。所使用的方法应产生与[RFC3611]中定义的突发数据包丢失条件相同的结果，但在时变抖动条件下可能产生不同的结果。
The use of RTCP for reporting is defined in [RFC3550]. [RFC3611] defines an extensible structure for reporting by using an RTCP Extended Report (XR). This document defines a new Extended Report block for use with [RFC3550] and [RFC3611].
[RFC3550]中定义了使用RTCP进行报告。[RFC3611]通过使用RTCP扩展报告（XR）定义报告的可扩展结构。本文档定义了一个新的扩展报告块，用于[RFC3550]和[RFC3611]。
The Performance Metrics Framework [RFC6390] provides guidance on the definition and specification of performance metrics. The "Guidelines for Use of the RTP Monitoring Framework" [RFC6792] provides guidelines for reporting block format using RTCP XR. The Metrics Block described in this document is in accordance with the guidelines in [RFC6390] and [RFC6792].
性能指标框架[RFC6390]提供了有关性能指标定义和规范的指导。“RTP监控框架使用指南”[RFC6792]提供了使用RTCP XR报告块格式的指南。本文件中描述的度量块符合[RFC6390]和[RFC6792]中的指南。
These metrics are applicable to a range of RTP applications that contain jitter buffers and don't use stream repair means, e.g., Forward Error Correction (FEC) [RFC5109] and/or retransmission [RFC4588].
这些指标适用于包含抖动缓冲器且不使用流修复手段的一系列RTP应用，例如前向纠错（FEC）[RFC5109]和/或重传[RFC4588]。
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].
本文件中的关键词“必须”、“不得”、“要求”、“应”、“不应”、“应”、“不应”、“建议”、“可”和“可选”应按照RFC 2119[RFC2119]中所述进行解释。
In addition, the following terms are defined:
此外，定义了以下术语：
Received, Lost, and Discarded
接收、丢失和丢弃
A packet shall be regarded as lost if it fails to arrive within an implementation-specific time window. A packet that arrives within this time window but is too early or late to be played out or thrown away before playout due to packet duplication or redundancy shall be regarded as discarded. A packet shall be classified as one of received (or OK), discarded, or lost. The metric "cumulative number of packets lost" defined in [RFC3550] reports a count of packets lost from the media stream (single Synchronization Source (SSRC) within a single RTP session). Similarly, the metric "number of packets discarded" defined in [DISCARD] reports a count of packets discarded from the media stream (single SSRC within single RTP session) arriving at the receiver. The post-repair Loss RLE metric, which is defined in [RFC5725], can be used to report the number of packets that are not recovered by any repair techniques that are in use.
如果数据包未能在特定于实现的时间窗口内到达，则该数据包应视为丢失。在该时间窗口内到达，但由于数据包重复或冗余而过早或延迟播放或在播放前丢弃的数据包应视为丢弃。数据包应分类为接收（或正常）、丢弃或丢失。[RFC3550]中定义的度量“累计丢失的数据包数”报告从媒体流（单个RTP会话中的单个同步源（SSRC））丢失的数据包计数。类似地，在[DISCARD]中定义的度量“丢弃的分组数”报告从到达接收器的媒体流（单个RTP会话中的单个SSRC）丢弃的分组的计数。[RFC5725]中定义的修复后丢失RLE度量可用于报告未通过使用的任何修复技术恢复的数据包数量。
Bursts and Gaps
爆发和缺口
The terms "burst" and "gap" are used in a manner consistent with that of RTCP XR [RFC3611]. RTCP XR views an RTP stream as being divided into bursts, which are periods when the loss rate is high enough to cause noticeable quality degradation (generally over 5 percent loss rate) and gaps, which are periods when lost packets are infrequent and hence quality is generally acceptable.
术语“突发”和“间隙”的使用方式与RTCP XR[RFC3611]一致。RTCP XR将RTP流视为分为突发，突发是指丢失率高到足以导致明显质量下降（通常超过5%的丢失率）的时段，而间隙是指丢失数据包不频繁的时段，因此质量通常是可接受的。
Metrics in this block report on burst/gap loss in the stream arriving at the RTP system. The measurement of these metrics is made at the receiving end of the RTP stream. Each instance of this Metrics Block refers by SSRC to a separate auxiliary Measurement Information Block [RFC6776], which describes the measurement periods in use (see RFC 6776, Section 4.2).
