Internet Engineering Task Force (IETF) P. Dutta
Request for Comments: 7361 F. Balus
Category: Standards Track Alcatel-Lucent
ISSN: 2070-1721 O. Stokes
Extreme Networks
G. Calvignac
Orange
D. Fedyk
Hewlett-Packard
September 2014
Internet Engineering Task Force (IETF) P. Dutta
Request for Comments: 7361 F. Balus
Category: Standards Track Alcatel-Lucent
ISSN: 2070-1721 O. Stokes
Extreme Networks
G. Calvignac
Orange
D. Fedyk
Hewlett-Packard
September 2014
LDP Extensions for Optimized MAC Address Withdrawal in a Hierarchical Virtual Private LAN Service (H-VPLS)
用于分层虚拟专用LAN服务（H-VPLS）中优化MAC地址提取的LDP扩展
Abstract
摘要
RFC 4762 describes a mechanism to remove or unlearn Media Access Control (MAC) addresses that have been dynamically learned in a Virtual Private LAN Service (VPLS) instance for faster convergence on topology changes. The procedure also removes MAC addresses in the VPLS that do not require relearning due to such topology changes. This document defines an enhancement to the MAC address withdraw procedure with an empty MAC list (RFC 4762); this enhancement enables a Provider Edge (PE) device to remove only the MAC addresses that need to be relearned. Additional extensions to RFC 4762 MAC withdraw procedures are specified to provide an optimized MAC flushing for the Provider Backbone Bridging (PBB) VPLS specified in RFC 7041.
RFC 4762描述了一种删除或取消学习在虚拟专用LAN服务（VPLS）实例中动态学习的媒体访问控制（MAC）地址的机制，以加快拓扑更改的收敛速度。该过程还将删除VPL中由于此类拓扑更改而不需要重新学习的MAC地址。本文件使用空MAC列表（RFC 4762）定义了对MAC地址撤回程序的增强；此增强功能使提供商边缘（PE）设备能够仅删除需要重新学习的MAC地址。RFC 4762 MAC撤回程序的附加扩展被指定为为RFC 7041中指定的提供商主干桥接（PBB）VPL提供优化的MAC刷新。
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/rfc7361.
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/rfc7361.
Copyright Notice
版权公告
Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2014 IETF信托基金和确定为文件作者的人员。版权所有。
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(http://trustee.ietf.org/license-info)自本文件出版之日起生效。请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本，并提供简化BSD许可证中所述的无担保。
Table of Contents
目录
1. Introduction ....................................................4
2. Terminology .....................................................6
2.1. Requirements Language ......................................6
3. Overview ........................................................6
3.1. MAC Flushing on Activation of Backup Spoke PW ..............8
3.1.1. MAC Flushing Initiated by PE-rs .....................8
3.1.2. MAC Flushing Initiated by MTU-s .....................8
3.2. MAC Flushing on Failure ....................................9
3.3. MAC Flushing in PBB-VPLS ..................................10
4. Problem Description ............................................10
4.1. MAC Flushing Optimization in VPLS Resiliency ..............10
4.1.1. MAC Flushing Optimization for Regular H-VPLS .......11
4.1.2. MAC Flushing Optimization for Native Ethernet
Access .............................................13
4.2. Black-Holing Issue in PBB-VPLS ............................13
5. Solution Description ...........................................14
5.1. MAC Flushing Optimization for VPLS Resiliency .............14
5.1.1. MAC Flush Parameters TLV ...........................15
5.1.2. Application of the MAC Flush TLV in
Optimized MAC Flushing .............................16
5.1.3. MAC Flush TLV Processing Rules for Regular VPLS ....17
5.1.4. Optimized MAC Flush Procedures .....................18
5.2. LDP MAC Flush Extensions for PBB-VPLS .....................19
5.2.1. MAC Flush TLV Processing Rules for PBB-VPLS ........20
5.2.2. Applicability of the MAC Flush Parameters TLV ......22
6. Operational Considerations .....................................23
7. IANA Considerations ............................................24
7.1. New LDP TLV ...............................................24
7.2. New Registry for MAC Flush Flags ..........................24
8. Security Considerations ........................................24
9. Contributing Author ............................................25
10. Acknowledgements ..............................................25
11. References ....................................................25
11.1. Normative References .....................................25
11.2. Informative References ...................................25
1. Introduction ....................................................4
2. Terminology .....................................................6
2.1. Requirements Language ......................................6
3. Overview ........................................................6
3.1. MAC Flushing on Activation of Backup Spoke PW ..............8
3.1.1. MAC Flushing Initiated by PE-rs .....................8
3.1.2. MAC Flushing Initiated by MTU-s .....................8
3.2. MAC Flushing on Failure ....................................9
3.3. MAC Flushing in PBB-VPLS ..................................10
4. Problem Description ............................................10
4.1. MAC Flushing Optimization in VPLS Resiliency ..............10
4.1.1. MAC Flushing Optimization for Regular H-VPLS .......11
4.1.2. MAC Flushing Optimization for Native Ethernet
Access .............................................13
4.2. Black-Holing Issue in PBB-VPLS ............................13
5. Solution Description ...........................................14
5.1. MAC Flushing Optimization for VPLS Resiliency .............14
5.1.1. MAC Flush Parameters TLV ...........................15
5.1.2. Application of the MAC Flush TLV in
Optimized MAC Flushing .............................16
5.1.3. MAC Flush TLV Processing Rules for Regular VPLS ....17
5.1.4. Optimized MAC Flush Procedures .....................18
5.2. LDP MAC Flush Extensions for PBB-VPLS .....................19
5.2.1. MAC Flush TLV Processing Rules for PBB-VPLS ........20
5.2.2. Applicability of the MAC Flush Parameters TLV ......22
6. Operational Considerations .....................................23
7. IANA Considerations ............................................24
7.1. New LDP TLV ...............................................24
7.2. New Registry for MAC Flush Flags ..........................24
8. Security Considerations ........................................24
9. Contributing Author ............................................25
10. Acknowledgements ..............................................25
11. References ....................................................25
11.1. Normative References .....................................25
11.2. Informative References ...................................25
A method of Virtual Private LAN Service (VPLS), also known as Transparent LAN Services (TLS), is described in [RFC4762]. A VPLS is created using a collection of one or more point-to-point pseudowires (PWs) [RFC4664] configured in a flat, full-mesh topology. The mesh topology provides a LAN segment or broadcast domain that is fully capable of learning and forwarding on Ethernet Media Access Control (MAC) addresses at the Provider Edge (PE) devices.
