Internet Engineering Task Force (IETF) W. Sun, Ed.
Request for Comments: 6777 SJTU
Category: Standards Track G. Zhang, Ed.
ISSN: 2070-1721 CATR
J. Gao
Huawei
G. Xie
UC Riverside
R. Papneja
Huawei
November 2012
Internet Engineering Task Force (IETF) W. Sun, Ed.
Request for Comments: 6777 SJTU
Category: Standards Track G. Zhang, Ed.
ISSN: 2070-1721 CATR
J. Gao
Huawei
G. Xie
UC Riverside
R. Papneja
Huawei
November 2012
Label Switched Path (LSP) Data Path Delay Metrics in Generalized MPLS and MPLS Traffic Engineering (MPLS-TE) Networks
广义MPLS和MPLS流量工程（MPLS-TE）网络中的标签交换路径（LSP）数据路径延迟度量
Abstract
摘要
When setting up a Label Switched Path (LSP) in Generalized MPLS (GMPLS) and MPLS Traffic Engineering (MPLS-TE) networks, the completion of the signaling process does not necessarily mean that the cross-connection along the LSP has been programmed accordingly and in a timely manner. Meanwhile, the completion of the signaling process may be used by LSP users or applications that control their use as an indication that the data path has become usable. The existence of the inconsistency between the signaling messages and cross-connection programming, and the possible failure of cross-connection programming, if not properly treated, will result in data loss or even application failure. Characterization of this performance can thus help designers to improve the way in which LSPs are used and to make applications or tools that depend on and use LSPs more robust. This document defines a series of performance metrics to evaluate the connectivity of the data path in the signaling process.
在通用MPLS（GMPLS）和MPLS流量工程（MPLS-TE）网络中设置标签交换路径（LSP）时，信令过程的完成并不一定意味着LSP上的交叉连接已被相应且及时地编程。同时，信令过程的完成可被LSP用户或控制其使用的应用程序用作数据路径已变得可用的指示。如果信令消息和交叉连接编程之间存在不一致，并且交叉连接编程可能失败，如果处理不当，将导致数据丢失甚至应用程序失败。因此，这种性能的表征可以帮助设计师改进LSP的使用方式，并使依赖和使用LSP的应用程序或工具更加健壮。本文档定义了一系列性能指标，用于评估信令过程中数据路径的连接性。
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/rfc6777.
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/rfc6777.
Copyright Notice
版权公告
Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2012 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
2. Conventions Used in This Document ...............................5
3. Overview of Performance Metrics .................................5
4. Terms Used in This Document .....................................6
5. A Singleton Definition for RRFD .................................7
5.1. Motivation .................................................7
5.2. Metric Name ................................................7
5.3. Metric Parameters ..........................................7
5.4. Metric Units ...............................................7
5.5. Definition .................................................8
5.6. Discussion .................................................8
5.7. Methodologies ..............................................9
6. A Singleton Definition for RSRD ................................10
6.1. Motivation ................................................10
6.2. Metric Name ...............................................10
6.3. Metric Parameters .........................................10
6.4. Metric Units ..............................................11
6.5. Definition ................................................11
6.6. Discussion ................................................11
6.7. Methodologies .............................................12
7. A Singleton Definition for PRFD ................................13
7.1. Motivation ................................................13
7.2. Metric Name ...............................................13
7.3. Metric Parameters .........................................13
7.4. Metric Units ..............................................13
7.5. Definition ................................................14
7.6. Discussion ................................................14
7.7. Methodologies .............................................15
1. Introduction ....................................................4
2. Conventions Used in This Document ...............................5
3. Overview of Performance Metrics .................................5
4. Terms Used in This Document .....................................6
5. A Singleton Definition for RRFD .................................7
5.1. Motivation .................................................7
5.2. Metric Name ................................................7
5.3. Metric Parameters ..........................................7
5.4. Metric Units ...............................................7
5.5. Definition .................................................8
5.6. Discussion .................................................8
5.7. Methodologies ..............................................9
6. A Singleton Definition for RSRD ................................10
6.1. Motivation ................................................10
6.2. Metric Name ...............................................10
6.3. Metric Parameters .........................................10
6.4. Metric Units ..............................................11
6.5. Definition ................................................11
6.6. Discussion ................................................11
6.7. Methodologies .............................................12
7. A Singleton Definition for PRFD ................................13
7.1. Motivation ................................................13
7.2. Metric Name ...............................................13
7.3. Metric Parameters .........................................13
7.4. Metric Units ..............................................13
7.5. Definition ................................................14
7.6. Discussion ................................................14
7.7. Methodologies .............................................15
8. A Singleton Definition for PSFD ................................16
8.1. Motivation ................................................16
8.2. Metric Name ...............................................16
8.3. Metric Parameters .........................................16
8.4. Metric Units ..............................................16
8.5. Definition ................................................17
8.6. Discussion ................................................17
8.7. Methodologies .............................................18
9. A Singleton Definition for PSRD ................................19
9.1. Motivation ................................................19
9.2. Metric Name ...............................................19
9.3. Metric Parameters .........................................19
9.4. Metric Units ..............................................19
9.5. Definition ................................................20
9.6. Discussion ................................................20
9.7. Methodologies .............................................21
10. A Definition for Samples of Data Path Delay ...................22
10.1. Metric Name ..............................................22
10.2. Metric Parameters ........................................22
10.3. Metric Units .............................................22
10.4. Definition ...............................................22
10.5. Discussion ...............................................23
10.6. Methodologies ............................................23
10.7. Typical Testing Cases ....................................23
10.7.1. With No LSP in the Network ........................23
10.7.2. With a Number of LSPs in the Network ..............24
11. Some Statistics Definitions for Metrics to Report .............24
11.1. The Minimum of the Metric ................................24
11.2. The Median of the Metric .................................24
11.3. The Percentile of the Metric .............................24
11.4. Failure Probability ......................................25
11.4.1. Failure Count .....................................25
11.4.2. Failure Ratio .....................................25
12. Security Considerations .......................................25
13. References ....................................................26
13.1. Normative References .....................................26
13.2. Informative References ...................................26
Appendix A. Acknowledgements ......................................27
Appendix B. Contributors ..........................................28
8. A Singleton Definition for PSFD ................................16
8.1. Motivation ................................................16
8.2. Metric Name ...............................................16
8.3. Metric Parameters .........................................16
8.4. Metric Units ..............................................16
8.5. Definition ................................................17
8.6. Discussion ................................................17
8.7. Methodologies .............................................18
9. A Singleton Definition for PSRD ................................19
9.1. Motivation ................................................19
9.2. Metric Name ...............................................19
9.3. Metric Parameters .........................................19
9.4. Metric Units ..............................................19
9.5. Definition ................................................20
9.6. Discussion ................................................20
9.7. Methodologies .............................................21
10. A Definition for Samples of Data Path Delay ...................22
10.1. Metric Name ..............................................22
10.2. Metric Parameters ........................................22
10.3. Metric Units .............................................22
10.4. Definition ...............................................22
10.5. Discussion ...............................................23
10.6. Methodologies ............................................23
10.7. Typical Testing Cases ....................................23
10.7.1. With No LSP in the Network ........................23
10.7.2. With a Number of LSPs in the Network ..............24
11. Some Statistics Definitions for Metrics to Report .............24
11.1. The Minimum of the Metric ................................24
11.2. The Median of the Metric .................................24
11.3. The Percentile of the Metric .............................24
11.4. Failure Probability ......................................25
11.4.1. Failure Count .....................................25
11.4.2. Failure Ratio .....................................25
12. Security Considerations .......................................25
13. References ....................................................26
13.1. Normative References .....................................26
13.2. Informative References ...................................26
Appendix A. Acknowledgements ......................................27
Appendix B. Contributors ..........................................28
Label Switched Paths (LSPs) are established, controlled, and allocated for use by management tools or directly by the components that use them. In this document, we call such management tools and the components that use LSPs "applications". Such applications may be Network Management Systems (NMSs); hardware or software components that forward data onto virtual links; programs or tools that use dedicated links; or any other user of an LSP.
建立、控制和分配标签交换路径（LSP），供管理工具使用或直接由使用它们的组件使用。在本文档中，我们将此类管理工具和使用LSP的组件称为“应用程序”。此类应用可以是网络管理系统（NMS）；将数据转发到虚拟链路的硬件或软件组件；使用专用链接的程序或工具；或LSP的任何其他用户。
Ideally, the completion of the signaling process means that the signaled LSP is ready to carry traffic. However, in actual implementations, vendors may choose to program the cross-connection in a pipelined manner, so that the overall LSP provisioning delay can be reduced. In such situations, the data path may not be ready for use instantly after the signaling process completes. Implementation deficiency may also cause inconsistency between the signaling process and data path provisioning. For example, if the data plane fails to program the cross-connection accordingly but does not manage to report this to the control plane, the signaling process may complete successfully while the corresponding data path will never become functional at all.
