Internet Engineering Task Force (IETF) D. Mohan, Ed.
Request for Comments: 7023 Nortel Networks
Category: Standards Track N. Bitar, Ed.
ISSN: 2070-1721 Verizon
A. Sajassi, Ed.
Cisco
S. Delord
Alcatel-Lucent
P. Niger
France Telecom
R. Qiu
Juniper
October 2013
Internet Engineering Task Force (IETF) D. Mohan, Ed.
Request for Comments: 7023 Nortel Networks
Category: Standards Track N. Bitar, Ed.
ISSN: 2070-1721 Verizon
A. Sajassi, Ed.
Cisco
S. Delord
Alcatel-Lucent
P. Niger
France Telecom
R. Qiu
Juniper
October 2013
MPLS and Ethernet Operations, Administration, and Maintenance (OAM) Interworking
MPLS和以太网操作、管理和维护（OAM）互通
Abstract
摘要
This document specifies the mapping of defect states between Ethernet Attachment Circuits (ACs) and associated Ethernet pseudowires (PWs) connected in accordance with the Pseudowire Emulation Edge-to-Edge (PWE3) architecture to realize an end-to-end emulated Ethernet service. It standardizes the behavior of Provider Edges (PEs) with respect to Ethernet PW and AC defects.
本文件规定了以太网连接电路（ACs）和根据伪线仿真边到边（PWE3）架构连接的相关以太网伪线（PW）之间的缺陷状态映射，以实现端到端仿真以太网服务。它标准化了提供商边缘（PE）在以太网PW和AC缺陷方面的行为。
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/rfc7023.
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/rfc7023.
Copyright Notice
版权公告
Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2013 IETF信托基金和确定为文件作者的人员。版权所有。
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(http://trustee.ietf.org/license-info)自本文件出版之日起生效。请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本，并提供简化BSD许可证中所述的无担保。
Table of Contents
目录
1. Introduction ....................................................4
1.1. Specification of Requirements ..............................4
2. Overview ........................................................4
2.1. Reference Model and Defect Locations .......................6
2.2. Abstract Defect States .....................................6
3. Abbreviations and Terminology ...................................7
3.1. Abbreviations ..............................................7
3.2. Terminology ................................................8
4. PW Status and Defects ...........................................9
4.1. Use of Native Service (NS) Notification ....................9
4.2. Use of PW Status Notification for MPLS PSNs ...............10
4.3. Use of BFD Diagnostic Codes ...............................10
4.4. PW Defect States Entry and Exit Criteria ..................11
4.4.1. PW Receive Defect State Entry and Exit .............11
4.4.2. PW Transmit Defect State Entry and Exit ............11
5. Ethernet AC Defect States Entry and Exit Criteria ..............12
5.1. AC Receive Defect State Entry and Exit ....................12
5.2. AC Transmit Defect State Entry and Exit ...................13
6. Ethernet AC and PW Defect States Interworking ..................14
6.1. PW Receive Defect State Entry Procedures ..................14
6.2. PW Receive Defect State Exit Procedures ...................15
6.3. PW Transmit Defect State Entry Procedures .................16
6.4. PW Transmit Defect State Exit Procedures ..................16
6.5. AC Receive Defect State Entry Procedures ..................16
6.6. AC Receive Defect State Exit Procedures ...................17
6.7. AC Transmit Defect State Entry Procedures .................17
6.8. AC Transmit Defect State Exit Procedures ..................18
7. Security Considerations ........................................18
8. Acknowledgments ................................................19
9. References .....................................................19
9.1. Normative References ......................................19
9.2. Informative References ....................................20
Appendix A. Ethernet Native Service Management ....................21
1. Introduction ....................................................4
1.1. Specification of Requirements ..............................4
2. Overview ........................................................4
2.1. Reference Model and Defect Locations .......................6
2.2. Abstract Defect States .....................................6
3. Abbreviations and Terminology ...................................7
3.1. Abbreviations ..............................................7
3.2. Terminology ................................................8
4. PW Status and Defects ...........................................9
4.1. Use of Native Service (NS) Notification ....................9
4.2. Use of PW Status Notification for MPLS PSNs ...............10
4.3. Use of BFD Diagnostic Codes ...............................10
4.4. PW Defect States Entry and Exit Criteria ..................11
4.4.1. PW Receive Defect State Entry and Exit .............11
4.4.2. PW Transmit Defect State Entry and Exit ............11
5. Ethernet AC Defect States Entry and Exit Criteria ..............12
5.1. AC Receive Defect State Entry and Exit ....................12
5.2. AC Transmit Defect State Entry and Exit ...................13
6. Ethernet AC and PW Defect States Interworking ..................14
6.1. PW Receive Defect State Entry Procedures ..................14
6.2. PW Receive Defect State Exit Procedures ...................15
6.3. PW Transmit Defect State Entry Procedures .................16
6.4. PW Transmit Defect State Exit Procedures ..................16
6.5. AC Receive Defect State Entry Procedures ..................16
6.6. AC Receive Defect State Exit Procedures ...................17
6.7. AC Transmit Defect State Entry Procedures .................17
6.8. AC Transmit Defect State Exit Procedures ..................18
7. Security Considerations ........................................18
8. Acknowledgments ................................................19
9. References .....................................................19
9.1. Normative References ......................................19
9.2. Informative References ....................................20
Appendix A. Ethernet Native Service Management ....................21
RFC 6310 [RFC6310] specifies the mapping and notification of defect states between a pseudowire (PW) and the Attachment Circuit (AC) of the end-to-end emulated service. It standardizes the behavior of Provider Edges (PEs) with respect to PW and AC defects for a number of technologies (e.g., Asynchronous Transfer Mode (ATM) and Frame Relay (FR)) emulated over PWs in MPLS and MPLS/IP Packet Switched Networks (PSNs). However, [RFC6310] does not describe this function for the Ethernet PW service owing to its unique characteristics.
RFC 6310[RFC6310]指定端到端仿真服务的伪线（PW）和连接电路（AC）之间的缺陷状态映射和通知。它标准化了在MPLS和MPLS/IP分组交换网络（PSN）中通过PWs仿真的许多技术（例如，异步传输模式（ATM）和帧中继（FR））的PW和AC缺陷的提供商边缘（PE）行为。但是，[RFC6310]由于其独特的特性，没有描述以太网PW服务的此功能。
This document specifies the mapping of defect states between ACs and associated Ethernet PWs connected in accordance with the PWE3 architecture [RFC3985] to realize an end-to-end emulated Ethernet service. This document augments the mapping of defect states between a PW and associated AC of the end-to-end emulated service in [RFC6310]. Similar to [RFC6310], the intent of this document is to standardize the behavior of PEs with respect to failures on Ethernet ACs and PWs, so that there is no ambiguity about the alarms generated and consequent actions undertaken by PEs in response to specific failure conditions.
本文件规定了根据PWE3体系结构[RFC3985]连接的ACs和相关以太网PW之间的缺陷状态映射，以实现端到端模拟以太网服务。本文档增强了[RFC6310]中端到端仿真服务的PW和相关AC之间的缺陷状态映射。与[RFC6310]类似，本文件旨在标准化PEs在以太网ACs和PWs故障方面的行为，从而使PEs针对特定故障条件产生的警报和随后采取的行动不存在歧义。
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。
There are a number of Operations, Administration, and Maintenance (OAM) technologies defined for Ethernet, providing various functionalities. This document covers the following Ethernet OAM mechanisms and their interworking with PW OAM mechanisms:
有许多为以太网定义的操作、管理和维护（OAM）技术，提供各种功能。本文档涵盖以下以太网OAM机制及其与PW OAM机制的互通：
- Ethernet Link OAM [802.3] - Ethernet Local Management Interface (E-LMI) [MEF16] - Ethernet Continuity Check (CC) [CFM] [Y.1731] - Ethernet Alarm Indication Signaling (AIS) and Remote Defect Indication (RDI) [Y.1731]
- 以太网链路OAM[802.3]-以太网本地管理接口（E-LMI）[MEF16]-以太网连续性检查（CC）[CFM][Y.1731]-以太网报警指示信令（AIS）和远程缺陷指示（RDI）[Y.1731]
Ethernet Link OAM [802.3] allows some link defect states to be detected and communicated across an Ethernet link. When an Ethernet AC is an Ethernet physical port, there may be some application of Ethernet Link OAM [802.3]. Further, E-LMI [MEF16] also allows for some Ethernet Virtual Circuit (EVC) defect states to be communicated across an Ethernet User Network Interface (UNI) where Ethernet UNI constitutes a single-hop Ethernet link (i.e., without any bridges
以太网链路OAM[802.3]允许通过以太网链路检测和通信某些链路缺陷状态。当以太网AC是以太网物理端口时，可能存在以太网链路OAM[802.3]的某些应用。此外，E-LMI[MEF16]还允许一些以太网虚拟电路（EVC）缺陷状态通过以太网用户网络接口（UNI）进行通信，其中以太网UNI构成单跳以太网链路（即，没有任何网桥）
compliant with IEEE 802.1Q/.1ad in between). There may be some application of E-LMI [MEF16] for failure notification across single-hop Ethernet ACs in certain deployments that specifically do not support IEEE Connectivity Fault Management [CFM] and/or ITU-T Y.1731 [Y.1731], simply referred to as CFM and Y.1731, respectively, in this document. Mechanisms based on Y.1731 and CFM are applicable in all types of Ethernet ACs. Ethernet Link OAM and E-LMI are optional, and their applicability is called out, where applicable.