此块中的指标报告到达RTP系统的流中的突发/间隙损失。这些度量的测量在RTP流的接收端进行。SSRC将该度量块的每个实例引用到一个单独的辅助度量信息块[RFC6776]，该信息块描述了使用中的度量周期（参见RFC 6776，第4.2节）。
This Metrics Block relies on the measurement period in the Measurement Information Block indicating the span of the report. Senders MUST send this block in the same compound RTCP packet as the Measurement Information Block. Receivers MUST verify that the measurement period is received in the same compound RTCP packet as this Metrics Block. If not, this Metrics Block MUST be discarded.
此度量块依赖于度量信息块中指示报告范围的度量周期。发送方必须在与测量信息块相同的复合RTCP数据包中发送此数据块。接收器必须验证测量周期是否在与此度量块相同的复合RTCP数据包中接收。如果不是，则必须放弃此度量块。
The structure of the Burst/Gap Loss Metrics Block is as follows.
突发/间隔丢失度量块的结构如下所示。
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=20 | I |C| resv. | Block Length = 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -+-+-+-+-+-+-+-+
| Threshold | Sum of Burst Durations (ms) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packets Lost in Bursts | Total... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ...Packets Expected in Bursts | Number of Bursts | Sum of|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ...Squares of Burst Durations (ms-squared) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=20 | I |C| resv. | Block Length = 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of Source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -+-+-+-+-+-+-+-+
| Threshold | Sum of Burst Durations (ms) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packets Lost in Bursts | Total... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ...Packets Expected in Bursts | Number of Bursts | Sum of|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ...Squares of Burst Durations (ms-squared) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Report Block Structure
图1：报告块结构
Block Type (BT): 8 bits
块类型（BT）：8位
A Burst/Gap Loss Metrics Block is identified by the constant 20.
突发/间隙丢失度量块由常数20标识。
Interval Metric flag (I): 2 bits
间隔度量标志（I）：2位
This field is used to indicate whether the burst/gap loss metrics are Sampled, Interval, or Cumulative metrics:
此字段用于指示突发/间隔损失度量是采样、间隔还是累积度量：
I=10: Interval Duration - the reported value applies to the most recent measurement interval duration between successive metrics reports.
I=10：间隔持续时间-报告值适用于连续度量报告之间的最新度量间隔持续时间。
I=11: Cumulative Duration - the reported value applies to the accumulation period characteristic of cumulative measurements.
I=11：累积持续时间-报告值适用于累积测量的累积周期特征。
I=01: Sampled Value - the reported value is a sampled instantaneous value.
I=01：采样值-报告值为采样瞬时值。
In this document, burst/gap loss metrics can only be measured over definite intervals and cannot be sampled. Also, the value I=00 is reserved for future use. Senders MUST NOT use the values I=00 or I=01. If a block is received with I=00 or I=01, the receiver MUST discard the block.
在本文件中，突发/间隙损失指标只能在确定的时间间隔内测量，不能取样。此外，值I=00保留供将来使用。发件人不得使用I=00或I=01的值。如果接收到I=00或I=01的块，接收器必须丢弃该块。
Loss and Discard Combination flag (C): 1 bit
丢失和丢弃组合标志（C）：1位
The 'C' flag is used to indicate whether the loss/discard report is combined with the burst/gap loss report in the same compound RTCP packet. The value is set to '1' if the loss/discard report and the burst gap loss report are combined. Otherwise, the value is set to '0'. If the 'C' flag is set to '1' but the burst/gap discard was not sent, the receiver MUST discard the burst/gap loss.
“C”标志用于指示丢失/丢弃报告是否与同一复合RTCP数据包中的突发/间隙丢失报告相结合。如果丢失/丢弃报告和突发间隔丢失报告合并，则该值设置为“1”。否则，该值将设置为“0”。如果“C”标志设置为“1”，但未发送突发/间隔丢弃，则接收器必须丢弃突发/间隔丢失。
Reserved (resv.): 5 bits
保留（resv.）：5位
These bits are reserved. They MUST be set to zero by senders and ignored by receivers (see [RFC6709], Section 4.2).