理想情况下，信令过程的完成意味着信令LSP准备好承载业务。然而，在实际实现中，供应商可以选择以流水线方式对交叉连接进行编程，以便减少总体LSP供应延迟。在这种情况下，在信令过程完成后，数据路径可能不会立即准备好使用。实现缺陷还可能导致信令过程和数据路径供应之间的不一致。例如，如果数据平面未能相应地编程交叉连接，但没有设法将此报告给控制平面，则信令过程可以成功完成，而相应的数据路径将永远不会起作用。
On the other hand, the completion of the signaling process may be used in many cases as an indication of data path connectivity. For example, when invoking through the User-Network Interface (UNI) [RFC4208], a client device or an application may use the reception of the correct Resv message as an indication that the data path is fully functional and start to transmit traffic. This will result in data loss or even application failure.
另一方面，信令过程的完成在许多情况下可被用作数据路径连接的指示。例如，当通过用户网络接口（UNI）[RFC4208]进行调用时，客户机设备或应用程序可以使用正确Resv消息的接收作为数据路径完全工作并开始传输业务的指示。这将导致数据丢失甚至应用程序失败。
Although RSVP(-TE) specifications have suggested that the cross-connections are programmed before signaling messages are propagated upstream, it is still worthwhile to verify the conformance of an implementation and measure the delay, when necessary.
尽管RSVP（-TE）规范建议在信令消息向上游传播之前对交叉连接进行编程，但仍然值得验证实现的一致性，并在必要时测量延迟。
This document defines a series of performance metrics to evaluate the connectivity of the data path during the signaling process. The metrics defined in this document complement the control plane metrics defined in [RFC5814]. These metrics can be used to verify the conformance of implementations against related specifications, as elaborated in [RFC6383]. They also can be used to build more robust applications.
本文档定义了一系列性能指标，以评估信令过程中数据路径的连接性。本文件中定义的指标补充了[RFC5814]中定义的控制平面指标。这些指标可用于验证实现与相关规范的一致性，如[RFC6383]所述。它们还可用于构建更健壮的应用程序。
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].
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。
In this memo, we define five performance metrics to characterize the performance of data path provisioning with GMPLS/MPLS-TE signaling. These metrics complement the metrics defined in [RFC5814], in the sense that the completion of the signaling process for an LSP and the programming of cross-connections along the LSP may not be consistent. The performance metrics in [RFC5814] characterize the performance of LSP provisioning from the pure signaling point of view, while the metric in this document takes into account the validity of the data path.
在本备忘录中，我们定义了五个性能指标来描述使用GMPLS/MPLS-TE信令的数据路径供应的性能。这些度量补充了[RFC5814]中定义的度量，即LSP信令过程的完成和沿着LSP的交叉连接编程可能不一致。[RFC5814]中的性能指标从纯信令的角度描述了LSP供应的性能，而本文中的指标考虑了数据路径的有效性。
The five metrics are:
这五项指标是：
o Resv Received, Forward Data (RRFD) - the delay between the point when the Resv message is received by the ingress node and the forward data path becomes ready for use.
o Resv Received，Forward Data（RRFD）—入口节点接收到Resv消息和前向数据路径准备就绪之间的延迟。
o Resv Sent, Reverse Data (RSRD) - the delay between the point when the Resv message is sent by the egress node and the reverse data path becomes ready for use.
o Resv发送，反向数据（RSRD）-出口节点发送Resv消息与反向数据路径准备就绪之间的延迟。
o PATH Received, Forward Data (PRFD) - the delay between the point when the PATH message is received by the egress node and the forward data path becomes ready for use.
o 接收到的路径，转发数据（PRFD）-出口节点接收到路径消息和转发数据路径准备使用之间的延迟。
o PATH Sent, Forward Data (PSFD) - the delay between the point when the PATH message is sent by the ingress node and the forward data path becomes ready for use.
o 发送的路径，转发数据（PSFD）-入口节点发送路径消息和转发数据路径准备就绪之间的延迟。
o PATH Sent, Reverse Data (PSRD) - the delay between the point when the PATH message is sent by the ingress node and the reverse data path becomes ready for use.
o 已发送路径，反向数据（PSRD）-入口节点发送路径消息和反向数据路径准备就绪之间的延迟。
As in [RFC5814], we continue to use the structures and notions introduced and discussed in the IP Performance Metrics (IPPM) Framework documents [RFC2330] [RFC2679] [RFC2681]. The reader is assumed to be familiar with the notions in those documents. The reader is also assumed to be familiar with the definitions in [RFC5814].
与[RFC5814]一样，我们继续使用IP性能指标（IPPM）框架文件[RFC2330][RFC2679][RFC2681]中介绍和讨论的结构和概念。假定读者熟悉这些文件中的概念。假定读者熟悉[RFC5814]中的定义。
o Forward data path - the data path from the ingress node to the egress node. Instances of a forward data path include the data path of a unidirectional LSP and a data path from the ingress node to the egress node in a bidirectional LSP.
o 转发数据路径-从入口节点到出口节点的数据路径。前向数据路径的实例包括单向LSP的数据路径和双向LSP中从入口节点到出口节点的数据路径。
o Reverse data path - the data path from the egress node to the ingress node in a bidirectional LSP.
o 反向数据路径-双向LSP中从出口节点到入口节点的数据路径。
o Data path delay - the time needed to complete the data path configuration, in relation to the signaling process. Five types of data path delay are defined in this document, namely RRFD, RSRD, PRFD, PSFD, and PSRD. Data path delay as used in this document must be distinguished from the transmission delay along the data path, i.e., the time needed to transmit traffic from one side of the data path to the other.
o 数据路径延迟-完成数据路径配置所需的时间，与信令过程有关。本文件中定义了五种类型的数据路径延迟，即RRFD、RSRD、PRFD、PSFD和PSRD。本文件中使用的数据路径延迟必须与沿数据路径的传输延迟区分开来，即从数据路径的一侧向另一侧传输流量所需的时间。
o Error-free signal - data-plane-specific indication of connectivity of the data path. For example, for interfaces capable of packet switching, the reception of the first error-free packet from one side of the LSP to the other may be used as the error-free signal. For Synchronous Digital Hierarchy/Synchronous Optical Network (SDH/SONET) cross-connects, the disappearance of alarm can be used as the error-free signal. Throughout this document, we will use "error-free signal" as a general term. An implementation must choose a proper data path signal that is specific to the data path technology being tested.
o 无错误信号-数据路径连接的数据平面特定指示。例如，对于能够分组交换的接口，从LSP的一侧到另一侧的第一无差错分组的接收可以用作无差错信号。对于同步数字体系/同步光网络（SDH/SONET）交叉连接，报警消失可用作无错误信号。在本文档中，我们将使用“无错误信号”作为通用术语。实现必须选择特定于正在测试的数据路径技术的适当数据路径信号。
o Ingress/egress node - in this memo, an ingress/egress node means a measurement endpoint with both control plane and data plane features. Typically, the control plane part on an ingress/egress node interacts with the control plane of the network under test. The data plane part of an ingress/egress node will generate data path signals and send the signal to the data plane of the network under test, or receive data path signals from the network under test.
o 入口/出口节点-在本备忘录中，入口/出口节点指具有控制平面和数据平面特征的测量端点。通常，入口/出口节点上的控制平面部分与被测网络的控制平面交互。入口/出口节点的数据平面部分将生成数据路径信号并将该信号发送到被测网络的数据平面，或从被测网络接收数据路径信号。
This part defines a metric for forward data path delay when an LSP is set up.
本部分定义了设置LSP时前向数据路径延迟的度量。
As described in [RFC6383], the completion of the RSVP-TE signaling process does not necessarily mean that the cross-connections along the LSP being set up are in place and ready to carry traffic. This metric defines the time difference between the reception of a Resv message by the ingress node and the completion of the cross-connection programming along the forward data path.
