Internet Engineering Task Force (IETF) V. Singh, Ed.
Request for Comments: 7243 J. Ott
Category: Standards Track Aalto University
ISSN: 2070-1721 I. Curcio
Nokia Research Center
May 2014
Internet Engineering Task Force (IETF) V. Singh, Ed.
Request for Comments: 7243 J. Ott
Category: Standards Track Aalto University
ISSN: 2070-1721 I. Curcio
Nokia Research Center
May 2014
RTP Control Protocol (RTCP) Extended Report (XR) Block for the Bytes Discarded Metric
丢弃字节度量的RTP控制协议（RTCP）扩展报告（XR）块
Abstract
摘要
The RTP Control Protocol (RTCP) is used in conjunction with the Real-time Transport Protocol (RTP) to provide a variety of short-term and long-term reception statistics. The available reporting may include aggregate information across longer periods of time as well as individual packet reporting. This document specifies a report computing the bytes discarded from the de-jitter buffer after successful reception.
RTP控制协议（RTCP）与实时传输协议（RTP）结合使用，以提供各种短期和长期接收统计数据。可用的报告可以包括跨较长时间段的聚合信息以及单个分组报告。本文档指定了一个报告，该报告计算成功接收后从消除抖动缓冲区丢弃的字节数。
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/rfc7243.
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/rfc7243.
Copyright Notice
版权公告
Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2014 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 ....................................................3
2. Terminology .....................................................4
3. Bytes Discarded Report Block ....................................4
4. Protocol Operation ..............................................6
4.1. Reporting Node (Receiver) ..................................6
4.2. Media Sender ...............................................6
5. SDP Signaling ...................................................7
6. Security Considerations .........................................7
7. IANA Considerations .............................................8
7.1. XR Report Block Registration ...............................8
7.2. SDP Parameter Registration .................................8
7.3. Contact Information for IANA Registrations .................8
8. Acknowledgments .................................................8
9. References ......................................................9
9.1. Normative References .......................................9
9.2. Informative References .....................................9
Appendix A. Metrics Represented Using the Template from RFC 6390 ..11
1. Introduction ....................................................3
2. Terminology .....................................................4
3. Bytes Discarded Report Block ....................................4
4. Protocol Operation ..............................................6
4.1. Reporting Node (Receiver) ..................................6
4.2. Media Sender ...............................................6
5. SDP Signaling ...................................................7
6. Security Considerations .........................................7
7. IANA Considerations .............................................8
7.1. XR Report Block Registration ...............................8
7.2. SDP Parameter Registration .................................8
7.3. Contact Information for IANA Registrations .................8
8. Acknowledgments .................................................8
9. References ......................................................9
9.1. Normative References .......................................9
9.2. Informative References .....................................9
Appendix A. Metrics Represented Using the Template from RFC 6390 ..11
RTP [RFC3550] provides a transport for real-time media flows such as audio and video together with the RTP Control Protocol (RTCP), which provides periodic feedback about the media streams received in a specific duration. In addition, RTCP can be used for timely feedback about individual events to report (e.g., packet loss) [RFC4585]. Both long-term and short-term feedback enable a media sender to adapt its media transmission and/or encoding dynamically to the observed path characteristics.
RTP[RFC3550]与RTP控制协议（RTCP）一起为实时媒体流（如音频和视频）提供传输，RTP控制协议（RTCP）提供关于在特定持续时间内接收的媒体流的定期反馈。此外，RTCP可用于及时反馈要报告的单个事件（例如，数据包丢失）[RFC4585]。长期和短期反馈使媒体发送者能够根据观察到的路径特征动态地调整其媒体传输和/或编码。
[RFC3611] defines RTCP Extended Reports as a detailed reporting framework to provide more than just the coarse Receiver Report (RR) statistics. The detailed reporting may enable a media sender to react more appropriately to the observed networking conditions as these can be characterized better, although at the expense of extra overhead.
