Internet Engineering Task Force (IETF) A. Charny
Request for Comments: 6662
Category: Experimental J. Zhang
ISSN: 2070-1721 Cisco Systems
G. Karagiannis
University of Twente
M. Menth
University of Tuebingen
T. Taylor, Ed.
Huawei Technologies
July 2012
Internet Engineering Task Force (IETF) A. Charny
Request for Comments: 6662
Category: Experimental J. Zhang
ISSN: 2070-1721 Cisco Systems
G. Karagiannis
University of Twente
M. Menth
University of Tuebingen
T. Taylor, Ed.
Huawei Technologies
July 2012
Pre-Congestion Notification (PCN) Boundary-Node Behavior for the Single Marking (SM) Mode of Operation
单一标记（SM）运行模式下的拥塞前通知（PCN）边界节点行为
Abstract
摘要
Pre-Congestion Notification (PCN) is a means for protecting the quality of service for inelastic traffic admitted to a Diffserv domain. The overall PCN architecture is described in RFC 5559. This memo is one of a series describing possible boundary-node behaviors for a PCN-domain. The behavior described here is that for a form of measurement-based load control using two PCN marking states: not-marked and excess-traffic-marked. This behavior is known informally as the Single Marking (SM) PCN-boundary-node behavior.
预拥塞通知（PCN）是一种保护允许进入Diffserv域的非弹性流量的服务质量的方法。RFC 5559中描述了整个PCN体系结构。本备忘录是描述PCN域可能的边界节点行为的系列备忘录之一。这里描述的行为是，对于一种基于测量的负载控制形式，使用两种PCN标记状态：未标记和标记过多流量。这种行为非正式地称为单标记（SM）PCN边界节点行为。
Status of This Memo
关于下段备忘
This document is not an Internet Standards Track specification; it is published for examination, experimental implementation, and evaluation.
本文件不是互联网标准跟踪规范；它是为检查、实验实施和评估而发布的。
This document defines an Experimental Protocol for the Internet community. 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). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741.
本文档为互联网社区定义了一个实验协议。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。并非IESG批准的所有文件都适用于任何级别的互联网标准；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/rfc6662.
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/rfc6662.
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
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2. [SM-Specific] Assumed Core Network Behavior for SM . . . . . . 8
3. Node Behaviors . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2. Behavior of the PCN-Egress-Node . . . . . . . . . . . . . 9
3.2.1. Data Collection . . . . . . . . . . . . . . . . . . . 9
3.2.2. Reporting the PCN Data . . . . . . . . . . . . . . . . 10
3.2.3. Optional Report Suppression . . . . . . . . . . . . . 10
3.3. Behavior at the Decision Point . . . . . . . . . . . . . . 11
3.3.1. Flow Admission . . . . . . . . . . . . . . . . . . . . 11
3.3.2. Flow Termination . . . . . . . . . . . . . . . . . . . 12
3.3.3. Decision Point Action for Missing
PCN-Boundary-Node Reports . . . . . . . . . . . . . . 14
3.4. Behavior of the Ingress Node . . . . . . . . . . . . . . . 15
3.5. Summary of Timers and Associated Configurable Durations . 15
3.5.1. Recommended Values for the Configurable Durations . . 17
4. Specification of Diffserv Per-Domain Behavior . . . . . . . . 17
4.1. Applicability . . . . . . . . . . . . . . . . . . . . . . 17
4.2. Technical Specification . . . . . . . . . . . . . . . . . 18
4.2.1. Classification and Traffic Conditioning . . . . . . . 18
4.2.2. PHB Configuration . . . . . . . . . . . . . . . . . . 18
4.3. Attributes . . . . . . . . . . . . . . . . . . . . . . . . 18
4.4. Parameters . . . . . . . . . . . . . . . . . . . . . . . . 18
4.5. Assumptions . . . . . . . . . . . . . . . . . . . . . . . 19
4.6. Example Uses . . . . . . . . . . . . . . . . . . . . . . . 19
4.7. Environmental Concerns . . . . . . . . . . . . . . . . . . 19
4.8. Security Considerations . . . . . . . . . . . . . . . . . 19
5. Operational and Management Considerations . . . . . . . . . . 19
5.1. Deployment of the SM Edge Behavior . . . . . . . . . . . . 19
5.1.1. Selection of Deployment Options and Global
Parameters . . . . . . . . . . . . . . . . . . . . . . 19
5.1.2. Specification of Node- and Link-Specific Parameters . 21
5.1.3. Installation of Parameters and Policies . . . . . . . 22
5.1.4. Activation and Verification of All Behaviors . . . . . 23
5.2. Management Considerations . . . . . . . . . . . . . . . . 24
5.2.1. Event Logging in the PCN-Domain . . . . . . . . . . . 24
5.2.1.1. Logging Loss and Restoration of Contact . . . . . 24
5.2.1.2. Logging Flow Termination Events . . . . . . . . . 26
5.2.2. Provision and Use of Counters . . . . . . . . . . . . 27
6. Security Considerations . . . . . . . . . . . . . . . . . . . 28
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 28
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.1. Normative References . . . . . . . . . . . . . . . . . . . 29
8.2. Informative References . . . . . . . . . . . . . . . . . . 30
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2. [SM-Specific] Assumed Core Network Behavior for SM . . . . . . 8
3. Node Behaviors . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2. Behavior of the PCN-Egress-Node . . . . . . . . . . . . . 9
3.2.1. Data Collection . . . . . . . . . . . . . . . . . . . 9
3.2.2. Reporting the PCN Data . . . . . . . . . . . . . . . . 10
3.2.3. Optional Report Suppression . . . . . . . . . . . . . 10
3.3. Behavior at the Decision Point . . . . . . . . . . . . . . 11
3.3.1. Flow Admission . . . . . . . . . . . . . . . . . . . . 11
3.3.2. Flow Termination . . . . . . . . . . . . . . . . . . . 12
3.3.3. Decision Point Action for Missing
PCN-Boundary-Node Reports . . . . . . . . . . . . . . 14
3.4. Behavior of the Ingress Node . . . . . . . . . . . . . . . 15
3.5. Summary of Timers and Associated Configurable Durations . 15
3.5.1. Recommended Values for the Configurable Durations . . 17
4. Specification of Diffserv Per-Domain Behavior . . . . . . . . 17
4.1. Applicability . . . . . . . . . . . . . . . . . . . . . . 17
4.2. Technical Specification . . . . . . . . . . . . . . . . . 18
4.2.1. Classification and Traffic Conditioning . . . . . . . 18
4.2.2. PHB Configuration . . . . . . . . . . . . . . . . . . 18
4.3. Attributes . . . . . . . . . . . . . . . . . . . . . . . . 18
4.4. Parameters . . . . . . . . . . . . . . . . . . . . . . . . 18
4.5. Assumptions . . . . . . . . . . . . . . . . . . . . . . . 19
4.6. Example Uses . . . . . . . . . . . . . . . . . . . . . . . 19
4.7. Environmental Concerns . . . . . . . . . . . . . . . . . . 19
4.8. Security Considerations . . . . . . . . . . . . . . . . . 19
5. Operational and Management Considerations . . . . . . . . . . 19
5.1. Deployment of the SM Edge Behavior . . . . . . . . . . . . 19
5.1.1. Selection of Deployment Options and Global
Parameters . . . . . . . . . . . . . . . . . . . . . . 19
5.1.2. Specification of Node- and Link-Specific Parameters . 21
5.1.3. Installation of Parameters and Policies . . . . . . . 22
5.1.4. Activation and Verification of All Behaviors . . . . . 23
5.2. Management Considerations . . . . . . . . . . . . . . . . 24
5.2.1. Event Logging in the PCN-Domain . . . . . . . . . . . 24
5.2.1.1. Logging Loss and Restoration of Contact . . . . . 24
5.2.1.2. Logging Flow Termination Events . . . . . . . . . 26
5.2.2. Provision and Use of Counters . . . . . . . . . . . . 27
6. Security Considerations . . . . . . . . . . . . . . . . . . . 28
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 28
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8.1. Normative References . . . . . . . . . . . . . . . . . . . 29
8.2. Informative References . . . . . . . . . . . . . . . . . . 30
The objective of Pre-Congestion Notification (PCN) is to protect the quality of service (QoS) of inelastic flows within a Diffserv domain, in a simple, scalable, and robust fashion. Two mechanisms are used: admission control to decide whether to admit or block a new flow request and, in abnormal circumstances, flow termination to decide whether to terminate some of the existing flows. To achieve this, the overall rate of PCN-traffic is metered on every link in the PCN-domain, and PCN-packets are appropriately marked when certain configured rates are exceeded. These configured rates are below the rate of the link, thus providing notification to PCN-boundary-nodes about incipient overloads before any congestion occurs (hence the "pre" part of "pre-congestion notification"). The level of marking allows decisions to be made about whether to admit or terminate PCN-flows. For more details, see [RFC5559].
预拥塞通知（PCN）的目标是以一种简单、可扩展和健壮的方式保护Diffserv域中非弹性流的服务质量（QoS）。使用两种机制：允许控制来决定是否允许或阻止新的流请求，在异常情况下，流终止来决定是否终止某些现有流。为了实现这一点，在PCN域中的每个链路上测量PCN流量的总速率，并且当超过某些配置速率时，适当地标记PCN数据包。这些配置的速率低于链路速率，因此在任何拥塞发生之前向PCN边界节点提供关于初始过载的通知（因此是“预拥塞通知”的“预”部分）。标记级别允许决定是否接纳或终止PCN流。有关更多详细信息，请参阅[RFC5559]。
This document describes an experimental edge-node behavior to implement PCN in a network. The experiment may be run in a network in which a substantial proportion of the traffic carried is in the form of inelastic flows and where admission control of micro-flows is applied at the edge. For the effects of PCN to be observable, the committed bandwidth (i.e., level of non-best-effort traffic) on at least some links of the network should be near or at link capacity. The amount of effort required to prepare the network for the experiment (see Section 5.1) may constrain the size of network to which it is applied. The purposes of the experiment are:
本文档描述了在网络中实现PCN的实验性边缘节点行为。实验可以在一个网络中进行，在该网络中，所承载的交通量的很大一部分是以非弹性流的形式进行的，并且在该网络的边缘应用了微流的准入控制。为了能够观察到PCN的影响，网络的至少一些链路上的承诺带宽（即，非尽力而为的流量水平）应接近或处于链路容量。为实验准备网络所需的工作量（见第5.1节）可能会限制应用网络的大小。实验的目的是：
o to validate the specification of the SM edge behavior;
o 验证SM边缘行为规范；
o to evaluate the effectiveness of the SM edge behavior in preserving quality of service for admitted flows; and
o 评估SM边缘行为在保持接纳流服务质量方面的有效性；和
o to evaluate PCN's potential for reducing the amount of capital and operational costs in comparison to alternative methods of assuring quality of service.
o 与确保服务质量的替代方法相比，评估PCN在降低资本和运营成本方面的潜力。
For the first two objectives, the experiment should run long enough for the network to experience sharp peaks of traffic in at least some directions. It would also be desirable to observe PCN performance in the face of failures in the network. A period on the order of a month or two in busy season may be enough. The third objective is more difficult and could require observation over a period long enough for traffic demand to grow to the point where additional capacity must be provisioned at some points in the network.