如[RFC6383]所述，RSVP-TE信令过程的完成并不一定意味着沿着正在建立的LSP的交叉连接已经就位并准备好承载业务。该度量定义入口节点接收Resv消息与沿前向数据路径完成交叉连接编程之间的时间差。
RRFD is useful for the following reasons:
RRFD之所以有用，原因如下：
o For the reasons described in [RFC6383], the data path may not be ready for use instantly after the completion of the RSVP-TE signaling process. The delay itself is part of the implementation performance.
o 由于[RFC6383]中所述的原因，RSVP-TE信令过程完成后，数据路径可能无法立即准备好使用。延迟本身是实现性能的一部分。
o The completion of the signaling process may be used by application designers as an indication of data path connectivity. The existence of this delay and the potential failure of cross-connection programming, if not properly treated, will result in data loss or application failure. The typical value of this delay can thus help designers to improve the application model.
o 信令过程的完成可被应用设计者用作数据路径连接的指示。此延迟的存在和交叉连接编程的潜在故障，如果处理不当，将导致数据丢失或应用程序故障。因此，此延迟的典型值可以帮助设计者改进应用程序模型。
RRFD = Resv Received, Forward Data path
RRFD=接收到的Resv，转发数据路径
o ID0, the ingress Label Switching Router (LSR) ID
o ID0，入口标签交换路由器（LSR）ID
o ID1, the egress LSR ID
o ID1，出口LSR ID
o T, a time when the setup is attempted
o T、 尝试安装的时间
The value of RRFD is either a real number of milliseconds or undefined.
RRFD的值为毫秒实数或未定义。
For a real number dT,
对于实数dT，
RRFD from ingress node ID0 to egress node ID1 at T is dT
T处从入口节点ID0到出口节点ID1的RRFD是dT
means that
意味着
o ingress node ID0 sends a PATH message to egress node ID1,
o 入口节点ID0向出口节点ID1发送路径消息，
o the last bit of the corresponding Resv message is received by ingress node ID0 at T, and
o 相应Resv消息的最后一位由T处的入口节点ID0接收，并且
o an error-free signal is received by egress node ID1 by using a data-plane-specific test pattern at T+dT.
o 出口节点ID1通过在T+dT处使用特定于数据平面的测试图案来接收无差错信号。
The following issues are likely to come up in practice:
在实践中可能会出现以下问题：
o The accuracy of RRFD depends on the clock resolution of both the ingress node and egress node. Clock synchronization between the ingress node and egress node is required.
o RRFD的精度取决于入口节点和出口节点的时钟分辨率。入口节点和出口节点之间需要时钟同步。
o The accuracy of RRFD is also dependent on how the error-free signal is received and may differ significantly when the underlying data plane technology is different. For instance, for an LSP between a pair of Ethernet interfaces, the ingress node may use a rate-based method to verify the connectivity of the data path and use the reception of the first error-free frame as the error-free signal. In this case, the interval between two successive frames has a significant impact on accuracy. It is RECOMMENDED that the ingress node use small intervals, under the condition that the injected traffic does not exceed the capacity of the forward data path. The value of such intervals MUST be reported.
o RRFD的精度还取决于无差错信号的接收方式，并且当底层数据平面技术不同时，可能会有显著差异。例如，对于一对以太网接口之间的LSP，入口节点可以使用基于速率的方法来验证数据路径的连接性，并使用第一无差错帧的接收作为无差错信号。在这种情况下，两个连续帧之间的间隔对精度有重大影响。建议入口节点在注入流量不超过前向数据路径容量的情况下使用小间隔。必须报告此类间隔的值。
o The accuracy of RRFD is also dependent on the time needed to propagate the error-free signal from the ingress node to the egress node. A typical value for propagating the error-free signal from the ingress node to the egress node under the same measurement setup MAY be reported. The methodology to obtain such values is outside the scope of this document.
o RRFD的精度还取决于将无差错信号从入口节点传播到出口节点所需的时间。可以报告在相同测量设置下将无差错信号从入口节点传播到出口节点的典型值。获取此类值的方法不在本文件范围内。
o The accuracy of this metric is also dependent on the physical-layer serialization/deserialization of the test signal for certain data path technologies. For instance, for an LSP between a pair
o 该度量的准确性还取决于某些数据路径技术的测试信号的物理层序列化/反序列化。例如，对于一对之间的LSP
of low-speed Ethernet interfaces, the time needed to serialize/ deserialize a large frame may not be negligible. In this case, it is RECOMMENDED that the ingress node use small frames. The average length of the frame MAY be reported.
对于低速以太网接口，序列化/反序列化大帧所需的时间可能不可忽略。在这种情况下，建议入口节点使用小帧。可以报告帧的平均长度。
o It is possible that under some implementations, a node may program the cross-connection before it sends a PATH message further downstream, and the data path may be ready for use before a Resv message reaches the ingress node. In such cases, RRFD can be a negative value. It is RECOMMENDED that a PRFD measurement be carried out to further characterize the forward data path delay when a negative RRFD value is observed.
o 可能的是，在一些实现下，节点可以在向下游发送路径消息之前对交叉连接进行编程，并且数据路径可以在Resv消息到达入口节点之前准备好使用。在这种情况下，RRFD可以是负值。建议进行PRFD测量，以进一步表征观察到负RRFD值时的前向数据路径延迟。
o If an error-free signal is received by the egress node before a PATH message is sent on the ingress node, an error MUST be reported and the measurement SHOULD terminate.
o 如果在入口节点上发送路径消息之前，出口节点接收到无错误信号，则必须报告错误并终止测量。
o If the corresponding Resv message is received but no error-free signal is received by the egress node within a reasonable period of time, i.e., a threshold, RRFD MUST be treated as undefined. The value of the threshold MUST be reported.
o 如果接收到相应的Resv消息，但出口节点在合理的时间段内（即阈值）没有接收到无错误信号，则必须将RRFD视为未定义。必须报告阈值的值。
o If the LSP setup fails, this metric value MUST NOT be counted.
o 如果LSP设置失败，则不得计算此度量值。
Generally, the methodology would proceed as follows:
一般而言，该方法将按以下步骤进行：
o Make sure that the network has enough resources to set up the requested LSP.
o 确保网络有足够的资源来设置请求的LSP。
o Start the data path measurement and/or monitoring procedures on the ingress node and egress node. If an error-free signal is received by the egress node before a PATH message is sent, report an error and terminate the measurement.
o 在入口节点和出口节点上启动数据路径测量和/或监控程序。如果出口节点在发送路径消息之前接收到无错误信号，则报告错误并终止测量。
o At the ingress node, form the PATH message according to the LSP requirements and send the message towards the egress node.
o 在入口节点，根据LSP要求形成路径消息，并向出口节点发送消息。
o Upon receiving the last bit of the corresponding Resv message, take the timestamp (T1) on the ingress node as soon as possible.
o 在接收到相应Resv消息的最后一位后，尽快在入口节点上获取时间戳（T1）。
o When an error-free signal is observed on the egress node, take the timestamp (T2) as soon as possible. An estimate of RRFD (T2 - T1) can be computed.
o 当在出口节点上观察到无错误信号时，尽快获取时间戳（T2）。可以计算RRFD（T2-T1）的估计值。
o If the corresponding Resv message arrives but no error-free signal is received within a reasonable period of time by the ingress node, RRFD is deemed to be undefined.
o 如果相应的Resv消息到达，但是入口节点在合理的时间段内没有接收到无错误信号，则RRFD被视为未定义。
o If the LSP setup fails, RRFD is not counted.
o 如果LSP设置失败，则不计算RRFD。
This part defines a metric for reverse data path delay when an LSP is set up.
本部分定义了设置LSP时反向数据路径延迟的度量。
As described in [RFC6383], the completion of the RSVP-TE signaling process does not necessarily mean that the cross-connections along the LSP being set up are in place and ready to carry traffic. This metric defines the time difference between the completion of the signaling process and the completion of the cross-connection programming along the reverse data path. This metric MAY be used together with RRFD to characterize the data path delay of a bidirectional LSP.
如[RFC6383]所述，RSVP-TE信令过程的完成并不一定意味着沿着正在建立的LSP的交叉连接已经就位并准备好承载业务。该度量定义了信令过程的完成与反向数据路径上交叉连接编程的完成之间的时间差。该度量可与RRFD一起用于表征双向LSP的数据路径延迟。
RSRD is useful for the following reasons:
RSRD之所以有用，原因如下：
o For the reasons described in [RFC6383], the data path may not be ready for use instantly after the completion of the RSVP-TE signaling process. The delay itself is part of the implementation performance.
o 由于[RFC6383]中所述的原因，RSVP-TE信令过程完成后，数据路径可能无法立即准备好使用。延迟本身是实现性能的一部分。
o The completion of the signaling process may be used by application designers as an indication of data path connectivity. The existence of this delay and the possible failure of cross-connection programming, if not properly treated, will result in data loss or application failure. The typical value of this delay can thus help designers to improve the application model.
o 信令过程的完成可被应用设计者用作数据路径连接的指示。此延迟的存在和交叉连接编程的可能失败，如果处理不当，将导致数据丢失或应用程序失败。因此，此延迟的典型值可以帮助设计者改进应用程序模型。
RSRD = Resv Sent, Reverse Data path
RSRD=已发送Resv，反向数据路径
o ID0, the ingress LSR ID
o ID0，入口LSR ID
o ID1, the egress LSR ID
o ID1，出口LSR ID
o T, a time when the setup is attempted
o T、 尝试安装的时间
The value of RSRD is either a real number of milliseconds or undefined.
