Internet Engineering Task Force (IETF) G. Almes
Request for Comments: 7679 Texas A&M
STD: 81 S. Kalidindi
Obsoletes: 2679 Ixia
Category: Standards Track M. Zekauskas
ISSN: 2070-1721 Internet2
A. Morton, Ed.
AT&T Labs
January 2016
Internet Engineering Task Force (IETF) G. Almes
Request for Comments: 7679 Texas A&M
STD: 81 S. Kalidindi
Obsoletes: 2679 Ixia
Category: Standards Track M. Zekauskas
ISSN: 2070-1721 Internet2
A. Morton, Ed.
AT&T Labs
January 2016
A One-Way Delay Metric for IP Performance Metrics (IPPM)
IP性能度量的单向延迟度量（IPPM）
Abstract
摘要
This memo defines a metric for one-way delay of packets across Internet paths. It builds on notions introduced and discussed in the IP Performance Metrics (IPPM) Framework document, RFC 2330; the reader is assumed to be familiar with that document. This memo makes RFC 2679 obsolete.
此备忘录定义了跨Internet路径的数据包单向延迟的度量。它建立在IP性能度量（IPPM）框架文件RFC 2330中介绍和讨论的概念之上；假定读者熟悉该文档。此备忘录使RFC 2679过时。
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/rfc7679.
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/rfc7679.
Copyright Notice
版权公告
Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2016 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 ....................................................4
1.1. Motivation .................................................4
2. General Issues regarding Time ...................................6
3. A Singleton Definition for One-Way Delay ........................7
3.1. Metric Name ................................................7
3.2. Metric Parameters ..........................................7
3.3. Metric Units ...............................................7
3.4. Definition .................................................7
3.5. Discussion .................................................8
3.6. Methodologies ..............................................9
3.7. Errors and Uncertainties ..................................10
3.7.1. Errors or Uncertainties Related to Clocks ..........10
3.7.2. Errors or Uncertainties Related to Wire
Time vs. Host Time .................................11
3.7.3. Calibration of Errors and Uncertainties ............12
3.8. Reporting the Metric ......................................14
3.8.1. Type-P .............................................14
3.8.2. Loss Threshold .....................................15
3.8.3. Calibration Results ................................15
3.8.4. Path ...............................................15
4. A Definition for Samples of One-Way Delay ......................15
4.1. Metric Name ...............................................16
4.2. Metric Parameters .........................................16
4.3. Metric Units ..............................................16
4.4. Definition ................................................17
4.5. Discussion ................................................17
4.6. Methodologies .............................................18
4.7. Errors and Uncertainties ..................................18
4.8. Reporting the Metric ......................................18
5. Some Statistics Definitions for One-Way Delay ..................18
5.1. Type-P-One-way-Delay-Percentile ...........................19
5.2. Type-P-One-way-Delay-Median ...............................19
5.3. Type-P-One-way-Delay-Minimum ..............................20
5.4. Type-P-One-way-Delay-Inverse-Percentile ...................20
6. Security Considerations ........................................21
7. Changes from RFC 2679 ..........................................22
8. References .....................................................24
8.1. Normative References ......................................24
8.2. Informative References ....................................25
Acknowledgements ..................................................26
Authors' Addresses ................................................27
1. Introduction ....................................................4
1.1. Motivation .................................................4
2. General Issues regarding Time ...................................6
3. A Singleton Definition for One-Way Delay ........................7
3.1. Metric Name ................................................7
3.2. Metric Parameters ..........................................7
3.3. Metric Units ...............................................7
3.4. Definition .................................................7
3.5. Discussion .................................................8
3.6. Methodologies ..............................................9
3.7. Errors and Uncertainties ..................................10
3.7.1. Errors or Uncertainties Related to Clocks ..........10
3.7.2. Errors or Uncertainties Related to Wire
Time vs. Host Time .................................11
3.7.3. Calibration of Errors and Uncertainties ............12
3.8. Reporting the Metric ......................................14
3.8.1. Type-P .............................................14
3.8.2. Loss Threshold .....................................15
3.8.3. Calibration Results ................................15
3.8.4. Path ...............................................15
4. A Definition for Samples of One-Way Delay ......................15
4.1. Metric Name ...............................................16
4.2. Metric Parameters .........................................16
4.3. Metric Units ..............................................16
4.4. Definition ................................................17
4.5. Discussion ................................................17
4.6. Methodologies .............................................18
4.7. Errors and Uncertainties ..................................18
4.8. Reporting the Metric ......................................18
5. Some Statistics Definitions for One-Way Delay ..................18
5.1. Type-P-One-way-Delay-Percentile ...........................19
5.2. Type-P-One-way-Delay-Median ...............................19
5.3. Type-P-One-way-Delay-Minimum ..............................20
5.4. Type-P-One-way-Delay-Inverse-Percentile ...................20
6. Security Considerations ........................................21
7. Changes from RFC 2679 ..........................................22
8. References .....................................................24
8.1. Normative References ......................................24
8.2. Informative References ....................................25
Acknowledgements ..................................................26
Authors' Addresses ................................................27
This memo defines a metric for one-way delay of packets across Internet paths. It builds on notions introduced and discussed in the IPPM Framework document, [RFC2330]; the reader is assumed to be familiar with that document and its recent update [RFC7312].
此备忘录定义了跨Internet路径的数据包单向延迟的度量。它以IPPM框架文件[RFC2330]中介绍和讨论的概念为基础；假定读者熟悉该文档及其最新更新[RFC7312]。
This memo is intended to be parallel in structure to a companion document for Packet Loss ("A One-way Packet Loss Metric for IPPM") [RFC7680].
本备忘录旨在在结构上与分组丢失的配套文件（“IPPM的单向分组丢失度量”）[RFC7680]平行。
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 [RFC2119]. Although [RFC2119] was written with protocols in mind, the key words are used in this document for similar reasons. They are used to ensure the results of measurements from two different implementations are comparable and to note instances when an implementation could perturb the network.
本文件中的关键词“必须”、“不得”、“必需”、“应”、“不应”、“应”、“不应”、“建议”、“可”和“可选”应按照[RFC2119]中所述进行解释。尽管[RFC2119]是在考虑协议的情况下编写的，但出于类似的原因，本文档中使用了关键词。它们用于确保两个不同实现的测量结果具有可比性，并用于记录一个实现可能干扰网络的实例。
Whenever a technical term from the IPPM Framework document is first used in this memo, it will be tagged with a trailing asterisk. For example, "term*" indicates that "term" is defined in the Framework document.
本备忘录中首次使用IPPM框架文件中的技术术语时，将使用尾随星号进行标记。例如，“术语*”表示在框架文档中定义了“术语”。
The structure of the memo is as follows:
备忘录的结构如下：
o A 'singleton*' analytic metric, called Type-P-One-way-Delay, will be introduced to measure a single observation of one-way delay.
o 将引入称为P型单向延迟的“单例*”分析度量来测量单向延迟的单个观测值。
o Using this singleton metric, a 'sample*' called Type-P-One-way-Delay-Poisson-Stream is introduced to measure a sequence of singleton delays sent at times taken from a Poisson process, defined in Section 11.1.1 of [RFC2330].
o 使用此单例度量，引入了一个称为Type-P-One-way-Delay-Poisson-Stream的“sample*”，以测量在从泊松过程中获取的时间发送的单例延迟序列，如[RFC2330]第11.1.1节所定义。
o Using this sample, several 'statistics*' of the sample will be defined and discussed. This progression from singleton to sample to statistics, with clear separation among them, is important.
o 使用此样本，将定义和讨论样本的几个“统计数据*”。这种从单一样本到样本再到统计的过程，在它们之间有明确的分离，是很重要的。
Understanding one-way delay of a Type-P* packet from a source host* to a destination host is useful for several reasons:
理解P型数据包从源主机*到目标主机*的单向延迟有助于以下几个原因：
o Some applications do not perform well (or at all) if end-to-end delay between hosts is large relative to some threshold value.
o 如果主机之间的端到端延迟相对于某个阈值较大，则某些应用程序的性能不好（或根本不好）。
o Erratic variation in delay makes it difficult (or impossible) to support many real-time applications.
o 延迟的不稳定变化使得支持许多实时应用程序变得困难（或不可能）。
o The larger the value of delay, the more difficult it is for transport-layer protocols to sustain high bandwidths.
o 延迟值越大，传输层协议就越难以维持高带宽。
o The minimum value of this metric provides an indication of the delay due only to propagation and transmission delay.
o 该度量的最小值提供仅由传播和传输延迟引起的延迟的指示。
o The minimum value of this metric provides an indication of the delay that will likely be experienced when the path* traversed is lightly loaded.
o 该度量的最小值提供了当路径*被轻装时可能经历的延迟指示。
o Values of this metric above the minimum provide an indication of the congestion present in the path.
o 此度量值高于最小值表示路径中存在的拥塞。
The measurement of one-way delay instead of round-trip delay is motivated by the following factors:
测量单向延迟而非往返延迟的原因如下：
o In today's Internet, the path from a source to a destination may be different than the path from the destination back to the source ("asymmetric paths"), such that different sequences of routers are used for the forward and reverse paths. Therefore, round-trip measurements actually measure the performance of two distinct paths together. Measuring each path independently highlights the performance difference between the two paths that may traverse different Internet service providers and even radically different types of networks (for example, research versus commodity networks, or networks with asymmetric link capacities, or wireless versus wireline access).
o 在今天的互联网中，从源到目的地的路径可能不同于从目的地返回到源的路径（“非对称路径”），因此不同的路由器序列用于正向和反向路径。因此，往返测量实际上同时测量两条不同路径的性能。独立测量每条路径突出了两条路径之间的性能差异，这两条路径可能穿越不同的互联网服务提供商，甚至是根本不同类型的网络（例如，研究网络与商品网络，或具有不对称链路容量的网络，或无线网络与有线网络）。
o Even when the two paths are symmetric, they may have radically different performance characteristics due to asymmetric queuing.
o 即使这两条路径是对称的，由于非对称排队，它们也可能具有完全不同的性能特征。
o Performance of an application may depend mostly on the performance in one direction. For example, a TCP-based communication will experience reduced throughput if congestion occurs in one direction of its communication. Troubleshooting may be simplified if the congested direction of TCP transmission can be identified.
o 应用程序的性能可能主要取决于一个方向上的性能。例如，如果在一个通信方向发生拥塞，基于TCP的通信将经历吞吐量降低。如果可以确定TCP传输的拥塞方向，则可以简化故障排除。
o In networks in which quality of service (QoS) is enabled, provisioning in one direction may be radically different than provisioning in the reverse direction and thus the QoS guarantees differ. Measuring the paths independently allows the verification of both guarantees.
o 在启用了服务质量（QoS）的网络中，在一个方向上的供应可能与在相反方向上的供应完全不同，因此QoS保证不同。独立测量路径可以验证两种保证。
It is outside the scope of this document to say precisely how delay metrics would be applied to specific problems.