对于前两个目标，实验应运行足够长的时间，以使网络至少在某些方向上经历流量的急剧峰值。在网络出现故障时，最好观察PCN的性能。旺季一到两个月的时间就足够了。第三个目标更加困难，可能需要在足够长的时间内进行观察，以使流量需求增长到必须在网络中的某些点提供额外容量的程度。
Section 3 of this document specifies a detailed set of algorithms and procedures used to implement the PCN mechanisms for the SM mode of operation. Since the algorithms depend on specific metering and marking behavior at the interior nodes, it is also necessary to specify the assumptions made about PCN-interior-node behavior (Section 2). Finally, because PCN uses Diffserv codepoint (DSCP) values to carry its markings, a specification of PCN-boundary-node behavior must include the per-domain behavior (PDB) template specified in [RFC3086], filled out with the appropriate content (Section 4).
本文件第3节规定了一套详细的算法和程序，用于实现SM运行模式的PCN机制。由于算法取决于内部节点的特定计量和标记行为，因此也有必要指定关于PCN内部节点行为的假设（第2节）。最后，由于PCN使用Diffserv codepoint（DSCP）值进行标记，因此PCN边界节点行为规范必须包括[RFC3086]中指定的每域行为（PDB）模板，并填写适当的内容（第4节）。
Note that the terms "block" or "terminate" actually translate to one or more of several possible courses of action, as discussed in Section 3.6 of [RFC5559]. The choice of which action to take for blocked or terminated flows is a matter of local policy.
请注意，术语“阻止”或“终止”实际上转化为几种可能的行动方案中的一种或多种，如[RFC5559]第3.6节所述。对于阻塞或终止的流量，选择采取哪种措施是当地政策的问题。
A companion document [RFC6661] specifies the Controlled Load (CL) PCN-boundary-node behavior. This document and [RFC6661] have a great deal of text in common. To simplify the task of the reader, the text in the present document that is specific to the SM PCN-boundary-node behavior is preceded by the phrase "[SM-specific]". A similar distinction for CL-specific text is made in [RFC6661].
配套文件[RFC6661]规定了受控荷载（CL）PCN边界节点行为。本文件与[RFC6661]有许多共同之处。为了简化读者的任务，本文档中特定于SM PCN边界节点行为的文本前面加上短语“[SM specific]”。[RFC6661]中对CL特定文本进行了类似的区分。
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。
This document uses the following terms defined in Section 2 of [RFC5559]:
本文件使用[RFC5559]第2节中定义的以下术语：
o PCN-domain
o PCN域
o PCN-ingress-node
o 入口节点
o PCN-egress-node
o 出口节点
o PCN-interior-node
o 内节点
o PCN-boundary-node
o 边界节点
o PCN-flow
o PCN流
o ingress-egress-aggregate
o 进出集料
o PCN-excess-rate
o PCN超额率
o PCN-admissible-rate
o PCN容许率
o PCN-supportable-rate
o 可支持速率
o PCN-marked
o PCN标记
o excess-traffic-marked
o 超量交通标志
It also uses the terms PCN-traffic and PCN-packet, for which the definition is repeated from [RFC5559] because of their importance to the understanding of the text that follows:
它还使用了术语PCN通信量和PCN数据包，由于它们对理解以下文本的重要性，因此[RFC5559]中重复了这两个术语的定义：
PCN-traffic, PCN-packets, PCN-BA A PCN-domain carries traffic of different Diffserv behavior aggregates (BAs) [RFC2474]. The PCN-BA uses the PCN mechanisms to carry PCN-traffic, and the corresponding packets are PCN-packets. The same network will carry traffic of other Diffserv BAs. The PCN-BA is distinguished by a combination of the Diffserv codepoint and the ECN field.
PCN流量，PCN数据包，PCN-BA PCN域承载不同区分服务行为聚合（BAs）的流量[RFC2474]。PCN-BA使用PCN机制承载PCN流量，相应的数据包为PCN数据包。同一网络将承载其他Diffserv BAs的流量。PCN-BA通过区分服务代码点和ECN字段的组合来区分。
This document uses the following term from [RFC5670]:
本文件使用[RFC5670]中的以下术语：
o excess-traffic-meter.
o 超额交通量表。
To complete the list of borrowed terms, this document reuses the following terms and abbreviations defined in Section 2 of [RFC6660]:
为完成借用术语列表，本文件重复使用[RFC6660]第2节中定义的以下术语和缩写：
o not-PCN codepoint;
o 不是PCN码点；
o not-marked (NM) codepoint;
o 未标记（NM）码点；
o excess-traffic-marked (ETM) codepoint.
o 超额流量标记（ETM）代码点。
This document defines the following additional terms:
本文件定义了以下附加术语：
Decision Point The node that makes the decision about which flows to admit and to terminate. In a given network deployment, this can be the PCN-ingress-node or a centralized control node. In either case, the PCN-ingress-node is the point where the decisions are enforced.
决策点决定接纳和终止哪个流的节点。在给定的网络部署中，这可以是PCN入口节点或集中控制节点。无论哪种情况，PCN入口节点都是执行决策的点。
NM-rate The rate of not-marked PCN-traffic received at a PCN-egress-node for a given ingress-egress-aggregate in octets per second. For further details, see Section 3.2.1.
NM rate—在PCN出口节点接收到的给定入口-出口聚合的未标记PCN流量的速率，以八位字节/秒为单位。有关更多详细信息，请参见第3.2.1节。
ETM-rate The rate of excess-traffic-marked PCN-traffic received at a PCN-egress-node for a given ingress-egress-aggregate in octets per second. For further details, see Section 3.2.1.
ETM rate在PCN出口节点接收到的给定入口-出口聚合的标记为PCN traffic的多余流量的速率，以八位字节/秒为单位。有关更多详细信息，请参见第3.2.1节。
PCN-sent-rate The rate of PCN-traffic received at a PCN-ingress-node and destined for a given ingress-egress-aggregate in octets per second. For further details, see Section 3.4.
PCN sent rate在PCN入口节点处接收到并发送到给定入口-出口聚合的PCN通信量的速率（以八位字节/秒为单位）。有关更多详细信息，请参见第3.4节。
Congestion level estimate (CLE) The ratio of PCN-marked to total PCN-traffic (measured in octets) received for a given ingress-egress-aggregate during a given measurement period. The CLE is used to derive the PCN-admission-state (Section 3.3.1) and is also used by the report suppression procedure (Section 3.2.3) if report suppression is activated.
拥塞水平估计（CLE）：在给定的测量周期内，对于给定的入口-出口聚合，标记的PCN与接收的PCN总流量（以八位字节为单位）的比率。CLE用于推导PCN准入状态（第3.3.1节），如果激活了报告抑制，也可用于报告抑制程序（第3.2.3节）。
PCN-admission-state The state ("admit" or "block") derived by the Decision Point for a given ingress-egress-aggregate based on statistics about PCN-packet marking. The Decision Point decides to admit or block new flows offered to the aggregate based on the current value of the PCN-admission-state. For further details, see Section 3.3.1.
PCN接纳状态根据PCN数据包标记的统计信息，由给定入口-出口聚合的决策点导出的状态（“接纳”或“块”）。决策点根据PCN允许状态的当前值决定允许或阻止提供给聚合的新流。有关更多详细信息，请参见第3.3.1节。
Sustainable aggregate rate (SAR) The estimated maximum rate of PCN-traffic that can be carried in a given ingress-egress-aggregate at a given moment without risking degradation of quality of service for the admitted flows. The intention is that if the PCN-sent-rate of every ingress-egress-aggregate passing through a given link is limited to its sustainable aggregate rate, the total rate of PCN-traffic flowing through the link will be limited to the PCN-supportable-rate for that link. An estimate of the sustainable aggregate rate for a given ingress-egress-aggregate is derived as part of the flow termination procedure and is used to determine how much PCN-traffic needs to be terminated. For further details, see Section 3.3.2.
可持续聚合速率（SAR）：在给定时刻，在给定入口-出口聚合中可承载的PCN流量的估计最大速率，而不会降低允许流量的服务质量。其目的是，如果通过给定链路的每个进出聚合的PCN发送速率限制在其可持续聚合速率内，则流经该链路的PCN流量的总速率将限制在该链路的PCN可支持速率内。作为流量终止程序的一部分，导出了给定入口-出口聚合的可持续聚合速率估计值，并用于确定需要终止多少PCN流量。有关更多详细信息，请参见第3.3.2节。
CLE-reporting-threshold A configurable value against which the CLE is compared as part of the report suppression procedure. For further details, see Section 3.2.3.
CLE报告阈值可配置的值，作为报告抑制过程的一部分，将CLE与之进行比较。有关更多详细信息，请参见第3.2.3节。
CLE-limit A configurable value against which the CLE is compared to determine the PCN-admission-state for a given ingress-egress-aggregate. For further details, see Section 3.3.1.
CLE limit一个可配置值，与CLE进行比较，以确定给定入口-出口聚合的PCN准入状态。有关更多详细信息，请参见第3.3.1节。
T_meas A configurable time interval that defines the measurement period over which the PCN-egress-node collects statistics relating to PCN-traffic marking. At the end of the interval, the PCN-egress-node calculates the values NM-rate and ETM-rate as defined above and sends a report to the Decision Point, subject to the operation of the report suppression feature. For further details, see Section 3.2.
T_表示一个可配置的时间间隔，该时间间隔定义了PCN出口节点收集与PCN流量标记相关的统计数据的测量周期。在间隔结束时，PCN出口节点根据报告抑制功能的操作，计算如上定义的NM rate和ETM rate值，并向决策点发送报告。有关更多详细信息，请参见第3.2节。
T_maxsuppress A configurable time interval after which the PCN-egress-node MUST send a report to the Decision Point for a given ingress-egress-aggregate regardless of the most recent values of the CLE. This mechanism provides the Decision Point with a periodic confirmation of liveness when report suppression is activated. For further details, see Section 3.2.3.
T_maxsuppress一个可配置的时间间隔，在此时间间隔之后，PCN出口节点必须向决策点发送给定进出口聚合的报告，而不管CLE的最新值如何。当激活报告抑制时，此机制为决策点提供活动性的定期确认。有关更多详细信息，请参见第3.2.3节。
T_fail An interval after which the Decision Point concludes that communication from a given PCN-egress-node has failed if it has received no reports from the PCN-egress-node during that interval. For further details, see Section 3.3.3.
T_fail一段时间间隔，在此时间间隔之后，如果给定的PCN出口节点在该时间间隔内未收到来自该PCN出口节点的报告，则决策点认为该节点的通信已失败。有关更多详细信息，请参见第3.3.3节。
T_crit A configurable interval used in the calculation of T_fail. For further details, see Section 3.3.3.