RSRD的值为毫秒实数或未定义。
For a real number dT,
对于实数dT，
RSRD from ingress node ID0 to egress node ID1 at T is dT
T处从入口节点ID0到出口节点ID1的RSRD是dT
means that
意味着
o ingress node ID0 sends a PATH message to egress node ID1,
o 入口节点ID0向出口节点ID1发送路径消息，
o the last bit of the corresponding Resv message is sent by egress node ID1 at T, and
o 对应Resv消息的最后一位由T处的出口节点ID1发送，并且
o an error-free signal is received by the ingress node ID0 using a data-plane-specific test pattern at T+dT.
o 入口节点ID0使用T+dT处的数据平面特定测试模式接收无错误信号。
The following issues are likely to come up in practice:
在实践中可能会出现以下问题：
o The accuracy of RSRD depends on the clock resolution of both the ingress node and egress node. Clock synchronization between the ingress node and egress node is required.
o RSRD的精度取决于入口节点和出口节点的时钟分辨率。入口节点和出口节点之间需要时钟同步。
o The accuracy of RSRD is also dependent on how the error-free signal is received and may differ significantly when the underlying data plane technology is different. For instance, for an LSP between a pair of Ethernet interfaces, the egress node (sometimes the tester) may use a rate-based method to verify the connectivity of the data path and use the reception of the first error-free frame as the error-free signal. In this case, the interval between two successive frames has a significant impact on accuracy. It is RECOMMENDED in this case that the egress node use small intervals, under the condition that the injected traffic does not exceed the capacity of the reverse data path. The value of the interval MUST be reported.
o RSRD的精度还取决于无差错信号的接收方式，并且当底层数据平面技术不同时，RSRD的精度可能会显著不同。例如，对于一对以太网接口之间的LSP，出口节点（有时测试仪）可以使用基于速率的方法来验证数据路径的连接性，并使用第一无差错帧的接收作为无差错信号。在这种情况下，两个连续帧之间的间隔对精度有重大影响。在这种情况下，建议出口节点在注入流量不超过反向数据路径容量的情况下使用小间隔。必须报告间隔的值。
o The accuracy of RSRD is also dependent on the time needed to propagate the error-free signal from the egress node to the ingress node. A typical value for propagating the error-free signal from the egress node to the ingress node under the same measurement setup MAY be reported. The methodology to obtain such values is outside the scope of this document.
o RSRD的精度还取决于将无差错信号从出口节点传播到入口节点所需的时间。可以报告在相同测量设置下将无差错信号从出口节点传播到入口节点的典型值。获取此类值的方法不在本文件范围内。
o The accuracy of this metric is also dependent on the physical-layer serialization/deserialization of the test signal for certain data path technologies. For instance, for an LSP between a pair of low-speed Ethernet interfaces, the time needed to serialize/ deserialize a large frame may not be negligible. In this case, it is RECOMMENDED that the egress node use small frames. The average length of the frame MAY be reported.
o 该度量的准确性还取决于某些数据路径技术的测试信号的物理层序列化/反序列化。例如，对于一对低速以太网接口之间的LSP，序列化/反序列化大帧所需的时间可能不可忽略。在这种情况下，建议出口节点使用小帧。可以报告帧的平均长度。
o If the corresponding Resv message is sent but no error-free signal is received by the ingress node within a reasonable period of time, i.e., a threshold, RSRD MUST be treated as undefined. The value of the threshold MUST be reported.
o 如果发送了相应的Resv消息，但入口节点在合理的时间段（即阈值）内未接收到无错误信号，则必须将RSRD视为未定义。必须报告阈值的值。
o If an error-free signal is received before a PATH message is sent on the ingress node, an error MUST be reported and the measurement SHOULD terminate.
o 如果在入口节点上发送路径消息之前收到无错误信号，则必须报告错误，并且测量应终止。
o If the LSP setup fails, this metric value MUST NOT be counted.
o 如果LSP设置失败，则不得计算此度量值。
Generally, the methodology would proceed as follows:
一般而言，该方法将按以下步骤进行：
o Make sure that the network has enough resources to set up the requested LSP.
o 确保网络有足够的资源来设置请求的LSP。
o Start the data path measurement and/or monitoring procedures on the ingress node and egress node. If an error-free signal is received by the ingress node before a PATH message is sent, report an error and terminate the measurement.
o 在入口节点和出口节点上启动数据路径测量和/或监控程序。如果入口节点在发送路径消息之前收到无错误信号，则报告错误并终止测量。
o At the ingress node, form the PATH message according to the LSP requirements and send the message towards the egress node.
o 在入口节点，根据LSP要求形成路径消息，并向出口节点发送消息。
o Upon sending the last bit of the corresponding Resv message, take the timestamp (T1) on the egress node as soon as possible.
o 在发送相应Resv消息的最后一位时，尽快获取出口节点上的时间戳（T1）。
o When an error-free signal is observed on the ingress node, take the timestamp (T2) as soon as possible. An estimate of RSRD (T2 - T1) can be computed.
o 当在入口节点上观察到无错误信号时，尽快获取时间戳（T2）。可以计算RSRD（T2-T1）的估计值。
o If the LSP setup fails, RSRD is not counted.
o 如果LSP设置失败，RSRD不计算在内。
o If no error-free signal is received within a reasonable period of time by the ingress node, RSRD is deemed to be undefined.
o 如果入口节点在合理的时间段内未接收到无差错信号，则认为RSRD未定义。
This part defines a metric for forward data path delay when an LSP is set up.
本部分定义了设置LSP时前向数据路径延迟的度量。
In an RSVP-TE implementation, when setting up an LSP, each node may choose to program the cross-connection before it sends a PATH message further downstream. In this case, the forward data path may become ready for use before the signaling process completes, i.e., before the Resv message reaches the ingress node. This metric can be used to identify such an implementation practice and give useful information to application designers.
在RSVP-TE实现中，当设置LSP时，每个节点可以选择在向下游发送路径消息之前对交叉连接进行编程。在这种情况下，转发数据路径可以在信令过程完成之前，即，在Resv消息到达入口节点之前准备好使用。此度量可用于识别此类实现实践，并为应用程序设计者提供有用的信息。
PRFD is useful for the following reasons:
PRFD之所以有用，原因如下：
o PRFD can be used to identify an RSVP-TE implementation practice in which cross-connections are programmed before a PATH message is sent downstream.
o PRFD可用于识别RSVP-TE实施实践，在这种实践中，交叉连接在路径消息发送到下游之前进行编程。
o The value of PRFD may also help application designers to fine-tune their application model.
o PRFD的值还可以帮助应用程序设计人员微调其应用程序模型。
PRFD = PATH Received, Forward Data path
PRFD=接收路径，转发数据路径
o ID0, the ingress LSR ID
o ID0，入口LSR ID
o ID1, the egress LSR ID
o ID1，出口LSR ID
o T, a time when the setup is attempted
o T、 尝试安装的时间
The value of PRFD is either a real number of milliseconds or undefined.