符合IEEE 802.1Q/.1ad（介于两者之间）。E-LMI[MEF16]可能在某些部署中用于单跳以太网ACs的故障通知，这些部署特别不支持IEEE连接故障管理[CFM]和/或ITU-T Y.1731[Y.1731]，在本文件中分别简称为CFM和Y.1731。基于Y.1731和CFM的机制适用于所有类型的以太网ACs。以太网链路OAM和E-LMI是可选的，在适用的情况下，它们的适用性将被调用。
Native service (NS) OAM may be transported transparently over the corresponding PW as user data. This is referred to as the "single emulated OAM loop mode" per [RFC6310]. For Ethernet, as an example, CFM continuity check messages (CCMs) between two Maintenance Entity Group End Points (MEPs) can be transported transparently as user data over the corresponding PW. At MEP locations, service failure is detected when CCMs are not received over an interval that is 3.5 times the local CCM transmission interval. This is one of the failure conditions detected via continuity check. MEP peers can exist between customer edge (CE) endpoints (MEPs of a given Maintenance Entity Group (MEG) reside on the CEs), between PE pairs (the MEPs of a given MEG reside on the PEs), or between the CE and PE (the MEPs of a given MEG reside on the PE and CE), as long as the MEG level nesting rules are maintained. It should be noted that Ethernet allows the definition of up to 8 MEG levels, each comprised of MEPs (Down MEPs and Up MEPs) and Maintenance Entity Group Intermediate Points (MIPs). These levels can be nested or touching. MEPs and MIPs generate and process messages in the same MEG level. Thus, in this document, when we refer to messages sent by a MEP or a MIP to a peer MEP or MIP, these MEPs and MIPs are in the same MEG level.
本机服务（NS）OAM可以作为用户数据在相应的PW上透明地传输。根据[RFC6310]，这被称为“单模拟OAM循环模式”。例如，对于以太网，两个维护实体组端点（MEP）之间的CFM连续性检查消息（CCM）可以作为相应PW上的用户数据透明地传输。在MEP位置，当在本地CCM传输间隔3.5倍的时间间隔内未接收到CCM时，检测到服务故障。这是通过连续性检查检测到的故障条件之一。MEP对等点可以存在于客户边缘（CE）端点之间（给定维护实体组（MEG）的MEP位于CEs上）、PE对之间（给定MEG的MEP位于PEs上）或CE和PE之间（给定MEG的MEP位于PE和CE上），只要维护MEG级嵌套规则。应注意，以太网允许定义多达8个MEG级别，每个级别由MEP（向下MEP和向上MEP）和维护实体组中间点（MIP）组成。这些级别可以嵌套或接触。MEP和MIP在同一MEG级别生成和处理消息。因此，在本文档中，当我们参考由MEP或MIP发送给对等MEP或MIP的消息时，这些MEP和MIP处于相同的MEG级别。
When interworking two networking domains, such as native Ethernet and PWs to provide an end-to-end emulated service, there is a need to identify the failure domain and location even when a PE supports both the NS OAM mechanisms and the PW OAM mechanisms. In addition, scalability constraints may not allow running proactive monitoring, such as CCMs with transmission enabled, at a PE to detect the failure of an EVC across the PW domain. Thus, network-driven alarms generated upon failure detection in the NS or PW domain and their mappings to the other domain are needed. There are also cases where a PE MAY not be able to process NS OAM messages received on the PW even when such messages are defined, as in the case of Ethernet, necessitating the need for fault notification message mapping between the PW domain and the NS domain.
当将两个网络域（如本机以太网和PWs）互通以提供端到端模拟服务时，即使PE同时支持NS OAM机制和PW OAM机制，也需要识别故障域和位置。此外，可伸缩性约束可能不允许在PE处运行主动式监视，例如启用传输的CCMs，以检测PW域中EVC的故障。因此，需要在NS或PW域中检测到故障时生成网络驱动报警，并将其映射到其他域。还有一些情况下，PE可能无法处理在PW上接收的NS OAM消息，即使在定义了此类消息的情况下，如在以太网的情况下，也需要PW域和NS域之间的故障通知消息映射。
For Multi-Segment PWs (MS-PWs) [RFC5659], Switching PEs (S-PEs) are not aware of the NS. Thus, failure detection and notification at S-PEs will be based on PW OAM mechanisms. Mapping between PW OAM and NS OAM will be required at the Terminating PEs (T-PEs) to propagate the failure notification to the EVC end points.
对于多段PWs（MS PWs）[RFC5659]，交换PE（S-PE）不知道NS。因此，S-PEs的故障检测和通知将基于PW OAM机制。终端PEs（T-PEs）需要PW OAM和NS OAM之间的映射，以将故障通知传播到EVC端点。
Figure 1 was used in [RFC6310]; it is reproduced in this document as a reference to highlight defect locations.
图1用于[RFC6310]；本文件中复制了该文件，作为突出缺陷位置的参考。
ACs PSN tunnel ACs
+----+ +----+
+----+ | PE1|==================| PE2| +----+
| |---(a)---(b)..(c)......PW1..(d)..(e)..(f)---(g)---| |
| CE1| (N1) | | | | (N2) |CE2 |
| |----------|............PW2.............|----------| |
+----+ | |==================| | +----+
^ +----+ +----+ ^
| Provider Edge 1 Provider Edge 2 |
| |
|<-------------- Emulated Service ---------------->|
ACs PSN tunnel ACs
+----+ +----+
+----+ | PE1|==================| PE2| +----+
| |---(a)---(b)..(c)......PW1..(d)..(e)..(f)---(g)---| |
| CE1| (N1) | | | | (N2) |CE2 |
| |----------|............PW2.............|----------| |
+----+ | |==================| | +----+
^ +----+ +----+ ^
| Provider Edge 1 Provider Edge 2 |
| |
|<-------------- Emulated Service ---------------->|
Customer Customer Edge 1 Edge 2
客户边缘1边缘2
Figure 1: PWE3 Network Defect Locations
图1:PWE3网络缺陷位置
Abstract defect states are also introduced in [RFC6310]. As shown in Figure 2, this document uses the same conventions as [RFC6310]. It may be noted, however, that CE devices, shown in Figure 2, do not necessarily have to be end customer devices. These are essentially devices in client network segments that are connecting to the Packet Switched Network (PSN) for the emulated services.
[RFC6310]中还介绍了抽象缺陷状态。如图2所示，本文档使用与[RFC6310]相同的约定。然而，可以注意到，图2中所示的CE设备不一定必须是终端客户设备。这些基本上是客户端网段中连接到分组交换网络（PSN）的设备，用于模拟服务。
+-----+
----AC receive ----->| |-----PW transmit---->
CE1 | PE1 | PE2/CE2
<---AC transmit------| |<----PW receive-----
+-----+
(arrows indicate direction of user traffic impacted by a defect)
+-----+
----AC receive ----->| |-----PW transmit---->
CE1 | PE1 | PE2/CE2
<---AC transmit------| |<----PW receive-----
+-----+
(arrows indicate direction of user traffic impacted by a defect)
Figure 2: Transmit and Receive Defect States and Notifications
图2：发送和接收缺陷状态和通知
The procedures outlined in this document define the entry and exit criteria for each of the four defect states with respect to Ethernet ACs and corresponding PWs; this document also defines the consequent actions that PE1 MUST support to properly interwork these defect states and corresponding notification messages between the PW domain and the native service (NS) domain. Receive defect state SHOULD have precedence over transmit defect state in terms of handling, when both transmit and receive defect states are identified simultaneously.