[RFC3611]将RTCP扩展报告定义为一个详细的报告框架，提供的不仅仅是粗略的接收方报告（RR）统计数据。详细报告可以使媒体发送者能够对观察到的网络条件作出更适当的反应，因为这些条件可以被更好地描述，尽管以额外开销为代价。
In addition to lost packets, [RFC3611] defines the notion of "discarded" packets: packets that were received but dropped from the de-jitter buffer because they were either too early (for buffering) or too late (for playout). The "discard rate" metric is part of the VoIP metrics report block even though it is not just applicable to audio: it is specified as the fraction of discarded packets since the beginning of the session. See Section 4.7.1 of [RFC3611]. The discard metric is believed to be applicable to a large class of RTP applications that use a de-jitter buffer [RFC5481].
除了丢失的数据包外，[RFC3611]还定义了“丢弃”数据包的概念：由于数据包太早（用于缓冲）或太晚（用于播放），而从去抖动缓冲区接收但丢弃的数据包。“丢弃率”指标是VoIP指标报告块的一部分，尽管它不仅适用于音频：它被指定为自会话开始以来丢弃的数据包的分数。参见[RFC3611]第4.7.1节。丢弃度量被认为适用于使用去抖动缓冲器[RFC5481]的一大类RTP应用程序。
Recently proposed extensions to the Extended Reports (XR) reporting suggest enhancing the discard metric:
最近建议对扩展报告（XR）报告进行扩展，建议增强丢弃度量：
o Reporting the number of discarded packets in a measurement interval, i.e., during either the last reporting interval or since the beginning of the session, as indicated by a flag in the suggested XR report [RFC7002]. If an endpoint needs to report packet discard due to other reasons than early- and late-arrival (for example, discard due to duplication, redundancy, etc.) then it should consider using the Discarded Packets Report Block [RFC7002].
o 报告测量间隔内丢弃数据包的数量，即在最后一个报告间隔期间或会话开始后，如建议的XR报告[RFC7002]中的标志所示。如果一个端点由于其他原因而不是早到晚（例如，由于重复、冗余等而丢弃），则需要报告报文丢弃，那么它应该考虑使用丢弃的分组报告块[RCF702]。
o Reporting gaps and bursts of discarded packets during a measurement interval, i.e., the last reporting interval or the duration of the session [RFC7003].
o 在测量间隔（即最后一个报告间隔或会话持续时间）期间报告丢弃数据包的间隔和突发[RFC7003]。
o Reporting run-length encoding of a discarded packet during a measurement interval, i.e., between a set of sequence numbers [RFC7097].
o 在测量间隔期间，即在一组序列号之间，报告丢弃数据包的运行长度编码[RFC7097]。
However, none of these metrics allow a receiver to report precisely the number of RTP payload bytes that were discarded. While this information could in theory be derived from high-frequency reporting on the number of discarded packets [RFC7002] or from the Discard RLE (Run Length Encoding) report [RFC7097], these two mechanisms do not appear feasible. The former would require an unduly high amount of reporting that still might not be sufficient due to the non-deterministic scheduling of RTCP packets. The latter incurs significant complexity (by storing a map of sequence numbers and packet sizes) and reporting overhead.
但是，这些指标都不允许接收器精确报告被丢弃的RTP有效负载字节数。虽然理论上可以从丢弃数据包数量的高频报告[RFC7002]或从丢弃RLE（运行长度编码）报告[RFC7097]中得出此信息，但这两种机制似乎不可行。前者需要过高的报告量，但由于RTCP数据包的非确定性调度，报告量可能仍然不够。后者带来了巨大的复杂性（通过存储序列号和数据包大小的映射）和报告开销。
An XR block is defined in this document to indicate the number of RTP payload bytes discarded, per interval or for the duration of the session, similar to the other XR blocks.
本文档中定义了一个XR块，以指示每个间隔或会话期间丢弃的RTP有效负载字节数，与其他XR块类似。
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 BCP 14, [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BCP 14、[RFC2119]中所述进行解释。
The terminology defined in RTP [RFC3550] and in the extensions for XR reporting [RFC3611] applies.