PRFD的值为毫秒实数或未定义。
For a real number dT,
对于实数dT，
PRFD from ingress node ID0 to egress node ID1 at T is dT
T处从入口节点ID0到出口节点ID1的PRFD是dT
means that
意味着
o ingress node ID0 sends a PATH message to egress node ID1,
o 入口节点ID0向出口节点ID1发送路径消息，
o the last bit of the PATH message is received by egress node ID1 at T, and
o 路径消息的最后一位由T处的出口节点ID1接收，并且
o an error-free signal is received by the egress node ID1 using a data-plane-specific test pattern at T+dT.
o 出口节点ID1在T+dT处使用数据平面特定测试图案接收无差错信号。
The following issues are likely to come up in practice:
在实践中可能会出现以下问题：
o The accuracy of PRFD depends on the clock resolution of the egress node. Clock synchronization between the ingress node and egress node is not required.
o PRFD的精度取决于出口节点的时钟分辨率。入口节点和出口节点之间不需要时钟同步。
o The accuracy of PRFD is also dependent on how the error-free signal is received and may differ significantly when the underlying data plane technology is different. For instance, for an LSP between a pair of Ethernet interfaces, the egress node (sometimes the tester) may use a rate-based method to verify the connectivity of the data path and use the reception of the first error-free frame as the error-free signal. In this case, the interval between two successive frames has a significant impact on accuracy. It is RECOMMENDED in this case that the ingress node use small intervals, under the condition that the injected traffic does not exceed the capacity of the forward data path. The value of the interval MUST be reported.
o PRFD的精度还取决于无差错信号的接收方式，并且当底层数据平面技术不同时，PRFD的精度可能会显著不同。例如，对于一对以太网接口之间的LSP，出口节点（有时测试仪）可以使用基于速率的方法来验证数据路径的连接性，并使用第一无差错帧的接收作为无差错信号。在这种情况下，两个连续帧之间的间隔对精度有重大影响。在这种情况下，建议入口节点在注入流量不超过前向数据路径容量的情况下使用小间隔。必须报告间隔的值。
o The accuracy of PRFD is also dependent on the time needed to propagate the error-free signal from the ingress node to the egress node. A typical value for propagating the error-free signal from the ingress node to the egress node under the same measurement setup MAY be reported. The methodology to obtain such values is outside the scope of this document.
o PRFD的精度还取决于将无差错信号从入口节点传播到出口节点所需的时间。可以报告在相同测量设置下将无差错信号从入口节点传播到出口节点的典型值。获取此类值的方法不在本文件范围内。
o The accuracy of this metric is also dependent on the physical-layer serialization/deserialization of the test signal for certain data path technologies. For instance, for an LSP between a pair
o 该度量的准确性还取决于某些数据路径技术的测试信号的物理层序列化/反序列化。例如，对于一对之间的LSP
of low-speed Ethernet interfaces, the time needed to serialize/ deserialize a large frame may not be negligible. In this case, it is RECOMMENDED that the ingress node use small frames. The average length of the frame MAY be reported.
对于低速以太网接口，序列化/反序列化大帧所需的时间可能不可忽略。在这种情况下，建议入口节点使用小帧。可以报告帧的平均长度。
o If an error-free signal is received before a PATH message is sent, an error MUST be reported and the measurement SHOULD terminate.
o 如果在发送PATH消息之前收到无错误信号，则必须报告错误并终止测量。
o If the LSP setup fails, this metric value MUST NOT be counted.
o 如果LSP设置失败，则不得计算此度量值。
o This metric SHOULD be used together with RRFD. It is RECOMMENDED that a PRFD measurement be carried out after a negative RRFD value has already been observed.
o 该指标应与RRFD一起使用。建议在观察到负RRFD值后进行PRFD测量。
Generally, the methodology would proceed as follows:
一般而言，该方法将按以下步骤进行：
o Make sure that the network has enough resources to set up the requested LSP.
o 确保网络有足够的资源来设置请求的LSP。
o Start the data path measurement and/or monitoring procedures on the ingress node and egress node. If an error-free signal is received by the egress node before a PATH message is sent, report an error and terminate the measurement.
o 在入口节点和出口节点上启动数据路径测量和/或监控程序。如果出口节点在发送路径消息之前接收到无错误信号，则报告错误并终止测量。
o At the ingress node, form the PATH message according to the LSP requirements and send the message towards the egress node.
o 在入口节点，根据LSP要求形成路径消息，并向出口节点发送消息。
o Upon receiving the last bit of the PATH message, take the timestamp (T1) on the egress node as soon as possible.
o 在接收到路径消息的最后一位后，尽快在出口节点上获取时间戳（T1）。
o When an error-free signal is observed on the egress node, take the timestamp (T2) as soon as possible. An estimate of PRFD (T2 - T1) can be computed.
o 当在出口节点上观察到无错误信号时，尽快获取时间戳（T2）。可以计算PRFD（T2-T1）的估计值。
o If the LSP setup fails, PRFD is not counted.
o 如果LSP设置失败，则不计算PRFD。
o If no error-free signal is received within a reasonable period of time by the egress node, PRFD is deemed to be undefined.
o 如果出口节点在合理的时间段内未接收到无差错信号，则认为PRFD未定义。
This part defines a metric for forward data path delay when an LSP is set up.
本部分定义了设置LSP时前向数据路径延迟的度量。
As described in [RFC6383], the completion of the RSVP-TE signaling process does not necessarily mean that the cross-connections along the LSP being set up are in place and ready to carry traffic. This metric defines the time difference between the point when the PATH message is sent by the ingress node and the completion of the cross-connection programming along the LSP forward data path.
如[RFC6383]所述，RSVP-TE信令过程的完成并不一定意味着沿着正在建立的LSP的交叉连接已经就位并准备好承载业务。此度量定义入口节点发送路径消息的时间点与沿LSP前向数据路径完成交叉连接编程之间的时间差。
PSFD is useful for the following reasons:
PSFD之所以有用，原因如下：
o For the reasons described in [RFC6383], the data path setup delay may not be consistent with the control plane LSP setup delay. The data path setup delay metric is more precise for LSP setup performance measurement.
o 由于[RFC6383]中所述的原因，数据路径设置延迟可能与控制平面LSP设置延迟不一致。数据路径设置延迟度量对于LSP设置性能测量更精确。
o The completion of the signaling process may be used by application designers as an indication of data path connectivity. The difference between the control plane setup delay and data path delay, and the potential failure of cross-connection programming, if not properly treated, will result in data loss or application failure. This metric can thus help designers to improve the application model.
o 信令过程的完成可被应用设计者用作数据路径连接的指示。控制平面设置延迟和数据路径延迟之间的差异，以及交叉连接编程的潜在故障，如果处理不当，将导致数据丢失或应用程序故障。因此，此度量可以帮助设计人员改进应用程序模型。
PSFD = PATH Sent, Forward Data path
PSFD=发送路径，转发数据路径
o ID0, the ingress LSR ID
o ID0，入口LSR ID
o ID1, the egress LSR ID
o ID1，出口LSR ID
o T, a time when the setup is attempted
o T、 尝试安装的时间
The value of PSFD is either a real number of milliseconds or undefined.
PSFD的值为毫秒的实数或未定义。
For a real number dT,
对于实数dT，
PSFD from ingress node ID0 to egress node ID1 at T is dT
T处从入口节点ID0到出口节点ID1的PSFD是dT
means that
意味着
o ingress node ID0 sends the first bit of a PATH message to egress node ID1 at T, and
o 入口节点ID0将路径消息的第一位发送到T处的出口节点ID1，并且
o an error-free signal is received by the egress node ID1 using a data-plane-specific test pattern at T+dT.
o 出口节点ID1在T+dT处使用数据平面特定测试图案接收无差错信号。
The following issues are likely to come up in practice:
在实践中可能会出现以下问题：
o The accuracy of PSFD depends on the clock resolution of both the ingress node and egress node. Clock synchronization between the ingress node and egress node is required.
o PSFD的精度取决于入口节点和出口节点的时钟分辨率。入口节点和出口节点之间需要时钟同步。
o The accuracy of PSFD is also dependent on how the error-free signal is received and may differ significantly when the underlying data plane technology is different. For instance, for an LSP between a pair of Ethernet interfaces, the ingress node may use a rate-based method to verify the connectivity of the data path and use the reception of the first error-free frame as the error-free signal. In this case, the interval between two successive frames has a significant impact on accuracy. It is RECOMMENDED that the ingress node use small intervals, under the condition that the injected traffic does not exceed the capacity of the forward data path. The value of the interval MUST be reported.
o PSFD的精度还取决于无差错信号的接收方式，当底层数据平面技术不同时，可能会有显著差异。例如，对于一对以太网接口之间的LSP，入口节点可以使用基于速率的方法来验证数据路径的连接性，并使用第一无差错帧的接收作为无差错信号。在这种情况下，两个连续帧之间的间隔对精度有重大影响。建议入口节点在注入流量不超过前向数据路径容量的情况下使用小间隔。必须报告间隔的值。
o The accuracy of PSFD is also dependent on the time needed to propagate the error-free signal from the ingress node to the egress node. A typical value for propagating the error-free signal from the ingress node to the egress node under the same measurement setup MAY be reported. The methodology to obtain such values is outside the scope of this document.
o PSFD的精度还取决于将无差错信号从入口节点传播到出口节点所需的时间。可以报告在相同测量设置下将无差错信号从入口节点传播到出口节点的典型值。获取此类值的方法不在本文件范围内。
o The accuracy of this metric is also dependent on the physical-layer serialization/deserialization of the test signal for certain data path technologies. For instance, for an LSP between a pair
o 该度量的准确性还取决于某些数据路径技术的测试信号的物理层序列化/反序列化。例如，对于一对之间的LSP
of low-speed Ethernet interfaces, the time needed to serialize/ deserialize a large frame may not be negligible. In this case, it is RECOMMENDED that the ingress node use small frames. The average length of the frame MAY be reported.