T_crit计算T_fail时使用的可配置间隔。有关更多详细信息，请参见第3.3.3节。
This section describes the assumed behavior for PCN-interior-nodes in the PCN-domain. The SM mode of operation assumes that:
本节描述PCN域中PCN内部节点的假定行为。SM操作模式假定：
o PCN-interior-nodes perform excess-traffic-marking of PCN-packets according to the rules specified in [RFC5670].
o PCN内部节点根据[RFC5670]中指定的规则执行PCN数据包的过量流量标记。
o For IP transport, excess-traffic-marking of PCN-packets uses the excess-traffic-marked (ETM) codepoint defined in [RFC6660]; for MPLS transport, an equivalent marking is used as discussed in Appendix C of [RFC6660].
o 对于IP传输，PCN数据包的过量流量标记使用[RFC6660]中定义的过量流量标记（ETM）代码点；对于MPLS传输，如[RFC6660]附录C所述，使用等效标记。
o On each link, the reference rate for the excess-traffic-meter is configured to be equal to the PCN-admissible-rate for the link.
o 在每个链路上，超额流量表的参考速率配置为等于链路的PCN容许速率。
o The set of valid codepoint transitions is as shown in Sections 5.2.1 and 5.2.3.1 of [RFC6660].
o 有效码点转换集如[RFC6660]第5.2.1节和第5.2.3.1节所示。
This section describes the behavior of the PCN-ingress-node, PCN-egress-node, and the Decision Point (which MAY be collocated with the PCN-ingress-node).
本节描述PCN入口节点、PCN出口节点和决策点（可与PCN入口节点并置）的行为。
The PCN-egress-node collects the rates of not-marked and excess-traffic-marked PCN-traffic for each ingress-egress-aggregate and reports them to the Decision Point. For a detailed description, see Section 3.2.
PCN出口节点收集每个入口-出口聚合的未标记流量和标记为PCN的过量流量的速率，并将其报告给决策点。有关详细说明，请参见第3.2节。
The PCN-ingress-node enforces flow admission and termination decisions. It also reports the rate of PCN-traffic sent to a given ingress-egress-aggregate when requested by the Decision Point. For details, see Section 3.4.
PCN入口节点执行流接纳和终止决策。当决策点请求时，它还报告发送到给定入口-出口聚合的PCN流量的速率。有关详细信息，请参见第3.4节。
Finally, the Decision Point makes flow admission decisions and selects flows to terminate based on the information provided by the PCN-ingress-node and PCN-egress-node for a given ingress-egress-aggregate. For details, see Section 3.3.
最后，决策点根据PCN入口节点和PCN出口节点为给定入口-出口聚合提供的信息做出流接纳决策并选择要终止的流。有关详细信息，请参见第3.3节。
Specification of a signaling protocol to report rates to the Decision Point is out of scope of this document. If the PCN-ingress-node is chosen as the Decision Point, [RSVP-PCN] specifies an appropriate signaling protocol.
用于向决策点报告速率的信令协议的规范不在本文档的范围内。如果选择PCN入口节点作为决策点，[RSVP-PCN]指定适当的信令协议。
Section 5.1.2 describes how to derive the filters by means of which PCN-ingress-nodes and PCN-egress-nodes are able to classify incoming packets into ingress-egress-aggregates.
第5.1.2节描述了如何推导过滤器，通过该过滤器，PCN入口节点和PCN出口节点能够将传入数据包分类为入口-出口聚合。
The PCN-egress-node needs to meter the PCN-traffic it receives in order to calculate the following rates for each ingress-egress-aggregate passing through it. These rates SHOULD be calculated at the end of each measurement period based on the PCN-traffic observed during that measurement period. The duration of a measurement period is equal to the configurable value T_meas. For further information, see Section 3.5.
PCN出口节点需要测量其接收到的PCN流量，以便为通过它的每个入口-出口聚合计算以下速率。这些速率应在每个测量周期结束时根据该测量周期内观察到的PCN流量进行计算。测量周期的持续时间等于可配置值T_meas。有关更多信息，请参见第3.5节。
o NM-rate: octets per second of PCN-traffic in PCN-packets that are not-marked (i.e., marked with the NM codepoint);
o NM速率：未标记（即，用NM码点标记）的PCN数据包中每秒PCN流量的八位字节数；
o ETM-rate: octets per second of PCN-traffic in PCN-packets that are excess-traffic-marked (i.e., marked with the ETM codepoint).
o ETM速率：标记有过量流量（即，用ETM码点标记）的PCN数据包中，每秒PCN流量的八位字节。
Note: metering the PCN-traffic continuously and using equal-length measurement intervals minimizes the statistical variance introduced by the measurement process itself. On the other hand, the operation of PCN is not affected if the starting and ending times of the measurement intervals for different ingress-egress-aggregates are different.
注：连续计量PCN流量并使用等长测量间隔将测量过程本身引入的统计方差降至最低。另一方面，如果不同进出集料的测量间隔的开始和结束时间不同，则PCN的运行不受影响。
Unless the report suppression option described in Section 3.2.3 is activated, the PCN-egress-node MUST report the latest values of NM-rate and ETM-rate to the Decision Point each time that it calculates them.
除非激活第3.2.3节中描述的报告抑制选项，否则PCN出口节点必须在每次计算NM速率和ETM速率时，向决策点报告NM速率和ETM速率的最新值。
Report suppression MUST be provided as a configurable option, along with two configurable parameters, the CLE-reporting-threshold and the maximum report suppression interval T_maxsuppress. The default value of the CLE-reporting-threshold is zero. The CLE-reporting-threshold MUST NOT exceed the CLE-limit configured at the Decision Point. For further information on T_maxsuppress, see Section 3.5.
报告抑制必须作为一个可配置选项提供，以及两个可配置参数，CLE报告阈值和最大报告抑制间隔T_maxsuppress。CLE报告阈值的默认值为零。CLE报告阈值不得超过决策点配置的CLE限制。有关T_maxsuppress的更多信息，请参见第3.5节。
If the report suppression option is enabled, the PCN-egress-node MUST apply the following procedure to decide whether to send a report to the Decision Point, rather than sending a report automatically at the end of each measurement interval.
如果启用了报告抑制选项，则PCN出口节点必须应用以下过程来决定是否向决策点发送报告，而不是在每个测量间隔结束时自动发送报告。
1. As well as the quantities NM-rate and ETM-rate, the PCN-egress-node MUST calculate the congestion level estimate (CLE) for each measurement interval. The CLE is computed as:
1. 除了NM速率和ETM速率之外，PCN出口节点还必须计算每个测量间隔的拥塞水平估计（CLE）。CLE的计算公式为：
[SM-specific] CLE = ETM-rate / (NM-rate + ETM-rate)
[SM特定]CLE=ETM速率/（NM速率+ETM速率）
if any PCN-traffic was observed, or CLE = 0 if all the rates are zero.
如果观察到任何PCN流量，或如果所有速率均为零，则CLE=0。
2. If the CLE calculated for the latest measurement interval is greater than the CLE-reporting-threshold and/or the CLE calculated for the immediately previous interval was greater than the CLE-reporting-threshold, then the PCN-egress-node MUST send a report to the Decision Point. The contents of the report are described below.
2. 如果为最新测量间隔计算的CLE大于CLE报告阈值和/或为上一个间隔计算的CLE大于CLE报告阈值，则PCN出口节点必须向决策点发送报告。报告的内容如下所述。
The reason for taking into account the CLE of the previous interval is to ensure that the Decision Point gets immediate feedback if the CLE has dropped below the CLE-reporting-threshold. This is essential if the Decision Point is running the flow termination procedure and observing whether (further) flow termination is needed. See Section 3.3.2.
考虑上一间隔的CLE的原因是，如果CLE下降到CLE报告阈值以下，则确保决策点立即得到反馈。如果决策点正在运行流终止程序并观察是否需要（进一步）流终止，则这一点至关重要。见第3.3.2节。
3. If an interval T_maxsuppress has elapsed since the last report was sent to the Decision Point, then the PCN-egress-node MUST send a report to the Decision Point regardless of the CLE value.
3. 如果自上次报告发送到决策点以来，间隔T_maxsuppress已过，则无论CLE值如何，PCN出口节点都必须向决策点发送报告。
4. If neither of the preceding conditions holds, the PCN-egress-node MUST NOT send a report for the latest measurement interval.
4. 如果上述两个条件均不成立，则PCN出口节点不得发送最新测量间隔的报告。
Each report sent to the Decision Point when report suppression has been activated MUST contain the values of NM-rate, ETM-rate, and CLE that were calculated for the most recent measurement interval.
激活报告抑制后发送到决策点的每个报告必须包含为最近测量间隔计算的NM速率、ETM速率和CLE值。
The above procedure ensures that at least one report is sent per interval (T_maxsuppress + T_meas). This demonstrates to the Decision Point that both the PCN-egress-node and the communication path between that node and the Decision Point are in operation.
上述过程确保每个间隔（T_maxsuppress+T_meas）至少发送一份报告。这向决策点证明PCN出口节点以及该节点与决策点之间的通信路径都在运行。
Operators can choose to use PCN procedures just for flow admission, or just for flow termination, or for both. Decision Points MUST implement both mechanisms, but configurable options MUST be provided to activate or deactivate PCN-based flow admission and flow termination independently of each other at a given Decision Point.
操作员可以选择使用PCN程序仅用于流量进入，或仅用于流量终止，或同时用于两者。决策点必须实现这两种机制，但必须提供可配置的选项，以在给定决策点独立地激活或停用基于PCN的流准入和流终止。
If PCN-based flow termination is enabled but PCN-based flow admission is not, flow termination operates as specified in this document.
如果启用了基于PCN的流量终止，但未启用基于PCN的流量准入，则流量终止将按照本文档中的规定进行操作。
Logically, some other system of flow admission control is in operation, but the description of such a system is out of scope of this document and depends on local arrangements.
从逻辑上讲，其他一些流量允许控制系统正在运行，但此类系统的描述超出了本文件的范围，取决于当地安排。
The Decision Point determines the PCN-admission-state for a given ingress-egress-aggregate each time it receives a report from the egress node. It makes this determination on the basis of the congestion level estimate (CLE). If the CLE is provided in the egress-node report, the Decision Point SHOULD use the reported value. If the CLE was not provided in the report, the Decision Point MUST calculate it based on the other values provided in the report, using the formula:
决策点在每次接收到来自出口节点的报告时确定给定入口-出口聚合的PCN接纳状态。它根据拥塞水平估计（CLE）进行确定。如果出口节点报告中提供了CLE，则决策点应使用报告的值。如果报告中未提供CLE，决策点必须根据报告中提供的其他值，使用以下公式计算CLE：
[SM-specific] CLE = ETM-rate / (NM-rate + ETM-rate)
[SM特定]CLE=ETM速率/（NM速率+ETM速率）
if any PCN-traffic was observed, or CLE = 0 if all the rates are zero.
如果观察到任何PCN流量，或如果所有速率均为零，则CLE=0。
The Decision Point MUST compare the reported or calculated CLE to a configurable value, the CLE-limit. If the CLE is less than the CLE-limit, the PCN-admission-state for that aggregate MUST be set to "admit"; otherwise, it MUST be set to "block".
决策点必须将报告或计算的CLE与可配置值（CLE限制）进行比较。如果CLE小于CLE限制，则该聚合的PCN允许状态必须设置为“允许”；否则，必须将其设置为“块”。
If the PCN-admission-state for a given ingress-egress-aggregate is "admit", the Decision Point SHOULD allow new flows to be admitted to that aggregate. If the PCN-admission-state for a given ingress-egress-aggregate is "block", the Decision Point SHOULD NOT allow new flows to be admitted to that aggregate. These actions MAY be modified by policy in specific cases, but such policy intervention risks defeating the purpose of using PCN.