RTP[RFC3550]和XR报告扩展[RFC3611]中定义的术语适用。
The Bytes Discarded Report Block uses the following format, which follows the model of the framework for performance metric development [RFC6390].
Bytes Discarded报告块使用以下格式，该格式遵循性能度量开发框架[RFC6390]的模型。
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=26 | I |E|Reserved | Block length=2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of RTP payload bytes discarded |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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=26 | I |E|Reserved | Block length=2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of RTP payload bytes discarded |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: XR Bytes Discarded Report Block
图1:XR字节丢弃报告块
Block Type (BT): 8 bits. A Bytes Discarded Packets Report Block is identified by the constant 26.
块类型（BT）：8位。字节丢弃分组报告块由常数26标识。
Interval Metric flag (I): 2 bits. It is used to indicate whether the discard metric is an Interval or a Cumulative metric, that is, whether the reported value applies to the most recent measurement
间隔度量标志（I）：2位。它用于指示丢弃度量是间隔度量还是累积度量，即报告的值是否适用于最近的度量
interval duration between successive reports (I=10, the Interval Duration) or to the accumulation period characteristic of cumulative measurements (I=11, the Cumulative Duration). Since the bytes discarded are not measured at a particular time instance but over one or several reporting intervals, the metric MUST NOT be reported as a Sampled Metric (I=01). In addition, the value I=00 is reserved and MUST NOT be sent, and it MUST be discarded when received.
连续报告之间的间隔持续时间（I=10，间隔持续时间）或累积测量的累积周期特征（I=11，累积持续时间）。由于丢弃的字节不是在特定的时间实例上测量的，而是在一个或多个报告间隔内测量的，因此不得将该度量报告为采样度量（I=01）。此外，值I=00是保留的，不得发送，并且在接收时必须丢弃。
Early bit (E): It is introduced to distinguish between packets discarded due to early arrival and those discarded due to late arrival. The E bit is set to '1' if it reports bytes discarded due to early arrival and is set to '0' if it reports bytes discarded due to late arrival. If a duplicate packet is received and discarded, these duplicate packets are ignored and not reported. In case both early and late discarded packets shall be reported, two Bytes Discarded report blocks MUST be included.
早期比特（E）：用于区分由于提前到达而丢弃的数据包和由于延迟到达而丢弃的数据包。如果E位报告由于提前到达而丢弃的字节，则将其设置为“1”；如果E位报告由于延迟到达而丢弃的字节，则将其设置为“0”。如果接收到并丢弃了重复数据包，则忽略并不报告这些重复数据包。如果同时报告早期和晚期丢弃的数据包，则必须包括两个字节丢弃的报告块。
Reserved: 5 bits. This field is reserved for future definition. In the absence of such definition, the bits in this field MUST be set to zero and MUST be ignored by the receiver.
保留：5位。此字段保留供将来定义。在没有这种定义的情况下，此字段中的位必须设置为零，并且必须被接收器忽略。
Block length: 16 bits. It MUST be set to 2, in accordance with the definition of this field in [RFC3611]. The block MUST be discarded if the block length is set to a different value.
块长度：16位。根据[RFC3611]中该字段的定义，必须将其设置为2。如果块长度设置为不同的值，则必须丢弃该块。
Number of RTP payload bytes discarded: It is a 32-bit unsigned integer value indicating the total number of bytes discarded. The 'bytes discarded' corresponds to the RTP payload size of every RTP packet that is discarded (due to early or late arrival). Hence, the 'bytes discarded' ignores the size of any RTP header extensions and the size of the padding bits. Also the discarded packet is associated to the interval in which it was discarded, not when it was expected.