对于低速以太网接口，序列化/反序列化大帧所需的时间可能不可忽略。在这种情况下，建议入口节点使用小帧。可以报告帧的平均长度。
o If an error-free signal is received before a PATH message is sent, an error MUST be reported and the measurement SHOULD terminate.
o 如果在发送PATH消息之前收到无错误信号，则必须报告错误并终止测量。
o If the LSP setup fails, this metric value MUST NOT be counted.
o 如果LSP设置失败，则不得计算此度量值。
o If the PATH message is sent by the ingress node but no error-free signal is received by the egress node within a reasonable period of time, i.e., a threshold, PSFD MUST be treated as undefined. The value of the threshold MUST be reported.
o 如果路径消息由入口节点发送，但出口节点在合理的时间段（即阈值）内未接收到无错误信号，则必须将PSFD视为未定义。必须报告阈值的值。
Generally, the methodology would proceed as follows:
一般而言，该方法将按以下步骤进行：
o Make sure that the network has enough resources to set up the requested LSP.
o 确保网络有足够的资源来设置请求的LSP。
o Start the data path measurement and/or monitoring procedures on the ingress node and egress node. If an error-free signal is received by the egress node before a PATH message is sent, report an error and terminate the measurement.
o 在入口节点和出口节点上启动数据路径测量和/或监控程序。如果出口节点在发送路径消息之前接收到无错误信号，则报告错误并终止测量。
o At the ingress node, form the PATH message according to the LSP requirements and send the message towards the egress node. A timestamp (T1) may be stored locally in the ingress node when the PATH message packet is sent towards the egress node.
o 在入口节点，根据LSP要求形成路径消息，并向出口节点发送消息。当路径消息分组被发送到出口节点时，时间戳（T1）可以本地存储在入口节点中。
o When an error-free signal is observed on the egress node, take the timestamp (T2) as soon as possible. An estimate of PSFD (T2 - T1) can be computed.
o 当在出口节点上观察到无错误信号时，尽快获取时间戳（T2）。可以计算PSFD（T2-T1）的估计值。
o If the LSP setup fails, PSFD is not counted.
o 如果LSP设置失败，则不计算PSFD。
o If no error-free signal is received within a reasonable period of time by the egress node, PSFD is deemed to be undefined.
o 如果出口节点在合理的时间段内没有接收到无差错信号，则认为PSFD未定义。
This part defines a metric for reverse data path delay when an LSP is set up.
本部分定义了设置LSP时反向数据路径延迟的度量。
This metric defines the time difference between the point when the ingress node sends the PATH message and the completion of the cross-connection programming along the LSP reverse data path. This metric MAY be used together with PSFD to characterize the data path delay of a bidirectional LSP.
此度量定义入口节点发送路径消息的时间点与沿LSP反向数据路径完成交叉连接编程之间的时间差。该度量可与PSFD一起用于表征双向LSP的数据路径延迟。
PSRD is useful for the following reasons:
PSRD之所以有用，原因如下：
o For the reasons described in [RFC6383], the data path setup delay may not be consistent with the control plane LSP setup delay. The data path setup delay metric is more precise for LSP setup performance measurement.
o 由于[RFC6383]中所述的原因，数据路径设置延迟可能与控制平面LSP设置延迟不一致。数据路径设置延迟度量对于LSP设置性能测量更精确。
o The completion of the signaling process may be used by application designers as an indication of data path connectivity. The difference between the control plane setup delay and data path delay, and the potential failure of cross-connection programming, if not properly treated, will result in data loss or application failure. This metric can thus help designers to improve the application model.
o 信令过程的完成可被应用设计者用作数据路径连接的指示。控制平面设置延迟和数据路径延迟之间的差异，以及交叉连接编程的潜在故障，如果处理不当，将导致数据丢失或应用程序故障。因此，此度量可以帮助设计人员改进应用程序模型。
PSRD = PATH Sent, Reverse Data path
PSRD=发送的路径，反向数据路径
o ID0, the ingress LSR ID
o ID0，入口LSR ID
o ID1, the egress LSR ID
o ID1，出口LSR ID
o T, a time when the setup is attempted
o T、 尝试安装的时间
The value of PSRD is either a real number of milliseconds or undefined.
PSRD的值为毫秒实数或未定义。
For a real number dT,
对于实数dT，
PSRD from ingress node ID0 to egress node ID1 at T is dT
T处从入口节点ID0到出口节点ID1的PSRD是dT
means that
意味着
o ingress node ID0 sends the first bit of a PATH message to egress node ID1 at T, and
o 入口节点ID0将路径消息的第一位发送到T处的出口节点ID1，并且
o an error-free signal is received through the reverse data path by the ingress node ID0 using a data-plane-specific test pattern at T+dT.
o 入口节点ID0使用T+dT处的数据平面特定测试模式通过反向数据路径接收无错误信号。
The following issues are likely to come up in practice:
在实践中可能会出现以下问题：
o The accuracy of PSRD depends on the clock resolution of the ingress node. Clock synchronization between the ingress node and egress node is not required.
o PSRD的精度取决于入口节点的时钟分辨率。入口节点和出口节点之间不需要时钟同步。
o The accuracy of PSRD is also dependent on how the error-free signal is received and may differ significantly when the underlying data plane technology is different. For instance, for an LSP between a pair of Ethernet interfaces, the egress node may use a rate-based method to verify the connectivity of the data path and use the reception of the first error-free frame as the error-free signal. In this case, the interval between two successive frames has a significant impact on accuracy. It is RECOMMENDED that the egress node use small intervals, under the condition that the injected traffic does not exceed the capacity of the forward data path. The value of the interval MUST be reported.
o PSRD的精度还取决于无差错信号的接收方式，并且当底层数据平面技术不同时，可能会有显著差异。例如，对于一对以太网接口之间的LSP，出口节点可以使用基于速率的方法来验证数据路径的连接性，并使用第一无差错帧的接收作为无差错信号。在这种情况下，两个连续帧之间的间隔对精度有重大影响。建议出口节点在注入流量不超过前向数据路径容量的情况下使用小间隔。必须报告间隔的值。
o The accuracy of PSRD is also dependent on the time needed to propagate the error-free signal from the egress node to the ingress node. A typical value for propagating the error-free signal from the egress node to the ingress node under the same measurement setup MAY be reported. The methodology to obtain such values is outside the scope of this document.
o PSRD的精度还取决于将无差错信号从出口节点传播到入口节点所需的时间。可以报告在相同测量设置下将无差错信号从出口节点传播到入口节点的典型值。获取此类值的方法不在本文件范围内。
o The accuracy of this metric is also dependent on the physical-layer serialization/deserialization of the test signal for certain data path technologies. For instance, for an LSP between a pair
o 该度量的准确性还取决于某些数据路径技术的测试信号的物理层序列化/反序列化。例如，对于一对之间的LSP
of low-speed Ethernet interfaces, the time needed to serialize/ deserialize a large frame may not be negligible. In this case, it is RECOMMENDED that the egress node use small frames. The average length of the frame MAY be reported.