如果给定入口-出口集合的PCN允许状态为“允许”，则决策点应允许新流允许进入该集合。如果给定入口-出口集合的PCN允许状态为“阻塞”，则决策点不应允许新流进入该集合。在特定情况下，政策可能会修改这些措施，但此类政策干预可能会破坏使用PCN的目的。
A performance study of this admission control method is presented in [MeLe12].
[MeLe12]中介绍了这种接纳控制方法的性能研究。
[SM-specific] When the PCN-admission-state computed on the basis of the CLE is "block" for the given ingress-egress-aggregate, the Decision Point MUST request the PCN-ingress-node to provide an estimate of the rate (PCN-sent-rate) at which the PCN-ingress-node is receiving PCN-traffic that is destined for the given ingress-egress-aggregate.
[SM-specific]当基于CLE计算的PCN接入状态对于给定的入口-出口聚合是“阻塞”时，决策点必须请求PCN入口节点提供PCN入口节点接收目的地为给定入口-出口聚合的PCN流量的速率（PCN发送速率）的估计值。
If the Decision Point is collocated with the PCN-ingress-node, the request and response are internal operations.
如果决策点与PCN入口节点并置，则请求和响应是内部操作。
The Decision Point MUST then wait, for both the requested rate from the PCN-ingress-node and the next report from the PCN-egress-node for the ingress-egress-aggregate concerned. If this next egress-node report also includes a non-zero value for the ETM-rate, the Decision Point MUST determine the amount of PCN-traffic to terminate using the following steps:
然后，决策点必须等待来自PCN入口节点的请求速率和来自PCN出口节点的有关入口-出口聚合的下一个报告。如果下一个出口节点报告还包括ETM速率的非零值，则决策点必须使用以下步骤确定要终止的PCN通信量：
1. [SM-specific] The sustainable aggregate rate (SAR) for the given ingress-egress-aggregate is estimated using the formula:
1. [SM特定]使用以下公式估算给定入口-出口骨料的可持续骨料率（SAR）：
SAR = U * NM-Rate
SAR=U*NM速率
for the latest reported interval, where U is a configurable factor greater than one and is the same for all ingress-egress-aggregates. In effect, the value of the PCN-supportable-rate for each link is approximated by the expression
对于最新报告的时间间隔，其中U是大于1的可配置因子，并且对于所有入口-出口聚合是相同的。实际上，每个链路的PCN可支持速率的值由表达式近似表示
U * PCN-admissible-rate
U*PCN容许率
rather than being calculated explicitly.
而不是被明确计算。
2. The amount of traffic to be terminated is the difference:
2. 要终止的通信量为差值：
PCN-sent-rate - SAR,
PCN发送速率-SAR，
where PCN-sent-rate is the value provided by the PCN-ingress-node.
其中，PCN发送速率是PCN入口节点提供的值。
See Section 3.3.3 for a discussion of appropriate actions if the Decision Point fails to receive a timely response to its request for the PCN-sent-rate.
如果决策点未能及时收到对其PCN发送速率请求的响应，请参阅第3.3.3节，了解有关适当措施的讨论。
If the difference calculated in the second step is positive (traffic rate to be terminated), the Decision Point SHOULD select PCN-flows for termination. To that end, the Decision Point MAY use upper rate limits for individual PCN-flows (known, e.g., from resource signaling used to establish the PCN-flows) and select a set of PCN-flows whose sum of upper rate limits is up to the traffic rate to be terminated. Then, these PCN-flows are terminated. The use of upper limits on PCN-flow rates avoids over-termination.
如果第二步计算的差值为正（要终止的流量），决策点应选择PCN流量进行终止。为此，决策点可以使用单个PCN流的速率上限（已知，例如，来自用于建立PCN流的资源信令），并选择速率上限之和达到要终止的业务速率的一组PCN流。然后，终止这些PCN流。使用PCN流量上限可避免过度终止。
Termination may be continuously needed after consecutive measurement intervals for various reasons, e.g., if the used upper rate limits overestimate the actual flow rates. For such cases it is RECOMMENDED that enough time elapses between successive termination events to allow the effects of previous termination events to be reflected in the measurements upon which the termination decisions are based; otherwise, over-termination may occur. See [Satoh10] and Sections 4.2 and 4.3 of [MeLe10].
由于各种原因，在连续测量间隔后，可能需要连续终止，例如，如果使用的流量上限过高估计了实际流量。对于此类情况，建议在连续终止事件之间经过足够的时间，以便在终止决策所依据的测量中反映先前终止事件的影响；否则，可能会发生过度终止。参见[Satoh10]和[MeLe10]第4.2节和第4.3节。
In general, the selection of flows for termination MAY be guided by policy.
一般来说，终止流的选择可能受策略的指导。
The Decision Point SHOULD log each round of termination as described in Section 5.2.1.2.
决策点应按照第5.2.1.2节所述记录每轮终止。
The Decision Point SHOULD start a timer t_recvFail when it receives a report from the PCN-egress-node. t_recvFail is reset each time a new report is received from the PCN-egress-node. t_recvFail expires if it reaches the value T_fail. T_fail is calculated according to the following logic:
当决策点接收到来自PCN出口节点的报告时，它应该启动计时器t_recvFail。每次从PCN出口节点收到新报告时，都会重置t_recvFail。如果t_recvFail达到值t_fail，则t_recvFail将过期。T_fail根据以下逻辑计算：
a. T_fail = the configurable duration T_crit, if report suppression is not deployed;
a. T_fail=如果未部署报告抑制，则可配置的持续时间T_crit；
b. T_fail = T_crit also if report suppression is deployed and the last report received from the PCN-egress-node contained a CLE value greater than CLE-reporting-threshold (Section 3.2.3);
b. T_fail=T_crit，如果部署了报告抑制，并且从PCN出口节点收到的最后一份报告包含的CLE值大于CLE报告阈值（第3.2.3节）；
c. T_fail = 3 * T_maxsuppress (Section 3.2.3) if report suppression is deployed and the last report received from the PCN-egress-node contained a CLE value less than or equal to CLE-reporting-threshold.
c. T_fail=3*T_maxsuppress（第3.2.3节），如果部署了报告抑制，并且从PCN出口节点接收到的最后一份报告包含小于或等于CLE报告阈值的CLE值。
If timer t_recvFail expires for a given PCN-egress-node, the Decision Point SHOULD notify management. A log format is defined for that purpose in Section 5.2.1.1. Other actions depend on local policy, but MAY include blocking of new flows destined for the PCN-egress-node concerned until another report is received from it. Termination of already admitted flows is also possible, but could be triggered by "Destination unreachable" messages received at the PCN-ingress-node.
如果给定PCN出口节点的计时器t_recvFail过期，决策点应通知管理层。第5.2.1.1节为此目的定义了日志格式。其他操作取决于本地策略，但可能包括阻止发送至相关PCN出口节点的新流量，直到收到来自该节点的另一个报告。也可以终止已经允许的流，但可能由PCN入口节点接收到的“目的地不可到达”消息触发。
If a centralized Decision Point sends a request for the estimated value of PCN-sent-rate to a given PCN-ingress-node and fails to receive a response in a reasonable amount of time, the Decision Point SHOULD repeat the request once. [SM-specific] If the second request to the PCN-ingress-node also fails, the Decision Point SHOULD notify management. The log format defined in Section 5.2.1.1 is also suitable for this case.
如果集中决策点向给定的PCN入口节点发送PCN发送速率估计值的请求，并且未能在合理的时间内收到响应，则决策点应重复该请求一次。[SM specific]如果对PCN入口节点的第二次请求也失败，决策点应通知管理层。第5.2.1.1节中定义的日志格式也适用于这种情况。
The response timer t_sndFail with upper bound T_crit is specified in Section 3.5. The use of T_crit is an approximation. A more precise limit would be on the order of two round-trip times, plus an allowance for processing at each end, plus an allowance for variance in these values.
第3.5节规定了具有上限t_临界值的响应计时器t_sndFail。T_crit的使用是一种近似。更精确的限制是两次往返时间，加上两端处理的余量，再加上这些值的差异余量。
See Section 3.5 for suggested values of the configurable durations T_crit and T_maxsuppress.
关于可配置持续时间T_crit和T_maxsuppress的建议值，请参见第3.5节。
The PCN-ingress-node MUST provide the estimated current rate of PCN-traffic received at that node and destined for a given ingress-egress-aggregate in octets per second (the PCN-sent-rate) when the Decision Point requests it. The way this rate estimate is derived is a matter of implementation.
当决策点请求时，PCN入口节点必须提供在该节点接收并发送到给定入口-出口聚合的PCN流量的估计当前速率（以每秒八位字节为单位）（PCN发送速率）。得出该费率估算值的方法是一个实施问题。
For example, the rate that the PCN-ingress-node supplies can be based on a quick sample taken at the time the information is required.
例如，PCN入口节点提供的速率可以基于在需要信息时采集的快速样本。
Here is a summary of the timers used in the procedures just described:
以下是刚才描述的过程中使用的计时器的摘要：
t_meas
图米亚斯
Where used: PCN-egress-node.
使用位置：PCN出口节点。
Used in procedure: data collection (Section 3.2.1).
用于程序：数据收集（第3.2.1节）。
Incidence: one per ingress-egress-aggregate.
发生率：每个入口-出口骨料一个。
Reset: immediately on expiry.
重置：到期后立即重置。
Expiry: when it reaches the configurable duration T_meas.
到期：当达到可配置的持续时间T_meas时。
Action on expiry: calculate NM-rate and ETM-rate and proceed to the applicable reporting procedure (Section 3.2.2 or Section 3.2.3).
到期时的措施：计算NM费率和ETM费率，并继续执行适用的报告程序（第3.2.2节或第3.2.3节）。
t_maxsuppress
特马克斯
Where used: PCN-egress-node.
使用位置：PCN出口节点。
Used in procedure: report suppression (Section 3.2.3).
用于程序：报告抑制（第3.2.3节）。
Incidence: one per ingress-egress-aggregate.
发生率：每个入口-出口骨料一个。
Reset: when the next report is sent, either after expiry or because the CLE has exceeded the reporting threshold.
重置：在到期后或由于CLE已超过报告阈值而发送下一份报告时。
Expiry: when it reaches the configurable duration T_maxsuppress.
到期：当达到可配置的持续时间T_maxsuppress时。
Action on expiry: send a report to the Decision Point the next time the reporting procedure (Section 3.2.3) is invoked, regardless of the value of CLE.
到期时的操作：在下次调用报告程序（第3.2.3节）时向决策点发送报告，无论CLE的值如何。
t_recvFail
t_recvFail
Where used: Decision Point.
使用位置：决策点。
Used in procedure: failure detection (Section 3.3.3).
用于程序：故障检测（第3.3.3节）。
Incidence: one per ingress-egress-aggregate.
发生率：每个入口-出口骨料一个。
Reset: when a report is received for the ingress-egress-aggregate.