本文件中概述的程序定义了以太网ACs和相应PWs的四种缺陷状态的进入和退出标准；本文档还定义了PE1必须支持的后续操作，以便在PW域和本机服务（NS）域之间正确地互通这些缺陷状态和相应的通知消息。当发送和接收缺陷状态同时被识别时，接收缺陷状态在处理方面应优先于发送缺陷状态。
Following is a summary of the defect states from the viewpoint of PE1 in Figure 2:
以下是从图2中PE1的角度总结的缺陷状态：
- A PW receive defect at PE1 impacts PE1's ability to receive traffic on the PW. Entry and exit criteria for the PW receive defect state are described in Section 4.4.1.
- PE1处的PW接收缺陷影响PE1接收PW流量的能力。PW接收缺陷状态的进入和退出标准见第4.4.1节。
- A PW transmit defect at PE1 impacts PE1's ability to send user traffic toward CE2. PE1 MAY be notified of a PW transmit defect via a Reverse Defect Indication from PE2, which could point to problems associated with PE2's inability to receive traffic on the PW or PE2's inability to transmit traffic on its local AC. Entry and exit criteria for the PW transmit defect state are described in Section 4.4.2.
- PE1处的PW传输缺陷影响PE1向CE2发送用户流量的能力。可通过PE2的反向缺陷指示通知PE1 PW传输缺陷，这可能指向与PE2无法在PW上接收流量或PE2无法在其本地AC上传输流量相关的问题。PW传输缺陷状态的进入和退出标准在第4.4.2节中描述。
- An AC receive defect at PE1 impacts PE1's ability to receive user traffic from the client domain attached to PE1 via that AC. Entry and exit criteria for the AC receive defect state are described in Section 5.1.
- PE1处的AC接收缺陷影响PE1通过该AC从连接到PE1的客户端域接收用户流量的能力。第5.1节描述了AC接收缺陷状态的进入和退出标准。
- An AC transmit defect at PE1 impacts PE1's ability to send user traffic on the local AC. Entry and exit criteria for the AC transmit defect state are described in Section 5.2.
- PE1处的交流传输缺陷影响PE1在本地交流上发送用户流量的能力。第5.2节描述了交流传输缺陷状态的进入和退出标准。
AC Attachment Circuit AIS Alarm Indication Signal BFD Bidirectional Forwarding Detection CC Continuity Check CCM Continuity Check Message CE Customer Edge CV Connectivity Verification E-LMI Ethernet Local Management Interface EVC Ethernet Virtual Circuit LDP Label Distribution Protocol LoS Loss of Signal MA Maintenance Association MD Maintenance Domain ME Maintenance Entity MEG Maintenance Entity Group MEP MEG End Point MIP MEG Intermediate Point MPLS Multiprotocol Label Switching MS-PW Multi-Segment Pseudowire NS Native Service OAM Operations, Administration, and Maintenance PE Provider Edge PSN Packet Switched Network PW Pseudowire RDI Remote Defect Indication when used in the context of CCM RDI Reverse Defect Indication when used to semantically refer to defect indication in the reverse direction S-PE Switching Provider Edge T-PE Terminating Provider Edge TLV Type-Length Value VCCV Virtual Circuit Connectivity Verification
交流连接电路AIS报警指示信号BFD双向转发检测CC连续性检查CCM连续性检查消息CE客户边缘CV连接验证E-LMI以太网本地管理接口EVC以太网虚拟电路LDP标签分配协议LoS信号丢失MA维护协会MD维护域ME维护实体MEG维护实体组MEP MEG端点MIP MEG中间点MPLS多协议标签交换MS-PW多段伪线NS本机服务OAM操作、管理、，和维护PE提供商边缘PSN分组交换网络PW伪线RDI远程缺陷指示，当用于CCM RDI反向缺陷指示时，用于语义上指反向S-PE交换提供商边缘T-PE终端提供商边缘TLV类型长度值VCCV虚拟电路中的缺陷指示连通性验证
This document uses the following terms with corresponding definitions:
本文件使用以下术语及相应定义：
- MEG Level: identifies a value in the range of 0-7 associated with an Ethernet OAM frame. MEG level identifies the span of the Ethernet OAM frame.
- MEG级别：标识与以太网OAM帧相关的0-7范围内的值。MEG级别标识以太网OAM帧的范围。
- MEG End Point (MEP): is responsible for origination and termination of OAM frames for a given MEG.
- MEG端点（MEP）：负责给定MEG的OAM帧的发起和终止。
- MEG Intermediate Point (MIP): is located between peer MEPs and can process OAM frames but does not initiate them.
- MEG中间点（MIP）：位于对等MEP之间，可以处理OAM帧，但不会启动它们。
- MPLS PSN: a PSN that makes use of MPLS Label-Switched Paths [RFC3031] as the tunneling technology to forward PW packets.
- MPLS PSN：利用MPLS标签交换路径[RFC3031]作为隧道技术转发PW数据包的PSN。
- MPLS/IP PSN: a PSN that makes use of MPLS-in-IP tunneling [RFC4023] to tunnel MPLS-labeled PW packets over IP tunnels.
- MPLS/IP PSN：一种PSN，利用IP隧道[RFC4023]中的MPLS在IP隧道上隧道MPLS标记的PW数据包。
Further, this document also uses the terminology and conventions used in [RFC6310].
此外，本文件还使用了[RFC6310]中使用的术语和约定。
[RFC6310] introduces a range of defects that impact PW status. All these defect conditions are applicable for Ethernet PWs.
[RFC6310]引入了一系列影响PW状态的缺陷。所有这些缺陷条件都适用于以太网PWs。
Similarly, there are different mechanisms described in [RFC6310] to detect PW defects, depending on the PSN type (e.g., MPLS PSN or MPLS/IP PSN). Any of these mechanisms can be used when monitoring the state of Ethernet PWs. [RFC6310] also discusses the applicability of these failure detection mechanisms.
类似地，[RFC6310]中描述了检测PW缺陷的不同机制，这取决于PSN类型（例如，MPLS PSN或MPLS/IP PSN）。在监视以太网PWs的状态时，可以使用这些机制中的任何一种。[RFC6310]还讨论了这些故障检测机制的适用性。
When two PEs terminate an Ethernet PW with associated MEPs, each PE can use native service (NS) OAM capabilities for failure notifications by transmitting appropriate NS OAM messages over the corresponding PW to the remote PE. Options include:
当两个PE通过关联的MEP终止以太网PW时，每个PE可以通过相应的PW向远程PE发送适当的NS OAM消息，使用本机服务（NS）OAM功能进行故障通知。选择包括：
- Sending of AIS frames from the local MEP to the MEP on the remote PE when the MEP needs to convey PE receive defects and when CCM transmission is disabled.
- 当MEP需要传输PE接收缺陷且CCM传输被禁用时，从本地MEP向远程PE上的MEP发送AIS帧。
- Suspending transmission of CCM frames from the local MEP to the peer MEP on the remote PE to convey PE receive defects when CCM transmission is enabled.
- 在启用CCM传输时，暂停从本地MEP到远程PE上对等MEP的CCM帧传输，以传输PE接收缺陷。
- Setting the RDI bit in transmitted CCM frames when loss of CCMs from the peer MEP is detected or when the PE needs to convey PW reverse defects.
- 当检测到来自对等MEP的CCM丢失或PE需要传输PW反向缺陷时，在传输的CCM帧中设置RDI位。
Similarly, when the defect conditions are cleared, a PE can take one of the following actions, depending on the mechanism that was used for failure notification, to clear the defect state on the peer PE:
类似地，当缺陷条件被清除时，PE可以根据用于故障通知的机制，采取以下操作之一，以清除对等PE上的缺陷状态：
- Stopping AIS frame transmission from the local MEP to the MEP on the remote PE to clear PW receive defects.
- 停止从本地MEP到远程PE上的MEP的AIS帧传输，以清除PW接收缺陷。
- Resuming transmission of CCM frames from the local MEP to the peer MEP on the remote PE to clear PW forward defect notification when CCM transmission is enabled.
- 在启用CCM传输时，恢复从本地MEP到远程PE上对等MEP的CCM帧传输，以清除PW转发缺陷通知。
- Clearing the RDI bit in transmitted CCM frames to clear PW transmit defect notification when CCM transmission is enabled.