对于低速以太网接口，序列化/反序列化大帧所需的时间可能不可忽略。在这种情况下，建议出口节点使用小帧。可以报告帧的平均长度。
o If an error-free signal is received before a PATH message is sent, an error MUST be reported and the measurement SHOULD terminate.
o 如果在发送PATH消息之前收到无错误信号，则必须报告错误并终止测量。
o If the LSP setup fails, this metric value MUST NOT be counted.
o 如果LSP设置失败，则不得计算此度量值。
o If the PATH message is sent by the ingress node but no error-free signal is received by the ingress node within a reasonable period of time, i.e., a threshold, PSRD MUST be treated as undefined. The value of the threshold MUST be reported.
o 如果路径消息由入口节点发送，但入口节点在合理的时间段（即阈值）内未接收到无错误信号，则必须将PSRD视为未定义。必须报告阈值的值。
Generally, the methodology would proceed as follows:
一般而言，该方法将按以下步骤进行：
o Make sure that the network has enough resources to set up the requested LSP.
o 确保网络有足够的资源来设置请求的LSP。
o Start the data path measurement and/or monitoring procedures on the ingress node and egress node. If an error-free signal is received by the egress node before a PATH message is sent, report an error and terminate the measurement.
o 在入口节点和出口节点上启动数据路径测量和/或监控程序。如果出口节点在发送路径消息之前接收到无错误信号，则报告错误并终止测量。
o At the ingress node, form the PATH message according to the LSP requirements and send the message towards the egress node. A timestamp (T1) may be stored locally in the ingress node when the PATH message packet is sent towards the egress node.
o 在入口节点，根据LSP要求形成路径消息，并向出口节点发送消息。当路径消息分组被发送到出口节点时，时间戳（T1）可以本地存储在入口节点中。
o When an error-free signal is observed on the ingress node, take the timestamp (T2) as soon as possible. An estimate of PSRD (T2 - T1) can be computed.
o 当在入口节点上观察到无错误信号时，尽快获取时间戳（T2）。可以计算PSRD（T2-T1）的估计值。
o If the LSP setup fails, PSRD is not counted.
o 如果LSP设置失败，则不计算PSRD。
o If no error-free signal is received within a reasonable period of time by the ingress node, PSRD is deemed to be undefined.
o 如果入口节点在合理的时间段内未接收到无差错信号，则认为PSRD未定义。
In Sections 5, 6, 7, 8, and 9, we defined the singleton metrics of data path delay. Now, we define how to get one particular sample of such a delay. Sampling is done to select a particular portion of singleton values of the given parameters. As in [RFC2330], we use Poisson sampling as an example.
在第5、6、7、8和9节中，我们定义了数据路径延迟的单例度量。现在，我们定义如何获得这种延迟的一个特定样本。采样是为了选择给定参数的单个值的特定部分。与[RFC2330]一样，我们使用泊松抽样作为示例。
Type <X> data path delay sample, where X is either RRFD, RSRD, PRFD, PSFD, or PSRD.
输入<X>数据路径延迟样本，其中X为RRFD、RSRD、PRFD、PSFD或PSRD。
o ID0, the ingress LSR ID
o ID0，入口LSR ID
o ID1, the egress LSR ID
o ID1，出口LSR ID
o T0, a time
o T0，一次
o Tf, a time
o Tf，一次
o Lambda, a rate in reciprocal milliseconds
o Lambda，以毫秒为单位的速率
o Th, the LSP holding time
o 第四，LSP保持时间
o Td, the maximum waiting time for successful LSP setup
o Td，成功设置LSP的最长等待时间
o Ts, the maximum waiting time for an error-free signal
o Ts，无错误信号的最大等待时间
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 when setup is attempted
o T、 尝试安装的时间
o dT, either a real number of milliseconds or undefined
o dT，毫秒的实数或未定义
Given T0, Tf, and Lambda, compute a pseudo-random 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 times in this process, we obtain the value of a data path delay sample of type <X> at this time. The value of the sample is the sequence made
给定T0、Tf和Lambda，计算一个伪随机泊松过程，从T0或T0之前开始，以平均到达率Lambda结束，在Tf或之后结束。然后选择大于或等于T0且小于或等于Tf的时间值。在这个过程中的每一次，我们都会获得此时<X>类型的数据路径延迟样本的值。样本的值是所做的序列
up of the resulting <time, type <X> data path delay> pairs. If there are no such pairs, the sequence is of length zero and the sample is said to be empty.
生成的<time，type<X>数据路径延迟>对的上限。如果没有这样的对，序列的长度为零，样本称为空。
The following issues are likely to come up in practice:
在实践中可能会出现以下问题：
o The parameters Lambda, Th, and Td should be carefully chosen, as explained in the discussions for LSP setup delay (see [RFC5814]).
o 应仔细选择参数Lambda、Th和Td，如LSP设置延迟讨论中所述（见[RFC5814]）。
o The parameter Ts should be carefully chosen and MUST be reported along with the LSP forward/reverse data path delay sample.
o 应仔细选择参数Ts，并且必须与LSP正向/反向数据路径延迟样本一起报告。
Generally, the methodology would proceed as follows:
一般而言，该方法将按以下步骤进行：
o Select specific times, using the specified Poisson arrival process.
o 使用指定的泊松到达过程选择特定时间。
o Set up the LSP and obtain the value of type <X> data path delay.
o 设置LSP并获取类型<X>数据路径延迟的值。
o Release the LSP after Th, and wait for the next Poisson arrival process.
o 在Th之后释放LSP，并等待下一个泊松到达过程。
Data path delay with no LSP in the network is important because this reflects the inherent delay of a device implementation. The minimum value provides an indication of the delay that will likely be experienced when an LSP data path is configured under light traffic load.
网络中没有LSP的数据路径延迟非常重要，因为这反映了设备实现的固有延迟。最小值指示在轻交通负载下配置LSP数据路径时可能会经历的延迟。
Make sure that there is no LSP in the network, and proceed with the methodologies described in Section 10.6.
确保网络中没有LSP，并按照第10.6节所述方法进行操作。
Data path delay with a number of LSPs in the network is important because it reflects the performance of an operational network with considerable load. This delay may vary significantly as the number of existing LSPs varies. It can be used as a scalability metric of a device implementation.
网络中具有多个LSP的数据路径延迟非常重要，因为它反映了具有相当大负载的运行网络的性能。随着现有LSP数量的变化，该延迟可能会发生显著变化。它可以用作设备实现的可伸缩性度量。
o Set up the required number of LSPs.
o 设置所需数量的LSP。
o Wait until the network reaches a stable state.
o 等待网络达到稳定状态。
o Then proceed with the methodologies described in Section 10.6.
o 然后按照第10.6节所述的方法进行操作。
Given the samples of the performance metric, we now offer several statistics of these samples to report. From these statistics, we can draw some useful conclusions regarding a GMPLS network. The value of these metrics is either a real number of milliseconds or undefined. In the following discussion, we only consider the finite values.
考虑到性能指标的样本，我们现在提供了这些样本的几个统计数据以供报告。从这些统计数据中，我们可以得出一些关于GMPLS网络的有用结论。这些度量的值要么是毫秒的实数，要么是未定义的。在下面的讨论中，我们只考虑有限值。
The minimum of the metric is the minimum of all the dT values in the sample. In computing this, undefined values SHOULD be treated as infinitely large. Note that this means that the minimum could thus be undefined if all the dT values are undefined. In addition, the metric minimum SHOULD be set to undefined if the sample is empty.
度量的最小值是样本中所有dT值的最小值。在计算时，未定义的值应视为无穷大。注意，这意味着如果所有dT值都未定义，则最小值可能未定义。此外，如果样本为空，则度量最小值应设置为未定义。
The median of the metric is the median of the dT values in the given sample. In computing the median, the undefined values MUST NOT be included. The median SHOULD be set to undefined if all the dT values are undefined, or if the sample is empty. When the number of defined values in the given sample is small, the metric median may not be typical and SHOULD be used carefully.
度量的中位数是给定样本中dT值的中位数。在计算中值时，不得包括未定义的值。如果所有dT值未定义，或者样本为空，则中值应设置为未定义。当给定样本中定义值的数量较少时，公制中值可能不是典型值，应谨慎使用。
The "empirical distribution function" (EDF) of a set of scalar measurements is a function F(x), which, for any x, gives the fractional proportion of the total measurements that were <= x.
一组标量测量值的“经验分布函数”（EDF）是一个函数F（x），对于任何x，它给出了小于等于x的总测量值的分数比例。
Given a percentage X, the Xth percentile of the metric means the smallest value of x for which F(x) >= X. In computing the percentile, undefined values MUST NOT be included.
给定一个百分比X，度量的第X百分位表示X的最小值，其中F（X）>=X。在计算百分位时，不得包括未定义的值。
See [RFC2330] for further details.
有关更多详细信息，请参见[RFC2330]。
Given the samples of the performance metric, we now offer two statistics of failure events of these samples to report: Failure Count and Failure Ratio. The two statistics can be applied to both the forward data path and reverse data path. For example, when a sample of RRFD has been obtained, the forward data path failure statistics can be obtained, while a sample of RSRD can be used to calculate the reverse data path failure statistics. Detailed definitions of Failure Count and Failure Ratio are given below.
给定性能指标的样本，我们现在提供两个要报告的样本故障事件统计信息：故障计数和故障率。这两个统计信息可应用于正向数据路径和反向数据路径。例如，当已获得RRFD的样本时，可获得正向数据路径故障统计，而RSRD的样本可用于计算反向数据路径故障统计。下面给出了故障计数和故障率的详细定义。
Failure Count is defined as the number of the undefined value of the corresponding performance metric in a sample. The value of Failure Count is an integer.