[RFC4762]中描述了一种虚拟专用LAN服务（VPLS）方法，也称为透明LAN服务（TLS）。VPLS是使用一个或多个点对点伪线（PW）[RFC4664]的集合创建的，这些伪线在平面全网格拓扑中配置。网状拓扑提供了一个LAN段或广播域，完全能够在提供商边缘（PE）设备上学习和转发以太网媒体访问控制（MAC）地址。
This VPLS full-mesh core configuration can be augmented with additional non-meshed spoke nodes to provide a Hierarchical VPLS (H-VPLS) service [RFC4762]. Throughout this document, this configuration is referred to as "regular" H-VPLS.
该VPLS全网状核心配置可通过额外的非网状辐射节点进行扩充，以提供分层VPLS（H-VPLS）服务[RFC4762]。在本文件中，此配置称为“常规”H-VPL。
[RFC7041] describes how Provider Backbone Bridging (PBB) can be integrated with VPLS to allow for useful PBB capabilities while continuing to avoid the use of the Multiple Spanning Tree Protocol (MSTP) in the backbone. The combined solution, referred to as "PBB-VPLS", results in better scalability in terms of number of service instances, PWs, and C-MAC (Customer MAC) addresses that need to be handled in the VPLS PEs, depending on the location of the I-component in the PBB-VPLS topology.
[RFC7041]描述了如何将提供商主干桥接（PBB）与VPL集成，以实现有用的PBB功能，同时继续避免在主干中使用多生成树协议（MSTP）。被称为“PBB-VPLS”的组合解决方案在VPLS PEs中需要处理的服务实例、PWs和C-MAC（客户MAC）地址数量方面具有更好的可扩展性，具体取决于I组件在PBB-VPLS拓扑中的位置。
A MAC address withdrawal mechanism for VPLS is described in [RFC4762] to remove or unlearn MAC addresses for faster convergence on topology changes in resilient H-VPLS topologies. Note that the H-VPLS topology discussed in [RFC4762] describes the two-tier hierarchy in VPLS as the basic building block of H-VPLS, but it is possible to have a multi-tier hierarchy in an H-VPLS.
[RFC4762]中描述了VPLS的MAC地址提取机制，用于删除或取消MAC地址，以便在弹性H-VPLS拓扑中的拓扑变化上更快地收敛。请注意，[RFC4762]中讨论的H-VPLS拓扑将VPLS中的两层层次结构描述为H-VPLS的基本构造块，但在H-VPLS中也可以有多层层次结构。
Figure 1 is reproduced from [RFC4762] and illustrates dual-homing in H-VPLS.
图1是从[RFC4762]复制的，并说明了H-VPLS中的双归巢。
PE2-rs
+--------+
| |
| -- |
| / \ |
CE-1 | \S / |
\ | -- |
\ +--------+
\ MTU-s PE1-rs / |
+--------+ +--------+ / |
| | | | / |
| -- | Primary PW | -- |---/ |
| / \ |- - - - - - - - - - - | / \ | |
| \S / | | \S / | |
| -- | | -- |---\ |
+--------+ +--------+ \ |
/ \ \ |
/ \ +--------+
/ \ | |
CE-2 \ | -- |
\ Secondary PW | / \ |
- - - - - - - - - - - - - - - - - | \S / |
| -- |
+--------+
PE3-rs
PE2-rs
+--------+
| |
| -- |
| / \ |
CE-1 | \S / |
\ | -- |
\ +--------+
\ MTU-s PE1-rs / |
+--------+ +--------+ / |
| | | | / |
| -- | Primary PW | -- |---/ |
| / \ |- - - - - - - - - - - | / \ | |
| \S / | | \S / | |
| -- | | -- |---\ |
+--------+ +--------+ \ |
/ \ \ |
/ \ +--------+
/ \ | |
CE-2 \ | -- |
\ Secondary PW | / \ |
- - - - - - - - - - - - - - - - - | \S / |
| -- |
+--------+
PE3-rs
Figure 1: An Example of a Dual-Homed MTU-s
图1：双宿MTU-s的示例
An example usage of the MAC flushing mechanism is the dual-homed H-VPLS where an edge device called the Multi-Tenant Unit switch (MTU-s) [RFC4762] is connected to two PE devices via a primary spoke PW and backup spoke PW, respectively. Such redundancy is designed to protect against the failure of the primary spoke PW or primary PE device. There could be multiple methods of dual-homing in H-VPLS that are not described in [RFC4762]. For example, note the following statement from Section 10.2.1 of [RFC4762].
MAC刷新机制的一个示例用法是双宿H-VPLS，其中称为多租户单元交换机（MTU-s）[RFC4762]的边缘设备分别通过主分支PW和备份分支PW连接到两个PE设备。这种冗余设计用于防止主辐条PW或主PE设备出现故障。H-VPLS中可能存在[RFC4762]中未描述的多种双归宿方法。例如，请注意[RFC4762]第10.2.1节中的以下陈述。
How a spoke is designated primary or secondary is outside the scope of this document. For example, a spanning tree instance running between only the MTU-s and the two PE-rs nodes is one possible method. Another method could be configuration.
如何将辐条指定为主辐条或辅助辐条不在本文档的范围内。例如，仅在MTU-s和两个PE-rs节点之间运行的生成树实例是一种可能的方法。另一种方法是配置。
This document intends to clarify several H-VPLS dual-homing models that are deployed in practice and various use cases of LDP-based MAC flushing in these models.
本文件旨在阐明几个实际部署的H-VPLS双归宿模型以及这些模型中基于LDP的MAC刷新的各种用例。
This document uses the terminology defined in [RFC7041], [RFC5036], [RFC4447], and [RFC4762].
本文件使用[RFC7041]、[RFC5036]、[RFC4447]和[RFC4762]中定义的术语。
Throughout this document, "Virtual Private LAN Service" (VPLS) refers to the emulated bridged LAN service offered to a customer. "H-VPLS" refers to the hierarchical connectivity or layout of the MTU-s and the Provider Edge routing- and switching-capable (PE-rs) devices offering the VPLS [RFC4762].