确切地说延迟度量将如何应用于特定问题超出了本文档的范围。
{Comment: The terminology below differs from that defined by ITU-T documents (e.g., G.810, "Definitions and terminology for synchronization networks" and I.356, "B-ISDN ATM layer cell transfer performance") but is consistent with the IPPM Framework document. In general, these differences derive from the different backgrounds; the ITU-T documents historically have a telephony origin, while the authors of this document (and the Framework document) have a computer systems background. Although the terms defined below have no direct equivalent in the ITU-T definitions, after our definitions we will provide a rough mapping. However, note one potential confusion: our definition of "clock" is the computer operating systems definition denoting a time-of-day clock, while the ITU-T definition of clock denotes a frequency reference.}
{注释：以下术语与ITU-T文件定义的术语不同（例如，g.810，“同步网络的定义和术语”和I.356，“B-ISDN ATM层信元传输性能”）但与IPPM框架文件一致。一般来说，这些差异来自不同的背景；ITU-T文件历史上有电话来源，而本文件（和框架文件）的作者具有计算机系统背景。虽然以下定义的术语在ITU-T定义中没有直接的等效项，但在我们的定义之后，我们将提供一个粗略的映射。但是，请注意一个潜在的混淆：我们对“时钟”的定义是计算机操作系统定义，表示一天中的时间时钟，而ITU-T时钟定义表示频率参考。}
Whenever a time (i.e., a moment in history) is mentioned here, it is understood to be measured in seconds (and fractions) relative to UTC.
每当这里提到一个时间（即历史上的一个时刻）时，它都被理解为以秒（和分数）为单位相对于UTC进行测量。
As described more fully in the Framework document, there are four distinct, but related notions of clock uncertainty:
正如框架文件中更全面地描述的，时钟不确定性有四个不同但相关的概念：
synchronization*
同步*
measures the extent to which two clocks agree on what time it is. For example, the clock on one host might be 5.4 msec ahead of the clock on a second host. {Comment: A rough ITU-T equivalent is "time error".}
测量两个时钟在时间上的一致程度。例如，一台主机上的时钟可能比另一台主机上的时钟早5.4毫秒。{注释：粗略的ITU-T等价物是“时间错误”。}
accuracy*
准确度*
measures the extent to which a given clock agrees with UTC. For example, the clock on a host might be 27.1 msec behind UTC. {Comment: A rough ITU-T equivalent is "time error from UTC".}
测量给定时钟与UTC一致的程度。例如，主机上的时钟可能比UTC慢27.1毫秒。{注释：粗略的ITU-T等价物是“UTC时间错误”。}
resolution*
决议*
specification of the smallest unit by which the clock's time is updated. It gives a lower bound on the clock's uncertainty. For example, the clock on an old Unix host might tick only once every 10 msec, and thus have a resolution of only 10 msec. {Comment: A very rough ITU-T equivalent is "sampling period".}
用于更新时钟时间的最小单位的规格。它给出了时钟不确定性的下限。例如，旧Unix主机上的时钟可能仅每10毫秒滴答一次，因此分辨率仅为10毫秒。{注释：一个非常粗略的ITU-T等价物是“采样周期”。}
skew*
歪斜*
measures the change of accuracy, or of synchronization, with time. For example, the clock on a given host might gain 1.3 msec per hour and thus be 27.1 msec behind UTC at one time and only 25.8 msec an
测量精度或同步度随时间的变化。例如，给定主机上的时钟可能每小时增加1.3毫秒，因此一次比UTC慢27.1毫秒，一次仅25.8毫秒
hour later. In this case, we say that the clock of the given host has a skew of 1.3 msec per hour relative to UTC, which threatens accuracy. We might also speak of the skew of one clock relative to another clock, which threatens synchronization. {Comment: A rough ITU-T equivalent is "time drift".}
一小时后。在这种情况下，我们说给定主机的时钟相对于UTC每小时有1.3毫秒的偏差，这威胁到准确性。我们也可以说一个时钟相对于另一个时钟的倾斜，这威胁到同步。{注释：粗略的ITU-T等价物是“时间漂移”。}
Type-P-One-way-Delay
P型单向延迟
o Src, the IP address of a host
o Src，主机的IP地址
o Dst, the IP address of a host
o Dst，主机的IP地址
o T, a time
o T、 一段时间
o Tmax, a loss threshold waiting time
o Tmax，损失阈值等待时间
The value of a Type-P-One-way-Delay is either a real number or an undefined (informally, infinite) number of seconds.
P型单向延迟的值可以是实数，也可以是未定义的（非正式地说是无限的）秒数。
For a real number dT, >>the *Type-P-One-way-Delay* from Src to Dst at T is dT<< means that Src sent the first bit of a Type-P packet to Dst at wire time* T and that Dst received the last bit of that packet at wire time T+dT.
对于实数dT，>>在T从Src到Dst的*Type-P-One-way-Delay*为dT<<意味着Src在连线时间*T将Type-P数据包的第一位发送到Dst，而Dst在连线时间T+dT接收到该数据包的最后一位。
>>The *Type-P-One-way-Delay* from Src to Dst at T is undefined (informally, infinite)<< means that Src sent the first bit of a Type-P packet to Dst at wire time T and that Dst did not receive that packet (within the loss threshold waiting time, Tmax).
>>从Src到T处Dst的*Type-P-One-way-Delay*未定义（非正式地说，无限）<<意味着Src在连线时间T向Dst发送了Type-P数据包的第一位，而Dst没有接收到该数据包（在丢失阈值等待时间Tmax内）。
Suggestions for what to report and metric values appear in Section 3.8 after a discussion of the metric, methodologies for measuring the metric, and error analysis.
在讨论度量、度量方法和误差分析后，第3.8节给出了报告内容和度量值的建议。
Type-P-One-way-Delay is a relatively simple analytic metric, and one that we believe will afford effective methods of measurement.
P型单向延迟是一个相对简单的分析指标，我们相信它将提供有效的测量方法。
The following issues are likely to come up in practice:
在实践中可能会出现以下问题：
o Real delay values will be positive. Therefore, it does not make sense to report a negative value as a real delay. However, an individual zero or negative delay value might be useful as part of a stream when trying to discover a distribution of a stream of delay values.
o 实际延迟值将为正值。因此，将负值报告为实际延迟是没有意义的。然而，当试图发现延迟值流的分布时，作为流的一部分，单个零或负延迟值可能是有用的。
o Since delay values will often be as low as the 100 usec to 10 msec range, it will be important for Src and Dst to synchronize very closely. Global Positioning System (GPS) systems afford one way to achieve synchronization to within several tens of usec. Ordinary application of NTP may allow synchronization to within several msec, but this depends on the stability and symmetry of delay properties among those NTP agents used, and this delay is what we are trying to measure. A combination of some GPS-based NTP servers and a conservatively designed and deployed set of other NTP servers should yield good results. This was tested in [RFC6808], where a GPS measurement system's results compared well with a GPS-based NTP synchronized system for the same intercontinental path.
o 由于延迟值通常低至100 usec至10 ms的范围，因此Src和Dst必须非常紧密地同步。全球定位系统（GPS）系统提供了一种在几十个usec内实现同步的方法。NTP的普通应用可能允许同步在几毫秒内，但这取决于所使用的NTP代理之间延迟特性的稳定性和对称性，我们正试图测量这种延迟。一些基于GPS的NTP服务器和一组保守设计和部署的其他NTP服务器的组合应该会产生良好的结果。这在[RFC6808]中进行了测试，其中GPS测量系统的结果与基于GPS的NTP同步系统在相同的洲际路径上进行了很好的比较。
o A given methodology will have to include a way to determine whether a delay value is infinite or whether it is merely very large (and the packet is yet to arrive at Dst). As noted by Mahdavi and Paxson [RFC2678], simple upper bounds (such as the 255 seconds theoretical upper bound on the lifetimes of IP packets [RFC791]) could be used; but good engineering, including an understanding of packet lifetimes, will be needed in practice. {Comment: Note that, for many applications of these metrics, the harm in treating a large delay as infinite might be zero or very small. A TCP data packet, for example, that arrives only after several multiples of the RTT may as well have been lost. See Section 4.1.1 of [RFC6703] for examination of unusual packet delays and application performance estimation.}
o 给定的方法必须包括确定延迟值是无限大还是非常大（数据包尚未到达Dst）的方法。正如Mahdavi和Paxson[RFC2678]所指出的，可以使用简单的上限（例如IP数据包[RFC791]寿命的255秒理论上限）；但在实践中需要良好的工程设计，包括对数据包寿命的理解。{注释：注意，对于这些指标的许多应用，将大延迟视为无限的危害可能为零或很小。例如，仅在RTT的几倍之后到达的TCP数据包也可能丢失。请参阅[RFC6703]的第4.1.1节用于检查异常数据包延迟和应用程序性能评估。}
o If the packet is duplicated along the path (or paths) so that multiple non-corrupt copies arrive at the destination, then the packet is counted as received, and the first copy to arrive determines the packet's one-way delay.
o 如果数据包沿着路径（一个或多个路径）复制，以便多个未损坏的副本到达目的地，则数据包被计为已接收，并且到达的第一个副本确定数据包的单向延迟。
o If the packet is fragmented and if, for whatever reason, reassembly does not occur, then the packet will be deemed lost.
o 如果数据包被分割，并且无论出于何种原因，没有重新组装，那么数据包将被视为丢失。
o A given methodology will include a way to determine whether the packet is standard-formed, the default criteria for all metric definitions defined in Section 15 of [RFC2330], otherwise the packet will be deemed lost. Note: At this time, the definition of standard-formed packets only applies to IPv4, but also see [IPPM-UPDATES].
o 给定方法将包括确定数据包是否为标准格式的方法，以及[RFC2330]第15节中定义的所有度量定义的默认标准，否则数据包将被视为丢失。注意：此时，标准格式数据包的定义仅适用于IPv4，但也请参见[IPPM-UPDATES]。
As with other Type-P-* metrics, the detailed methodology will depend on the Type-P (e.g., protocol number, UDP/TCP port number, size, Differentiated Services (DS) Field [RFC2780]).