故障计数定义为样本中相应性能指标的未定义值的数目。失败计数的值是一个整数。
Failure Ratio is the percentage of the number of failure events to the total number of requests in a sample. Here, a failure event means that the signaling completes with no error, while no error-free signal is observed. The calculation for Failure Ratio is defined as follows:
Failure Ratio是样本中失败事件数占请求总数的百分比。这里，故障事件意味着信令完成时没有错误，而没有观察到无错误信号。失效率的计算定义如下：
Failure Ratio = Number of undefined value/(Number of valid metric values + Number of undefined value) * 100%.
失效率=未定义值的数量/（有效度量值的数量+未定义值的数量）*100%。
In the control plane, since the measurement endpoints must be conformant to signaling specifications and behave as normal signaling endpoints, it will not incur security issues other than normal LSP provisioning. However, 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.
在控制平面中，由于测量端点必须符合信令规范，并且表现为正常的信令端点，因此除了正常的LSP供应之外，它不会引起安全问题。但是，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。
In the data plane, the measurement endpoint MUST use a signal that is consistent with what is specified in the control plane. For example, in a packet switched case, the traffic injected into the data plane
在数据平面中，测量端点必须使用与控制平面中指定的信号一致的信号。例如，在分组交换的情况下，注入数据平面的业务量
MUST NOT exceed the specified rate in the corresponding LSP setup request. In a wavelength switched case, the measurement endpoint MUST use the specified or negotiated lambda with appropriate power.
不得超过相应LSP设置请求中指定的速率。在波长切换的情况下，测量端点必须使用具有适当功率的指定或协商的λ。
The security considerations pertaining to the original RSVP protocol [RFC2205] and its TE extensions [RFC3209] also remain relevant.
与原始RSVP协议[RFC2205]及其TE扩展[RFC3209]相关的安全注意事项也仍然相关。
[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。
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S. Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, September 1997.
[RFC2205]Braden，B.，Zhang，L.，Berson，S.，Herzog，S.，和S.Jamin，“资源预留协议（RSVP）——第1版功能规范”，RFC 22052997年9月。
[RFC2679] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way Delay Metric for IPPM", RFC 2679, September 1999.
[RFC2679]Almes，G.，Kalidini，S.，和M.Zekauskas，“IPPM的单向延迟度量”，RFC 2679，1999年9月。
[RFC2681] Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip Delay Metric for IPPM", RFC 2681, September 1999.
[RFC2681]Almes，G.，Kalidini，S.，和M.Zekauskas，“IPPM的往返延迟度量”，RFC 2681，1999年9月。
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001.
[RFC3209]Awduche，D.，Berger，L.，Gan，D.，Li，T.，Srinivasan，V.，和G.Swallow，“RSVP-TE：LSP隧道RSVP的扩展”，RFC 3209，2001年12月。
[RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis, "Framework for IP Performance Metrics", RFC 2330, May 1998.
[RFC2330]Paxson，V.，Almes，G.，Mahdavi，J.，和M.Mathis，“IP性能度量框架”，RFC 2330，1998年5月。
[RFC4208] Swallow, G., Drake, J., Ishimatsu, H., and Y. Rekhter, "Generalized Multiprotocol Label Switching (GMPLS) User-Network Interface (UNI): Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Support for the Overlay Model", RFC 4208, October 2005.
[RFC4208]Swallow，G.，Drake，J.，Ishimatsu，H.，和Y.Rekhter，“通用多协议标签交换（GMPLS）用户网络接口（UNI）：覆盖模型的资源预留协议流量工程（RSVP-TE）支持”，RFC 4208，2005年10月。
[RFC5814] Sun, W. and G. Zhang, "Label Switched Path (LSP) Dynamic Provisioning Performance Metrics in Generalized MPLS Networks", RFC 5814, March 2010.
[RFC5814]Sun，W.和G.Zhang，“广义MPLS网络中的标签交换路径（LSP）动态资源调配性能指标”，RFC 5814，2010年3月。
[RFC6383] Shiomoto, K. and A. Farrel, "Advice on When It Is Safe to Start Sending Data on Label Switched Paths Established Using RSVP-TE", RFC 6383, September 2011.
[RFC6383]Shiomoto，K.和A.Farrel，“关于何时开始在使用RSVP-TE建立的标签交换路径上安全发送数据的建议”，RFC 6383，2011年9月。
We wish to thank Adrian Farrel, Lou Berger, and Al Morton for their comments and help. We also wish to thank Klaas Wierenga and Alexey Melnikov for their reviews.
我们要感谢阿德里安·法雷尔、卢·伯杰和艾尔·莫顿的评论和帮助。我们还要感谢克拉斯·韦伦加和阿列克谢·梅尔尼科夫的评论。
This document contains ideas as well as text that have appeared in existing IETF documents. The authors wish to thank G. Almes, S. Kalidindi, and M. Zekauskas.
本文件包含已出现在现有IETF文件中的想法和文本。作者希望感谢G.Almes、S.Kalidini和M.Zekauskas。
We also wish to thank Weisheng Hu, Yaohui Jin, and Wei Guo in the state key laboratory of advanced optical communication systems and networks for their valuable comments. We also wish to thank the National Natural Science Foundation of China (NSFC) and the 863 program of China for their support.
我们还要感谢先进光通信系统与网络国家重点实验室胡伟生、金耀辉和郭伟的宝贵意见。我们也感谢中国国家自然科学基金（NSFC）和中国863计划的支持。
Bin Gu IXIA Oriental Kenzo Plaza 8M, 48 Dongzhimen Wai Street Dongcheng District Beijing 200240 China
中国北京市东城区东直门外大街48号滨谷东方健三广场8M邮编：200240
Phone: +86 13611590766
EMail: BGu@ixiacom.com
Phone: +86 13611590766
EMail: BGu@ixiacom.com
Xueqin Wei Fiberhome Telecommunication Technology Co., Ltd. Wuhan China
中国武汉雪芹威光纤家庭通信技术有限公司
Phone: +86 13871127882
EMail: xqwei@fiberhome.com.cn
Phone: +86 13871127882
EMail: xqwei@fiberhome.com.cn
Tomohiro Otani KDDI R&D Laboratories, Inc. 2-1-15 Ohara Kamifukuoka Saitama 356-8502 Japan
大谷智博KDDI研发实验室有限公司2-1-15日本大原县斋玉町市356-8502
Phone: +81-49-278-7357
EMail: tm-otani@kddi.com
Phone: +81-49-278-7357
EMail: tm-otani@kddi.com
Ruiquan Jing China Telecom Beijing Research Institute 118 Xizhimenwai Avenue Beijing 100035 China
中国电信北京研究院北京西直门外大街118号瑞泉京100035
Phone: +86-10-58552000
EMail: jingrq@ctbri.com.cn
Phone: +86-10-58552000
EMail: jingrq@ctbri.com.cn
Authors' Addresses
作者地址
Weiqiang Sun (editor) Shanghai Jiao Tong University 800 Dongchuan Road Shanghai 200240 China
孙伟强（编辑）上海交通大学东川路800号中国上海200240
Phone: +86 21 3420 5359
EMail: sun.weiqiang@gmail.com
Phone: +86 21 3420 5359
EMail: sun.weiqiang@gmail.com
Guoying Zhang (editor) China Academy of Telecommunication Research, MIIT, China No. 52 Hua Yuan Bei Lu, Haidian District Beijing 100191 China
张国英（编辑）中国电信研究院，工信部，中国北京市海淀区花园北路52号，邮编：100191
Phone: +86 1062300103
EMail: zhangguoying@catr.cn
Phone: +86 1062300103
EMail: zhangguoying@catr.cn
Jianhua Gao Huawei Technologies Co., Ltd. China
中国高建华华为技术有限公司
Phone: +86 755 28973237
EMail: gjhhit@huawei.com
Phone: +86 755 28973237
EMail: gjhhit@huawei.com
Guowu Xie University of California, Riverside 900 University Ave. Riverside, CA 92521 USA
郭国燮加利福尼亚大学，河滨900大学，河滨，CA，美国92521
Phone: +1 951 237 8825
EMail: xieg@cs.ucr.edu
Phone: +1 951 237 8825
EMail: xieg@cs.ucr.edu
Rajiv Papneja Huawei Technologies Santa Clara, CA 95050 Reston, VA 20190 USA
美国弗吉尼亚州圣克拉拉市拉吉夫·帕普尼亚华为技术公司，邮编：95050雷斯顿，邮编：20190
EMail: rajiv.papneja@huawei.com
EMail: rajiv.papneja@huawei.com