丢弃的RTP有效负载字节数：它是一个32位无符号整数值，指示丢弃的字节总数。“被丢弃的字节”对应于每个被丢弃的RTP数据包的RTP有效负载大小（由于提前或延迟到达）。因此，“字节丢弃”忽略任何RTP头扩展的大小和填充位的大小。此外，丢弃的数据包与丢弃它的时间间隔相关联，而不是与预期的时间相关联。
If the Interval Metric flag is set as I=11, the value in the field indicates the number of RTP payload bytes discarded from the start of the session; if the Interval Metric flag is set as I=10, it indicates the number of bytes discarded in the most recent reporting interval.
如果间隔度量标志设置为I＝11，则该字段中的值指示从会话开始丢弃的RTP有效负载字节数；如果Interval Metric标志设置为I=10，则表示在最近的报告间隔中丢弃的字节数。
If the XR block follows a Measurement Information Block [RFC6776] in the same RTCP compound packet, then the cumulative (I=11) or the interval (I=10) for this report block corresponds to the values of the "measurement duration" in the Measurement Information Block.
如果XR块跟随同一RTCP复合数据包中的测量信息块[RFC6776]，则此报告块的累积（I=11）或间隔（I=10）对应于测量信息块中的“测量持续时间”值。
If the receiver sends the Bytes Discarded Report Block without the Measurement Information Block, then the Bytes Discarded Report Block MUST be sent in conjunction with an RTCP Receiver Report (RR) as a compound RTCP packet.
如果接收器发送不带测量信息块的字节丢弃报告块，则字节丢弃报告块必须与RTCP接收器报告（RR）一起作为复合RTCP数据包发送。
This section describes the behavior of the reporting node (i.e., the media receiver) and the media sender.
本节描述报告节点（即媒体接收器）和媒体发送者的行为。
The media receiver MAY send the Bytes Discarded Reports as part of the regularly scheduled RTCP packets as per RFC 3550. It MAY also include Bytes Discarded Reports in immediate or early feedback packets as per [RFC4585].
媒体接收器可根据RFC 3550将丢弃的字节报告作为定期调度的RTCP分组的一部分发送。根据[RFC4585]，它还可以包括立即或早期反馈数据包中丢弃的报告字节。
Transmission of the RTCP XR Bytes Discarded Report is up to the discretion of the media receiver, as is the reporting granularity. However, it is RECOMMENDED that the media receiver signals the bytes discarded packets using the method defined in this document. When reporting several metrics in a single RTCP packet, the reporting intervals for the report blocks are synchronized, therefore the media receiver may choose to additionally send the Discarded Packets [RFC7002] or Discard RLE [RFC7097] Report Block to assist the media sender in correlating the bytes discarded to the packets discarded in that particular interval.
RTCP XR Bytes Discarded报告的传输由媒体接收器决定，报告粒度也是如此。但是，建议媒体接收器使用本文档中定义的方法向丢弃的数据包发送信号。当在单个RTCP数据包中报告多个度量时，报告块的报告间隔是同步的，因此媒体接收器可以选择另外发送丢弃的数据包[RFC7002]或丢弃RLE[RFC7097]报告块，用于帮助媒体发送方将丢弃的字节与在该特定间隔内丢弃的数据包相关联。
If all packets over a reporting period were discarded, the media receiver MAY use the Discarded Packets Report Block [RFC7002] instead.
如果报告周期内的所有数据包都被丢弃，则媒体接收器可以改为使用丢弃的数据包报告块[RFC7002]。
The media sender MUST be prepared to operate without receiving any Bytes Discarded reports. If Bytes Discarded reports are generated by the media receiver, the media sender cannot rely on all these reports being received, nor can the media sender rely on a regular generation pattern from the media receiver.
媒体发送器必须准备好在不接收任何报告的情况下运行。如果媒体接收器生成被丢弃的字节报告，则媒体发送器不能依赖于接收到的所有这些报告，媒体发送器也不能依赖于来自媒体接收器的常规生成模式。
However, if the media sender receives any RTCP reports but no Bytes Discarded report blocks and is aware that the media receiver supports Bytes Discarded report blocks, it MAY assume that no packets were discarded by the media receiver.