与其他类型P-*指标一样，详细方法将取决于类型P（例如，协议号、UDP/TCP端口号、大小、差异化服务（DS）字段[RFC2780]）。
Generally, for a given Type-P, the methodology would proceed as follows:
一般而言，对于给定的P型，方法如下：
o Arrange that Src and Dst are synchronized; that is, that they have clocks that are very closely synchronized with each other and each fairly close to the actual time.
o 安排Src和Dst同步；也就是说，它们的时钟彼此非常同步，并且每个时钟都非常接近实际时间。
o At the Src host, select Src and Dst IP addresses, and form a test packet of Type-P with these addresses. Any 'padding' portion of the packet needed only to make the test packet a given size should be filled with randomized bits to avoid a situation in which the measured delay is lower than it would otherwise be, due to compression techniques along the path. Also, see Section 3.1.2 of [RFC7312].
o 在Src主机上，选择Src和Dst IP地址，并使用这些地址形成类型为P的测试数据包。数据包的任何“填充”部分仅用于使测试数据包达到给定大小，应使用随机位填充，以避免由于路径上的压缩技术，测量的延迟低于其他情况。此外，请参见[RFC7312]第3.1.2节。
o At the Dst host, arrange to receive the packet.
o 在Dst主机上，安排接收数据包。
o At the Src host, place a timestamp in the prepared Type-P packet, and send it towards Dst (ideally minimizing time before sending).
o 在Src主机上，在准备好的Type-P数据包中放置一个时间戳，并将其发送到Dst（理想情况下，在发送之前最小化时间）。
o If the packet arrives within a reasonable period of time, take a timestamp as soon as possible upon the receipt of the packet. By subtracting the two timestamps, an estimate of one-way delay can be computed. Error analysis of a given implementation of the method must take into account the closeness of synchronization between Src and Dst. If the delay between Src's timestamp and the actual sending of the packet is known, then the estimate could be adjusted by subtracting this amount; uncertainty in this value must be taken into account in error analysis. Similarly, if the delay between the actual receipt of the packet and Dst's timestamp is known, then the estimate could be adjusted by subtracting this amount; uncertainty in this value must be taken into account in error analysis. See "Errors and Uncertainties" (Section 3.7) for a more detailed discussion.
o 如果数据包在合理的时间段内到达，则在收到数据包后尽快获取时间戳。通过减去这两个时间戳，可以计算出单向延迟的估计值。对给定方法实现的错误分析必须考虑Src和Dst之间同步的紧密性。如果Src的时间戳和分组的实际发送之间的延迟是已知的，则可以通过减去该量来调整估计；误差分析中必须考虑该值的不确定性。类似地，如果包的实际接收和Dst的时间戳之间的延迟是已知的，则可以通过减去该量来调整估计；误差分析中必须考虑该值的不确定性。有关更详细的讨论，请参见“误差和不确定性”（第3.7节）。
o If the packet fails to arrive within a reasonable period of time, Tmax, the one-way delay is taken to be undefined (informally, infinite). Note that the threshold of "reasonable" is a parameter of the metric. These points are examined in detail in [RFC6703], including analysis preferences to assign undefined delay to packets that fail to arrive with the difficulties emerging from the informal "infinite delay" assignment, and an estimation of an upper bound on waiting time for packets in transit. Further, enforcing a specific constant waiting time on stored singletons of one-way delay is compliant with this specification and may allow the results to serve more than one reporting audience.
o 如果数据包未能在合理的时间段Tmax内到达，则认为单向延迟是未定义的（非正式地说是无限的）。请注意，“合理”的阈值是度量的一个参数。[RFC6703]中详细研究了这些点，包括将未定义的延迟分配给无法到达的数据包的分析偏好，以及对传输中数据包等待时间上限的估计。此外，在单向延迟的存储单例上强制执行特定的恒定等待时间符合本规范，并且可以允许结果服务于多个报告受众。
Issues such as the packet format, the means by which Dst knows when to expect the test packet, and the means by which Src and Dst are synchronized are outside the scope of this document. {Comment: We plan to document the implementation techniques of our work in much more detail elsewhere; we encourage others to do so as well.}
数据包格式、Dst知道何时期望测试数据包的方法以及Src和Dst同步的方法等问题不在本文件的范围内。{评论：我们计划在其他地方更详细地记录我们工作的实施技术；我们鼓励其他人也这样做。}
The description of any specific measurement method should include an accounting and analysis of various sources of error or uncertainty. The Framework document provides general guidance on this point, but we note here the following specifics related to delay metrics:
任何特定测量方法的描述应包括对各种误差或不确定性来源的核算和分析。框架文件提供了关于这一点的一般指导，但我们注意到以下与延迟度量相关的细节：
o Errors or uncertainties due to uncertainties in the clocks of the Src and Dst hosts.
o Src和Dst主机时钟不确定性导致的错误或不确定性。
o Errors or uncertainties due to the difference between 'wire time' and 'host time'.
o 由于“连线时间”和“主机时间”之间的差异而导致的错误或不确定性。
In addition, the loss threshold may affect the results. Each of these are discussed in more detail below, along with a section (Section 3.7.3) on accounting for these errors and uncertainties.
此外，损失阈值可能会影响结果。下面将详细讨论每一项，以及关于这些误差和不确定性的说明的章节（第3.7.3节）。
The uncertainty in a measurement of one-way delay is related, in part, to uncertainties in the clocks of the Src and Dst hosts. In the following, we refer to the clock used to measure when the packet was sent from Src as the source clock, we refer to the clock used to measure when the packet was received by Dst as the destination clock, we refer to the observed time when the packet was sent by the source clock as Tsource, and we refer to the observed time when the packet was received by the destination clock as Tdest. Alluding to the notions of synchronization, accuracy, resolution, and skew mentioned in the Introduction, we note the following:
单向延迟测量的不确定性部分与Src和Dst主机时钟的不确定性有关。在下文中，我们将用于测量数据包何时从Src发送的时钟称为源时钟，将用于测量数据包何时被Dst接收的时钟称为目标时钟，将数据包何时由源时钟发送的观测时间称为Tsource，我们将目标时钟接收数据包时的观测时间称为Tdest。关于引言中提到的同步、精度、分辨率和倾斜的概念，我们注意到以下几点：
o Any error in the synchronization between the source clock and the destination clock will contribute to error in the delay measurement. We say that the source clock and the destination clock have a synchronization error of Tsynch if the source clock is Tsynch ahead of the destination clock. Thus, if we know the value of Tsynch exactly, we could correct for clock synchronization by adding Tsynch to the uncorrected value of Tdest-Tsource.
o 源时钟和目标时钟之间的同步中的任何错误都将导致延迟测量中的错误。我们说，如果源时钟比目标时钟先同步，则源时钟和目标时钟的同步误差为Tsynch。因此，如果我们准确地知道Tsynch的值，我们可以通过将Tsynch添加到Tdest Tsource的未更正值来更正时钟同步。
o The accuracy of a clock is important only in identifying the time at which a given delay was measured. Accuracy, per se, has no importance to the accuracy of the measurement of delay. When computing delays, we are interested only in the differences between clock values, not the values themselves.
o 时钟的准确性仅在确定测量给定延迟的时间时才重要。准确度本身对延迟测量的准确度并不重要。当计算延迟时，我们只关心时钟值之间的差异，而不是值本身。
o The resolution of a clock adds to uncertainty about any time measured with it. Thus, if the source clock has a resolution of 10 msec, then this adds 10 msec of uncertainty to any time value measured with it. We will denote the resolution of the source clock and the destination clock as Rsource and Rdest, respectively.
o 时钟的分辨率增加了用它测量的任何时间的不确定性。因此，如果源时钟的分辨率为10毫秒，则这会给用它测量的任何时间值增加10毫秒的不确定性。我们将源时钟和目标时钟的分辨率分别表示为Rsource和Rdest。
o The skew of a clock is not so much an additional issue as it is a realization of the fact that Tsynch is itself a function of time. Thus, if we attempt to measure or to bound Tsynch, this needs to be done periodically. Over some periods of time, this function can be approximated as a linear function plus some higher order terms; in these cases, one option is to use knowledge of the linear component to correct the clock. Using this correction, the residual Tsynch is made smaller but remains a source of uncertainty that must be accounted for. We use the function Esynch(t) to denote an upper bound on the uncertainty in synchronization. Thus, |Tsynch(t)| <= Esynch(t).
o 时钟的偏移与其说是一个额外的问题，不如说是一个认识到Tsynch本身就是时间的函数这一事实的问题。因此，如果我们试图测量或绑定Tsynch，则需要定期进行。在一段时间内，该函数可以近似为线性函数加上一些高阶项；在这些情况下，一种选择是使用线性组件的知识来校正时钟。使用此校正，剩余Tsynch变小，但仍然是必须考虑的不确定性来源。我们使用函数Esynch（t）来表示同步中不确定性的上界。因此，| Tsynch（t）|<=Esynch（t）。
Taking these items together, we note that naive computation Tdest-Tsource will be off by Tsynch(t) +/- (Rsource + Rdest). Using the notion of Esynch(t), we note that these clock-related problems introduce a total uncertainty of Esynch(t)+ Rsource + Rdest. This estimate of total clock-related uncertainty should be included in the error/uncertainty analysis of any measurement implementation.