- 当CCM传输启用时，清除传输的CCM帧中的RDI位以清除PW传输缺陷通知。
RFC 4447 [RFC4447] specifies that for PWs that have been set up using the Label Distribution Protocol (LDP), the default mechanism to signal status and defects for ACs and PWs is the LDP status notification message. For PWs established over an MPLS or MPLS/IP PSN using other mechanisms (e.g., static configuration), in-band signaling using VCCV-BFD [RFC5885] SHOULD be used to convey AC and PW status and defects. Alternatively, the mechanisms defined in [RFC6478] MAY be used.
RFC 4447[RFC4447]规定，对于使用标签分发协议（LDP）建立的PWs，向ACs和PWs发送状态和缺陷信号的默认机制是LDP状态通知消息。对于使用其他机制（例如，静态配置）在MPLS或MPLS/IP PSN上建立的PW，应使用使用VCCV-BFD[RFC5885]的带内信令来传输AC和PW状态和缺陷。或者，可以使用[RFC6478]中定义的机制。
[RFC6310] identifies the following PW defect status code points:
[RFC6310]识别以下PW缺陷状态代码点：
- Forward defect: corresponds to a logical OR of Local Attachment Circuit (ingress) Receive Fault, Local PSN-facing PW (egress) Transmit Fault, and Pseudowire Not Forwarding fault.
- 正向缺陷：对应于本地连接电路（入口）接收故障、本地PSN面对PW（出口）传输故障和伪线不转发故障的逻辑OR。
- Reverse defect: corresponds to a logical OR of Local Attachment Circuit (egress) Transmit Fault and Local PSN-facing PW (ingress) Receive Fault.
- 反向缺陷：对应于本地连接电路（出口）传输故障和面向PW（入口）接收故障的本地PSN的逻辑OR。
There are also scenarios where a PE carries out PW label withdrawal instead of PW status notification. These include administrative disablement of the PW or loss of the Target LDP session with the peer PE.
也存在PE执行PW标签撤销而不是PW状态通知的情况。这些包括PW的管理禁用或与对等PE的目标LDP会话丢失。
When using VCCV, the control channel type and Connectivity Verification (CV) type are agreed on between the peer PEs using the VCCV parameter field signaled as a sub-TLV of the interface parameters TLV when using FEC 129 and the interface parameter sub-TLV when using FEC 128 [RFC5085].
当使用VCCV时，对等PE之间使用VCCV参数字段商定控制信道类型和连接验证（CV）类型，当使用FEC 129时，VCCV参数字段作为接口参数TLV的子TLV，当使用FEC 128时，接口参数子TLV[RFC5085]。
As defined in [RFC6310], when a CV type of 0x04 or 0x10 is used to indicate that BFD is used for PW fault detection only, PW defect is detected via the BFD session while other defects, such as AC defect or PE internal defects preventing it from forwarding traffic, are communicated via an LDP status notification message in MPLS and MPLS/IP PSNs or other mechanisms in L2TP/IP PSNs.
如[RFC6310]中所定义，当CV类型0x04或0x10用于指示BFD仅用于PW故障检测时，PW缺陷通过BFD会话检测，而其他缺陷（如AC缺陷或PE内部缺陷）阻止其转发流量，通过MPLS和MPLS/IP PSN中的LDP状态通知消息或L2TP/IP PSN中的其他机制进行通信。
Similarly, when a CV type of 0x08 or 0x20 is used to indicate that BFD is used for both PW fault detection and AC/PW fault notification, all defects are signaled via BFD.
类似地，当CV类型0x08或0x20用于指示BFD用于PW故障检测和AC/PW故障通知时，所有缺陷都通过BFD发出信号。
As described in Section 6.2.1 of [RFC6310], PE1 will enter the PW receive defect state if one or more of the following occur:
如[RFC6310]第6.2.1节所述，如果出现以下一种或多种情况，PE1将进入PW接收缺陷状态：
- It receives a Forward Defect Indication (FDI) from PE2 either indicating a receive defect on the remote AC or indicating that PE2 detected or was notified of a downstream PW fault.
- 它从PE2接收前向缺陷指示（FDI），指示远程AC上的接收缺陷，或指示PE2检测到或被通知下游PW故障。
- It detects loss of connectivity on the PSN tunnel upstream of PE1, which affects the traffic it receives from PE2.
- 它检测到PE1上游的PSN隧道上的连接丢失，这会影响它从PE2接收的流量。
- It detects a loss of PW connectivity through VCCV-BFD, VCCV-Ping, or NS OAM mechanisms (i.e., CC) when enabled, which affects the traffic it receives from PE2.
- 启用时，它通过VCCV-BFD、VCCV Ping或NS OAM机制（即CC）检测PW连接丢失，这会影响它从PE2接收的流量。
Note that if the PW LDP control session between the PEs fails, the PW is torn down and needs to be re-established. However, the consequent actions towards the ACs are the same as if the PW entered the receive defect state.
请注意，如果PEs之间的PW LDP控制会话失败，PW将被拆除，需要重新建立。然而，对ACs的后续动作与PW进入接收缺陷状态时相同。
PE1 will exit the PW receive defect state when the following conditions are met. Note that this may result in a transition to the PW operational state or the PW transmit defect state.
当满足以下条件时，PE1将退出PW接收缺陷状态。注意，这可能导致转换到PW操作状态或PW传输缺陷状态。
- All previously detected defects have disappeared. - PE2 cleared the FDI, if applicable.
- 以前检测到的所有缺陷都已消失。-PE2清除了FDI（如适用）。
PE1 will enter the PW transmit defect state if the following conditions occur:
如果出现以下情况，PE1将进入PW传输缺陷状态：
- It receives a Reverse Defect Indication (RDI) from PE2 either indicating a transmit fault on the remote AC or indicating that PE2 detected or was notified of an upstream PW fault.
- 它从PE2接收反向缺陷指示（RDI），指示远程AC上的传输故障，或指示PE2检测到上游PW故障或收到上游PW故障通知。
- It is not already in the PW receive defect state.
- 它尚未处于PW接收缺陷状态。
PE1 will exit the transmit defect state if it receives an OAM message from PE2 clearing the RDI or if it has entered the PW receive defect state.
如果PE1从PE2接收到清除RDI的OAM消息，或者如果PE1已进入PW接收缺陷状态，则PE1将退出传输缺陷状态。
PE1 enters the AC receive defect state if any of the following conditions is met:
如果满足以下任一条件，PE1进入AC接收缺陷状态：
- It detects or is notified of a physical-layer fault on the Ethernet interface. Ethernet link failure can be detected based on loss of signal (LoS) or via Ethernet Link OAM [802.3] critical link event notifications generated at an upstream node CE1 with "Dying Gasp" or "Critical Event" indication or via a client Signal Fail message [Y.1731].
- 它检测到以太网接口上的物理层故障或收到该故障的通知。以太网链路故障可基于信号丢失（LoS）或通过在上游节点CE1生成的带有“垂死喘息”或“严重事件”指示的以太网链路OAM[802.3]严重链路事件通知或通过客户端信号故障消息[Y.1731]进行检测。
- A MEP associated with the local AC receives an Ethernet AIS frame from CE1.
- 与本地AC相关联的MEP从CE1接收以太网AIS帧。
- A MEP associated with the local AC does not receive CCM frames from the peer MEP in the client domain (e.g., CE1) within an interval equal to 3.5 times the CCM transmission period configured for the MEP. This is the case when CCM transmission is enabled.
- 与本地AC相关联的MEP在等于为MEP配置的CCM传输周期的3.5倍的间隔内不从客户端域（例如，CE1）中的对等MEP接收CCM帧。这是启用CCM传输时的情况。
- A CCM has an Interface Status TLV indicating interface down. Other CCM Interface Status TLVs will not be used to indicate failure or recovery from failure.
- CCM具有指示接口关闭的接口状态TLV。其他CCM接口状态TLV将不用于指示故障或从故障中恢复。
It should be noted that when a MEP at a PE or a CE receives a CCM with the wrong MEG ID, MEP ID, or MEP level, the receiving PE or CE SHOULD treat such an event as an AC receive defect. In any case, if such events persist for 3.5 times the MEP local CCM transmission time, loss of continuity will be declared at the receiving end.