重置：当收到入口-出口聚合的报告时。
Expiry: when it reaches the calculated duration T_fail. As described in Section 3.3.3, T_fail is equal either to the configured duration T_crit or to the calculated value 3 * T_maxsuppress, where T_maxsuppress is a configured duration.
到期：当达到计算的持续时间T_失败。如第3.3.3节所述，T_fail等于配置的持续时间T_crit或计算值3*T_maxsuppress，其中T_maxsuppress是配置的持续时间。
Action on expiry: notify management, and possibly other actions.
到期时的措施：通知管理层，可能还有其他措施。
t_sndFail
t_sndFail
Where used: centralized Decision Point.
使用位置：集中决策点。
Used in procedure: failure detection (Section 3.3.3).
用于程序：故障检测（第3.3.3节）。
Incidence: only as required, one per outstanding request to a PCN-ingress-node.
发生率：仅根据需要，对PCN入口节点的每个未完成请求一个。
Started: when a request for the value of PCN-sent-traffic for a given ingress-egress-aggregate is sent to the PCN-ingress-node.
已启动：当向PCN入口节点发送对给定入口-出口聚合的PCN发送流量值的请求时。
Terminated without action: when a response is received before expiry.
无操作终止：在到期前收到响应时。
Expiry: when it reaches the configured duration T_crit.
到期：当达到配置的持续时间T_临界值时。
Action on expiry: as described in Section 3.3.3.
到期时的措施：如第3.3.3节所述。
The timers just described depend on three configurable durations, T_meas, T_maxsuppress, and T_crit. The recommendations given below for the values of these durations are all related to the intended PCN reaction time of 1 to 3 seconds. However, they are based on judgement rather than operational experience or mathematical derivation.
刚才描述的计时器取决于三个可配置的持续时间：T_meas、T_maxsuppress和T_crit。以下给出的这些持续时间值的建议均与1至3秒的预期PCN反应时间有关。然而，它们是基于判断，而不是操作经验或数学推导。
The value of T_meas is RECOMMENDED to be on the order of 100 to 500 ms to provide a reasonable trade-off between demands on network resources (PCN-egress-node and Decision Point processing, network bandwidth) and the time taken to react to impending congestion.
建议T_meas的值为100至500 ms，以便在对网络资源的需求（PCN出口节点和决策点处理、网络带宽）和对即将发生的拥塞作出反应所需的时间之间进行合理的权衡。
The value of T_maxsuppress is RECOMMENDED to be on the order of 3 to 6 seconds, for similar reasons to those for the choice of T_meas.
由于与选择T_meas类似的原因，建议T_maxsuppress的值为3到6秒。
The value of T_crit SHOULD NOT be less than 3 * T_meas. Otherwise, it could cause too many management notifications due to transient conditions in the PCN-egress-node or along the signaling path. A reasonable upper bound on T_crit is on the order of 3 seconds.
T_crit的值不应小于3*T_meas。否则，由于PCN出口节点或信令路径中的瞬态条件，它可能导致过多的管理通知。T_暴击的合理上限约为3秒。
This section provides the specification required by [RFC3086] for a per-domain behavior.
本节提供[RFC3086]要求的每域行为规范。
This section quotes [RFC5559].
本节引用[RFC5559]。
The PCN SM boundary-node behavior specified in this document is applicable to inelastic traffic (particularly video and voice) where quality of service for admitted flows is protected primarily by admission control at the ingress to the domain.
本文件中规定的PCN SM边界节点行为适用于非弹性流量（尤其是视频和语音），其中接入流的服务质量主要通过域入口的接入控制来保护。
In exceptional circumstances (e.g., due to rerouting as a result of network failures) already admitted flows may be terminated to protect the quality of service of the remaining flows. [SM-specific] The performance results in, e.g., [MeLe10], indicate that the SM boundary node behavior is more likely to terminate too many flows under such circumstances than the CL boundary-node behavior described in [RFC6661].
在特殊情况下（例如，由于网络故障导致的重新路由），可以终止已经接纳的流，以保护剩余流的服务质量。[SM-specific]例如[MeLe10]中的性能结果表明，在这种情况下，SM边界节点行为比[RFC6661]中描述的CL边界节点行为更有可能终止太多的流。
Packet classification and treatment at the PCN-ingress-node is described in Section 5.1 of [RFC6660].
[RFC6660]第5.1节描述了PCN入口节点的数据包分类和处理。
PCN packets are further classified as belonging or not belonging to an admitted flow. PCN packets not belonging to an admitted flow are "blocked". (See Section 1 for an understanding of how this term is interpreted.) Packets belonging to an admitted flow are policed to ensure that they adhere to the rate or flowspec that was negotiated during flow admission.
PCN分组进一步被分类为属于或不属于所接纳的流。不属于允许流的PCN数据包被“阻止”。（有关如何解释该术语的理解，请参见第1节。）对属于已接纳流的数据包进行策略，以确保它们遵守在流接纳期间协商的速率或流规范。
The PCN SM boundary-node behavior is a metering and marking behavior rather than a scheduling behavior. As a result, while the encoding uses a single DSCP value, that value can vary from one deployment to another. The PCN working group suggests using admission control for the following service classes (defined in [RFC4594]):
PCN SM边界节点行为是计量和标记行为，而不是调度行为。因此，虽然编码使用单个DSCP值，但该值可能因部署而异。PCN工作组建议对以下服务类别（定义见[RFC4594]）使用准入控制：
o Telephony (EF)
o 电话（EF）
o Real-time interactive (CS4)
o 实时交互（CS4）
o Broadcast Video (CS3)
o 广播视频（CS3）
o Multimedia Conferencing (AF4)
o 多媒体会议（AF4）
For a fuller discussion, see Appendix A of [RFC6660].
有关更全面的讨论，请参见[RFC6660]的附录a。
The purpose of this per-domain behavior is to achieve low loss and jitter for the target class of traffic. The design requirement for PCN was that recovery from overloads through the use of flow termination should happen within 1-3 seconds. PCN probably performs better than that.
这种每域行为的目的是为目标类流量实现低损耗和低抖动。PCN的设计要求是，应在1-3秒内通过使用流量终止从过载中恢复。PCN的表现可能比这更好。
The set of parameters that needs to be configured at each PCN-node and at the Decision Point is described in Section 5.1.
第5.1节描述了需要在每个PCN节点和决策点配置的参数集。
It is assumed that a specific portion of link capacity has been reserved for PCN-traffic.
假定链路容量的特定部分已预留给PCN流量。
The PCN SM behavior may be used to carry real-time traffic, particularly voice and video.
PCN SM行为可用于传输实时流量，尤其是语音和视频。
The PCN SM per-domain behavior could theoretically interfere with the use of end-to-end ECN due to reuse of ECN bits for PCN marking. Section 5.1 of [RFC6660] describes the actions that can be taken to protect ECN signaling. Appendix B of that document provides further discussion of how ECN and PCN can coexist.
理论上，PCN SM每个域的行为可能会干扰端到端ECN的使用，因为ECN位被重新用于PCN标记。[RFC6660]第5.1节描述了可采取的保护ECN信令的措施。该文件的附录B进一步讨论了ECN和PCN如何共存。
Please see the security considerations in [RFC5559] as well as those in [RFC2474] and [RFC2475].
请参阅[RFC5559]以及[RFC2474]和[RFC2475]中的安全注意事项。
Deployment of the PCN Single Marking edge behavior requires the following steps:
PCN单标记边缘行为的部署需要以下步骤：
o selection of deployment options and global parameter values;
o 选择部署选项和全局参数值；
o derivation of per-node and per-link information;
o 每个节点和每个链路信息的推导；
o installation, but not activation, of parameters and policies at all of the nodes in the PCN-domain;
o 在PCN域中的所有节点上安装参数和策略，但不激活；
o activation and verification of all behaviors.
o 激活和验证所有行为。
The first set of decisions affects the operation of the network as a whole. To begin with, the operator needs to make basic design decisions such as whether the Decision Point is centralized or collocated with the PCN-ingress-nodes, and whether per-flow and aggregate resource signaling as described in [RSVP-PCN] is deployed in the network. After that, the operator needs to decide:
第一组决策影响整个网络的运行。首先，运营商需要做出基本的设计决策，例如决策点是集中还是与PCN入口节点并置，以及[RSVP-PCN]中所述的每流和聚合资源信令是否部署在网络中。之后，操作员需要决定：
o whether PCN packets will be forwarded unencapsulated or in tunnels between the PCN-ingress-node and the PCN-egress-node. Encapsulation preserves incoming ECN settings and simplifies the PCN-egress-node's job when it comes to relating incoming packets to specific ingress-egress-aggregates, but lowers the path MTU and imposes the extra labor of encapsulation/decapsulation on the PCN-edge-nodes.
o 将在PCN入口节点和PCN出口节点之间的隧道中或在未封装的情况下转发PCN数据包。封装保留了传入ECN设置，并简化了PCN出口节点在将传入数据包与特定入口-出口聚合关联时的工作，但降低了路径MTU，并在PCN边缘节点上施加了额外的封装/去封装劳动。
o which service classes will be subject to PCN control and what DSCP will be used for each. (See [RFC6660] Appendix A for advice on this topic.)
o 哪些服务类别将受PCN控制，每个类别将使用何种DSCP。（有关此主题的建议，请参见[RFC6660]附录A。）
o the markings to be used at all nodes in the PCN-domain to indicate not-marked (NM) and excess-traffic-marked (ETM) PCN packets;
o 在PCN域中的所有节点上使用的标记，用于指示未标记（NM）和过量流量标记（ETM）PCN数据包；
o the marking rules for re-marking PCN-traffic leaving the PCN-domain;
o 重新标记离开PCN域的PCN流量的标记规则；
o whether PCN-based flow admission is enabled;
o 是否启用基于PCN的流量准入；
o whether PCN-based flow termination is enabled.
o 是否启用基于PCN的流终止。
The following parameters affect the operation of PCN itself. The operator needs to choose:
以下参数影响PCN本身的运行。操作员需要选择：
o the value of CLE-limit if PCN-based flow admission is enabled. [SM-specific] It is RECOMMENDED that the CLE-limit for SM be set fairly low, on the order of 5%.
o 如果启用基于PCN的流量允许，则CLE限制的值。[SM特定]建议将SM的CLE限制设置得相当低，大约为5%。
o the value of the collection interval T_meas. For a recommended range of values, see Section 3.5.1 above.
o 收集间隔T_的值为。有关建议的数值范围，请参见上文第3.5.1节。
o whether report suppression is to be enabled at the PCN-egress-nodes and if so, the values of CLE-reporting-threshold and T_maxsuppress. It is reasonable to leave CLE-reporting-threshold at its default value (zero, as specified in Section 3.2.3). For a recommended range of values of T_maxsuppress, see Section 3.5.1 above.
o 是否在PCN出口节点启用报告抑制功能，如果启用，则为CLE reporting threshold和T_maxsuppress的值。将CLE报告阈值保留在其默认值（零，如第3.2.3节所述）是合理的。有关T_maxsuppress的建议值范围，请参见上文第3.5.1节。
o the value of the duration T_crit, which the Decision Point uses in deciding whether communications with a given PCN-edge-node have failed. For a recommended range of values of T_crit, see Section 3.5.1 above.
o 持续时间T_crit的值，决策点用于确定与给定PCN边缘节点的通信是否失败。有关T_临界值的建议范围，请参见上文第3.5.1节。
o [SM-specific] The factor U that is used in the flow termination procedure (Section 3.3.2). An operational definition for U is given in that section, but it may be thought of as a contingency factor providing a buffer to handle flow peaks above the aggregate
o [SM特定]流量终止程序（第3.3.2节）中使用的系数U。该节给出了U的操作定义，但它可能被认为是一个应急因素，提供了一个缓冲区来处理聚合上方的流量峰值
levels expected when flows are admitted. A reasonable value for U is between 1.2 and 2. Larger values of U tend to cause more over-termination of traffic during peaks, but raise the average link utilization level.