在本文档中，“虚拟专用LAN服务”（VPLS）是指提供给客户的模拟桥接LAN服务。“H-VPLS”是指MTU-s和提供VPLS的提供商边缘路由和交换能力（PE-rs）设备的分层连接或布局[RFC4762]。
The terms "spoke node" and "MTU-s" in H-VPLS are used interchangeably.
H-VPLS中的术语“辐射节点”和“MTU-s”可以互换使用。
"Spoke PW" refers to the Pseudowire (PW) that provides connectivity between MTU-s and PE-rs nodes.
“辐射PW”是指在MTU-s和PE-rs节点之间提供连接的伪线（PW）。
"Mesh PW" refers to the PW that provides connectivity between PE-rs nodes in a VPLS full-mesh core.
“网状PW”是指在VPLS全网状核心中的PE rs节点之间提供连接的PW。
"MAC flush message" refers to a Label Distribution Protocol (LDP) address withdraw message without a MAC List TLV.
“MAC刷新消息”是指没有MAC列表TLV的标签分发协议（LDP）地址撤回消息。
A MAC flush message "in the context of a PW" refers to the message that has been received over the LDP session that is used to set up the PW used to provide connectivity in VPLS. The MAC flush message carries the context of the PW in terms of the Forwarding Equivalence Class (FEC) TLV associated with the PW [RFC4762] [RFC4447].
MAC刷新消息“在PW上下文中”是指通过LDP会话接收的消息，该消息用于设置用于在VPLS中提供连接的PW。MAC flush消息根据与PW[RFC4762][rfc447]相关联的转发等价类（FEC）TLV携带PW的上下文。
In general, "MAC flushing" refers to the method of initiating and processing MAC flush messages across a VPLS instance.
通常，“MAC刷新”是指跨VPLS实例启动和处理MAC刷新消息的方法。
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。
When the MTU-s switches over to the backup PW, the requirement is to flush the MAC addresses learned in the corresponding Virtual Switch Instance (VSI) in peer PE devices participating in the full mesh, to avoid the black-holing of frames to those addresses. This is accomplished by sending an LDP address withdraw message -- a new message defined in this document -- from the PE that is no longer
当MTU-s切换到备份PW时，要求刷新在参与完整网格的对等PE设备中的相应虚拟交换机实例（VSI）中学习到的MAC地址，以避免帧对这些地址的黑洞。这是通过从不再存在的PE发送LDP地址撤回消息（本文档中定义的新消息）来实现的
connected to the MTU-s with the primary PW. The new message contains a list of MAC addresses to be removed and is sent to all other PEs over the corresponding LDP sessions.
通过主PW连接到MTU-s。新消息包含要删除的MAC地址列表，并通过相应的LDP会话发送给所有其他PE。
In order to minimize the impact on LDP convergence time and scalability when a MAC List TLV contains a large number of MAC addresses, many implementations use an LDP address withdraw message with an empty MAC list. When a PE-rs switch in the full mesh of H-VPLS receives this message, it also flushes MAC addresses that are not affected due to the topology change, thus leading to unnecessary flooding and relearning. Throughout this document, the term "MAC flush message" is used to specify an LDP address withdraw message with an empty MAC list as described in [RFC4762]. The solutions described in this document are applicable only to LDP address withdraw messages with empty MAC lists.
为了在MAC列表TLV包含大量MAC地址时最小化对LDP收敛时间和可伸缩性的影响，许多实现使用具有空MAC列表的LDP地址撤回消息。当H-VPLS全网中的PE-rs交换机收到此消息时，它还会刷新未受拓扑更改影响的MAC地址，从而导致不必要的泛洪和重新学习。在本文件中，术语“MAC刷新消息”用于指定具有空MAC列表的LDP地址撤销消息，如[RFC4762]所述。本文档中描述的解决方案仅适用于具有空MAC列表的LDP地址撤回消息。
In a VPLS topology, the core PWs remain active and learning happens on the PE-rs nodes. However, when the VPLS topology changes, the PE-rs must relearn using MAC address withdrawal or flushing. As per the MAC address withdrawal processing rules in [RFC4762], a PE device, on receiving a MAC flush message, removes all MAC addresses associated with the specified VPLS instance (as indicated in the FEC TLV) except the MAC addresses learned over the PW associated with this signaling session over which the message was received. Throughout this document, we use the terminology "positive" MAC flushing or "flush-all-but-mine" for this type of MAC flush message and its actions.
在VPLS拓扑中，核心PW保持活动状态，学习在PE rs节点上进行。然而，当VPLS拓扑改变时，PE rs必须使用MAC地址撤回或刷新重新学习。根据[RFC4762]中的MAC地址撤销处理规则，PE设备在接收MAC刷新消息时，移除与指定VPLS实例（如FEC TLV中所示）相关联的所有MAC地址，除了通过PW学习的与接收消息的该信令会话相关联的MAC地址。在本文档中，对于这种类型的MAC刷新消息及其操作，我们使用术语“积极”MAC刷新或“除我之外的所有刷新”。
This document introduces an optimized "negative" MAC flush message, described in Section 3.2, that can be configured to improve the response to topology changes in a number of Ethernet topologies where the Service Level Agreement (SLA) is dependent on minimal disruption and fast restoration of affected traffic. This new message is used in the case of Provider Backbone Bridging (PBB) topologies to restrict the flushing to a set of service instances (I-SIDs). It is also important to note that the MAC flush message described in [RFC4762], which is called "a positive MAC flush message" in this document, MUST always be handled for Backbone MACs (B-MACs) in cases where the core nodes change or fail. In dual-homed or multi-homed edge topologies, the procedures in this document augment [RFC4762] messages and provide less disruption for those cases.
本文档介绍了第3.2节所述的优化“负面”MAC刷新消息，该消息可配置为改进对许多以太网拓扑中拓扑更改的响应，其中服务级别协议（SLA）依赖于最小中断和受影响流量的快速恢复。此新消息用于提供商主干桥接（PBB）拓扑，以将刷新限制为一组服务实例（I-SID）。还需要注意的是，[RFC4762]中描述的MAC刷新消息在本文档中称为“正MAC刷新消息”，在核心节点发生变化或故障的情况下，必须始终为主干MAC（B-MAC）处理该消息。在双宿或多宿边缘拓扑中，本文档中的过程增加[RFC4762]消息，并为这些情况提供较少的中断。
This section describes scenarios where MAC flush withdrawal is initiated on activation of a backup PW in H-VPLS.