应注意，当PE或CE的MEP接收到具有错误MEG ID、MEP ID或MEP级别的CCM时，接收PE或CE应将此类事件视为AC接收缺陷。在任何情况下，如果此类事件持续3.5倍于MEP本地CCM传输时间，则接收端将宣布连续性丧失。
PE1 exits the AC receive defect state if all of the conditions that resulted in entering the defect state are cleared. This includes all of the following conditions:
如果导致进入缺陷状态的所有条件均已清除，则PE1将退出AC接收缺陷状态。这包括以下所有条件：
- Any physical-layer fault on the Ethernet interface, if detected or where PE1 was notified previously, is removed (e.g., loss of signal (LoS) cleared or Ethernet Link OAM [802.3] critical link event notifications with "Dying Gasp" or "Critical Event" indications cleared at an upstream node CE1).
- 如果检测到以太网接口上的任何物理层故障或之前通知过PE1，则删除该故障（例如，清除信号丢失（LoS）或以太网链路OAM[802.3]关键链路事件通知，并在上游节点CE1清除“垂死喘息”或“关键事件”指示）。
- A MEP associated with the local AC does not receive any Ethernet AIS frame within a period indicated by previously received AIS if AIS resulted in entering the defect state.
- 如果AIS导致进入缺陷状态，则与本地AC相关联的MEP在先前接收到的AIS指示的时间内不会接收到任何以太网AIS帧。
- A MEP associated with the local AC and configured with CCM enabled receives a configured number (e.g., 3 or more) of consecutive CCM frames from the peer MEP on CE1 within an interval equal to a multiple (3.5) of the CCM transmission period configured for the MEP.
- 与本地AC相关联且配置为启用CCM的MEP在等于为MEP配置的CCM传输周期的倍数（3.5）的间隔内从CE1上的对等MEP接收配置数量（例如，3个或更多）的连续CCM帧。
- CCM indicates interface status up.
- CCM指示接口状态向上。
PE1 enters the AC transmit defect state if any of the following conditions is met:
如果满足以下任一条件，PE1进入交流传输缺陷状态：
- It detects or is notified of a physical-layer fault on the Ethernet interface where the AC is configured (e.g., via loss of signal (LoS) or Ethernet Link OAM [802.3] critical link event notifications generated at an upstream node CE1 with "Link Fault" indication).
- 它在配置AC的以太网接口上检测或被通知物理层故障（例如，通过信号丢失（LoS）或在上游节点CE1生成的带有“链路故障”指示的以太网链路OAM[802.3]关键链路事件通知）。
- A MEP configured with CCM transmission enabled and associated with the local AC receives a CCM frame, with its RDI (Remote Defect Indication) bit set, from the peer MEP in the client domain (e.g., CE1).
- 配置为启用CCM传输并与本地AC相关联的MEP从客户端域（例如，CE1）中的对等MEP接收CCM帧及其RDI（远程缺陷指示）比特集。
PE1 exits the AC transmit defect state if all of the conditions that resulted in entering the defect state are cleared. This includes all of the following conditions:
如果导致进入缺陷状态的所有条件均已清除，则PE1将退出AC传输缺陷状态。这包括以下所有条件：
- Any physical-layer fault on the Ethernet interface, if detected or where PE1 was notified previously, is removed (e.g., LoS cleared or Ethernet Link OAM [802.3] critical link event notifications with "Link Fault" indication cleared at an upstream node CE1).
- 如果检测到以太网接口上的任何物理层故障或之前通知PE1，则将删除该故障（例如，LoS清除或以太网链路OAM[802.3]关键链路事件通知，在上游节点CE1处清除“链路故障”指示）。
- A MEP configured with CCM transmission enabled and associated with the local AC does not receive a CCM frame with the RDI bit set, having received a previous CCM frame with the RDI bit set from the peer MEP in the client domain (e.g., CE1).
- 配置为启用CCM传输并与本地AC相关联的MEP在从客户端域（例如，CE1）中的对等MEP接收到具有RDI比特集的先前CCM帧后，不接收具有RDI比特集的CCM帧。
When the PW status on PE1 transitions from working to PW receive defect state, PE1's ability to receive user traffic from CE2 is impacted. As a result, PE1 needs to notify CE1 about this problem.
当PE1上的PW状态从工作状态过渡到PW接收缺陷状态时，PE1从CE2接收用户流量的能力受到影响。因此，PE1需要将此问题通知CE1。
Upon entry to the PW receive defect state, the following MUST be done:
进入PW接收缺陷状态后，必须执行以下操作：
- If PE1 is configured with a Down MEP associated with the local AC and CCM transmission is not enabled, the MEP associated with the AC MUST transmit AIS frames periodically to the peer MEP in the client domain (e.g., on CE1) based on the configured AIS transmission period.
- 如果PE1配置有与本地AC相关联的下行MEP，且未启用CCM传输，则与AC相关联的MEP必须基于配置的AIS传输周期定期向客户端域（例如，在CE1上）中的对等MEP传输AIS帧。
- If PE1 is configured with a Down MEP associated with the local AC, CCM transmission is enabled, and the MEP associated with the AC is configured to support the Interface Status TLV in CCMs, the MEP associated with the AC MUST transmit CCM frames with the Interface Status TLV as being Down to the peer MEP in the client domain (e.g., on CE1).
- 如果PE1配置有与本地AC相关联的Down MEP，则启用CCM传输，并且与AC相关联的MEP配置为支持CCMs中的接口状态TLV，则与AC相关联的MEP必须将接口状态TLV为Down的CCM帧传输到客户端域（例如，在CE1上）中的对等MEP。
- If PE1 is configured with a Down MEP associated with the local AC, CCM transmission is enabled, and the MEP associated with the AC is configured to not support the Interface Status TLV in CCMs, the MEP associated with the AC MUST stop transmitting CCM frames to the peer MEP in the client domain (e.g., on CE1).
- 如果PE1配置有与本地AC相关联的下行MEP，则启用CCM传输，并且与AC相关联的MEP配置为不支持CCMs中的接口状态TLV，则与AC相关联的MEP必须停止向客户端域（例如，在CE1上）中的对等MEP发送CCM帧。
- If PE1 is configured to run E-LMI [MEF16] with CE1 and if E-LMI is used for failure notification, PE1 MUST transmit an E-LMI asynchronous STATUS message with report type Single EVC Asynchronous Status indicating that the PW is Not Active.
- 如果PE1配置为使用CE1运行E-LMI[MEF16]，并且如果E-LMI用于故障通知，则PE1必须发送一条E-LMI异步状态消息，该消息的报告类型为Single EVC asynchronous STATUS，指示PW未激活。
Further, when PE1 enters the receive defect state, it MUST assume that PE2 has no knowledge of the defect and MUST send a reverse defect failure notification to PE2. For MPLS PSN or MPLS/IP PSN, this is either done via a PW status notification message indicating a reverse defect or done via a VCCV-BFD diagnostic code of reverse defect if a VCCV CV type of 0x08 or 0x20 had been negotiated. When a native service OAM mechanism is supported on PE1, it can also use the NS OAM notification as specified in Section 4.1.
此外，当PE1进入接收缺陷状态时，它必须假设PE2不知道该缺陷，并且必须向PE2发送反向缺陷故障通知。对于MPLS PSN或MPLS/IP PSN，这可以通过指示反向缺陷的PW状态通知消息完成，或者如果已协商VCCV类型0x08或0x20，则可以通过反向缺陷的VCCV-BFD诊断代码完成。当PE1上支持本机服务OAM机制时，它还可以使用第4.1节中指定的NS OAM通知。
If PW receive defect state is entered as a result of a forward defect notification from PE2 or via loss of control adjacency, no additional action is needed since PE2 is expected to be aware of the defect.
如果PW接收缺陷状态是由于来自PE2的转发缺陷通知或通过失去控制邻接而进入的，则无需采取额外措施，因为PE2预计会意识到该缺陷。
When the PW status transitions from PW receive defect state to working, PE1's ability to receive user traffic from CE2 is restored. As a result, PE1 needs to cease defect notification to CE1 by performing the following:
当PW状态从PW接收缺陷状态转换为工作状态时，PE1从CE2接收用户流量的能力将恢复。因此，PE1需要通过执行以下操作停止向CE1发出缺陷通知：
- If PE1 is configured with a Down MEP associated with the local AC and CCM transmission is not enabled, the MEP associated with the AC MUST stop transmitting AIS frames towards the peer MEP in the client domain (e.g., on CE1).