这些位是保留的。发送方必须将其设置为零，接收方必须忽略（见[RFC6709]，第4.2节）。
Block Length: 16 bits
块长度：16位
The length of this report block in 32-bit words, minus one. For the Burst/Gap Loss Metrics Block, the block length is equal to 5. The block MUST be discarded if the block length is set to a different value.
此报表块的长度（32位字）减去1。对于突发/间隙丢失度量块，块长度等于5。如果块长度设置为不同的值，则必须丢弃该块。
SSRC of Source: 32 bits
源的SSRC：32位
As defined in Section 4.1 of [RFC3611].
如[RFC3611]第4.1节所定义。
Threshold: 8 bits
阈值：8位
The Threshold is equivalent to Gmin in [RFC3611], i.e., the number of successive packets that must be received prior to and following a lost packet in order for this lost packet to be regarded as part of a gap. Note that the threshold is calculated in accordance with the Gmin Calculation defined in Section 4.7.2 of RFC 3611.
阈值相当于[RFC3611]中的Gmin，即必须在丢失的数据包之前和之后接收的连续数据包的数量，以便将该丢失的数据包视为间隙的一部分。注意，阈值是根据RFC 3611第4.7.2节中定义的Gmin计算得出的。
Sum of Burst Durations (ms): 24 bits
突发持续时间之和（毫秒）：24位
The total duration of bursts of lost packets in the period of the report (Interval or Cumulative).
报告期间丢失数据包突发的总持续时间（间隔或累积）。
The measured value is an unsigned value. If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE MUST be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFFFF MUST be reported.
测量值为无符号值。如果测量值超过0xFFFFFD，则必须报告值0xFFFFFE以指示超量程测量。如果测量不可用，则必须报告值0xFFFFFF。
Packets Lost in Bursts: 24 bits
突发丢失的数据包：24位
The total number of packets lost during loss bursts.
丢失突发期间丢失的数据包总数。
The measured value is an unsigned value. If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE MUST be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFFFF MUST be reported.
测量值为无符号值。如果测量值超过0xFFFFFD，则必须报告值0xFFFFFE以指示超量程测量。如果测量不可用，则必须报告值0xFFFFFF。
Total Packets Expected in Bursts: 24 bits
突发中预期的数据包总数：24位
The total number of packets expected during loss bursts (that is, the sum of received packets and lost packets).
丢失突发期间预期的数据包总数（即接收到的数据包和丢失的数据包之和）。
The measured value is an unsigned value. If the measured value exceeds 0xFFFFFD, the value 0xFFFFFE MUST be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFFFF MUST be reported.
测量值为无符号值。如果测量值超过0xFFFFFD，则必须报告值0xFFFFFE以指示超量程测量。如果测量不可用，则必须报告值0xFFFFFF。
Number of Bursts: 16 bits
突发数：16位
The number of bursts in the period of the report (Interval or Cumulative).
报告期间的突发次数（间隔或累积）。
The measured value is an unsigned value. If the measured value exceeds 0xFFFD, the value 0xFFFE MUST be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFF MUST be reported.
测量值为无符号值。如果测量值超过0xFFFD，则必须报告值0xFFFE以指示超量程测量。如果测量不可用，则必须报告值0xFFFF。
Sum of Squares of Burst Durations (ms-squared): 36 bits
突发持续时间的平方和（ms平方）：36位
The sum of the squares of burst durations (where individual burst durations are expressed in ms) in the period of the report (Interval or Cumulative). The units for this quantity are milliseconds-squared.
报告期间（间隔或累积）内突发持续时间的平方和（其中单个突发持续时间以ms表示）。此数量的单位为毫秒平方。
The measured value is an unsigned value. If the measured value exceeds 0xFFFFFFFFD, the value 0xFFFFFFFFE MUST be reported to indicate an over-range measurement. If the measurement is unavailable, the value 0xFFFFFFFFF MUST be reported.
测量值为无符号值。如果测量值超过0xFFFFFFD，则必须报告值0xFFFFFFFFFFE以指示超出范围测量。如果测量不可用，则必须报告值0xFFFFFFFFFFF。
The metrics described here are intended to be used as described in this section, in conjunction with information from the Measurement Information Block [RFC6776] and also with the metric "cumulative number of packets lost" provided in standard RTCP [RFC3550].