把这些项放在一起，我们注意到原始计算Tdest Tsource将被Tsynch（t）+/-（Rsource+Rdest）关闭。使用Esynch（t）的概念，我们注意到这些与时钟相关的问题引入了Esynch（t）+Rsource+Rdest的总体不确定性。任何测量实施的误差/不确定度分析中都应包括与时钟相关的总不确定度的估计值。
As we have defined one-way delay, we would like to measure the time between when the test packet leaves the network interface of Src and when it (completely) arrives at the network interface of Dst: we refer to these as "wire times." If the timings are themselves performed by software on Src and Dst, however, then this software can
正如我们定义的单向延迟，我们希望测量测试数据包离开Src网络接口和（完全）到达Dst网络接口之间的时间：我们将这些称为“连线时间”。但是，如果计时本身由软件在Src和Dst上执行，则此软件可以
only directly measure the time between when Src grabs a timestamp just prior to sending the test packet and when Dst grabs a timestamp just after having received the test packet: we refer to these two points as "host times".
仅直接测量Src在发送测试数据包之前获取时间戳和Dst在收到测试数据包之后获取时间戳之间的时间：我们将这两点称为“主机时间”。
We note that some systems perform host time stamping on the network-interface hardware, in an attempt to minimize the difference from wire times.
我们注意到，一些系统在网络接口硬件上执行主机时间戳，以尽量减少与连线时间的差异。
To the extent that the difference between wire time and host time is accurately known, this knowledge can be used to correct for host time measurements, and the corrected value more accurately estimates the desired (wire-time) metric.
在准确知道导线时间和主机时间之间的差异的情况下，此知识可用于校正主机时间测量值，并且校正值可更准确地估计所需（导线时间）度量。
To the extent, however, that the difference between wire time and host time is uncertain, this uncertainty must be accounted for in an analysis of a given measurement method. We denote by Hsource an upper bound on the uncertainty in the difference between wire time and host time on the Src host, and similarly define Hdest for the Dst host. We then note that these problems introduce a total uncertainty of Hsource+Hdest. This estimate of total wire-vs-host uncertainty should be included in the error/uncertainty analysis of any measurement implementation.
然而，在一定程度上，导线时间和主机时间之间的差异是不确定的，在分析给定测量方法时必须考虑这种不确定性。我们用Hsource表示Src主机上的连线时间和主机时间之差的不确定性上限，并类似地定义Dst主机的Hdest。然后我们注意到，这些问题引入了Hsource+Hdest的总体不确定性。在任何测量实施的误差/不确定度分析中，应包括导线与主机总不确定度的估计值。
Generally, the measured values can be decomposed as follows:
通常，测量值可分解如下：
measured value = true value + systematic error + random error
measured value = true value + systematic error + random error
If the systematic error (the constant bias in measured values) can be determined, it can be compensated for in the reported results.
如果可以确定系统误差（测量值中的恒定偏差），则可以在报告的结果中对其进行补偿。
reported value = measured value - systematic error
报告值=测量值-系统误差
therefore:
因此：
reported value = true value + random error
报告值=真实值+随机误差
The goal of calibration is to determine the systematic and random error generated by the hosts themselves in as much detail as possible. At a minimum, a bound ("e") should be found such that the reported value is in the range (true value - e) to (true value + e) at least 95% of the time. We call "e" the calibration error for the measurements. It represents the degree to which the values produced by the measurement host are repeatable; that is, how closely an actual delay of 30 ms is reported as 30 ms. {Comment: 95% was chosen because (1) some confidence level is desirable to be able to remove
校准的目标是尽可能详细地确定主机自身产生的系统和随机误差。至少应找到一个界限（“e”），以便报告的值至少在95%的时间内处于（真值-e）到（真值+e）的范围内。我们称“e”为测量的校准误差。它表示测量主机产生的值可重复的程度；也就是说，30毫秒的实际延迟被报告为30毫秒。{注释：选择95%是因为（1）需要某种置信水平才能消除
outliers, which will be found in measuring any physical property; (2) a particular confidence level should be specified so that the results of independent implementations can be compared; and (3) even with a prototype user-level implementation, 95% was loose enough to exclude outliers.}
测量任何物理属性时会发现的异常值；（2） 应指定特定的置信水平，以便能够比较独立实现的结果；（3）即使在原型用户级实现中，95%也足够宽松，可以排除异常值
From the discussion in the previous two sections, the error in measurements could be bounded by determining all the individual uncertainties, and adding them together to form:
根据前两节中的讨论，测量误差可通过确定所有单个不确定度并将其相加形成：
Esynch(t) + Rsource + Rdest + Hsource + Hdest.
Esynch（t）+Rsource+Rdest+Hsource+Hdest。
However, reasonable bounds on both the clock-related uncertainty captured by the first three terms and the host-related uncertainty captured by the last two terms should be possible by careful design techniques and calibrating the hosts using a known, isolated network in a lab.
然而，通过仔细设计技术和在实验室中使用已知的隔离网络校准主机，前三项捕获的时钟相关不确定性和后两项捕获的主机相关不确定性的合理界限应是可能的。
For example, the clock-related uncertainties are greatly reduced through the use of a GPS time source. The sum of Esynch(t) + Rsource + Rdest is small and is also bounded for the duration of the measurement because of the global time source.
例如，通过使用GPS时间源，大大降低了与时钟相关的不确定性。Esynch（t）+Rsource+Rdest之和很小，并且由于全局时间源，在测量期间也是有界的。
The host-related uncertainties, Hsource + Hdest, could be bounded by connecting two hosts back-to-back with a high-speed serial link or isolated LAN segment. In this case, repeated measurements are measuring the same one-way delay.
通过使用高速串行链路或隔离LAN段背靠背连接两台主机，可以限制与主机相关的不确定性，即Hsource+Hdest。在这种情况下，重复测量是测量相同的单向延迟。
If the test packets are small, such a network connection has a minimal delay that may be approximated by zero. The measured delay therefore contains only systematic and random error in the measurement hosts. The "average value" of repeated measurements is the systematic error, and the variation is the random error.
如果测试数据包很小，则这种网络连接具有可近似为零的最小延迟。因此，测量的延迟仅包含测量主机中的系统和随机误差。重复测量的“平均值”是系统误差，变化是随机误差。
One way to compute the systematic error, and the random error to a 95% confidence is to repeat the experiment many times -- at least hundreds of tests. The systematic error would then be the median. The random error could then be found by removing the systematic error from the measured values. The 95% confidence interval would be the range from the 2.5th percentile to the 97.5th percentile of these deviations from the true value. The calibration error "e" could then be taken to be the largest absolute value of these two numbers, plus the clock-related uncertainty. {Comment: as described, this bound is relatively loose since the uncertainties are added, and the absolute value of the largest deviation is used. As long as the resulting value is not a significant fraction of the measured values, it is a
计算系统误差和95%置信度的随机误差的一种方法是重复实验多次——至少数百次测试。系统误差即为中位数。然后，可以通过从测量值中去除系统误差来发现随机误差。95%的置信区间是这些偏离真实值的2.5%到97.5%之间的范围。然后，校准误差“e”可被视为这两个数字的最大绝对值，加上与时钟相关的不确定度。{注释：如上所述，由于添加了不确定度，因此该界限相对宽松，并使用了最大偏差的绝对值。只要所得值不是测量值的重要部分，则为
reasonable bound. If the resulting value is a significant fraction of the measured values, then more exact methods will be needed to compute the calibration error.}
合理的界限。如果结果值是测量值的重要部分，则需要更精确的方法来计算校准误差。}
Note that random error is a function of measurement load. For example, if many paths will be measured by one host, this might increase interrupts, process scheduling, and disk I/O (for example, recording the measurements), all of which may increase the random error in measured singletons. Therefore, in addition to minimal load measurements to find the systematic error, calibration measurements should be performed with the same measurement load that the hosts will see in the field.
请注意，随机误差是测量负载的函数。例如，如果一台主机将测量多条路径，这可能会增加中断、进程调度和磁盘I/O（例如，记录测量），所有这些都可能会增加测量单例中的随机错误。因此，除了最小负载测量以发现系统误差外，还应使用主机在现场看到的相同测量负载进行校准测量。
We wish to reiterate that this statistical treatment refers to the calibration of the host; it is used to "calibrate the meter stick" and say how well the meter stick reflects reality.
我们希望重申，这种统计处理是指主机的校准；它用于“校准仪表杆”，并说明仪表杆反映现实的程度。
In addition to calibrating the hosts for finite one-way delay, two checks should be made to ensure that packets reported as losses were really lost. First, the threshold for loss should be verified. In particular, ensure the "reasonable" threshold is reasonable: that it is very unlikely a packet will arrive after the threshold value, and therefore the number of packets lost over an interval is not sensitive to the error bound on measurements. Second, consider the possibility that a packet arrives at the network interface, but is lost due to congestion on that interface or to other resource exhaustion (e.g. buffers) in the host.