本节描述在H-VPLS中激活备份PW时启动MAC刷新撤回的场景。
[RFC4762] specifies that on failure of the primary PW it is PE3-rs (Figure 1) that initiates MAC flushing towards the core. However, note that PE3-rs can initiate MAC flushing only when PE3-rs is dual-homing "aware" -- that is, there is some redundancy management protocol running between the MTU-s and its host PE-rs devices. The scope of this document is applicable to several dual-homing or multi-homing protocols. This document illustrates that multi-homing can be improved with negative MAC flushing. One example is BGP-based multi-homing in LDP-based VPLS, which uses the procedures defined in [VPLS-MH]. In this method of dual-homing, PE3-rs would neither forward any traffic to the MTU-s nor receive any traffic from the MTU-s while PE1-rs is acting as a primary (or designated forwarder).
[RFC4762]规定，在主PW发生故障时，PE3 rs（图1）将启动MAC向堆芯的刷新。然而，请注意，只有当PE3 rs是双归宿“感知”时，PE3 rs才能启动MAC刷新——也就是说，MTU-s与其主机PE rs设备之间运行一些冗余管理协议。本文件的范围适用于几种双归宿或多归宿协议。本文档说明了使用负MAC刷新可以改进多归宿。一个例子是基于LDP的VPLS中基于BGP的多归宿，它使用[VPLS-MH]中定义的过程。在这种双归宿方法中，当PE1 rs充当主（或指定的转发器）时，PE3 rs既不会将任何通信转发给MTU-s，也不会从MTU-s接收任何通信。
When dual-homing is achieved by manual configuration in the MTU-s, the hosting PE-rs devices are dual-homing "agnostic", and PE3-rs cannot initiate MAC flush messages. PE3-rs can send or receive traffic over the backup PW, since the dual-homing control is with the MTU-s only. When the backup PW is made active by the MTU-s, the MTU-s triggers a MAC flush message. The message is sent over the LDP session associated with the newly activated PW. On receiving the MAC flush message from the MTU-s, PE3-rs (the PE-rs device with a now-active PW) would flush all the MAC addresses it has learned, except the ones learned over the newly activated spoke PW. PE3-rs further initiates a MAC flush message to all other PE devices in the core. Note that a forced switchover to the backup PW can also be invoked by the MTU-s due to maintenance or administrative activities on the former primary spoke PW.
当通过MTU-s中的手动配置实现双归位时，主机PE rs设备为双归位“不可知”，并且PE3 rs无法启动MAC刷新消息。PE3 rs可以通过备用PW发送或接收通信量，因为双归巢控制仅与MTU-s一起使用。当MTU-s激活备份PW时，MTU-s触发MAC刷新消息。该消息通过与新激活的PW相关联的LDP会话发送。在接收到来自MTU-s的MAC刷新消息时，PE3-rs（具有当前激活PW的PE-rs设备）将刷新其已读入的所有MAC地址，但通过新激活的分支PW读入的MAC地址除外。PE3 rs进一步向核心中的所有其他PE设备发起MAC刷新消息。注意，由于前主分支PW上的维护或管理活动，MTU-s也可以调用强制切换到备用PW。
The method of MAC flushing initiated by the MTU-s is modeled after Topology Change Notification (TCN) in the Rapid Spanning Tree Protocol (RSTP) [IEEE.802.1Q-2011]. When a bridge switches from a failed link to the backup link, the bridge sends out a TCN message over the newly activated link. Upon receiving this message, the upstream bridge flushes its entire list of MAC addresses, except the ones received over this link. The upstream bridge then sends the TCN message out of its other ports in that spanning tree instance. The message is further relayed along the spanning tree by the other bridges.
MTU-s发起的MAC刷新方法是根据快速生成树协议（RSTP）[IEEE.802.1Q-2011]中的拓扑更改通知（TCN）建模的。当网桥从故障链路切换到备份链路时，网桥将通过新激活的链路发送TCN消息。收到此消息后，上游网桥将刷新其MAC地址的整个列表，通过此链路接收的MAC地址除外。然后，上游网桥从生成树实例中的其他端口发送TCN消息。消息由其他网桥沿生成树进一步转发。
The MAC flushing information is propagated in the control plane. The control-plane message propagation is associated with the data path and hence follows propagation rules similar to those used for forwarding in the LDP data plane. For example, PE-rs nodes follow the data-plane "split-horizon" forwarding rules in H-VPLS (refer to Section 4.4 of [RFC4762]). Therefore, a MAC flush message is propagated in the context of mesh PW(s) when it is received in the context of a spoke PW. When a PE-rs node receives a MAC flush message in the context of a mesh PW, then it is not propagated to other mesh PWs.
MAC刷新信息在控制平面中传播。控制平面消息传播与数据路径相关联，因此遵循与LDP数据平面中用于转发的传播规则相似的传播规则。例如，PE rs节点遵循H-VPLS中的数据平面“拆分地平线”转发规则（参考[RFC4762]第4.4节）。因此，当在分支PW的上下文中接收MAC刷新消息时，MAC刷新消息在网状PW的上下文中传播。当PE-rs节点在mesh PW的上下文中接收到MAC flush消息时，它不会传播到其他mesh PW。
MAC flushing on failure, or "negative" MAC flushing, is introduced in this document. Negative MAC flushing is an improvement on the current practice of sending a MAC flush message with an empty MAC list as described in Section 3.1.1. We use the term "negative" MAC flushing or "flush-all-from-me" for this kind of flushing action as opposed to the "positive" MAC flush action in [RFC4762]. In negative MAC flushing, the MAC flushing is initiated by PE1-rs (Figure 1) on detection of failure of the primary spoke PW. The MAC flush message is sent to all participating PE-rs devices in the VPLS full mesh. PE1-rs should initiate MAC flushing only if PE1-rs is dual-homing aware. (If PE1-rs is dual-homing agnostic, the policy is to not initiate MAC flushing on failure, since that could cause unnecessary flushing in the case of a single-homed MTU-s.) The specific dual-homing protocols for this scenario are outside the scope of this document, but the operator can choose to use the optimized MAC flushing described in this document or the [RFC4762] procedures.