此处描述的指标拟与本节所述的指标一起使用，与来自测量信息块[RFC6776]的信息以及标准RTCP[RFC3550]中提供的指标“累计丢失数据包数”一起使用。
These metrics provide information relevant to statistical parameters, including:
这些指标提供与统计参数相关的信息，包括：
o the fraction of packets lost during bursts (i.e., Burst Loss Rate in [SUMSTAT]), which can be calculated using the metric "Packets Loss in Bursts" and the metric "Total Packets Expected in Bursts" provided in the Burst/Gap Loss Metrics Block.
o 突发期间丢失的数据包分数（即，[SUMSTAT]中的突发丢失率），可使用突发/间隙丢失度量块中提供的度量“突发中的数据包丢失”和度量“突发中预期的数据包总数”来计算。
o the fraction of packets lost during gaps (i.e., Gap Loss Rate in [SUMSTAT]), which can be calculated using the metric "Packets Loss in Bursts" and the metric "Total Packets Expected in Bursts" provided in the Burst/Gap Loss Metrics Block.
o 在间隔期间丢失的数据包的分数（即[SUMSTAT]中的间隔丢失率），可以使用突发/间隔丢失度量块中提供的度量“突发中的数据包丢失”和度量“突发中预期的数据包总数”来计算。
o burst duration mean [SUMSTAT], which can be calculated using the metric "Packets Loss in Bursts" and the metric "Total Packets Expected in Bursts" provided in the Burst/Gap Loss Metrics Block.
o 突发持续时间平均值[SUMSTAT]，可使用突发/间隔丢失度量块中提供的度量“突发中的数据包丢失”和度量“突发中预期的数据包总数”来计算。
o burst duration variance [SUMSTAT], which can be calculated using the metric "Packets Loss in Bursts" and the metric "Total Packets Expected in Bursts" provided in the Burst/Gap Loss Metrics Block.
o 突发持续时间方差[SUMSTAT]，可使用突发/间隔丢失度量块中提供的度量“突发中的数据包丢失”和度量“突发中预期的数据包总数”来计算。
The details on calculation of these parameters in the metrics are described in [SUMSTAT].
[SUMSTAT]中描述了度量中这些参数的计算细节。
This Metrics Block is applicable to a broad range of RTP applications. Where the metric is used with a Voice-over-IP (VoIP) application and the stream repair means is not available, the following considerations apply.
此度量块适用于广泛的RTP应用程序。如果该度量用于IP语音（VoIP）应用程序，且流修复手段不可用，则以下注意事项适用。
RTCP XR views a call as being divided into bursts, which are periods when the loss rate is high enough to cause noticeable call quality degradation (generally over 5 percent loss rate), and gaps, which are periods when lost packets are infrequent and hence call quality is generally acceptable.
RTCP XR将呼叫分为突发和间隔，突发是指丢失率高到足以导致明显的呼叫质量下降（通常超过5%的丢失率）的时段，间隔是指丢失数据包不频繁的时段，因此呼叫质量通常是可接受的。
If Voice Activity Detection is used, the Burst and Gap Durations shall be determined as if silence packets had been sent, i.e., a period of silence in excess of Gmin packets will terminate a burst condition.
如果使用语音活动检测，则应确定突发和间隔持续时间，如同发送了静默数据包一样，即，超过Gmin数据包的静默时间将终止突发条件。
The recommended value for the threshold Gmin in [RFC3611] causes a burst during which the call quality is degraded to a similar extent as it would be during a typical Pulse Code Modulation (PCM) Severely Errored Second.
[RFC3611]中阈值Gmin的建议值会导致突发，在此期间，呼叫质量降级的程度与典型脉冲编码调制（PCM）严重出错时的程度相似。
[RFC3611] defines the use of the Session Description Protocol (SDP) [RFC4566] for signaling the use of XR blocks. XR blocks MAY be used without prior signaling.
[RFC3611]定义了会话描述协议（SDP）[RFC4566]的使用，用于发送使用XR块的信号。XR块可以在没有事先信令的情况下使用。
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. The ABNF [RFC5234] syntax is below.