但是，如果媒体发送方接收到任何RTCP报告，但没有丢弃字节的报告块，并且知道媒体接收方支持丢弃字节的报告块，则可以假定媒体接收方没有丢弃任何数据包。
The media sender SHOULD accept the Bytes Discarded Report Block only if it is received in a compound RTCP receiver report or if it is preceded by a Measurement Information Block [RFC6776]. Under all other circumstances, it MUST ignore the block.
仅当在复合RTCP接收器报告中接收到字节丢弃报告块，或之前有测量信息块[RFC6776]时，媒体发送方才应接受字节丢弃报告块。在所有其他情况下，它必须忽略该块。
A participant of a media session MAY use SDP to signal its support for the report block specified in this document or use them without any prior signaling (see Section 5 of [RFC3611]).
媒体会话的参与者可以使用SDP来表示其支持本文档中指定的报告块，也可以在没有任何事先信号的情况下使用SDP（参见[RFC3611]第5节）。
For signaling in SDP, the RTCP XR attribute as defined in [RFC3611] MUST be used. The SDP [RFC4566] attribute 'xr-format' defined in RFC 3611 is augmented to indicate the Bytes Discarded metric. This is described in the following ABNF [RFC5234]:
对于SDP中的信令，必须使用[RFC3611]中定义的RTCP XR属性。RFC 3611中定义的SDP[RFC4566]属性“xr format”被扩充以指示丢弃的字节度量。以下ABNF[RFC5234]中对此进行了描述：
rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)]
CRLF ; defined in [RFC3611]
rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)]
CRLF ; defined in [RFC3611]
xr-format =/ xr-discard-bytes
xr format=/xr丢弃字节
xr-discard-bytes = "discard-bytes"
xr-discard-bytes = "discard-bytes"
The parameter 'discard-bytes' to indicate support for the Bytes Discarded Report Block is defined in Section 3.
第3节中定义了参数“discard bytes”，用于指示对已丢弃字节报告块的支持。
When SDP is used in the offer/answer context, the mechanism defined in [RFC3611] for unilateral "rtcp-xr" attribute parameters applies (see 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”属性参数定义的机制适用（参见[RFC3611]第5.2节）。
The Bytes Discarded block does not provide per-packet statistics, hence the risk to confidentiality documented in Section 7, paragraph 3 of [RFC3611] does not apply. In some situations, returning very detailed error information (e.g., over-range measurement or measurement unavailable) using this report block can provide an attacker with insight into the security processing. For example, assume that the attacker sends a packet with a stale timestamp (i.e., time in the past) to the receiver. If the receiver now sends a discard report with the same number of bytes as the payload of the injected packet, the attacker can infer that no security processing was performed. If, on the other hand, the attacker does not receive a discard report, it can equivalently assume that the security procedures were performed on the packet.
丢弃字节块不提供每个数据包的统计信息，因此[RFC3611]第7节第3段中记录的保密风险不适用。在某些情况下，使用此报告块返回非常详细的错误信息（例如，超范围测量或测量不可用）可以让攻击者深入了解安全处理。例如，假设攻击者向接收方发送带有过时时间戳（即过去的时间）的数据包。如果接收器现在发送的丢弃报告的字节数与注入数据包的有效负载相同，则攻击者可以推断未执行任何安全处理。另一方面，如果攻击者没有收到丢弃报告，则可以等效地假定安全过程是在数据包上执行的。
Implementers should therefore consider the guidance in [RFC7202] for using appropriate security mechanisms, i.e., where security is a concern, the implementation should apply encryption and authentication to the report block. For example, this can be achieved by using the AVPF profile together with the Secure RTP
因此，实施者应该考虑[RCF7202]中使用适当的安全机制的指导，即，在安全性方面，实施应该对报告块应用加密和认证。例如，这可以通过将AVPF配置文件与安全RTP一起使用来实现
profile as defined in [RFC3711]; an appropriate combination of the two profiles (an "SAVPF") is specified in [RFC5124]. However, other mechanisms also exist (documented in [RFC7201]) and might be more suitable.