除了校准主机的有限单向延迟外，还应进行两次检查，以确保报告为丢失的数据包确实丢失。首先，应验证损失阈值。特别是，确保“合理”阈值是合理的：数据包不太可能在阈值之后到达，因此在一段时间间隔内丢失的数据包数量对测量值上的错误界限不敏感。其次，考虑数据包到达网络接口的可能性，但是由于该接口上的拥塞或主机中的其他资源耗尽（例如缓冲器）而丢失。
The calibration and context in which the metric is measured MUST be carefully considered and SHOULD always be reported along with metric results. We now present four items to consider: the Type-P of test packets, the threshold of infinite delay (if any), error calibration, and the path traversed by the test packets. This list is not exhaustive; any additional information that could be useful in interpreting applications of the metrics should also be reported (see [RFC6703] for extensive discussion of reporting considerations for different audiences).
必须仔细考虑测量公制的校准和环境，并应始终与公制结果一起报告。现在，我们提出了四个需要考虑的项目：测试数据包的类型P、无限延迟阈值（如果有）、错误校准和测试数据包通过的路径。这份清单并非详尽无遗；还应报告可能有助于解释指标应用的任何其他信息（关于不同受众报告注意事项的广泛讨论，请参见[RFC6703]）。
As noted in Section 13 of the Framework document [RFC2330], the value of the metric may depend on the type of IP packets used to make the measurement, or "Type-P". The value of Type-P-One-way-Delay could change if the protocol (UDP or TCP), port number, size, or arrangement for special treatment (e.g., IP DS Field [RFC2780], Explicit Congestion Notification (ECN) [RFC3168], or RSVP) changes.
如框架文件[RFC2330]第13节所述，度量值可能取决于用于进行测量的IP数据包的类型，或“type-P”。如果协议（UDP或TCP）、端口号、大小或特殊处理安排（例如，IP DS字段[RFC2780]、显式拥塞通知（ECN）[RFC3168]或RSVP）发生变化，则类型-P-单向延迟的值可能会发生变化。
Additional packet distinctions identified in future extensions of the Type-P definition will apply. The exact Type-P used to make the measurements MUST be accurately reported.
在P型定义的未来扩展中确定的附加数据包区别将适用。必须准确报告用于进行测量的准确P型。
In addition, the threshold (or methodology to distinguish) between a large finite delay and loss MUST be reported.
此外，必须报告大型有限延迟和损失之间的阈值（或区分方法）。
o If the systematic error can be determined, it SHOULD be removed from the measured values.
o 如果可以确定系统误差，应将其从测量值中删除。
o You SHOULD also report the calibration error, e, such that the true value is the reported value plus or minus e, with 95% confidence (see the last section.)
o 还应报告校准误差e，以便真实值为报告值加上或减去e，置信度为95%（见最后一节）
o If possible, the conditions under which a test packet with finite delay is reported as lost due to resource exhaustion on the measurement host SHOULD be reported.
o 如果可能，应报告具有有限延迟的测试数据包由于测量主机上的资源耗尽而丢失的情况。
Finally, the path traversed by the packet SHOULD be reported, if possible. In general, it is impractical to know the precise path a given packet takes through the network. The precise path may be known for certain Type-P on short or stable paths. If Type-P includes the record route (or loose-source route) option in the IP header, and the path is short enough, and all routers* on the path support record (or loose-source) route, then the path will be precisely recorded. This is impractical because the route must be short enough, many routers do not support (or are not configured for) record route, and use of this feature would often artificially worsen the performance observed by removing the packet from common-case processing. However, partial information is still valuable context. For example, if a host can choose between two links* (and hence, two separate routes from Src to Dst), then the initial link used is valuable context. {Comment: For example, with Merit's NetNow setup, a Src on one Network Access Point (NAP) can reach a Dst on another NAP by either of several different backbone networks.}
最后，如果可能的话，应该报告数据包经过的路径。通常，要知道给定数据包通过网络的精确路径是不切实际的。对于短路径或稳定路径上的某些P型，可能已知精确路径。如果Type-P在IP报头中包含记录路由（或松散源路由）选项，并且路径足够短，并且路径上的所有路由器*都支持记录（或松散源）路由，则将精确记录路径。这是不切实际的，因为路由必须足够短，许多路由器不支持（或未配置）记录路由，并且使用此功能通常会人为地降低从常见情况处理中删除数据包所观察到的性能。然而，部分信息仍然是有价值的。例如，如果主机可以在两条链路*（以及从Src到Dst的两条独立路由）之间进行选择，则使用的初始链路是有价值的上下文。{注释：例如，使用Merit的NetNow设置，一个网络接入点（NAP）上的Src可以通过几个不同的主干网络中的任何一个到达另一个NAP上的Dst。}
Given the singleton metric Type-P-One-way-Delay, we now define one particular sample of such singletons. The idea of the sample is to select a particular binding of the parameters Src, Dst, and Type-P, then define a sample of values of parameter T. The means for
给定单例度量类型-P-单向延迟，我们现在定义一个此类单例的特定样本。示例的思想是选择参数Src、Dst和Type-P的特定绑定，然后定义参数T值的示例
defining the values of T is to select a beginning time T0, a final time Tf, and an average rate lambda, then define a pseudorandom Poisson process of rate lambda, whose values fall between T0 and Tf.
定义T的值是选择开始时间T0、最终时间Tf和平均速率lambda，然后定义速率lambda的伪随机泊松过程，其值介于T0和Tf之间。
The time interval between successive values of T will then average 1/ lambda.
随后，T连续值之间的时间间隔将平均为1/lambda。
Note that Poisson sampling is only one way of defining a sample. Poisson has the advantage of limiting bias, but other methods of sampling will be appropriate for different situations. For example, a truncated Poisson distribution may be needed to avoid reactive network state changes during intervals of inactivity, see Section 4.6 of [RFC7312]. Sometimes the goal is sampling with a known bias, and [RFC3432] describes a method for periodic sampling with random start times.
请注意，泊松采样只是定义样本的一种方法。泊松法具有限制偏差的优点，但其他取样方法适用于不同的情况。例如，可能需要截断的泊松分布，以避免在非活动间隔期间发生反应性网络状态变化，请参见[RFC7312]第4.6节。有时，目标是使用已知偏差进行采样，[RFC3432]描述了一种使用随机开始时间进行周期采样的方法。
Type-P-One-way-Delay-Poisson-Stream
P型单向延迟泊松流
o Src, the IP address of a host
o Src，主机的IP地址
o Dst, the IP address of a host
o Dst，主机的IP地址
o T0, a time
o T0，一次
o Tf, a time
o Tf，一次
o Tmax, a loss threshold waiting time
o Tmax，损失阈值等待时间
o lambda, a rate in reciprocal seconds (or parameters for another distribution)
o lambda，以倒数秒为单位的速率（或其他分布的参数）
A sequence of pairs; the elements of each pair are:
成对的序列；每对的元素包括：
o T, a time, and
o T、 一次，和
o dT, either a real number or an undefined number of seconds.
o dT，一个实数或未定义的秒数。
The values of T in the sequence are monotonic increasing. Note that T would be a valid parameter to Type-P-One-way-Delay and that dT would be a valid value of Type-P-One-way-Delay.
序列中T的值是单调递增的。注意，T将是Type-P-One-way-Delay的有效参数，dT将是Type-P-One-way-Delay的有效值。
Given T0, Tf, and lambda, we compute a pseudorandom Poisson process beginning at or before T0, with average arrival rate lambda, and ending at or after Tf. Those time values greater than or equal to T0 and less than or equal to Tf are then selected. At each of the selected times in this process, we obtain one value of Type-P-One-way-Delay. The value of the sample is the sequence made up of the resulting <time, delay> pairs. If there are no such pairs, the sequence is of length zero and the sample is said to be empty.
给定T0、Tf和lambda，我们计算一个伪随机泊松过程，从T0开始或之前，平均到达率lambda，到Tf结束或之后。然后选择大于或等于T0且小于或等于Tf的时间值。在该过程中的每个选定时间，我们获得一个P型单向延迟值。样本值是由结果<时间，延迟>对组成的序列。如果没有这样的对，序列的长度为零，样本称为空。
The reader should be familiar with the in-depth discussion of Poisson sampling in the Framework document [RFC2330], which includes methods to compute and verify the pseudorandom Poisson process.
读者应熟悉框架文件[RFC2330]中对泊松抽样的深入讨论，其中包括计算和验证伪随机泊松过程的方法。
We specifically do not constrain the value of lambda except to note the extremes. If the rate is too large, then the measurement traffic will perturb the network and itself cause congestion. If the rate is too small, then you might not capture interesting network behavior. {Comment: We expect to document our experiences with, and suggestions for, lambda elsewhere, culminating in a "Best Current Practice" document.}
我们特别不限制lambda的值，除非注意极端情况。如果速率太大，则测量流量将干扰网络，并自身导致拥塞。如果速率太小，则可能无法捕获有趣的网络行为。{评论：我们希望记录我们在其他地方与lambda合作的经验和建议，最终形成一份“当前最佳实践”文件。}
Since a pseudorandom number sequence is employed, the sequence of times, and hence the value of the sample, is not fully specified. Pseudorandom number generators of good quality will be needed to achieve the desired qualities.
由于采用了伪随机数序列，因此没有完全指定时间序列以及样本值。为了达到所需的质量，需要高质量的伪随机数发生器。
The sample is defined in terms of a Poisson process both to avoid the effects of self-synchronization and also capture a sample that is statistically as unbiased as possible. {Comment: there is, of course, no claim that real Internet traffic arrives according to a Poisson arrival process.} The Poisson process is used to schedule the delay measurements. The test packets will generally not arrive at Dst according to a Poisson distribution, since they are influenced by the network.
根据泊松过程定义样本，以避免自同步的影响，并捕获统计上尽可能无偏的样本。{注释：当然，没有人声称真正的互联网流量是根据泊松到达过程到达的。}泊松过程用于安排延迟测量。测试数据包通常不会根据泊松分布到达Dst，因为它们受到网络的影响。
All the singleton Type-P-One-way-Delay metrics in the sequence will have the same values of Src, Dst, and Type-P.