本节增加了[RFC3611]中定义的SDP[RFC4566]属性“rtcp xr”，提供了“xr format”的附加值，以表示使用了本文档中定义的报告块。ABNF[RFC5234]语法如下所示。
xr-format =/ xr-bgl-block
xr format=/xr bgl块
xr-bgl-block = "burst-gap-loss"
xr-bgl-block = "burst-gap-loss"
When SDP is used in the offer/answer context, the SDP Offer/Answer usage defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters applies. For detailed usage of offer/answer for unilateral parameters, refer to Section 5.2 of [RFC3611].
在报价/应答上下文中使用SDP时，[RFC3611]中为单边“rtcp xr”属性参数定义的SDP报价/应答用法适用。有关单边参数的报价/应答的详细用法，请参阅[RFC3611]第5.2节。
New block types for RTCP XR are subject to IANA registration. For general guidelines on IANA considerations for RTCP XR, refer to [RFC3611].
RTCP XR的新块类型需要IANA注册。有关RTCP XR的IANA注意事项的一般指南，请参阅[RFC3611]。
This document assigns the block type value 20 in the IANA "RTP Control Protocol Extended Reports (RTCP XR) Block Type Registry" to the "Burst/Gap Loss Metrics Block".
本文档将IANA“RTP控制协议扩展报告（RTCP XR）块类型注册表”中的块类型值20分配给“突发/间隙损失度量块”。
This document also registers a new parameter "burst-gap-loss" in the "RTP Control Protocol Extended Reports (RTCP XR) Session Description Protocol (SDP) Parameters Registry".
本文档还在“RTP控制协议扩展报告（RTCP XR）会话描述协议（SDP）参数注册表”中注册了一个新参数“突发间隔丢失”。
The contact information for the registrations is:
注册的联系信息为：
Qin Wu (sunseawq@huawei.com)
秦武(sunseawq@huawei.com)
101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China
中国江苏省南京市雨花区软件大道101号210012
This block does not provide per-packet statistics, so the risk to confidentiality documented in Section 7, paragraph 3 of [RFC3611] does not apply. However, the gaps indicated within this block could be used to detect the timing of other events on the path between the sender and receiver. For example, a competing multimedia stream might cause a loss burst for the duration of the stream, allowing the receiver of this block to know when the competing stream was active. This risk is not a significant threat since the only information leaked is the timing of the loss, not the cause. Besides this, it is believed that this proposed RTCP XR report block introduces no other new security considerations beyond those described in [RFC3611].
该块不提供每包统计数据，因此[RFC3611]第7节第3段中记录的保密风险不适用。然而，该块中指示的间隙可用于检测发送方和接收方之间路径上其他事件的定时。例如，竞争多媒体流可能在流的持续时间内导致丢失突发，从而允许该块的接收器知道竞争流何时处于活动状态。这种风险不是重大威胁，因为泄露的唯一信息是损失的时间，而不是原因。除此之外，人们认为，除了[RFC3611]中所述的安全注意事项外，拟议的RTCP XR报告块没有引入其他新的安全注意事项。
Geoff Hunt wrote the initial draft of this document.
杰夫·亨特撰写了这份文件的初稿。
The authors gratefully acknowledge reviews and feedback provided by Bruce Adams, Philip Arden, Amit Arora, Bob Biskner, Kevin Connor, Claus Dahm, Randy Ethier, Roni Even, Jim Frauenthal, Albert Higashi, Tom Hock, Shane Holthaus, Paul Jones, Rajesh Kumar, Keith Lantz, Mohamed Mostafa, Amy Pendleton, Colin Perkins, Mike Ramalho, Ravi Raviraj, Albrecht Schwarz, Tom Taylor, Hideaki Yamada, Adam Roach, Dan Romascanu, Chris Lonvick, Alfred C. Morton Jr., Pete Resnick, Ted Lemon, Stephen Farrell, Richard Barnes, and Benoit Claise.
作者感谢Bruce Adams、Philip Arden、Amit Arora、Bob Biskner、Kevin Connor、Claus Dahm、Randy Ethier、Roni Even、Jim Frauenthal、Albert Higashi、Tom Hock、Shane Holthaus、Paul Jones、Rajesh Kumar、Keith Lantz、Mohamed Mostafa、Amy Pendleton、Colin Perkins、Mike Ramalho、Ravi Raviraj、，阿尔布雷希特·施瓦兹、汤姆·泰勒、山田英代基、亚当·罗奇、丹·罗马斯坎努、克里斯·隆维克、小阿尔弗雷德·C·莫顿、皮特·雷斯尼克、泰德·莱蒙、斯蒂芬·法雷尔、理查德·巴恩斯和贝诺特·克莱斯。
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July 2003.