- 如果PE1配置有与本地AC相关联的下行MEP，且未启用CCM传输，则与AC相关联的MEP必须停止向客户端域（例如，在CE1上）中的对等MEP传输AIS帧。
- If PE1 is configured with a Down MEP associated with the local AC, CCM transmission is enabled, and the MEP associated with the AC is configured to support the Interface Status TLV in CCMs, the MEP associated with the AC MUST transmit CCM frames with the Interface Status TLV as being Up to the peer MEP in the client domain (e.g., on CE1).
- 如果PE1配置有与本地AC相关联的下行MEP，CCM传输被启用，并且与AC相关联的MEP被配置为支持CCMs中的接口状态TLV，则与AC相关联的MEP必须将接口状态TLV为高达客户端域（例如，在CE1上）中的对等MEP的CCM帧传输。
- If PE1 is configured with a Down MEP associated with the local AC, CCM transmission is enabled, and the MEP associated with the AC is configured to not support the Interface Status TLV in CCMs, the MEP associated with the AC MUST resume transmitting CCM frames to the peer MEP in the client domain (e.g., on CE1).
- 如果PE1配置有与本地AC相关联的下行MEP，则启用CCM传输，并且与AC相关联的MEP配置为不支持CCMs中的接口状态TLV，则与AC相关联的MEP必须恢复将CCM帧传输到客户端域（例如，在CE1上）中的对等MEP。
- If PE1 is configured to run E-LMI [MEF16] with CE1 and E-LMI is used for fault notification, PE1 MUST transmit an E-LMI asynchronous STATUS message with report type Single EVC Asynchronous Status indicating that the PW is Active.
- 如果PE1配置为使用CE1运行E-LMI[MEF16]，并且E-LMI用于故障通知，则PE1必须发送一条E-LMI异步状态消息，该消息的报告类型为Single EVC asynchronous STATUS，指示PW处于活动状态。
Further, if the PW receive defect was explicitly detected by PE1, it MUST now notify PE2 about clearing of receive defect state by clearing the reverse defect notification. For PW over MPLS PSN or MPLS/IP PSN, this is either done via a PW status message indicating a working state or done via a VCCV-BFD diagnostic code if a VCCV CV type of 0x08 or 0x20 had been negotiated. When a native service OAM mechanism is supported on PE, it can also clear the NS OAM notification as specified in Section 4.1.
此外，如果PW接收缺陷被PE1明确检测到，它现在必须通过清除反向缺陷通知通知PE2关于接收缺陷状态的清除。对于MPLS PSN或MPLS/IP PSN上的PW，这可以通过指示工作状态的PW状态消息完成，或者如果已协商VCCV类型0x08或0x20，则通过VCCV-BFD诊断代码完成。当PE上支持本机服务OAM机制时，它还可以按照第4.1节的规定清除NS OAM通知。
If PW receive defect was established via notification from PE2 or via loss of control adjacency, no additional action is needed since PE2 is expected to be aware of the defect clearing.
如果PW接收缺陷是通过PE2的通知或通过失去控制邻接确定的，则无需采取额外措施，因为预计PE2会意识到缺陷清除。
When the PW status transitions from working to PW transmit defect state, PE1's ability to transmit user traffic to CE2 is impacted. As a result, PE1 needs to notify CE1 about this problem.
当PW状态从工作状态过渡到PW传输缺陷状态时，PE1向CE2传输用户流量的能力受到影响。因此，PE1需要将此问题通知CE1。
Upon entry to the PW transmit defect state, the following MUST be done:
进入PW传输缺陷状态后，必须执行以下操作：
- If PE1 is configured with a Down MEP associated with the local AC and CCM transmission is enabled, the MEP associated with the AC MUST set the RDI bit in transmitted CCM frames or send a status TLV with interface down to the peer MEP in the client domain (e.g., on CE1).
- 如果PE1配置有与本地AC相关联的下行MEP，且CCM传输已启用，则与AC相关联的MEP必须在传输的CCM帧中设置RDI位，或向客户端域（例如，在CE1上）中的对等MEP发送带有接口的状态TLV。
- If PE1 is configured to run E-LMI [MEF16] with CE1 and E-LMI is used for fault notification, PE1 MUST transmit an E-LMI asynchronous STATUS message with report type Single EVC Asynchronous Status indicating that the PW is Not Active.
- 如果PE1配置为使用CE1运行E-LMI[MEF16]，并且E-LMI用于故障通知，则PE1必须发送一条E-LMI异步状态消息，该消息的报告类型为Single EVC asynchronous STATUS，指示PW未激活。
- If the PW failure was detected by PE1 without receiving a reverse defect notification from PE2, PE1 MUST assume PE2 has no knowledge of the defect and MUST notify PE2 by sending an FDI.
- 如果PE1在未收到PE2的反向缺陷通知的情况下检测到PW故障，PE1必须假设PE2不知道该缺陷，并且必须通过发送FDI通知PE2。
When the PW status transitions from PW transmit defect state to working, PE1's ability to transmit user traffic to CE2 is restored. As a result, PE1 needs to cease defect notifications to CE1 and perform the following:
当PW状态从PW传输缺陷状态过渡到工作状态时，PE1向CE2传输用户流量的能力将恢复。因此，PE1需要停止向CE1发送缺陷通知，并执行以下操作：
- If PE1 is configured with a Down MEP associated with the local AC and CCM transmission is enabled, the MEP associated with the AC MUST clear the RDI bit in the transmitted CCM frames to the peer MEP or send a status TLV with interface up to the peer MEP in the client domain (e.g., on CE1).
- 如果PE1配置有与本地AC相关联的下行MEP，且CCM传输已启用，则与AC相关联的MEP必须清除传输的CCM帧中的RDI位到对等MEP，或向客户端域（例如，在CE1上）中的对等MEP发送带接口的状态TLV。
- If PE1 is configured to run E-LMI [MEF16] with CE1, PE1 MUST transmit an E-LMI asynchronous STATUS message with report type Single EVC Asynchronous Status indicating that the PW is Active.
- 如果PE1配置为使用CE1运行E-LMI[MEF16]，则PE1必须发送一条E-LMI异步状态消息，该消息的报告类型为Single EVC asynchronous STATUS，指示PW处于活动状态。
- PE1 MUST clear the FDI to PE2, if applicable.
- 如果适用，PE1必须将FDI转给PE2。
When AC status transitions from working to AC receive defect state, PE1's ability to receive user traffic from CE1 is impacted. As a result, PE1 needs to notify PE2 and CE1 about this problem.
当AC状态从工作状态过渡到AC接收缺陷状态时，PE1从CE1接收用户流量的能力受到影响。因此，PE1需要将此问题通知PE2和CE1。
If the AC receive defect is detected by PE1, it MUST notify PE2 in the form of a forward defect notification.
如果PE1检测到AC接收缺陷，则必须以转发缺陷通知的形式通知PE2。
When NS OAM is not supported on PE1, in PW over MPLS PSN or MPLS/IP PSN, a forward defect notification is either done via a PW status message indicating a forward defect or done via a VCCV-BFD diagnostic code of forward defect if a VCCV CV type of 0x08 or 0x20 had been negotiated.
当PE1上不支持NS OAM时，在PW over MPLS PSN或MPLS/IP PSN中，前向缺陷通知通过指示前向缺陷的PW状态消息完成，或者如果已协商VCCV类型0x08或0x20，则通过前向缺陷的VCCV-BFD诊断代码完成。
When a native service OAM mechanism is supported on PE1, it can also use the NS OAM notification as specified in Section 4.1.
当PE1上支持本机服务OAM机制时，它还可以使用第4.1节中指定的NS OAM通知。
In addition to the above actions, PE1 MUST perform the following:
除上述操作外，PE1还必须执行以下操作：
- If PE1 is configured with a Down MEP associated with the local AC and CCM transmission is enabled, the MEP associated with the AC MUST set the RDI bit in transmitted CCM frames.
- 如果PE1配置有与本地AC相关联的下行MEP，且CCM传输已启用，则与AC相关联的MEP必须在传输的CCM帧中设置RDI位。
When AC status transitions from AC receive defect state to working, PE1's ability to receive user traffic from CE1 is restored. As a result, PE1 needs to cease defect notifications to PE2 and CE1 and perform the following:
当AC状态从AC接收缺陷状态转换为工作状态时，PE1从CE1接收用户流量的能力将恢复。因此，PE1需要停止向PE2和CE1发送缺陷通知，并执行以下操作：
- When NS OAM is not supported on PE1, in PW over MPLS PSN or MPLS/IP PSN, the forward defect notification is cleared via a PW status message indicating a working state or via a VCCV-BFD diagnostic code if a VCCV CV type of 0x08 or 0x20 had been negotiated.