允许流量时的预期水平。U的合理值介于1.2和2之间。U值越大，在峰值期间会导致更多的流量过度终止，但会提高平均链路利用率水平。
Filters are required at both the PCN-ingress-node and the PCN-egress-node to classify incoming PCN packets by ingress-egress-aggregate. Because of the potential use of multipath routing in domains upstream of the PCN-domain, it is impossible to do such classification reliably at the PCN-egress-node based on the packet header contents as originally received at the PCN-ingress-node. (Packets with the same header contents could enter the PCN-domain at multiple PCN-ingress-nodes.) As a result, the only way to construct such filters reliably is to tunnel the packets from the PCN-ingress-node to the PCN-egress-node.
PCN入口节点和PCN出口节点都需要过滤器，以便根据入口-出口聚合对传入PCN数据包进行分类。由于在PCN域上游的域中可能使用多路径路由，因此不可能基于最初在PCN入口节点处接收的分组报头内容在PCN出口节点处可靠地进行这样的分类。（具有相同报头内容的数据包可以在多个PCN入口节点处进入PCN域。）因此，可靠构建此类过滤器的唯一方法是将数据包从PCN入口节点隧道到PCN出口节点。
The PCN-ingress-node needs filters in order to place PCN packets into the right tunnel in the first instance, and also to satisfy requests from the Decision Point for admission rates into specific ingress-egress-aggregates. These filters select the PCN-egress-node, but not necessarily a specific path through the network to that node. As a result, they are likely to be stable even in the face of failures in the network, except when the PCN-egress-node itself becomes unreachable. If all PCN packets will be tunneled, the PCN-ingress-node also needs to know the address of the peer PCN-egress-node associated with each filter.
PCN入口节点需要过滤器，以便在第一个实例中将PCN分组放入正确的隧道中，并且还满足来自决策点的关于进入特定入口-出口聚合的接纳率的请求。这些过滤器选择PCN出口节点，但不一定选择通过网络到达该节点的特定路径。因此，即使在网络出现故障时，它们也可能是稳定的，除非PCN出口节点本身变得不可访问。如果所有PCN数据包都将通过隧道传输，则PCN入口节点还需要知道与每个过滤器关联的对等PCN出口节点的地址。
Operators may wish to give some thought to the provisioning of alternate egress points for some or all ingress-egress-aggregates in case of failure of the PCN-egress-node. This could require the setting up of standby tunnels to these alternate egress points.
运营商可能希望考虑在PCN出口节点发生故障的情况下为一些或所有入口-出口聚合提供备用出口点。这可能需要在这些备用出口点设置备用隧道。
Each PCN-egress-node needs filters to classify incoming PCN packets by ingress-egress-aggregate, in order to gather measurements on a per-aggregate basis. If tunneling is used, these filters are constructed on the basis of the identifier of the tunnel from which the incoming packet has emerged (e.g., the source address in the outer header if IP encapsulation is used). The PCN-egress-node also needs to know the address of the Decision Point to which it sends reports for each ingress-egress-aggregate.
每个PCN出口节点都需要过滤器按照入口-出口聚合对传入PCN数据包进行分类，以便在每个聚合的基础上收集测量值。如果使用隧道，则这些过滤器基于已出现传入数据包的隧道的标识符（例如，如果使用IP封装，则外部报头中的源地址）构建。PCN出口节点还需要知道它为每个入口-出口聚合向其发送报告的决策点的地址。
A centralized Decision Point needs to have the address of the PCN-ingress-node corresponding to each ingress-egress-aggregate. Security considerations require that information also be prepared for a centralized Decision Point and each PCN-edge-node to allow them to authenticate each other.
集中式决策点需要具有对应于每个入口-出口聚合的PCN入口节点的地址。出于安全考虑，还需要为集中决策点和每个PCN边缘节点准备信息，以允许它们相互验证。
Turning to link-specific parameters, the operator needs to derive a value for the PCN-admissible-rate on each link in the network. The first two paragraphs of Section 5.2.2 of [RFC5559] discuss how these values may be derived. ([SM-specific] Confusingly, "PCN-admissible-rate" in the present context corresponds to "PCN-threshold-rate" in the cited paragraphs.)
关于链路特定参数，操作员需要推导网络中每个链路上的PCN容许速率值。[RFC5559]第5.2.2节的前两段讨论了如何推导这些值。（[SM-specific]令人困惑的是，本上下文中的“PCN接纳率”对应于引用段落中的“PCN阈值率”。）
As discussed in the previous two sections, every PCN node needs to be provisioned with a number of parameters and policies relating to its behavior in processing incoming packets. The Diffserv MIB [RFC3289] can be useful for this purpose, although it needs to be extended in some cases. This MIB covers packet classification, metering, counting, policing, dropping, and marking. The required extensions specifically include an encapsulation action following reclassification by ingress-egress-aggregate. In addition, the MIB has to be extended to include objects for marking the ECN field in the outer header at the PCN-ingress-node and an extension to the classifiers to include the ECN field at PCN-interior and PCN-egress-nodes. Finally, a new object may need to be defined at the PCN-interior-nodes to represent the packet-size-independent excess-traffic-marking metering algorithm.
如前两节所讨论的，每个PCN节点都需要提供与处理传入数据包的行为相关的许多参数和策略。Diffserv MIB[RFC3289]可用于此目的，但在某些情况下需要对其进行扩展。该MIB涵盖数据包分类、计量、计数、管理、丢弃和标记。所需的扩展特别包括通过入口-出口聚合重新分类后的封装操作。此外，MIB必须扩展以包括用于在PCN入口节点的外部报头中标记ECN字段的对象，以及分类器的扩展以包括PCN内部和PCN出口节点的ECN字段。最后，可能需要在PCN内部节点定义一个新对象，以表示与数据包大小无关的过量流量标记计量算法。
The value for the PCN-admissible-rate on each link on a node appears as a metering parameter. Operators should take note of the need to deploy excess-traffic meters either on the ingress or the egress side of each interior link, but not both (Appendix B.2 of [RFC5670].
节点上每个链路上的PCN容许速率值显示为计量参数。运营商应注意是否需要在每个内部链路的入口或出口侧部署多余的交通量计，但不能同时部署两个（RFC5670的附录B.2）。
The following additional information has to be configured by other means (e.g., additional MIBs, NETCONF models).
必须通过其他方式配置以下附加信息（例如，附加MIB、NETCONF模型）。
At the PCN-egress-node:
在PCN出口节点：
o the measurement interval T_meas (units of ms, range 50 to 1000);
o 测量间隔T_meas（毫秒单位，范围50至1000）；
o whether report suppression is to be applied;
o 是否应用报告抑制；
o if so, the interval T_maxsuppress (units of 100 ms, range 1 to 100) and the CLE-reporting-threshold (units of tenths of one percent, range 0 to 1000, default value 0);
o 如果是，间隔T_maxsuppress（100毫秒的单位，范围1到100）和CLE报告阈值（百分之一的十分之一的单位，范围0到1000，默认值0）；
o the address of the PCN-ingress-node for each ingress-egress-aggregate, if the Decision Point is collocated with the PCN-ingress-node and [RSVP-PCN] is not deployed;
o 如果决策点与PCN入口节点并置且[RSVP-PCN]未部署，则每个入口-出口聚合的PCN入口节点的地址；
o the address of the centralized Decision Point to which it sends its reports, if there is one.
o 它向其发送报告的集中决策点的地址（如果有）。
At the Decision Point:
在决策点：
o whether PCN-based flow admission is enabled;
o 是否启用基于PCN的流量准入；
o whether PCN-based flow termination is enabled;
o 是否启用基于PCN的流量终止；
o the value of CLE-limit (units of tenths of one percent, range 0 to 1000);
o CLE极限值（百分之一的十分之一单位，范围为0到1000）；
o [SM-specific] the value of the factor U used in the flow termination procedure;
o [SM-specific]流量终止程序中使用的系数U的值；
o the value of the interval T_crit (units of 100 ms, range 1 to 100);
o 间隔T_临界值（单位为100 ms，范围为1至100）；
o whether report suppression is to be applied;
o 是否应用报告抑制；
o if so, the interval T_maxsuppress (units of 100 ms, range 1 to 100) and the CLE-reporting-threshold (units of tenths of one percent, range 0 to 1000, default value 0). These MUST be the same values that are provisioned in the PCN-egress-nodes;
o 如果是，则间隔T_maxsuppress（100毫秒的单位，范围1到100）和CLE报告阈值（百分之一的十分之一的单位，范围0到1000，默认值0）。这些值必须与PCN出口节点中提供的值相同；
o if the Decision Point is centralized, the address of the PCN-ingress-node (and any other information needed to establish a security association) for each ingress-egress-aggregate.
o 如果决策点是集中的，则每个入口-出口聚合的PCN入口节点的地址（以及建立安全关联所需的任何其他信息）。
Depending on the testing strategy, it may be necessary to install the new configuration data in stages. This is discussed further below.
根据测试策略，可能需要分阶段安装新的配置数据。这将在下文进一步讨论。
It is certainly not within the scope of this document to advise on testing strategy, which operators undoubtedly have well in hand. Quite possibly an operator will prefer an incremental approach to activation and testing. Implementing the PCN marking scheme at PCN-ingress-nodes, corresponding scheduling behavior in downstream nodes, and re-marking at the PCN-egress-nodes is a large enough step in itself to require thorough testing before going further.
关于测试策略的建议当然不在本文件的范围内，运营商无疑已经掌握了测试策略。很可能操作员会更喜欢增量方法来激活和测试。在PCN入口节点执行PCN标记方案，在下游节点执行相应的调度行为，并在PCN出口节点重新标记，这本身就是一个足够大的步骤，需要在继续之前进行彻底的测试。
Testing will probably involve the injection of packets at individual nodes and tracking of how the node processes them. This work can make use of the counter capabilities included in the Diffserv MIB. The application of these capabilities to the management of PCN is discussed in the next section.
测试可能涉及在单个节点上注入数据包，并跟踪节点如何处理数据包。这项工作可以利用Diffserv MIB中包含的计数器功能。下一节将讨论这些功能在PCN管理中的应用。
This section focuses on the use of event logging and the use of counters supported by the Diffserv MIB [RFC3289] for the various monitoring tasks involved in management of a PCN network.