[RFC3550]Schulzrinne，H.，Casner，S.，Frederick，R.，和V.Jacobson，“RTP：实时应用的传输协议”，STD 64，RFC 35502003年7月。
[RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control Protocol Extended Reports (RTCP XR)", RFC 3611, November 2003.
[RFC3611]Friedman，T.，Caceres，R.，和A.Clark，“RTP控制协议扩展报告（RTCP XR）”，RFC 36112003年11月。
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session Description Protocol", RFC 4566, July 2006.
[RFC4566]Handley，M.，Jacobson，V.，和C.Perkins，“SDP：会话描述协议”，RFC4566，2006年7月。
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5234]Crocker，D.和P.Overell，“语法规范的扩充BNF:ABNF”，STD 68，RFC 5234，2008年1月。
[RFC5725] Begen, A., Hsu, D., and M. Lague, "Post-Repair Loss RLE Report Block Type for RTP Control Protocol (RTCP) Extended Reports (XRs)", RFC 5725, February 2010.
[RFC5725]Begen，A.，Hsu，D.，和M.Lague，“RTP控制协议（RTCP）扩展报告（XRs）的修复后损失RLE报告块类型”，RFC 5725，2010年2月。
[DISCARD] Clark, A., Huang, R., and Q. Wu, Ed., "RTP Control Protocol (RTCP) Extended Report (XR) Block for Discard Count metric Reporting", Work in Progress, April 2013.
[DISCARD]Clark，A.，Huang，R.，和Q.Wu，Ed.，“用于丢弃计数度量报告的RTP控制协议（RTCP）扩展报告（XR）块”，在建工程，2013年4月。
[RFC4588] Rey, J., Leon, D., Miyazaki, A., Varsa, V., and R. Hakenberg, "RTP Retransmission Payload Format", RFC 4588, July 2006.
[RFC4588]Rey，J.，Leon，D.，Miyazaki，A.，Varsa，V.，和R.Hakenberg，“RTP重传有效载荷格式”，RFC 4588，2006年7月。
[RFC5109] Li, A., "RTP Payload Format for Generic Forward Error Correction", RFC 5109, December 2007.
[RFC5109]Li，A.“通用前向纠错的RTP有效载荷格式”，RFC 5109，2007年12月。
[RFC6390] Clark, A. and B. Claise, "Guidelines for Considering New Performance Metric Development", BCP 170, RFC 6390, October 2011.
[RFC6390]Clark，A.和B.Claise，“考虑新性能指标开发的指南”，BCP 170，RFC 63902011年10月。
[RFC6709] Carpenter, B., Aboba, B., and S. Cheshire, "Design Considerations for Protocol Extensions", RFC 6709, September 2012.
[RFC6709]Carpenter，B.，Aboba，B.，和S.Cheshire，“协议扩展的设计考虑”，RFC 6709，2012年9月。
[RFC6776] Clark, A. and Q. Wu, "Measurement Identity and Information Reporting Using a Source Description (SDES) Item and an RTCP Extended Report (XR) Block", RFC 6776, October 2012.
[RFC6776]Clark，A.和Q.Wu，“使用源描述（SDES）项和RTCP扩展报告（XR）块的测量标识和信息报告”，RFC 6776，2012年10月。
[RFC6792] Wu, Q., Hunt, G., and P. Arden, "Guidelines for Use of the RTP Monitoring Framework", RFC 6792, November 2012.
[RFC6792]Wu，Q.，Hunt，G.，和P.Arden，“RTP监控框架的使用指南”，RFC 6792，2012年11月。
[SUMSTAT] Zorn, G., Schott, R., Wu, Q., Ed., and R. Huang, "RTP Control Protocol (RTCP) Extended Report (XR) Blocks for Summary Statistics Metrics Reporting", Work in Progress, March 2013.
[SUMSTAT]Zorn，G.，Schott，R.，Wu，Q.，Ed.，和R.Huang，“用于汇总统计指标报告的RTP控制协议（RTCP）扩展报告（XR）块”，正在进行的工作，2013年3月。
The six metrics defined in this document are described below using the template from Section 5.4.4 of RFC 6390.