- 当PE1上不支持NS OAM时，在PW over MPLS PSN或MPLS/IP PSN中，通过指示工作状态的PW状态消息或通过VCCV-BFD诊断代码（如果已协商VCCV类型0x08或0x20）清除前向缺陷通知。
- When a native service OAM mechanism is supported on PE1, PE1 clears the NS OAM notification as specified in Section 4.1.
- 当PE1上支持本机服务OAM机制时，PE1将按照第4.1节的规定清除NS OAM通知。
- If PE1 is configured with a Down MEP associated with the local AC and CCM transmission is enabled, the MEP associated with the AC MUST clear the RDI bit in transmitted CCM frames to the peer MEP in the client domain (e.g., on CE1).
- 如果PE1配置有与本地AC相关联的下行MEP，并且启用了CCM传输，则与AC相关联的MEP必须清除传输给客户端域（例如，在CE1上）中对等MEP的CCM帧中的RDI位。
When AC status transitions from working to AC transmit defect state, PE1's ability to transmit user traffic to CE1 is impacted. As a result, PE1 needs to notify PE2 about this problem.
当交流状态从工作状态过渡到交流传输缺陷状态时，PE1向CE1传输用户流量的能力受到影响。因此，PE1需要将此问题通知PE2。
If the AC transmit defect is detected by PE1, it MUST notify PE2 in the form of a reverse defect notification.
如果PE1检测到交流传输缺陷，则必须以反向缺陷通知的形式通知PE2。
When NS OAM is not supported on PE1, in PW over MPLS PSN or MPLS/IP PSN, a reverse defect notification is either done via a PW status message indicating a reverse defect or done via a VCCV-BFD diagnostic code of reverse defect if a VCCV CV type of 0x08 or 0x20 had been negotiated.
当PE1上不支持NS OAM时，在PW over MPLS PSN或MPLS/IP PSN中，反向缺陷通知通过指示反向缺陷的PW状态消息完成，或者如果已协商VCCV类型0x08或0x20，则通过反向缺陷的VCCV-BFD诊断代码完成。
When a native service OAM mechanism is supported on PE1, it can also use the NS OAM notification as specified in Section 4.1.
当PE1上支持本机服务OAM机制时，它还可以使用第4.1节中指定的NS OAM通知。
When AC status transitions from AC transmit defect state to working, PE1's ability to transmit user traffic to CE1 is restored. As a result, PE1 MUST clear the reverse defect notification to PE2.
当交流状态从交流传输缺陷状态过渡到工作状态时，PE1将用户通信量传输到CE1的能力将恢复。因此，PE1必须清除向PE2发出的反向缺陷通知。
When NS OAM is not supported on PE1, in PW over MPLS PSN or MPLS/IP PSN, the reverse defect notification is cleared via a PW status message indicating a working state or via a VCCV-BFD diagnostic code if a VCCV CV type of 0x08 or 0x20 had been negotiated.
当PE1上不支持NS OAM时，在PW over MPLS PSN或MPLS/IP PSN中，反向缺陷通知通过指示工作状态的PW状态消息或VCCV-BFD诊断代码（如果已协商VCCV类型0x08或0x20）清除。
When a native service OAM mechanism is supported on PE1, PE1 can clear NS OAM notification as specified in Section 4.1.
当PE1上支持本机服务OAM机制时，PE1可以按照第4.1节的规定清除NS OAM通知。
The OAM interworking mechanisms described in this document do not change the security functions inherent in the actual messages. All generic security considerations applicable to PW traffic specified in Section 10 of [RFC3985] are applicable to NS OAM messages transferred inside the PW.
本文档中描述的OAM互通机制不会改变实际消息中固有的安全功能。[RFC3985]第10节中规定的适用于PW通信的所有通用安全注意事项均适用于PW内传输的NS OAM消息。
The security considerations in Section 10 of [RFC5085] for VCCV apply to the OAM messages thus transferred. Security considerations applicable to the PWE3 control protocol as described in Section 8.2 of [RFC4447] apply to OAM indications transferred using the LDP status message.
[RFC5085]第10节中有关VCCV的安全注意事项适用于由此传输的OAM消息。[RFC4447]第8.2节所述适用于PWE3控制协议的安全注意事项适用于使用LDP状态消息传输的OAM指示。
Since the mechanisms of this document enable propagation of OAM messages and fault conditions between native service networks and PSNs, continuity of the end-to-end service depends on a trust relationship between the operators of these networks. Security considerations for such scenarios are discussed in Section 7 of [RFC5254].
由于本文档的机制允许在本机服务网络和PSN之间传播OAM消息和故障条件，因此端到端服务的连续性取决于这些网络的运营商之间的信任关系。[RFC5254]第7节讨论了此类场景的安全注意事项。
The authors are thankful to Samer Salam, Matthew Bocci, Yaakov Stein, David Black, Lizhong Jin, Greg Mirsky, Huub van Helvoort, and Adrian Farrel for their valuable input and comments.
作者感谢Samer Salam、Matthew Bocci、Yaakov Stein、David Black、Lizhong Jin、Greg Mirsky、Huub van Helvoort和Adrian Farrel的宝贵投入和评论。
[802.3] IEEE, "Part 3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications (Clause 57 for Operations, Administration, and Maintenance)", IEEE Std 802.3-2005, December 2005.
[802.3]IEEE，“第3部分：带冲突检测的载波侦听多址（CSMA/CD）接入方法和物理层规范（操作、管理和维护第57条）”，IEEE标准802.3-2005，2005年12月。
[CFM] IEEE, "Connectivity Fault Management clause of IEEE 802.1Q", IEEE 802.1Q, 2013.
[CFM]IEEE，“IEEE 802.1Q的连接故障管理条款”，IEEE 802.1Q，2013年。
[MEF16] Metro Ethernet Forum, "Ethernet Local Management Interface (E-LMI)", Technical Specification MEF16, January 2006.
[MEF16]城域以太网论坛，“以太网本地管理接口（E-LMI）”，技术规范MEF16，2006年1月。
[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。
[RFC4447] Martini, L., Ed., Rosen, E., El-Aawar, N., Smith, T., and G. Heron, "Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)", RFC 4447, April 2006.
[RFC4447]Martini，L.，Ed.，Rosen，E.，El Aawar，N.，Smith，T.，和G.Heron，“使用标签分发协议（LDP）的伪线设置和维护”，RFC 4447，2006年4月。
[RFC5085] Nadeau, T., Ed., and C. Pignataro, Ed., "Pseudowire Virtual Circuit Connectivity Verification (VCCV): A Control Channel for Pseudowires", RFC 5085, December 2007.
[RFC5085]Nadeau，T.，Ed.，和C.Pignataro，Ed.，“伪线虚拟电路连接验证（VCCV）：伪线的控制通道”，RFC 5085，2007年12月。
[RFC5885] Nadeau, T., Ed., and C. Pignataro, Ed., "Bidirectional Forwarding Detection (BFD) for the Pseudowire Virtual Circuit Connectivity Verification (VCCV)", RFC 5885, June 2010.
[RFC5885]Nadeau，T.，Ed.，和C.Pignataro，Ed.，“用于伪线虚拟电路连接验证（VCCV）的双向转发检测（BFD）”，RFC 58852010年6月。
[RFC6310] Aissaoui, M., Busschbach, P., Martini, L., Morrow, M., Nadeau, T., and Y(J). Stein, "Pseudowire (PW) Operations, Administration, and Maintenance (OAM) Message Mapping", RFC 6310, July 2011.
[RFC6310]Aissaoui，M.，Busschbach，P.，Martini，L.，Morrow，M.，Nadeau，T.，和Y（J）。Stein，“伪线（PW）操作、管理和维护（OAM）消息映射”，RFC63102011年7月。
[RFC6478] Martini, L., Swallow, G., Heron, G., and M. Bocci, "Pseudowire Status for Static Pseudowires", RFC 6478, May 2012.
[RFC6478]Martini，L.，Swallow，G.，Heron，G.，和M.Bocci，“静态伪线的伪线状态”，RFC 6478，2012年5月。
[Y.1731] ITU-T, "OAM functions and mechanisms for Ethernet based networks", ITU-T Y.1731, July 2011.