本文介绍了故障时MAC刷新，或“消极”MAC刷新。消极MAC刷新是对当前使用空MAC列表发送MAC刷新消息实践的改进，如第3.1.1节所述。与[RFC4762]中的“积极”MAC刷新操作相反，我们使用术语“消极”MAC刷新或“从我这里刷新所有”。在负MAC冲洗中，当检测到主辐条PW故障时，由PE1 rs（图1）启动MAC冲洗。MAC刷新消息被发送到VPLS全网中所有参与的PE rs设备。PE1 rs应仅在PE1 rs具有双重归位意识时启动MAC刷新。（如果PE1 rs是双归宿不可知的，则策略是在出现故障时不启动MAC刷新，因为在单归宿MTU-s的情况下，这可能会导致不必要的刷新。）此场景的特定双归宿协议不在本文档的范围内，但操作员可以选择使用本文档中描述的优化MAC刷新或[RFC4762]程序。
The procedure for negative MAC flushing is beneficial and results in less disruption than the [RFC4762] procedures, including when the MTU-s is dual-homed with a variety of Ethernet technologies, not just LDP. The negative MAC flush message is a more targeted MAC flush, and the other PE-rs nodes will flush only the specified MACs. This targeted MAC flush cannot be achieved with the MAC address withdraw message defined in [RFC4762]. Negative MAC flushing typically results in a smaller set of MACs to be flushed and results in less disruption for these topologies.
与[RFC4762]程序相比，负MAC刷新程序是有益的，并导致更少的中断，包括当MTU-s采用多种以太网技术（而不仅仅是LDP）进行双宿时。负面MAC刷新消息是更具针对性的MAC刷新，其他PE rs节点将仅刷新指定的MAC。使用[RFC4762]中定义的MAC地址撤销消息无法实现此目标MAC刷新。负MAC刷新通常会导致要刷新的MAC集较小，并且会减少对这些拓扑的中断。
Note that in the case of negative MAC flushing the list SHOULD be only the MACs for the affected MTU-s. If the list is empty, then the negative MAC flush procedures will result in flushing and relearning all attached MTU-s devices for the originating PE-rs.
注意，如果MAC刷新为负值，则列表应仅为受影响MTU-s的MAC。如果列表为空，则消极MAC刷新程序将导致刷新和重新学习原始PE-R的所有连接的MTU-s设备。
[RFC7041] describes how PBB can be integrated with VPLS to allow for useful PBB capabilities while continuing to avoid the use of MSTP in the backbone. The combined solution, referred to as "PBB-VPLS", results in better scalability in terms of the number of service instances, PWs, and C-MACs that need to be handled in the VPLS PE-rs devices. This document describes extensions to LDP MAC flushing procedures described in [RFC4762] that are required to build desirable capabilities for the PBB-VPLS solution.
[RFC7041]描述了如何将PBB与VPL集成，以实现有用的PBB功能，同时继续避免在主干中使用MSTP。被称为“PBB-VPLS”的组合解决方案在VPLS-PE-rs设备中需要处理的服务实例、PW和C-MAC的数量方面具有更好的可伸缩性。本文档描述了[RFC4762]中描述的LDP MAC刷新过程的扩展，这些扩展是为PBB-VPLS解决方案构建所需功能所必需的。
The solution proposed in this document is generic and is applicable when Multi-Segment Pseudowires (MS-PWs) [RFC6073] are used in interconnecting PE devices in H-VPLS. There could be other H-VPLS models not defined in this document where the solution may be applicable.
本文件中提出的解决方案是通用的，适用于H-VPLS中互连PE设备时使用多段伪线（MS PW）[RFC6073]。本文件中未定义的其他H-VPLS模型可能适用于该解决方案。
This section describes the problems in detail with respect to various MAC flushing actions described in Section 3.
本节详细描述了与第3节中描述的各种MAC刷新操作有关的问题。
This section describes the optimizations required in MAC flushing procedures when H-VPLS resiliency is provided by primary and backup spoke PWs.
本节描述了当主分支PWs和备份分支PWs提供H-VPLS弹性时，MAC刷新过程中所需的优化。
Figure 2 shows a dual-homed H-VPLS scenario for a VPLS instance, where the problem with the existing MAC flushing method is as explained in Section 3.
图2显示了VPLS实例的双宿主H-VPLS场景，其中现有MAC刷新方法的问题如第3节所述。
PE1-rs PE3-rs
+--------+ +--------+
| | | |
| -- | | -- |
Customer Site 1 | / \ |------------------| / \ |->Z
X->CE-1 /-----| \s / | | \s / |
\ primary spoke PW | -- | /------| -- |
\ / +--------+ / +--------+
\ (MTU-s)/ | \ / |
+--------+/ | \ / |
| | | \ / |
| -- | | \ / |
| / \ | | H-VPLS Full-Mesh Core|
| \s / | | / \ |
| -- | | / \ |
/+--------+\ | / \ |
/ backup spoke PW | / \ |
/ \ +--------+ \--------+--------+
Y->CE-2 \ | | | |
Customer Site 2 \------| -- | | -- |
| / \ |------------------| / \ |->
| \s / | | \s / |
| -- | | -- |
+--------+ +--------+
PE2-rs PE4-rs
PE1-rs PE3-rs
+--------+ +--------+
| | | |
| -- | | -- |
Customer Site 1 | / \ |------------------| / \ |->Z
X->CE-1 /-----| \s / | | \s / |
\ primary spoke PW | -- | /------| -- |
\ / +--------+ / +--------+
\ (MTU-s)/ | \ / |
+--------+/ | \ / |
| | | \ / |
| -- | | \ / |
| / \ | | H-VPLS Full-Mesh Core|
| \s / | | / \ |
| -- | | / \ |
/+--------+\ | / \ |
/ backup spoke PW | / \ |
/ \ +--------+ \--------+--------+
Y->CE-2 \ | | | |
Customer Site 2 \------| -- | | -- |
| / \ |------------------| / \ |->
| \s / | | \s / |
| -- | | -- |
+--------+ +--------+
PE2-rs PE4-rs
Figure 2: Dual-Homed MTU-s in Two-Tier Hierarchy H-VPLS
图2：两层层次结构H-VPLS中的双宿MTU-s