[RFC3711]中定义的剖面图；[RFC5124]中规定了两个配置文件的适当组合（“SAVPF”）。但是，也存在其他机制（见[RFC7201]），可能更合适。
The Bytes Discarded report is employed by the sender to perform congestion control, typically, for calculating goodput (i.e., throughput that is useful). In these cases, an attacker MAY drive the endpoint to lower its sending rate and under-utilize the link; therefore, media senders should choose appropriate security measures to mitigate such attacks.
发送方使用字节丢弃报告来执行拥塞控制，通常用于计算goodput（即有用的吞吐量）。在这些情况下，攻击者可能会驱动端点降低其发送速率，并降低链路的利用率；因此，媒体发件人应选择适当的安全措施来缓解此类攻击。
Lastly, the security considerations of [RFC3550], [RFC3611], and [RFC4585] apply.
最后，[RFC3550]、[RFC3611]和[RFC4585]的安全注意事项适用。
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 registers a new value in the IANA "RTP Control Protocol Extended Reports (RTCP XR) Block Type Registry": 26 for BDR (Bytes Discarded Report).
本文档在IANA“RTP控制协议扩展报告（RTCP XR）块类型注册表”中注册一个新值：26用于BDR（已丢弃的字节报告）。
This document registers a new parameter for the Session Description Protocol (SDP), "discard-bytes" in the "RTP Control Protocol Extended Reports (RTCP XR) Session Description Protocol (SDP) Parameters Registry".
本文档为会话描述协议（SDP）注册了一个新参数，“RTP控制协议扩展报告（RTCP XR）会话描述协议（SDP）参数注册表”中的“丢弃字节”。
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The authors would like to thank Benoit Claise, Alan Clark, Roni Even, Vijay Gurbani, Sam Hartman, Vinayak Hegde, Jeffrey Hutzelman, Barry Leiba, Colin Perkins, Dan Romascanu, Dan Wing, and Qin Wu for providing valuable feedback on this document during its development.
作者要感谢Benoit Claise、Alan Clark、Roni Een、Vijay Gurbani、Sam Hartman、Vinayak Hegde、Jeffrey Hutzelman、Barry Leiba、Colin Perkins、Dan Romascanu、Dan Wing和Qin Wu在本文件编制过程中提供了宝贵的反馈。
[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。
[RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, "Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, July 2006.
[RFC4585]Ott，J.，Wenger，S.，Sato，N.，Burmeister，C.，和J.Rey，“基于实时传输控制协议（RTCP）的反馈（RTP/AVPF）的扩展RTP配置文件”，RFC 45852006年7月。
[RFC5234] Crocker, D., Ed., and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5234]Crocker，D.，Ed.，和P.Overell，“语法规范的扩充BNF:ABNF”，STD 68，RFC 5234，2008年1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。
[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。
[RFC7002] Clark, A., Zorn, G., and Q. Wu, "RTP Control Protocol (RTCP) Extended Report (XR) Block for Discard Count Metric Reporting", RFC 7002, September 2013.
[RFC7002]Clark，A.，Zorn，G.，和Q.Wu，“用于丢弃计数度量报告的RTP控制协议（RTCP）扩展报告（XR）块”，RFC 7002，2013年9月。
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norrman, "The Secure Real-time Transport Protocol (SRTP)", RFC 3711, March 2004.
[RFC3711]Baugher，M.，McGrew，D.，Naslund，M.，Carrara，E.，和K.Norrman，“安全实时传输协议（SRTP）”，RFC 37112004年3月。
[RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/SAVPF)", RFC 5124, February 2008.
[RFC5124]Ott，J.和E.Carrara，“基于实时传输控制协议（RTCP）的反馈扩展安全RTP配置文件（RTP/SAVPF）”，RFC 51242008年2月。
[RFC5481] Morton, A. and B. Claise, "Packet Delay Variation Applicability Statement", RFC 5481, March 2009.