[Y.1731]ITU-T，“基于以太网的网络的OAM功能和机制”，ITU-T Y.17311911年7月。
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol Label Switching Architecture", RFC 3031, January 2001.
[RFC3031]Rosen，E.，Viswanathan，A.，和R.Callon，“多协议标签交换体系结构”，RFC 30312001年1月。
[RFC3985] Bryant, S., Ed., and P. Pate, Ed., "Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture", RFC 3985, March 2005.
[RFC3985]Bryant，S.，Ed.，和P.Pate，Ed.，“伪线仿真边到边（PWE3）架构”，RFC 39852005年3月。
[RFC4023] Worster, T., Rekhter, Y., and E. Rosen, Ed., "Encapsulating MPLS in IP or Generic Routing Encapsulation (GRE)", RFC 4023, March 2005.
[RFC4023]Worster，T.，Rekhter，Y.，和E.Rosen，编辑，“在IP或通用路由封装（GRE）中封装MPLS”，RFC4023，2005年3月。
[RFC5254] Bitar, N., Ed., Bocci, M., Ed., and L. Martini, Ed., "Requirements for Multi-Segment Pseudowire Emulation Edge-to-Edge (PWE3)", RFC 5254, October 2008.
[RFC5254]Bitar，N.，Ed.，Bocci，M.，Ed.，和L.Martini，Ed.，“多段伪线仿真边到边（PWE3）的要求”，RFC 5254，2008年10月。
[RFC5659] Bocci, M. and S. Bryant, "An Architecture for Multi-Segment Pseudowire Emulation Edge-to-Edge", RFC 5659, October 2009.
[RFC5659]Bocci，M.和S.Bryant，“多段伪线边到边仿真的体系结构”，RFC 5659，2009年10月。
This appendix is informative.
本附录为资料性附录。
Ethernet OAM mechanisms are broadly classified into two categories: Fault Management (FM) and Performance Monitoring (PM). ITU-T Y.1731 [Y.1731] provides coverage for both FM and PM while IEEE CFM [CFM] provides coverage for a subset of FM functions.
以太网OAM机制大致分为两类：故障管理（FM）和性能监视（PM）。ITU-T Y.1731[Y.1731]为FM和PM提供覆盖，而IEEE CFM[CFM]为FM功能的子集提供覆盖。
Ethernet OAM also introduces the concept of a Maintenance Entity (ME), which is used to identify the entity that needs to be managed. An ME is inherently a point-to-point association. However, in the case of a multipoint association, a Maintenance Entity Group (MEG) consisting of different MEs is used. IEEE 802.1 uses the concept of a Maintenance Association (MA), which is used to identify both point-to-point and multipoint associations. Each MEG/MA consists of MEG End Points (MEPs) that are responsible for originating OAM frames. In between the MEPs, there can also be MEG Intermediate Points (MIPs) that do not originate OAM frames but do respond to OAM frames from MEPs.
以太网OAM还引入了维护实体（ME）的概念，它用于标识需要管理的实体。ME本质上是一种点对点的关联。然而，在多点关联的情况下，使用由不同MEs组成的维护实体组（MEG）。IEEE 802.1使用维护关联（MA）的概念，该概念用于识别点到点和多点关联。每个MEG/MA由负责发起OAM帧的MEG端点（MEP）组成。在MEP之间，也可能存在MEG中间点（MIP），它们不发起OAM帧，但响应来自MEP的OAM帧。
Ethernet OAM allows for hierarchical Maintenance Entities to allow for simultaneous end-to-end and segment monitoring. This is achieved by having a provision of up to 8 MEG levels (MD levels), where each MEP or MIP is associated with a specific MEG level.
以太网OAM允许分层维护实体，以允许同时进行端到端和段监控。这是通过提供多达8个MEG水平（MD水平）来实现的，其中每个MEP或MIP与特定MEG水平相关。
It is important to note that the FM mechanisms common to both IEEE CFM [CFM] and ITU-T Y.1731 [Y.1731] are completely compatible.
需要注意的是，IEEE CFM[CFM]和ITU-T Y.1731[Y.1731]共有的FM机制完全兼容。
The common FM mechanisms include:
常见的FM机制包括：
1) Continuity Check Message (CCM)
1) 连续性检查消息（CCM）
2) Loopback Message (LBM) and Loopback Reply (LBR)
2) 环回消息（LBM）和环回回复（LBR）
3) Link Trace Message (LTM) and Link Trace Reply (LTR)
3) 链接跟踪消息（LTM）和链接跟踪回复（LTR）
CCMs are used for fault detection, including misconnections and misconfigurations. Typically, CCMs are sent as multicast frames or unicast frames and also allow RDI notifications. LBM and LBR are used to perform fault verification, while also allowing for MTU verification and CIR/EIR (Committed Information Rate / Excess Information Rate) measurements. LTM and LTR can be used for discovering the path traversed between a MEP and another target MIP/MEP in the same MEG. LTM and LTR also allow for fault localization.
CCMs用于故障检测，包括错误连接和错误配置。通常，CCM作为多播帧或单播帧发送，并且还允许RDI通知。LBM和LBR用于执行故障验证，同时还允许MTU验证和CIR/EIR（提交信息率/超额信息率）测量。LTM和LTR可用于发现MEP和同一MEG中另一目标MIP/MEP之间的路径。LTM和LTR还允许故障定位。
In addition, ITU-T Y.1731 [Y.1731] also specifies the following FM functions:
此外，ITU-T Y.1731[Y.1731]还规定了以下FM功能：
4) Alarm Indication Signal (AIS)
4) 报警指示信号（AIS）
AIS allows for fault notification to downstream and upstream nodes.
AIS允许向下游和上游节点发出故障通知。
Further, ITU-T Y.1731 [Y.1731] also specifies the following PM functions:
此外，ITU-T Y.1731[Y.1731]还规定了以下PM功能：
5) Loss Measurement Message (LMM) and Loss Measurement Reply (LMR)
5) 损耗测量信息（LMM）和损耗测量回复（LMR）
6) Delay Measurement Message (DMM) and Delay Measurement Reply (DMR)
6) 延迟测量消息（DMM）和延迟测量回复（DMR）
7) 1-way Delay Measurement (1DM)
7) 单向延迟测量（1DM）
While LMM and LMR are used to measure Frame Loss Ratio (FLR), DMM and DMR are used to measure single-ended (aka two-way) Frame Delay (FD) and Frame Delay Variation (FDV, also known as Jitter). 1DM can be used for dual-ended (aka one-way) FD and FDV measurements.
LMM和LMR用于测量帧丢失率（FLR），DMM和DMR用于测量单端（也称为双向）帧延迟（FD）和帧延迟变化（FDV，也称为抖动）。1DM可用于双端（亦称单向）FD和FDV测量。
Authors' Addresses
作者地址
Dinesh Mohan (editor) Nortel Networks EMail: dinmohan@hotmail.com
Dinesh Mohan（编辑）北电网络电子邮件：dinmohan@hotmail.com
Nabil Bitar (editor) Verizon 60 Sylvan Road Waltham, MA 02145 United States EMail: nabil.n.bitar@verizon.com
Nabil Bitar（编辑）Verizon 60 Sylvan Road Waltham，马萨诸塞州02145美国电子邮件：Nabil.n。bitar@verizon.com
Ali Sajassi (editor) Cisco 170 West Tasman Drive San Jose, CA 95134 United States EMail: sajassi@cisco.com
Ali Sajassi（编辑）Cisco 170西塔斯曼大道圣何塞，加利福尼亚95134美国电子邮件：sajassi@cisco.com
Simon Delord Alcatel-Lucent 215 Spring Street Melbourne Australia EMail: simon.delord@gmail.com
西蒙·德洛德·阿尔卡特·朗讯澳大利亚墨尔本春天街215号电子邮件：西蒙。delord@gmail.com
Philippe Niger France Telecom 2 av. Pierre Marzin 22300 Lannion France EMail: philippe.niger@orange.com
菲利普尼日尔法国电信2号av。Pierre Marzin 22300 Lannion France电子邮件：philippe。niger@orange.com
Ray Qiu Juniper 1194 North Mathilda Avenue Sunnyvale, CA 94089 United States EMail: rqiu@juniper.net
Ray Qiu Juniper 1194 North Mathilda Avenue Sunnyvale，CA 94089美国电子邮件：rqiu@juniper.net