本节重点介绍事件日志的使用以及Diffserv MIB[RFC3289]支持的计数器在PCN网络管理中所涉及的各种监控任务中的使用。
It is anticipated that event logging using SYSLOG [RFC5424] will be needed for fault management and potentially for capacity management. Implementations MUST be capable of generating logs for the following events:
预计故障管理和容量管理都需要使用SYSLOG[RFC5424]记录事件。实现必须能够为以下事件生成日志：
o detection of loss of contact between a Decision Point and a PCN-edge-node, as described in Section 3.3.3;
o 如第3.3.3节所述，检测决策点和PCN边缘节点之间的接触损失；
o successful receipt of a report from a PCN-egress-node, following detection of loss of contact with that node;
o 在检测到与PCN出口节点失去联系后，成功接收到该节点的报告；
o flow termination events.
o 流终止事件。
All of these logs are generated by the Decision Point. There is a strong likelihood in the first and third cases that the events are correlated with network failures at a lower level. This has implications for how often specific event types should be reported, so as not to contribute unnecessarily to log buffer overflow. Recommendations on this topic follow for each event report type.
所有这些日志都是由决策点生成的。在第一种和第三种情况下，事件很可能与较低级别的网络故障相关。这意味着应报告特定事件类型的频率，以免不必要地导致日志缓冲区溢出。对于每种事件报告类型，都有关于此主题的建议。
The field names (e.g., HOSTNAME, STRUCTURED-DATA) used in the following subsections are defined in [RFC5424].
[RFC5424]中定义了以下小节中使用的字段名（例如主机名、结构化数据）。
Section 3.3.3 describes the circumstances under which the Decision Point may determine that it has lost contact, either with a PCN-ingress-node or a PCN-egress-node, due to failure to receive an expected report. Loss of contact with a PCN-ingress-node is a case primarily applicable when the Decision Point is in a separate node. However, implementations MAY implement logging in the collocated case if the implementation is such that non-response to a request from the Decision Point function can occasionally occur due to processor load or other reasons.
第3.3.3节描述了在何种情况下，决策点可能会确定，由于未能收到预期报告，其已失去与PCN入口节点或PCN出口节点的联系。当决策点位于单独的节点时，与PCN入口节点失去联系是一种主要适用的情况。然而，如果实现是由于处理器负载或其他原因偶尔会发生对来自决策点函数的请求的不响应，则实现可以在并置情况下实现日志记录。
The log reporting the loss of contact with a PCN-ingress-node or PCN-egress-node MUST include the following content:
报告与PCN入口节点或PCN出口节点失去联系的日志必须包括以下内容：
o The HOSTNAME field MUST identify the Decision Point issuing the log.
o 主机名字段必须标识发出日志的决策点。
o A STRUCTURED-DATA element MUST be present, containing parameters identifying the node for which an expected report has not been received and the type of report lost (ingress or egress). It is RECOMMENDED that the SD-ID for the STRUCTURED-DATA element have the form "PCNNode" (without the quotes), which has been registered with IANA (see [RFC6661] for more information). The node identifier PARAM-NAME is RECOMMENDED to be "ID" (without the quotes). The identifier itself is subject to the preferences expressed in Section 6.2.4 of [RFC5424] for the HOSTNAME field. The report type PARAM-NAME is RECOMMENDED to be "RTyp" (without the quotes). The PARAM-VALUE for the RTyp field MUST be either "ingr" or "egr".
o 必须存在结构化数据元素，其中包含标识未收到预期报告的节点以及报告丢失类型（入口或出口）的参数。建议结构化数据元素的SD-ID采用“PCNNode”格式（不带引号），该格式已在IANA注册（有关更多信息，请参见[RFC6661]）。建议将节点标识符PARAM-NAME设置为“ID”（不带引号）。标识符本身受[RFC5424]第6.2.4节中主机名字段首选项的约束。建议报告类型PARAM-NAME为“RTyp”（不带引号）。RTyp字段的参数值必须为“ingr”或“egr”。
The following values are also RECOMMENDED for the indicated fields in this log, subject to local practice:
根据当地惯例，本日志中指示的字段也建议使用以下值：
o PRI initially set to 115, representing a Facility value of (14) "log alert" and a Severity level of (3) "Error Condition". Note that loss of contact with a PCN-egress-node implies that no new flows will be admitted to one or more ingress-egress-aggregates until contact is restored. The reason a higher severity level (lower value) is not proposed for the initial log is because any corrective action would probably be based on alerts at a lower subsystem level.
o PRI最初设置为115，表示设备值为（14）“日志警报”，严重程度为（3）“错误条件”。注意，与PCN出口节点的接触丢失意味着在恢复接触之前，不会允许新的流进入一个或多个入口-出口集合。没有为初始日志建议更高的严重性级别（较低的值）的原因是，任何纠正措施都可能基于较低子系统级别的警报。
o APPNAME set to "PCN" (without the quotes).
o APPNAME设置为“PCN”（不带引号）。
o MSGID set to "LOST" (without the quotes).
o MSGID设置为“丢失”（不带引号）。
If contact is not regained with a PCN-egress-node in a reasonable period of time (say, one minute), the log SHOULD be repeated, this time with a PRI value of 113, implying a Facility value of (14) "log alert" and a Severity value of (1) "Alert: action must be taken immediately". The reasoning is that by this time, any more general conditions should have been cleared, and the problem lies specifically with the PCN-egress-node concerned and the PCN application in particular.
如果在合理的时间段内（例如，一分钟）未与PCN出口节点恢复联系，则应重复日志，这次PRI值为113，这意味着设施值为（14）“日志警报”，严重性值为（1）“警报：必须立即采取行动”。理由是，到目前为止，任何更一般的条件都应该被清除，问题具体在于相关的PCN出口节点，特别是PCN应用程序。
Whenever a loss-of-contact log is generated for a PCN-egress-node, a log indicating recovery SHOULD be generated when the Decision Point next receives a report from the node concerned. The log SHOULD have the same content as just described for the loss-of-contact log, with the following differences:
每当为PCN出口节点生成联系丢失日志时，当决策点下次收到相关节点的报告时，应生成指示恢复的日志。日志的内容应与刚才描述的失去联系日志的内容相同，但有以下区别：
o PRI changes to 117, indicating a Facility value of (14) "log alert" and a Severity of (5) "Notice: normal but significant condition".
o PRI更改为117，表示设施值为（14）“日志警报”，严重性为（5）“通知：正常但重要条件”。
o MSGID changes to "RECVD" (without the quotes).
o MSGID更改为“RECVD”（不带引号）。
Section 3.3.2 describes the process whereby the Decision Point decides that flow termination is required for a given ingress-egress-aggregate, calculates how much flow to terminate, and selects flows for termination. This section describes a log that SHOULD be generated each time such an event occurs. (In the case where termination occurs in multiple rounds, one log SHOULD be generated per round.) The log may be useful in fault management, to indicate the service impact of a fault occurring in a lower-level subsystem. In the absence of network failures, it may also be used as an indication of an urgent need to review capacity utilization along the path of the ingress-egress-aggregate concerned.
第3.3.2节描述了决策点确定给定进出口集合需要终止流量、计算终止流量并选择终止流量的过程。本节介绍每次发生此类事件时应生成的日志。（在多轮终止的情况下，每轮应生成一个日志。）该日志可用于故障管理，以指示在较低级别子系统中发生的故障对服务的影响。在没有网络故障的情况下，它还可以被用作指示迫切需要沿着相关入口-出口聚合的路径审查容量利用率。
The log reporting a flow termination event MUST include the following content:
报告流终止事件的日志必须包括以下内容：
o The HOSTNAME field MUST identify the Decision Point issuing the log.
o 主机名字段必须标识发出日志的决策点。
o A STRUCTURED-DATA element MUST be present, containing parameters identifying the ingress and egress nodes for the ingress-egress-aggregate concerned, indicating the total amount of flow being terminated, and giving the number of flows terminated to achieve that objective.
o 必须存在结构化数据元素，其中包含识别相关进出口聚合的进出口节点的参数，指示终止的流量总量，并给出为实现该目标而终止的流量数量。
It is RECOMMENDED that the SD-ID for the STRUCTURED-DATA element have the form: "PCNTerm" (without the quotes), which has been registered with IANA (see [RFC6661] for more information). The parameter identifying the ingress node for the ingress-egress-aggregate is RECOMMENDED to have PARAM-NAME "IngrID" (without the quotes). The parameter identifying the egress node for the ingress-egress-aggregate is RECOMMENDED to have PARAM-NAME "EgrID" (without the quotes). Both identifiers are subject to the preferences expressed in Section 6.2.4 of [RFC5424] for the HOSTNAME field.
建议结构化数据元素的SD-ID采用“PCNTerm”（不带引号）格式，该格式已在IANA注册（更多信息请参见[RFC6661]）。建议为入口-出口聚合标识入口节点的参数使用PARAM-NAME“IngrID”（不带引号）。建议为入口-出口聚合标识出口节点的参数使用PARAM-NAME“EgrID”（不带引号）。这两个标识符都受[RFC5424]第6.2.4节中主机名字段首选项的约束。
The parameter giving the total amount of flow being terminated is RECOMMENDED to have PARAM-NAME "TermRate" (without the quotes). The PARAM-VALUE MUST be the target rate as calculated according to the procedures of Section 3.3.2, as an integer value in thousands of octets per second. The parameter giving the number of flows selected for termination is RECOMMENDED to have PARAM-NAME "FCnt" (without the quotes). The PARAM-VALUE for this parameter MUST be an integer, the number of flows selected.
建议给出终止流量总量的参数使用PARAM-NAME“TermRate”（不带引号）。PARAM-VALUE必须是根据第3.3.2节的程序计算的目标速率，作为整数值，以千位字节/秒为单位。建议给出为终止选择的流数的参数使用PARAM-NAME“FCnt”（不带引号）。此参数的PARAM-VALUE必须是一个整数，即所选的流数。
The following values are also RECOMMENDED for the indicated fields in this log, subject to local practice:
根据当地惯例，本日志中指示的字段也建议使用以下值：
o PRI initially set to 116, representing a Facility value of (14) "log alert" and a Severity level of (4) "Warning: warning conditions".
o PRI最初设置为116，表示设备值为（14）“日志警报”，严重性级别为（4）“警告：警告条件”。
o APPNAME set to "PCN" (without the quotes).
o APPNAME设置为“PCN”（不带引号）。
o MSGID set to "TERM" (without the quotes).
o MSGID设置为“TERM”（不带引号）。
The Diffserv MIB [RFC3289] allows for the provision of counters along the various possible processing paths associated with an interface and flow direction. It is RECOMMENDED that the PCN-nodes be instrumented as described below. It is assumed that the cumulative counts so obtained will be collected periodically for use in debugging, fault management, and capacity management.
Diffserv MIB[RFC3289]允许沿着与接口和流方向相关联的各种可能的处理路径提供计数器。建议如下所述检测PCN节点。假定将定期收集由此获得的累积计数，以用于调试、故障管理和容量管理。
PCN-ingress-nodes SHOULD provide the following counts for each ingress-egress-aggregate. Since the Diffserv MIB installs counters by interface and direction, aggregation of counts over multiple interfaces may be necessary to obtain total counts by ingress-egress-aggregate. It is expected that such aggregation will be performed by a central system rather than at the PCN-ingress-node.