[RFC5481]Morton，A.和B.Claise，“数据包延迟变化适用性声明”，RFC 54812009年3月。
[RFC7003] Clark, A., Huang, R., and Q. Wu, "RTP Control Protocol (RTCP) Extended Report (XR) Block for Burst/Gap Discard Metric Reporting", RFC 7003, September 2013.
[RFC7003]Clark，A.，Huang，R.，和Q.Wu，“用于突发/间隙丢弃度量报告的RTP控制协议（RTCP）扩展报告（XR）块”，RFC 7003，2013年9月。
[RFC7097] Ott, J., Singh, V., and I. Curcio, "RTP Control Protocol (RTCP) Extended Report (XR) for RLE of Discarded Packets", RFC 7097, January 2014.
[RFC7097]Ott，J.，Singh，V.，和I.Curcio，“丢弃数据包RLE的RTP控制协议（RTCP）扩展报告（XR）”，RFC 7097，2014年1月。
[RFC7201] Westerlund, M. and C. Perkins, "Options for Securing RTP Sessions", RFC 7201, April 2014.
[RFC7201]Westerlund，M.和C.Perkins，“保护RTP会话的选项”，RFC 7201，2014年4月。
[RFC7202] Perkins, C. and M. Westerlund, "Securing the RTP Framework: Why RTP Does Not Mandate a Single Media Security Solution", RFC 7202, April 2014.
[RFC7202]Perkins，C.和M.Westerlund，“保护RTP框架：为什么RTP不要求单一媒体安全解决方案”，RFC 7202，2014年4月。
a. RTP Payload Bytes Discarded Metric
a. RTP有效负载字节丢弃度量
* Metric Name: RTP Payload Bytes Discarded Metric
* 度量名称：RTP有效负载字节丢弃度量
* Metric Description: Total number of RTP payload bytes discarded over the period covered by this report.
* 指标说明：在本报告涵盖的期间内丢弃的RTP有效负载字节总数。
* Method of Measurement or Calculation: See the definition of "Number of RTP payload bytes discarded" in Section 3.
* 测量或计算方法：参见第3节中“丢弃的RTP有效负载字节数”的定义。
* Units of Measurement: See the definition of "Number of RTP payload bytes discarded" in Section 3.
* 测量单位：参见第3节中“丢弃的RTP有效负载字节数”的定义。
* Measurement Point(s) with Potential Measurement Domain: See the first paragraph of Section 3.
* 具有潜在测量域的测量点：见第3节第一段。
* Measurement Timing: See the last three paragraphs of Section 3 for measurement timing and for the Interval Metric flag.
* 测量定时：有关测量定时和间隔度量标志，请参见第3节最后三段。
* Use and applications: See the third paragraph of Section 1.
* 用途和应用：见第1节第3段。
* Reporting model: See RFC 3611.
* 报告模式：见RFC 3611。
Authors' Addresses
作者地址
Varun Singh (editor) Aalto University School of Electrical Engineering Otakaari 5 A Espoo, FIN 02150 Finland
Varun Singh（编辑）芬兰芬兰阿尔托大学电气工程学院Otakaari 5 A Espoo 02150
EMail: varun@comnet.tkk.fi
URI: http://www.netlab.tkk.fi/~varun/
EMail: varun@comnet.tkk.fi
URI: http://www.netlab.tkk.fi/~varun/
Joerg Ott Aalto University School of Electrical Engineering Otakaari 5 A Espoo, FIN 02150 Finland
芬兰芬兰埃斯波奥塔卡里5 A埃斯波约尔格奥特阿尔托大学电气工程学院，邮编：02150
EMail: jo@comnet.tkk.fi
EMail: jo@comnet.tkk.fi
Igor D.D. Curcio Nokia Research Center P.O. Box 1000 (Visiokatu 3) Tampere, FIN 33721 Finland
芬兰芬兰芬兰坦佩雷Igor D.D.Curcio诺基亚研究中心邮政信箱1000（Visiokatu 3）33721
EMail: igor.curcio@nokia.com
EMail: igor.curcio@nokia.com