In Figure 2, the MTU-s is dual-homed to PE1-rs and PE2-rs. Only the primary spoke PW is active at the MTU-s; thus, PE1-rs is acting as the active device (designated forwarder) to reach the full mesh in the VPLS instance. The MAC addresses of nodes located at access sites (behind CE-1 and CE-2) are learned at PE1-rs over the primary spoke PW. Let's say X represents a set of such MAC addresses located behind CE-1. MAC Z represents one of a possible set of other destination MACs. As packets flow from X to other MACs in the VPLS network, PE2-rs, PE3-rs, and PE4-rs learn about X on their respective mesh PWs terminating at PE1-rs. When the MTU-s switches to the backup spoke PW and activates it, PE2-rs becomes the active device (designated forwarder) to reach the full-mesh core for the MTU-s. Traffic entering the H-VPLS from CE-1 and CE-2 is diverted by the MTU-s to the spoke PW to PE2-rs. Traffic destined from PE2-rs,
在图2中，MTU-s与PE1-rs和PE2-rs双宿。只有主辐PW在MTU-s处处于活动状态；因此，PE1 rs充当主动设备（指定的转发器）以到达VPLS实例中的完整网格。位于接入站点（CE-1和CE-2后面）的节点的MAC地址通过主分支PW在PE1 rs上学习。假设X代表位于CE-1后面的一组这样的MAC地址。MAC Z表示一组可能的其他目标MAC中的一个。当数据包从X流到VPLS网络中的其他MAC时，PE2-R、PE3-R和PE4-R在各自的网状PW上了解到X，该网状PW终止于PE1-rs。当MTU-s切换到备用分支PW并激活它时，PE2-R成为活动设备（指定转发器），以到达MTU-s的完整网状核心。从CE-1和CE-2进入H-VPLS的交通由MTU-s分流至辐射PW至PE2-rs。从PE2-rs出发的交通，
PE3-rs, and PE4-rs to X will be black-holed until the MAC address aging timer expires (the default is 5 minutes) or a packet flows from X to other addresses through PE2-rs.
PE3-rs和PE4-rs到X将是黑洞，直到MAC地址老化计时器过期（默认为5分钟）或数据包通过PE2-rs从X流到其他地址。
For example, if a packet flows from MAC Z to MAC X after the backup spoke PW is active, packets from MAC Z travel from PE3-rs to PE1-rs and are dropped. However, if a packet with MAC X as source and MAC Z as destination arrives at PE2-rs, PE2-rs will now learn that MAC X is on the backup spoke PW and will forward to MAC Z. At this point, traffic from PE3-rs to MAC X will go to PE2-rs, since PE3-rs has also learned about MAC X. Therefore, a mechanism is required to make this learning more timely in cases where traffic is not bidirectional.
例如，如果在备份分支PW激活之后，数据包从MAC Z流到MAC X，则来自MAC Z的数据包从PE3 rs到PE1 rs并被丢弃。但是，如果以MAC X为源、MAC Z为目的地的数据包到达PE2 rs，则PE2 rs现在将了解到MAC X位于备份分支PW上，并将转发到MAC Z。此时，从PE3 rs到MAC X的流量将转到PE2 rs，因为PE3 rs也了解了MAC X。因此，在交通不是双向的情况下，需要一种机制使这种学习更及时。
To avoid traffic black-holing, the MAC addresses that have been learned in the upstream VPLS full mesh through PE1-rs must be relearned or removed from the MAC Forwarding Information Bases (FIBs) in the VSIs at PE2-rs, PE3-rs, and PE4-rs. If PE1-rs and PE2-rs are dual-homing agnostic, then on activation of the standby PW from the MTU-s, a MAC flush message will be sent by the MTU-s to PE2-rs that will flush all the MAC addresses learned in the VPLS instance at PE2-rs from all other PWs except the PW connected to the MTU-s.
为避免通信量黑洞，必须重新学习或从PE2 rs、PE3 rs和PE4-rs的VSI中的MAC转发信息库（FIB）中删除通过PE1 rs在上游VPLS全网中学习到的MAC地址。如果PE1 rs和PE2 rs是双归宿不可知的，则在从MTU-s激活备用PW时，MTU-s将向PE2 rs发送MAC刷新消息，该消息将刷新从所有其他PW（连接到MTU-s的PW除外）在PE2 rs的VPLS实例中获知的所有MAC地址。
PE2-rs further relays the MAC flush messages to all other PE-rs devices in the full mesh. The same processing rule applies for all those PE-rs devices: all the MAC addresses are flushed except the ones learned on the PW connected to PE2-rs. For example, at PE3-rs all of the MAC addresses learned from the PWs connected to PE1-rs and PE4-rs are flushed and relearned subsequently. Before the relearning happens, flooding of unknown destination MAC addresses takes place throughout the network. As the number of PE-rs devices in the full mesh increases, the number of unaffected MAC addresses flushed in a VPLS instance also increases, thus leading to unnecessary flooding and relearning. With a large number of VPLS instances provisioned in the H-VPLS network topology, the amount of unnecessary flooding and relearning increases. An optimization, described below, is required that will flush only the MAC addresses learned from the respective PWs between PE1-rs and other PE devices in the full mesh, to minimize the relearning and flooding in the network. In the example above, only the MAC addresses in sets X and Y (shown in Figure 2) need to be flushed across the core.
PE2 rs进一步将MAC刷新消息中继到全网中的所有其他PE rs设备。相同的处理规则适用于所有这些PE-rs设备：除了在连接到PE2-rs的PW上读入的MAC地址外，所有MAC地址都被刷新。例如，在PE3-rs上，从连接到PE1-rs和PE4-rs的PW上读入的所有MAC地址都被刷新并随后重新读入。在重新学习发生之前，未知目标MAC地址在整个网络中泛滥。随着全网格中PE rs设备数量的增加，在VPLS实例中刷新的未受影响的MAC地址数量也会增加，从而导致不必要的泛洪和重新学习。由于在H-VPLS网络拓扑中提供了大量VPLS实例，不必要的泛洪和重新学习的数量会增加。需要进行如下所述的优化，该优化将仅刷新PE1 rs和全网中其他PE设备之间从各个PW学习到的MAC地址，以最小化网络中的重新学习和泛洪。在上面的例子中，只有集合X和Y中的MAC地址（如图2所示）需要在核心上刷新。
The same case is applicable when PE1-rs and PE2-rs are dual-homing aware and participate in a designated forwarder election. When PE2-rs becomes the active device for the MTU-s, then PE2-rs MAY initiate MAC flushing towards the core. The receiving action of the MAC flush message in other PE-rs devices is the same as in MAC flushing initiated by the MTU-s. This is the behavior specified in [RFC4762].