序列中的所有单例Type-P单向延迟度量将具有相同的Src、Dst和Type-P值。
Note also that, given one sample that runs from T0 to Tf, and given new time values T0' and Tf' such that T0 <= T0' <= Tf' <= Tf, the subsequence of the given sample whose time values fall between T0' and Tf' are also a valid Type-P-One-way-Delay-Poisson-Stream sample.
还要注意，给定一个从T0运行到Tf的样本，并且给定新的时间值T0'和Tf'，使得T0<=T0'<=Tf'<=Tf'，其时间值介于T0'和Tf'之间的给定样本的子序列也是有效的P型单向延迟泊松流样本。
The methodologies follow directly from:
这些方法直接来自：
o The selection of specific times using the specified Poisson arrival process, and
o 使用指定的泊松到达过程选择特定时间，以及
o The methodologies discussion already given for the singleton Type-P-One-way-Delay metric.
o 已经给出了单例类型P单向延迟度量的方法论讨论。
Care must be given to correctly handle out-of-order arrival of test packets; it is possible that the Src could send one test packet at TS[i], then send a second one (later) at TS[i+1] while the Dst could receive the second test packet at TR[i+1], and then receive the first one (later) at TR[i]. Metrics for reordering may be found in [RFC4737].
必须注意正确处理无序到达的测试数据包；Src可能在TS[i]发送一个测试数据包，然后在TS[i+1]发送第二个（稍后），而Dst可能在TR[i+1]接收第二个测试数据包，然后在TR[i]接收第一个（稍后）。可在[RFC4737]中找到重新排序的指标。
In addition to sources of errors and uncertainties associated with methods employed to measure the singleton values that make up the sample, care must be given to analyze the accuracy of the Poisson process with respect to the wire times of the sending of the test packets. Problems with this process could be caused by several things, including problems with the pseudorandom number techniques used to generate the Poisson arrival process, or with jitter in the value of Hsource (mentioned above as uncertainty in the singleton delay metric). The Framework document shows how to use the Anderson-Darling test to verify the accuracy of a Poisson process over small time frames. {Comment: The goal is to ensure that test packets are sent "close enough" to a Poisson schedule and avoid periodic behavior.}
除了与用于测量构成样本的单态值的方法相关的误差和不确定性来源外，还必须注意分析与发送测试数据包的连线时间有关的泊松过程的准确性。该过程的问题可能由多种因素引起，包括用于生成泊松到达过程的伪随机数技术的问题，或Hsource值的抖动（如上所述为单态延迟度量中的不确定性）。框架文档展示了如何使用Anderson-Darling检验在小时间范围内验证泊松过程的准确性。{注释：目标是确保发送的测试数据包“足够接近”泊松时间表，并避免周期性行为。}
The calibration and context for the underlying singletons MUST be reported along with the stream. (See "Reporting the Metric" for Type-P-One-way-Delay in Section 3.8.)
底层单例的校准和上下文必须与流一起报告。（参见第3.8节中关于P型单向延迟的“报告度量”。）
Given the sample metric Type-P-One-way-Delay-Poisson-Stream, we now offer several statistics of that sample. These statistics are offered mostly to illustrate what could be done. See [RFC6703] for additional discussion of statistics that are relevant to different audiences.
给定样本度量类型P-单向延迟-泊松流，我们现在提供该样本的几种统计信息。提供这些统计数据主要是为了说明可以做些什么。有关与不同受众相关的统计数据的更多讨论，请参见[RFC6703]。
Given a Type-P-One-way-Delay-Poisson-Stream and a percent X between 0% and 100%, the Xth percentile of all the dT values in the stream. In computing this percentile, undefined values are treated as infinitely large. Note that this means that the percentile could thus be undefined (informally, infinite). In addition, the Type-P-One-way-Delay-Percentile is undefined if the sample is empty.
给定P型单向延迟泊松流和0%到100%之间的百分比X，流中所有dT值的第X百分位。在计算该百分位数时，未定义的值被视为无穷大。请注意，这意味着百分位数可能因此未定义（非正式地说是无限的）。此外，如果样本为空，则类型-P-单向延迟-百分比未定义。
For example: suppose we take a sample and the results are as follows:
例如：假设我们抽取一个样本，结果如下：
Stream1 = <
Stream1 = <
<T1, 100 msec>
<T1，100毫秒>
<T2, 110 msec>
<T2，110毫秒>
<T3, undefined>
<T3，未定义>
<T4, 90 msec>
<T4，90毫秒>
<T5, 500 msec>
<T5500毫秒>
>
>
Then, the 50th percentile would be 110 msec, since 90 msec and 100 msec are smaller and 500 msec and 'undefined' are larger. See Section 11.3 of [RFC2330] for computing percentiles.
然后，第50个百分位是110毫秒，因为90毫秒和100毫秒更小，500毫秒和“未定义”更大。计算百分位数见[RFC2330]第11.3节。
Note that if the possibility that a packet with finite delay is reported as lost is significant, then a high percentile (90th or 95th) might be reported as infinite instead of finite.
注意，如果具有有限延迟的数据包被报告为丢失的可能性很大，那么高百分位（第90或95位）可能被报告为无限而不是有限。
Given a Type-P-One-way-Delay-Poisson-Stream, the median of all the dT values in the stream. In computing the median, undefined values are treated as infinitely large. As with Type-P-One-way-Delay-Percentile, Type-P-One-way-Delay-Median is undefined if the sample is empty.
给定一个P型单向延迟泊松流，流中所有dT值的中值。在计算中值时，未定义的值被视为无穷大。与Type-P-One-way-Delay-Percentile一样，如果样本为空，则Type-P-One-way-Delay-Median未定义。
As noted in the Framework document, the median differs from the 50th percentile only when the sample contains an even number of values, in which case the mean of the two central values is used.
如框架文件所述，只有当样本包含偶数个值时，中位数才与第50百分位不同，在这种情况下，使用两个中心值的平均值。
For example, suppose we take a sample and the results are as follows:
例如，假设我们抽取一个样本，结果如下：
Stream2 = <
Stream2 = <
<T1, 100 msec>
<T1，100毫秒>
<T2, 110 msec>
<T2，110毫秒>
<T3, undefined>
<T3，未定义>
<T4, 90 msec>
<T4，90毫秒>
>
>
Then, the median would be 105 msec, the mean of 100 msec and 110 msec, the two central values.
然后，中位数将是105毫秒，100毫秒和110毫秒的平均值，这两个中心值。
Given a Type-P-One-way-Delay-Poisson-Stream, the minimum of all the dT values in the stream. In computing this, undefined values are treated as infinitely large. Note that this means that the minimum could thus be undefined (informally, infinite) if all the dT values are undefined. In addition, the Type-P-One-way-Delay-Minimum is undefined if the sample is empty.
给定一个P型单向延迟泊松流，流中所有dT值的最小值。在计算时，未定义的值被视为无穷大。注意，这意味着如果所有dT值都未定义，则最小值可能因此未定义（非正式地说，无限）。此外，如果样本为空，则类型-P-单向延迟-最小值未定义。
In the above example, the minimum would be 90 msec.
在上述示例中，最小值为90毫秒。
Note: This statistic is deprecated in this document because of lack of use.
注意：由于缺乏使用，此统计数据在本文档中不推荐使用。
Given a Type-P-One-way-Delay-Poisson-Stream and a time duration threshold, the fraction of all the dT values in the stream less than or equal to the threshold. The result could be as low as 0% (if all the dT values exceed threshold) or as high as 100%. Type-P-One-way-Delay-Inverse-Percentile is undefined if the sample is empty.
给定P型单向延迟泊松流和持续时间阈值，流中所有dT值的分数小于或等于阈值。结果可能低至0%（如果所有dT值超过阈值），或高达100%。如果样本为空，则类型-P-单向延迟-反向百分位数未定义。
In the above example, the Inverse-Percentile of 103 msec would be 50%.
在上面的例子中，103毫秒的反百分位为50%。
Conducting Internet measurements raises both security and privacy concerns. This memo does not specify an implementation of the metrics, so it does not directly affect the security of the Internet nor of applications that run on the Internet. However, implementations of these metrics must be mindful of security and privacy concerns.
进行互联网测量会引起安全和隐私问题。此备忘录未指定指标的实现，因此它不会直接影响Internet或在Internet上运行的应用程序的安全性。然而，这些指标的实现必须考虑安全和隐私问题。
There are two types of security concerns: potential harm caused by the measurements and potential harm to the measurements. The measurements could cause harm because they are active and inject packets into the network. The measurement parameters MUST be carefully selected so that the measurements inject trivial amounts of additional traffic into the networks they measure. If they inject "too much" traffic, they can skew the results of the measurement and in extreme cases cause congestion and denial of service.
有两种类型的安全问题：由测量引起的潜在危害和对测量的潜在危害。这些测量可能会造成危害，因为它们处于活动状态，并将数据包注入网络。必须仔细选择测量参数，以便测量将少量的额外流量注入到它们测量的网络中。如果它们注入了“过多”流量，则可能会扭曲测量结果，并在极端情况下导致拥塞和拒绝服务。
The measurements themselves could be harmed by routers giving measurement traffic a different priority than "normal" traffic or by an attacker injecting artificial measurement traffic. If routers can recognize measurement traffic and treat it separately, the measurements will not reflect actual user traffic. Therefore, the measurement methodologies SHOULD include appropriate techniques to reduce the probability that measurement traffic can be distinguished from "normal" traffic.
路由器给予测量流量不同于“正常”流量的优先级，或者攻击者注入人工测量流量，可能会损害测量本身。如果路由器能够识别测量流量并单独处理，那么测量将不会反映实际的用户流量。因此，测量方法应包括适当的技术，以降低测量流量可与“正常”流量区分的概率。
If an attacker injects packets emulating traffic that are accepted as legitimate, the loss ratio or other measured values could be corrupted. Authentication techniques, such as digital signatures, may be used where appropriate to guard against injected traffic attacks.