下文使用RFC 6390第5.4.4节中的模板描述了本文件中定义的六个指标。
a. Threshold Metric
a. 阈值度量
* Metric Name: Threshold in RTP
* 度量名称：RTP中的阈值
* Metric Description: The Threshold is equivalent to Gmin in [RFC3611], i.e., the number of successive RTP packets that must be received prior to and following a lost RTP packet in order for this lost RTP packet to be regarded as part of a gap.
* 度量说明：阈值相当于[RFC3611]中的Gmin，即在丢失的RTP数据包之前和之后必须接收的连续RTP数据包的数量，以便将该丢失的RTP数据包视为间隙的一部分。
* Method of Measurement or Calculation: See Section 3.2, Threshold definition.
* 测量或计算方法：见第3.2节，阈值定义。
* Units of Measurement: See Section 3.2, Threshold definition.
* 计量单位：见第3.2节，阈值定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 3, 1st paragraph.
* 具有潜在测量域的测量点：见第3节第1段。
* Measurement Timing: See Section 3, 2nd paragraph for measurement timing and Section 3.2 for Interval Metric flag.
* 测量定时：测量定时见第3节第2段，间隔公制标志见第3.2节。
* Use and Applications: See Section 1.4.
* 用途和应用：见第1.4节。
* Reporting Model: See RFC 3611.
* 报告模式：见RFC 3611。
b. Sum of Burst Durations Metric
b. 突发持续时间和度量
* Metric Name: Sum of Burst Durations in RTP
* 度量名称：RTP中突发持续时间的总和
* Metric Description: The total duration of bursts of lost RTP packets in the period of the report.
* 度量说明：报告期间丢失的RTP数据包突发的总持续时间。
* Method of Measurement or Calculation: See Section 3.2, Sum of Burst Durations definition.
* 测量或计算方法：见第3.2节，爆破持续时间总和定义。
* Units of Measurement: See Section 3.2, Sum of Burst Durations definition.
* 测量单位：见第3.2节，脉冲持续时间总和定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 3, 1st paragraph.
* 具有潜在测量域的测量点：见第3节第1段。
* Measurement Timing: See Section 3, 2nd paragraph for measurement timing and Section 3.2 for Interval Metric flag.
* 测量定时：测量定时见第3节第2段，间隔公制标志见第3.2节。
* Use and Applications: See Section 1.4.
* 用途和应用：见第1.4节。
* Reporting Model: See RFC 3611.
* 报告模式：见RFC 3611。
c. Packets Lost in Bursts Metric
c. 突发数据包丢失度量
* Metric Name: RTP Packets lost in bursts
* 度量名称：突发丢失的RTP数据包
* Metric Description: The total number of RTP packets lost during loss bursts.
* 度量说明：在丢失突发期间丢失的RTP数据包总数。
* Method of Measurement or Calculation: See Section 3.2, Packets Lost in Bursts definition.
* 测量或计算方法：见第3.2节，突发定义中丢失的数据包。
* Units of Measurement: See Section 3.2, Packets lost in bursts definition.
* 测量单位：见第3.2节，突发定义中丢失的数据包。
* Measurement Point(s) with Potential Measurement Domain: See Section 3, 1st paragraph.
* 具有潜在测量域的测量点：见第3节第1段。
* Measurement Timing: See Section 3, 2nd paragraph for measurement timing and Section 3.2 for Interval Metric flag.
* 测量定时：测量定时见第3节第2段，间隔公制标志见第3.2节。
* Use and Applications: See Section 1.4.
* 用途和应用：见第1.4节。
* Reporting Model: See RFC 3611.
* 报告模式：见RFC 3611。
d. Total Packets Expected in Bursts Metric
d. 突发度量中预期的数据包总数
* Metric Name: Total RTP packets expected in bursts
* 度量名称：突发中预期的RTP数据包总数
* Metric Description: The total number of RTP packets expected during loss bursts (that is, the sum of received RTP packets and lost RTP packets).
* 度量说明：丢失突发期间预期的RTP数据包总数（即，接收到的RTP数据包和丢失的RTP数据包之和）。
* Method of Measurement or Calculation: See Section 3.2, Total packets expected in bursts definition.