当PE1 rs和PE2 rs具有双重归巢意识并参与指定的货运代理选择时，同样的情况也适用。当PE2 rs成为MTU-s的有源设备时，PE2 rs可向核心发起MAC刷新。其他PE rs设备中MAC刷新消息的接收动作与MTU-s发起的MAC刷新相同。这是[RFC4762]中指定的行为。
The analysis in Section 4.1.1 applies also to the native Ethernet access into a VPLS. In such a scenario, one active endpoint and one or more standby endpoints terminate into two or more VPLS or H-VPLS PE-rs devices. Examples of this dual-homed access are ITU-T [ITU.G8032] access rings or any proprietary multi-chassis Link Aggregation Group (LAG) emulations. Upon failure of the active native Ethernet endpoint on PE1-rs, an optimized MAC flush message is required to be initiated by PE1-rs to ensure that on PE2-rs, PE3-rs, and PE4-rs only the MAC addresses learned from the respective PWs connected to PE1-rs are being flushed.
第4.1.1节中的分析也适用于接入VPLS的本机以太网。在这种情况下，一个活动端点和一个或多个备用端点终止于两个或多个VPL或H-VPLS PE rs设备。这种双宿接入的示例包括ITU-T[ITU.G8032]接入环或任何专有的多机箱链路聚合组（LAG）仿真。当PE1 rs上的活动本机以太网端点出现故障时，PE1 rs需要启动一条优化的MAC刷新消息，以确保在PE2 rs、PE3 rs和PE4 rs上，仅刷新从连接到PE1 rs的各个PW获悉的MAC地址。
In a PBB-VPLS deployment, a B-component VPLS (B-VPLS) may be used as infrastructure to support one or more I-component instances. The B-VPLS control plane (LDP Signaling) and learning of Backbone MACs (B-MACs) replace the I-component control plane and learning of Customer MACs (C-MACs) throughout the MPLS core. This raises an additional challenge related to black-hole avoidance in the I-component domain as described in this section. Figure 3 describes the case of a Customer Edge (CE) device (node A) dual-homed to two I-component instances located on two PBB-VPLS PEs (PE1-rs and PE2-rs).
在PBB-VPLS部署中，B组件VPLS（B-VPLS）可用作支持一个或多个I组件实例的基础设施。B-VPLS控制平面（LDP信令）和骨干MAC的学习（B-MAC）取代了整个MPLS核心中的I组件控制平面和客户MAC的学习（C-MAC）。如本节所述，这提出了一个与I-分量域中的黑洞避免相关的额外挑战。图3描述了客户边缘（CE）设备（节点a）与位于两个PBB-VPLS PE（PE1 rs和PE2 rs）上的两个I组件实例双宿的情况。
IP/MPLS Core
+--------------+
|PE2-rs |
+----+ |
|PBB | |
|VPLS| +-+ |
|(B2)|---|P| |
Stby/+----+ /+-+\ |PE3-rs
/ +----+ / \+----+
+---+/ |PBB |/ +-+ |PBB | +---+
C-MAC X--|CE |---|VPLS|---|P|--|VPLS|---|CE |--C-MAC Y
| |Act|(B1)| +-+ | | | |
+---+ +----+ +----+ +---+
A |PE1-rs | B
| |
+--------------+
IP/MPLS Core
+--------------+
|PE2-rs |
+----+ |
|PBB | |
|VPLS| +-+ |
|(B2)|---|P| |
Stby/+----+ /+-+\ |PE3-rs
/ +----+ / \+----+
+---+/ |PBB |/ +-+ |PBB | +---+
C-MAC X--|CE |---|VPLS|---|P|--|VPLS|---|CE |--C-MAC Y
| |Act|(B1)| +-+ | | | |
+---+ +----+ +----+ +---+
A |PE1-rs | B
| |
+--------------+
Figure 3: PBB Black-Holing Issue - CE Dual-Homing Use Case
图3:PBB黑洞问题-CE双归宿用例
The link between PE1-rs and CE-A is active (marked with A), while the link between CE-A and PE2-rs is in standby/blocked status. In the network diagram, C-MAC X is one of the MAC addresses located behind
PE1 rs和CE-A之间的链路处于活动状态（标有A），而CE-A和PE2 rs之间的链路处于待机/阻塞状态。在网络图中，C-MAC X是位于后面的MAC地址之一
CE-A in the customer domain, C-MAC Y is behind CE-B, and the B-VPLS instances on PE1-rs are associated with B-MAC B1 and PE2-rs with B-MAC B2.
客户域中的CE-A，C-MAC Y在CE-B之后，PE1 rs上的B-VPLS实例与B-MAC B1关联，PE2 rs与B-MAC B2关联。
As the packets flow from C-MAC X to C-MAC Y through PE1-rs with B-MAC B1, the remote PE-rs devices participating in the B-VPLS with the same I-SID (for example, PE3-rs) will learn the C-MAC X associated with B-MAC B1 on PE1-rs. Under a failure condition of the link between CE-A and PE1-rs and on activation of the link to PE2-rs, the remote PE-rs devices (for example, PE3-rs) will forward the traffic destined for C-MAC X to B-MAC B1, resulting in PE1-rs black-holing that traffic until the aging timer expires or a packet flows from X to Y through PE2-rs (B-MAC B2). This may take a long time (the default aging timer is 5 minutes) and may affect a large number of flows across multiple I-components.