如果攻击者注入模拟被接受为合法流量的数据包，则丢失率或其他测量值可能会损坏。在适当的情况下，可以使用诸如数字签名之类的认证技术来防止注入流量攻击。
When considering privacy of those involved in measurement or those whose traffic is measured, the sensitive information available to potential observers is greatly reduced when using active techniques that are within this scope of work. Passive observations of user traffic for measurement purposes raise many privacy issues. We refer the reader to the privacy considerations described in the Large Scale Measurement of Broadband Performance (LMAP) Framework [RFC7594], which covers active and passive techniques.
当考虑到参与测量的人或其流量被测量的人的隐私时，当使用此工作范围内的主动技术时，潜在观察者可用的敏感信息会大大减少。出于测量目的对用户流量进行被动观测会引起许多隐私问题。我们建议读者参考大规模宽带性能测量（LMAP）框架[RFC7594]中描述的隐私注意事项，该框架涵盖主动和被动技术。
Collecting measurements or using measurement results for reconnaissance to assist in subsequent system attacks is quite common. Access to measurement results, or control of the measurement systems to perform reconnaissance should be guarded against. See
收集测量值或使用测量结果进行侦察以协助后续系统攻击是很常见的。应防止接触测量结果或控制测量系统进行侦察。看见
Section 7 of [RFC7594] (Security Considerations of the LMAP Framework) for system requirements that help to avoid measurement system compromise.
[RFC7594]第7节（LMAP框架的安全注意事项）介绍了有助于避免测量系统受损的系统要求。
The text above constitutes a revision to RFC 2769, which is now an Internet Standard. This section tracks the changes from [RFC2679].
上述文本构成对RFC 2769的修订，RFC 2769现在是一个互联网标准。本节跟踪[RFC2679]中的更改。
[RFC6808] provides the test plan and results supporting [RFC2679] advancement along the Standards Track, according to the process in [RFC6576]. The conclusions of [RFC6808] list four minor modifications:
[RFC6808]根据[RFC6576]中的流程，提供了支持[RFC2679]沿着标准轨道前进的测试计划和结果。[RFC6808]的结论列出了四个小的修改：
1. Section 6.2.3 of [RFC6808] asserts that the assumption of post-processing to enforce a constant waiting time threshold is compliant and that the text of the RFC should be revised slightly to include this point. The applicability of post-processing was added in the last list item of Section 3.6.
1. [RFC6808]第6.2.3节声称，实施恒定等待时间阈值的后处理假设是符合的，RFC的文本应稍作修改，以包括这一点。第3.6节最后一个列表项中增加了后处理的适用性。
2. Section 6.5 of [RFC6808] indicates that the Type-P-One-way-Delay-Inverse-Percentile statistic has been ignored in both implementations, so it was a candidate for removal or deprecation in this document (this small discrepancy does not affect candidacy for advancement). This statistic was deprecated in Section 5.4.
2. [RFC6808]第6.5节指出，在两种实施方式中，类型-P-单向延迟-逆百分位数统计被忽略，因此它是本文件中删除或弃用的候选项（这一小差异不影响晋升候选项）。该统计数据在第5.4节中被弃用。
3. The IETF has reached consensus on guidance for reporting metrics in [RFC6703], and the memo is referenced in this document to incorporate recent experience where appropriate. This reference was added in the last list item of Section 3.6, Section 3.8, and in Section 5.
3. IETF已就[RFC6703]中的报告指标指南达成共识，本文件中引用了备忘录，以在适当情况下纳入近期经验。该参考添加在第3.6节、第3.8节和第5节的最后一个列表项中。
4. There is currently one erratum with status "Held for Document Update" (EID 398) for [RFC2679], and this minor revision and additional text was incorporated in this document in Section 5.1.
4. [RFC2679]目前有一个状态为“为文件更新而保留”（EID 398）的勘误表，本次小修订和补充文本包含在本文件第5.1节中。
A number of updates to the [RFC2679] text have been implemented in the text above to reference key IPPM RFCs that were approved after [RFC2679] and to address comments on the IPPM mailing list describing current conditions and experience.
上文对[RFC2679]文本进行了大量更新，以参考[RFC2679]之后批准的关键IPPM RFC，并解决IPPM邮件列表中描述当前条件和经验的评论。
1. Near the end of Section 1.1, there is an update of a network example using ATM, a clarification of TCP's affect on queue occupation, and discussion of the importance of one-way delay measurement.
1. 在第1.1节末尾，更新了使用ATM的网络示例，阐明了TCP对队列占用的影响，并讨论了单向延迟测量的重要性。
2. Explicit inclusion of the maximum waiting time input parameter in Sections 3.2 and 4.2, reflecting recognition of this parameter in more recent RFCs and ITU-T Recommendation Y.1540.
2. 在第3.2节和第4.2节中明确包含最大等待时间输入参数，反映了在最近的RFCs和ITU-T建议Y.1540中对该参数的认可。
3. Addition of a reference to RFC 6703 in the discussion of packet lifetime and application timeouts in Section 3.5.
3. 在第3.5节讨论数据包寿命和应用程序超时时，增加了对RFC 6703的参考。
4. Addition of a reference to the default requirement (that packets be standard-formed) from RFC 2330 as a new list item in Section 3.5.
4. 添加对RFC 2330中默认要求（即数据包为标准格式）的参考，作为第3.5节中的新列表项。
5. GPS-based NTP experience replaces "to be tested" in Section 3.5.
5. 基于GPS的NTP经验取代了第3.5节中的“待测试”。
6. Replaced "precedence" with updated terminology (DS Field) in Sections 3.6 and 3.8.1(with reference).
6. 用第3.6节和第3.8.1节（参考）中更新的术语（DS字段）替换“优先级”。
7. Added parenthetical guidance on minimizing the interval between timestamp placement to send time in Section 3.6.
7. 在第3.6节中增加了关于最小化时间戳放置到发送时间之间的间隔的附加指南。
8. Section 3.7.2 notes that some current systems perform host time stamping on the network-interface hardware.
8. 第3.7.2节指出，一些当前系统在网络接口硬件上执行主机时间戳。
9. "instrument" replaced by the defined term "host" in Section 3.7.3 and Section 3.8.3.
9. “仪器”替换为第3.7.3节和第3.8.3节中定义的术语“主机”。
10. Added reference to RFC 3432 regarding periodic sampling alongside Poisson sampling in Section 4 and also noted that a truncated Poisson distribution may be needed with modern networks as described in the IPPM Framework update [RFC7312].
10. 在第4节中增加了对RFC 3432关于周期性抽样和泊松抽样的参考，并注意到现代网络可能需要截断泊松分布，如IPPM框架更新[RFC7312]中所述。
11. Added a reference to RFC 4737 regarding reordering metrics in the related discussion of "Methodologies (Section 4.6).
11. 在“方法学”（第4.6节）的相关讨论中，增加了对RFC 4737关于重新排序指标的参考。
12. Modified the formatting of the example in Section 5.1 to match the original (issue with conversion to XML in this version).
12. 修改了第5.1节中示例的格式，以匹配原始格式（此版本中的转换为XML问题）。
13. Clarified the conclusions on two related points on harm to measurements (recognition of measurement traffic for unexpected priority treatment and attacker traffic which emulates measurement) in "Security Considerations (Section 6).
13. 澄清了“安全注意事项（第6节）”中关于测量危害的两个相关点的结论（识别意外优先级处理的测量流量和模拟测量的攻击者流量）。
14. Expanded and updated the material on Privacy and added cautions on the use of measurements for reconnaissance in "Security Considerations" (Section 6).
14. 在“安全注意事项”（第6节）中，扩展和更新了有关隐私的材料，并增加了关于使用测量进行侦察的注意事项。
Section 5.4.4 of [RFC6390] suggests a common template for performance metrics partially derived from previous IPPM and Benchmarking Methodology Working Group (BMWG) RFCs, but it also contains some new
[RFC6390]第5.4.4节提出了部分源自先前IPPM和基准方法工作组（BMWG）RFC的绩效指标通用模板，但也包含一些新的内容
items. All of the normative parts of [RFC6390] are covered, but not quite in the same section names or orientation. Several of the informative parts are covered. Maintaining the familiar outline of IPPM literature has both value and minimizes unnecessary differences between this revised RFC and current/future IPPM RFCs.
项目。[RFC6390]的所有规范性部分均已涵盖，但并不完全在相同的章节名称或方向中。介绍了其中的几个信息部分。维护熟悉的IPPM文献大纲既有价值，又能最大限度地减少修订后的RFC与当前/未来IPPM RFC之间不必要的差异。
The publication of [RFC6921] suggested an area where this memo might need updating. Packet transfer on Faster-Than-Light (FTL) networks could result in negative delays and packet reordering; however, both are covered as possibilities in the current text and no revisions are deemed necessary (we also note that [RFC6921] is an April 1st RFC).
[RFC6921]的发布提出了本备忘录可能需要更新的一个领域。超光速（FTL）网络上的数据包传输可能导致负延迟和数据包重新排序；然而，在当前文本中，这两种情况都被视为可能，不需要进行任何修订（我们还注意到，[RFC6921]是4月1日的RFC）。
[RFC791] Postel, J., "Internet Protocol", STD 5, RFC 791, DOI 10.17487/RFC0791, September 1981, <http://www.rfc-editor.org/info/rfc791>.
[RFC791]Postel，J.，“互联网协议”，STD 5，RFC 791，DOI 10.17487/RFC07911981年9月<http://www.rfc-editor.org/info/rfc791>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>.
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，DOI 10.17487/RFC2119，1997年3月<http://www.rfc-editor.org/info/rfc2119>.
[RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis, "Framework for IP Performance Metrics", RFC 2330, DOI 10.17487/RFC2330, May 1998, <http://www.rfc-editor.org/info/rfc2330>.
[RFC2330]Paxson，V.，Almes，G.，Mahdavi，J.，和M.Mathis，“IP性能度量框架”，RFC 2330，DOI 10.17487/RFC2330，1998年5月<http://www.rfc-editor.org/info/rfc2330>.