* 测量或计算方法：见第3.2节，突发定义中预期的总数据包。
* Units of Measurement: See Section 3.2, Total packets expected in bursts definition.
* 测量单位：见第3.2节，突发定义中预期的总数据包。
* Measurement Point(s) with Potential Measurement Domain: See Section 3, 1st paragraph.
* 具有潜在测量域的测量点：见第3节第1段。
* Measurement Timing: See Section 3, 2nd paragraph for measurement timing and Section 3.2 for Interval Metric flag.
* 测量定时：测量定时见第3节第2段，间隔公制标志见第3.2节。
* Use and Applications: See Section 1.4.
* 用途和应用：见第1.4节。
* Reporting Model: See RFC 3611.
* 报告模式：见RFC 3611。
e. Number of Bursts Metric
e. 突发数度量
* Metric Name: Number of bursts in RTP
* 度量名称：RTP中的突发数
* Metric Description: The total duration of bursts of lost RTP packets in the period of the report.
* 度量说明：报告期间丢失的RTP数据包突发的总持续时间。
* Method of Measurement or Calculation: See Section 3.2, Number of bursts definition.
* 测量或计算方法：见第3.2节，爆炸次数定义。
* Units of Measurement: See Section 3.2, Number of bursts definition.
* 测量单位：见第3.2节，脉冲数定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 3, 1st paragraph.
* 具有潜在测量域的测量点：见第3节第1段。
* Measurement Timing: See Section 3, 2nd paragraph for measurement timing and Section 3.2 for Interval Metric flag.
* 测量定时：测量定时见第3节第2段，间隔公制标志见第3.2节。
* Use and Applications: See Section 1.4.
* 用途和应用：见第1.4节。
* Reporting Model: See RFC 3611.
* 报告模式：见RFC 3611。
f. Sum of Squares of Burst Durations Metric
f. 突发持续时间平方和度量
* Metric Name: Sum of Squares of Burst Durations in RTP
* 度量名称：RTP中突发持续时间的平方和
* Metric Description: The sum of the squares of burst durations (where individual burst durations are expressed in ms) over in the period of the report.
* 度量说明：报告期间内突发持续时间的平方和（其中单个突发持续时间以ms表示）。
* Method of Measurement or Calculation: See Section 3.2, Sum of Squares of Burst Durations definition.
* 测量或计算方法：见第3.2节，爆破持续时间平方和定义。
* Units of Measurement: See Section 3.2, Sum of Squares of Burst Durations definition.
* 测量单位：见第3.2节，爆破持续时间平方和定义。
* Measurement Point(s) with Potential Measurement Domain: See Section 3, 1st paragraph.
* 具有潜在测量域的测量点：见第3节第1段。
* Measurement Timing: See Section 3, 2nd paragraph for measurement timing and Section 3.2 for Interval Metric flag.
* 测量定时：测量定时见第3节第2段，间隔公制标志见第3.2节。
* Use and Applications: See Section 1.4.
* 用途和应用：见第1.4节。
* Reporting Model: See RFC 3611.
* 报告模式：见RFC 3611。
Authors' Addresses
作者地址
Alan Clark Telchemy Incorporated 2905 Premiere Parkway, Suite 280 Duluth, GA 30097 USA
Alan Clark Telchemy Incorporated 2905 Premiere Parkway，美国佐治亚州德卢斯280号套房，邮编30097
EMail: alan.d.clark@telchemy.com
EMail: alan.d.clark@telchemy.com
Sunshine Zhang Shanghai Research Institute of China Telecom Corporation Limited No. 1835, South Pudong Road Shanghai 200122 China
中国电信股份有限公司上海研究院上海浦东南路1835号，邮编：200122
EMail: zhangyx@sttri.com.cn
EMail: zhangyx@sttri.com.cn
Jing Zhao Shanghai Research Institute of China Telecom Corporation Limited No. 1835, South Pudong Road Shanghai 200122 China
中国电信股份有限公司上海研究院上海浦东南路1835号，邮编：200122
EMail: zhaojing@sttri.com.cn
EMail: zhaojing@sttri.com.cn
Qin Wu (editor) Huawei 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China
秦武（编辑）中国江苏省南京市雨花区华为软件大道101号210012
EMail: sunseawq@huawei.com
EMail: sunseawq@huawei.com