PCN入口节点应为每个入口-出口聚合提供以下计数。由于Diffserv MIB按接口和方向安装计数器，因此可能需要对多个接口上的计数进行聚合，以通过入口-出口聚合获得总计数。预计这种聚合将由中央系统而不是在PCN入口节点执行。
o total PCN packets and octets that were received for that ingress-egress-aggregate but were dropped;
o 为该入口-出口聚合接收但被丢弃的PCN数据包和八位字节总数；
o total PCN packets and octets admitted to that aggregate.
o 允许加入该聚合的PCN数据包和八位字节总数。
PCN-interior-nodes SHOULD provide the following counts for each interface, noting that a given packet MUST NOT be counted more than once as it passes through the node:
PCN内部节点应为每个接口提供以下计数，注意给定数据包在通过节点时不得计数超过一次：
o total PCN packets and octets dropped;
o 丢弃的PCN数据包和八位字节总数；
o total PCN packets and octets forwarded without re-marking;
o 未重新标记转发的PCN数据包和八位字节总数；
o total PCN packets and octets re-marked to excess-traffic-marked.
o 总PCN数据包和八位字节被重新标记为标记的过量流量。
PCN-egress-nodes SHOULD provide the following counts for each ingress-egress-aggregate. As with the PCN-ingress-node, so with the PCN-egress-node it is expected that any necessary aggregation over multiple interfaces will be done by a central system.
PCN出口节点应为每个入口-出口聚合提供以下计数。与PCN入口节点一样，PCN出口节点的任何必要的多接口聚合都将由一个中央系统完成。
o total not-marked PCN packets and octets received;
o 接收到的未标记PCN数据包和八位字节总数；
o total excess-traffic-marked PCN packets and octets received.
o 接收到的标记为PCN数据包和八位字节的总超额流量。
The following continuously cumulative counters SHOULD be provided as indicated, but require new MIBs to be defined. If the Decision Point is not collocated with the PCN-ingress-node, the latter SHOULD provide a count of the number of requests for PCN-sent-rate received from the Decision Point and the number of responses returned to the Decision Point. The PCN-egress-node SHOULD provide a count of the number of reports sent to each Decision Point. Each Decision Point SHOULD provide the following:
应按指示提供以下连续累积计数器，但需要定义新的MIB。如果决策点未与PCN入口节点并置，后者应提供从决策点接收的PCN发送速率请求数和返回到决策点的响应数。PCN出口节点应提供发送到每个决策点的报告数量计数。每个决策点应提供以下内容：
o total number of requests for PCN-sent-rate sent to each PCN-ingress-node with which it is not collocated;
o 发送到未与之并置的每个PCN入口节点的PCN发送速率请求总数；
o total number of reports received from each PCN-egress-node;
o 从每个PCN出口节点接收的报告总数；
o total number of loss-of-contact events detected for each PCN-boundary-node;
o 每个PCN边界节点检测到的失去联系事件总数；
o total cumulative duration of "block" state in hundreds of milliseconds for each ingress-egress-aggregate;
o 每个入口-出口聚合的“块”状态的总累积持续时间（以数百毫秒为单位）；
o total number of rounds of flow termination exercised for each ingress-egress-aggregate.
o 为每个入口-出口骨料执行的流量终止总轮数。
[RFC5559] provides a general description of the security considerations for PCN. This memo introduces one new consideration, related to the use of a centralized Decision Point. The Decision Point itself is a trusted entity. However, its use implies the existence of an interface on the PCN-ingress-node through which communication of policy decisions takes place. That interface is a point of vulnerability that must be protected from denial-of-service attacks.
[RFC5559]提供了PCN安全注意事项的一般说明。本备忘录介绍了一个新的考虑事项，与使用集中决策点有关。决策点本身是一个受信任的实体。然而，它的使用意味着PCN入口节点上存在一个接口，通过该接口进行策略决策的通信。该接口是一个必须防止拒绝服务攻击的漏洞点。
Ruediger Geib, Philip Eardley, and Bob Briscoe have helped to shape the present document with their comments. Toby Moncaster gave a careful review to get it into shape for Working Group Last Call.
Ruediger Geib、Philip Eardley和Bob Briscoe通过他们的评论帮助形成了本文件。托比·蒙卡斯特（Toby Moncaster）为工作组的最后一次电话会议做了仔细的回顾，以使其成形。
Amongst the authors, Michael Menth deserves special mention for his constant and careful attention to both the technical content of this document and the manner in which it was expressed.
在作者中，Michael Minth值得特别提及，因为他对本文件的技术内容和表达方式始终给予了认真的关注。
David Harrington's careful AD review resulted not only in necessary changes throughout the document, but also the addition of the operations and management considerations (Section 5).
David Harrington仔细的广告审查不仅在整个文件中进行了必要的更改，还增加了运营和管理方面的考虑（第5节）。
Finally, reviews by Joel Halpern and Brian Carpenter helped to clarify how ingress-egress-aggregates are distinguished (Joel) and handling of packets that cannot be carried successfully as PCN-packets (Brian). They also made other suggestions to improve the document, as did Stephen Farrell, Sean Turner, and Pete Resnick.
最后，Joel Halpern和Brian Carpenter的评论有助于澄清如何区分进出聚合（Joel）以及如何处理不能作为PCN数据包成功传输的数据包（Brian）。他们还提出了其他改进该文件的建议，斯蒂芬·法雷尔、肖恩·特纳和皮特·雷斯尼克也是如此。
[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。
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers", RFC 2474, December 1998.
[RFC2474]Nichols，K.，Blake，S.，Baker，F.，和D.Black，“IPv4和IPv6头中区分服务字段（DS字段）的定义”，RFC 2474，1998年12月。
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z., and W. Weiss, "An Architecture for Differentiated Services", RFC 2475, December 1998.
[RFC2475]Blake，S.，Black，D.，Carlson，M.，Davies，E.，Wang，Z.，和W.Weiss，“差异化服务架构”，RFC 24751998年12月。
[RFC3086] Nichols, K. and B. Carpenter, "Definition of Differentiated Services Per Domain Behaviors and Rules for their Specification", RFC 3086, April 2001.
[RFC3086]Nichols，K.和B.Carpenter，“每域区分服务行为的定义及其规范规则”，RFC 3086，2001年4月。
[RFC3289] Baker, F., Chan, K., and A. Smith, "Management Information Base for the Differentiated Services Architecture", RFC 3289, May 2002.
[RFC3289]Baker，F.，Chan，K.和A.Smith，“差异化服务体系结构的管理信息库”，RFC 3289，2002年5月。
[RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424, March 2009.
[RFC5424]Gerhards，R.，“系统日志协议”，RFC 54242009年3月。
[RFC5559] Eardley, P., "Pre-Congestion Notification (PCN) Architecture", RFC 5559, June 2009.
[RFC5559]Eardley，P.，“拥塞前通知（PCN）体系结构”，RFC555592009年6月。
[RFC5670] Eardley, P., "Metering and Marking Behaviour of PCN-Nodes", RFC 5670, November 2009.
[RFC5670]Eardley，P.，“PCN节点的计量和标记行为”，RFC 56702009年11月。
[RFC6660] Briscoe, B., Moncaster, T., and M. Menth, "Encoding Three Pre-Congestion Notification (PCN) States in the IP Header Using a Single Diffserv Codepoint (DSCP)", RFC 6660, July 2012.
[RFC6660]Briscoe，B.，Moncaster，T.，和M.Menth，“使用单个Diffserv码点（DSCP）在IP报头中编码三种拥塞前通知（PCN）状态”，RFC 66602012年7月。
[MeLe10] Menth, M. and F. Lehrieder, "PCN-Based Measured Rate Termination", Computer Networks Journal (Elsevier), vol. 54, no. 13, pp. 2099-2116, September 2010.
[MeLe10]Minth，M.和F.Lehrieder，“基于PCN的测量速率终止”，《计算机网络杂志》（Elsevier），第54卷，第13期，第2099-2116页，2010年9月。
[MeLe12] Menth, M. and F. Lehrieder, "Performance of PCN-Based Admission Control under Challenging Conditions", IEEE/ ACM Transactions on Networking, vol. 20, no. 2, April 2012.
[MeLe12]Minth，M.和F.Lehrieder，“挑战性条件下基于PCN的准入控制的性能”，IEEE/ACM网络交易，第20卷，第2期，2012年4月。
[RFC4594] Babiarz, J., Chan, K., and F. Baker, "Configuration Guidelines for DiffServ Service Classes", RFC 4594, August 2006.
[RFC4594]Babiarz，J.，Chan，K.，和F.Baker，“区分服务服务类的配置指南”，RFC 45942006年8月。
[RFC6661] Charny, A., Huang, F., Karagiannis, G., Menth, M., and T. Taylor, Ed., "Pre-Congestion Notification (PCN) Boundary-Node Behavior for the Controlled Load (CL) Mode of Operation", RFC 6661, July 2012.
[RFC6661]Charny，A.，Huang，F.，Karagiannis，G.，Minth，M.，和T.Taylor，Ed.，“受控负载（CL）运行模式下的拥塞前通知（PCN）边界节点行为”，RFC 66612012年7月。
[RSVP-PCN] Karagiannis, G. and A. Bhargava, "Generic Aggregation of Resource ReSerVation Protocol (RSVP) for IPv4 And IPv6 Reservations over PCN domains", Work in Progress, July 2012.
[RSVP-PCN]Karagiannis，G.和A.Bhargava，“PCN域上IPv4和IPv6保留的资源保留协议（RSVP）的通用聚合”，正在进行的工作，2012年7月。
[Satoh10] Satoh, D. and H. Ueno, "Cause and Countermeasure of Overtermination for PCN-Based Flow Termination", Proceedings of IEEE Symposium on Computers and Communications (ISCC '10), pp. 155-161, Riccione, Italy, June 2010.
[Satoh10]Satoh，D.和H.Ueno，“基于PCN的流终止过度终止的原因和对策”，《IEEE计算机与通信研讨会论文集》（ISCC'10），第155-161页，意大利里奇奥尼，2010年6月。
Authors' Addresses
作者地址
Anna Charny USA
安娜·查尼美国
EMail: anna@mwsm.com
EMail: anna@mwsm.com
Xinyan (Joy) Zhang Cisco Systems 300 Apollo Drive Chelmsford, MA 01824 USA
新燕（久益）张思科系统美国马萨诸塞州切姆斯福德阿波罗大道300号01824
EMail: joyzhang@cisco.com
EMail: joyzhang@cisco.com
Georgios Karagiannis University of Twente P.O. Box 217 7500 AE Enschede, The Netherlands
乔治斯卡拉基安尼斯屯特大学邮政信箱217 7500 AE恩斯赫德，荷兰
Phone: +31 53 4894099
EMail: g.karagiannis@utwente.nl
Phone: +31 53 4894099
EMail: g.karagiannis@utwente.nl
Michael Menth University of Tuebingen Sand 13 72076 Tuebingen Germany
米迦勒蒙特大学图宾根沙特13德国72076
Phone: +49-7071-2970505
EMail: menth@uni-tuebingen.de
Phone: +49-7071-2970505
EMail: menth@uni-tuebingen.de
Tom Taylor (editor) Huawei Technologies Ottawa Canada
汤姆泰勒（编辑）华为技术加拿大渥太华
EMail: tom.taylor.stds@gmail.com
EMail: tom.taylor.stds@gmail.com