[RFC2678] Mahdavi, J. and V. Paxson, "IPPM Metrics for Measuring Connectivity", RFC 2678, DOI 10.17487/RFC2678, September 1999, <http://www.rfc-editor.org/info/rfc2678>.
[RFC2678]Mahdavi，J.和V.Paxson，“测量连接性的IPPM度量”，RFC 2678，DOI 10.17487/RFC2678，1999年9月<http://www.rfc-editor.org/info/rfc2678>.
[RFC2679] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way Delay Metric for IPPM", RFC 2679, DOI 10.17487/RFC2679, September 1999, <http://www.rfc-editor.org/info/rfc2679>.
[RFC2679]Almes，G.，Kalidini，S.，和M.Zekauskas，“IPPM的单向延迟度量”，RFC 2679，DOI 10.17487/RFC2679，1999年9月<http://www.rfc-editor.org/info/rfc2679>.
[RFC2780] Bradner, S. and V. Paxson, "IANA Allocation Guidelines For Values In the Internet Protocol and Related Headers", BCP 37, RFC 2780, DOI 10.17487/RFC2780, March 2000, <http://www.rfc-editor.org/info/rfc2780>.
[RFC2780]Bradner，S.和V.Paxson，“互联网协议和相关报头中值的IANA分配指南”，BCP 37，RFC 2780，DOI 10.17487/RFC2780，2000年3月<http://www.rfc-editor.org/info/rfc2780>.
[RFC3432] Raisanen, V., Grotefeld, G., and A. Morton, "Network performance measurement with periodic streams", RFC 3432, DOI 10.17487/RFC3432, November 2002, <http://www.rfc-editor.org/info/rfc3432>.
[RFC3432]Raisanen，V.，Grotefeld，G.，和A.Morton，“周期流的网络性能测量”，RFC 3432，DOI 10.17487/RFC3432，2002年11月<http://www.rfc-editor.org/info/rfc3432>.
[RFC6576] Geib, R., Ed., Morton, A., Fardid, R., and A. Steinmitz, "IP Performance Metrics (IPPM) Standard Advancement Testing", BCP 176, RFC 6576, DOI 10.17487/RFC6576, March 2012, <http://www.rfc-editor.org/info/rfc6576>.
[RFC6576]Geib，R.，Ed.，Morton，A.，Fardid，R.，和A.Steinmitz，“IP性能度量（IPPM）标准推进测试”，BCP 176，RFC 6576，DOI 10.17487/RFC6576，2012年3月<http://www.rfc-editor.org/info/rfc6576>.
[RFC7312] Fabini, J. and A. Morton, "Advanced Stream and Sampling Framework for IP Performance Metrics (IPPM)", RFC 7312, DOI 10.17487/RFC7312, August 2014, <http://www.rfc-editor.org/info/rfc7312>.
[RFC7312]Fabini，J.和A.Morton，“IP性能度量的高级流和采样框架（IPPM）”，RFC 7312，DOI 10.17487/RFC7312，2014年8月<http://www.rfc-editor.org/info/rfc7312>.
[RFC7680] Almes, G., Kalidini, S., Zekauskas, M., and A. Morton, Ed., "A One-Way Loss Metric for IP Performance Metrics (IPPM)", RFC 7680, DOI 10.17487/RFC7680, January 2016, <http://www.rfc-editor.org/info/rfc7680>.
[RFC7680]Almes，G.，Kalidini，S.，Zekauskas，M.，和A.Morton，Ed.，“IP性能度量（IPPM）的单向损失度量”，RFC 7680，DOI 10.17487/RFC7680，2016年1月<http://www.rfc-editor.org/info/rfc7680>.
[IPPM-UPDATES] Morton, A., Fabini, J., Elkins, N., Ackermann, M., and V. Hegde, "Updates for IPPM's Active Metric Framework: Packets of Type-P and Standard-Formed Packets", Work in Progress, draft-morton-ippm-2330-stdform-typep-02, December 2015.
[IPPM-更新]Morton，A.，Fabini，J.，Elkins，N.，Ackermann，M.，和V.Hegde，“IPPM主动度量框架的更新：P型数据包和标准格式数据包”，正在进行的工作，草稿-Morton-IPPM-2330-stdform-typep-022015年12月。
[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition of Explicit Congestion Notification (ECN) to IP", RFC 3168, DOI 10.17487/RFC3168, September 2001, <http://www.rfc-editor.org/info/rfc3168>.
[RFC3168]Ramakrishnan，K.，Floyd，S.，和D.Black，“向IP添加显式拥塞通知（ECN）”，RFC 3168，DOI 10.17487/RFC3168，2001年9月<http://www.rfc-editor.org/info/rfc3168>.
[RFC4737] Morton, A., Ciavattone, L., Ramachandran, G., Shalunov, S., and J. Perser, "Packet Reordering Metrics", RFC 4737, DOI 10.17487/RFC4737, November 2006, <http://www.rfc-editor.org/info/rfc4737>.
[RFC4737]Morton，A.，Ciavattone，L.，Ramachandran，G.，Shalunov，S.，和J.Perser，“数据包重新排序度量”，RFC 4737，DOI 10.17487/RFC4737，2006年11月<http://www.rfc-editor.org/info/rfc4737>.
[RFC6390] Clark, A. and B. Claise, "Guidelines for Considering New Performance Metric Development", BCP 170, RFC 6390, DOI 10.17487/RFC6390, October 2011, <http://www.rfc-editor.org/info/rfc6390>.
[RFC6390]Clark，A.和B.Claise，“考虑新绩效指标开发的指南”，BCP 170，RFC 6390，DOI 10.17487/RFC6390，2011年10月<http://www.rfc-editor.org/info/rfc6390>.
[RFC6703] Morton, A., Ramachandran, G., and G. Maguluri, "Reporting IP Network Performance Metrics: Different Points of View", RFC 6703, DOI 10.17487/RFC6703, August 2012, <http://www.rfc-editor.org/info/rfc6703>.
[RFC6703]Morton，A.，Ramachandran，G.，和G.Maguluri，“报告IP网络性能指标：不同观点”，RFC 6703，DOI 10.17487/RFC6703，2012年8月<http://www.rfc-editor.org/info/rfc6703>.
[RFC6808] Ciavattone, L., Geib, R., Morton, A., and M. Wieser, "Test Plan and Results Supporting Advancement of RFC 2679 on the Standards Track", RFC 6808, DOI 10.17487/RFC6808, December 2012, <http://www.rfc-editor.org/info/rfc6808>.
[RFC6808]Ciavattone，L.，Geib，R.，Morton，A.，和M.Wieser，“支持在标准轨道上推进RFC 2679的测试计划和结果”，RFC 6808，DOI 10.17487/RFC6808，2012年12月<http://www.rfc-editor.org/info/rfc6808>.
[RFC6921] Hinden, R., "Design Considerations for Faster-Than-Light (FTL) Communication", RFC 6921, DOI 10.17487/RFC6921, April 2013, <http://www.rfc-editor.org/info/rfc6921>.
[RFC6921]Hinden，R.，“超光速（FTL）通信的设计考虑”，RFC 6921，DOI 10.17487/RFC6921，2013年4月<http://www.rfc-editor.org/info/rfc6921>.
[RFC7594] Eardley, P., Morton, A., Bagnulo, M., Burbridge, T., Aitken, P., and A. Akhter, "A Framework for Large-Scale Measurement of Broadband Performance (LMAP)", RFC 7594, DOI 10.17487/RFC7594, September 2015, <http://www.rfc-editor.org/info/rfc7594>.
[RFC7594]Eardley，P.，Morton，A.，Bagnulo，M.，Burbridge，T.，Aitken，P.，和A.Akhter，“宽带性能的大规模测量框架（LMAP）”，RFC 7594，DOI 10.17487/RFC7594，2015年9月<http://www.rfc-editor.org/info/rfc7594>.
Acknowledgements
致谢
For [RFC2679], special thanks are due to Vern Paxson of Lawrence Berkeley Labs for his helpful comments on issues of clock uncertainty and statistics. Thanks also to Garry Couch, Will Leland, Andy Scherrer, Sean Shapira, and Roland Wittig for several useful suggestions.
对于[RFC2679]，特别感谢劳伦斯伯克利实验室的Vern Paxson对时钟不确定性和统计问题的有益评论。还要感谢加里·科奇、威尔·利兰、安迪·舍勒、肖恩·沙皮拉和罗兰·维蒂格提出了一些有用的建议。
For this document, thanks to Joachim Fabini, Ruediger Geib, Nalini Elkins, and Barry Constantine for sharing their measurement experience as part of their careful reviews. Brian Carpenter and Scott Bradner provided useful feedback at IETF Last Call.
对于本文档，感谢Joachim Fabini、Ruediger Geib、Nalini Elkins和Barry Constantine分享他们的测量经验，作为他们仔细审查的一部分。Brian Carpenter和Scott Bradner在IETF的最后一次通话中提供了有用的反馈。
Authors' Addresses
作者地址
Guy Almes Texas A&M
盖伊·阿尔姆斯德克萨斯A&M
Email: almes@acm.org
Email: almes@acm.org
Sunil Kalidindi Ixia
苏尼尔卡利迪伊希亚酒店
Email: skalidindi@ixiacom.com
Email: skalidindi@ixiacom.com
Matt Zekauskas Internet2
Matt Zekauskas互联网2
Email: matt@internet2.edu
Email: matt@internet2.edu
Al Morton (editor) AT&T Labs 200 Laurel Avenue South Middletown, NJ 07748 United States
美国新泽西州劳雷尔大道南米德尔顿200号AT&T实验室Al Morton（编辑）07748
Phone: +1 732 420 1571
Fax: +1 732 368 1192
Email: acmorton@att.com
URI: http://home.comcast.net/~acmacm/
Phone: +1 732 420 1571
Fax: +1 732 368 1192
Email: acmorton@att.com
URI: http://home.comcast.net/~acmacm/