当分组通过具有B-MAC B1的PE1 rs从C-MAC X流向C-MAC Y时，具有相同I-SID（例如，PE3 rs）的参与B-vpl的远程PE-rs设备将学习与PE1-rs上的B-MAC B1相关联的C-MAC X。在CE-a和PE1 rs之间的链路的故障条件下以及到PE2 rs的链路的激活时，远程PE-rs设备（例如，PE3-rs）将目的地为C-MAC X的业务转发到B-MAC B1，从而导致PE1-rs对该业务进行黑洞，直到老化计时器到期或分组通过PE2-rs（B-MAC B2）从X流向Y为止。这可能需要很长时间（默认老化计时器为5分钟），并且可能会影响多个I组件之间的大量流。
A possible solution to this issue is to use the existing LDP MAC flushing method as specified in [RFC4762] to flush the B-MAC associated with the PE-rs in the B-VPLS domain where the failure occurred. This will automatically flush the C-MAC-to-B-MAC association in the remote PE-rs devices. This solution has the disadvantage of producing a lot of unnecessary MAC flushing in the B-VPLS domain as there was no failure or topology change affecting the Backbone domain.
该问题的一个可能解决方案是使用[RFC4762]中规定的现有LDP MAC刷新方法来刷新发生故障的B-VPLS域中与PE rs关联的B-MAC。这将自动刷新远程PE rs设备中的C-MAC到B-MAC关联。此解决方案的缺点是在B-VPLS域中产生大量不必要的MAC刷新，因为没有影响主干域的故障或拓扑更改。
A better solution -- one that would propagate the I-component events through the backbone infrastructure (B-VPLS) -- is required in order to flush only the C-MAC-to-B-MAC associations in the remote PBB-VPLS-capable PE-rs devices. Since there are no I-component control-plane exchanges across the PBB backbone, extensions to the B-VPLS control plane are required to propagate the I-component MAC flushing events across the B-VPLS.
为了只刷新支持PBB VPLS的远程PE-rs设备中的C-MAC-to-B-MAC关联，需要一个更好的解决方案，即通过主干基础设施（B-VPLS）传播I组件事件。由于PBB主干上没有I组件控制平面交换，因此需要对B-VPLS控制平面进行扩展，以便在B-VPLS上传播I组件MAC刷新事件。
This section describes the solution for the problem space described in Section 4.
本节介绍第4节所述问题空间的解决方案。
The basic principle of the optimized MAC flush mechanism is explained with reference to Figure 2. The optimization is achieved by initiating MAC flushing on failure as described in Section 3.2.
优化MAC刷新机制的基本原理如图2所示。如第3.2节所述，通过在故障时启动MAC冲洗来实现优化。
PE1-rs would initiate MAC flushing towards the core on detection of failure of the primary spoke PW between the MTU-s and PE1-rs (or status change from active to standby [RFC6718]). This method is referred to as "MAC flushing on failure" throughout this document.
当检测到MTU-s和PE1 rs之间的主辐条PW故障时（或状态从活动变为备用[RFC6718]），PE1 rs将向堆芯发起MAC刷新。在本文件中，该方法称为“故障时MAC刷新”。
The MAC flush message would indicate to receiving PE-rs devices to flush all MACs learned over the PW in the context of the VPLS for which the MAC flush message is received. Each PE-rs device in the full mesh that receives the message identifies the VPLS instance and its respective PW that terminates in PE1-rs from the FEC TLV received in the message and/or LDP session. Thus, the PE-rs device flushes only the MAC addresses learned from that PW connected to PE1-rs, minimizing the required relearning and the flooding throughout the VPLS domain.
MAC flush消息将指示接收PE-rs设备在接收MAC flush消息的vpl的上下文中刷新通过PW学习的所有MAC。接收消息的完整网状网中的每个PE-rs设备从在消息和/或LDP会话中接收的FEC TLV中识别VPLS实例及其各自的PW，其在PE1-rs中终止。因此，PE-rs设备仅刷新从连接到PE1-rs的PW获悉的MAC地址，从而最大限度地减少整个VPLS域中所需的重新学习和泛洪。
This section defines a generic MAC Flush Parameters TLV for LDP [RFC5036]. Throughout this document, the MAC Flush Parameters TLV is also referred to as the "MAC Flush TLV". A MAC Flush TLV carries information on the desired action at the PE-rs device receiving the message and is used for optimized MAC flushing in VPLS. The MAC Flush TLV can also be used for the [RFC4762] style of MAC flushing as explained in Section 3.
本节定义了LDP[RFC5036]的通用MAC刷新参数TLV。在本文件中，MAC刷新参数TLV也称为“MAC刷新TLV”。MAC刷新TLV携带接收消息的PE rs设备上所需操作的信息，并用于VPLS中的优化MAC刷新。MAC刷新TLV也可用于第3节中解释的[RFC4762]类型的MAC刷新。
The MAC Flush Parameters TLV is described below:
MAC刷新参数TLV描述如下：
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|1| MAC Flush TLV (0x0406) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Sub-TLV Type | Sub-TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLV Variable-Length Value |
| " |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|1| MAC Flush TLV (0x0406) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Sub-TLV Type | Sub-TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLV Variable-Length Value |
| " |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The U-bit and F-bit [RFC5036] are set to forward if unknown so that potential intermediate VPLS PE-rs devices unaware of the new TLV can just propagate it transparently. In the case of a B-VPLS network that has PBB-VPLS in the core with no I-components attached, this message can still be useful to edge B-VPLS devices that do have the I-components with the I-SIDs and understand the message. The MAC Flush Parameters TLV type is 0x0406, as assigned by IANA. The encoding of the TLV follows the standard LDP TLV encoding described in [RFC5036].
U位和F位[RFC5036]设置为“未知时向前”，以便不知道新TLV的潜在中间VPLS PE rs设备可以透明地传播它。如果B-VPLS网络的核心中有PBB-VPLS，并且没有连接I组件，则此消息对于边缘B-VPLS设备仍然有用，这些设备具有I-SID的I组件，并且可以理解此消息。MAC刷新参数TLV类型为0x0406，由IANA分配。TLV的编码遵循[RFC5036]中描述的标准LDP TLV编码。
The TLV value field contains a 1-byte Flag field used as described below. Further, the TLV value MAY carry one or more sub-TLVs. Any sub-TLV definition for the above TLV MUST address the actions in combination with other existing sub-TLVs.
TLV值字段包含一个1字节的标志字段，如下所述。此外，TLV值可以携带一个或多个子TLV。上述TLV的任何子TLV定义必须结合其他现有子TLV解决行动。
The detailed format for the Flags bit vector is described below:
标志位向量的详细格式如下所述：
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|C|N| MBZ | (MBZ = MUST Be Zero)
+-+-+-+-+-+-+-+-+
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|C|N| MBZ | (MBZ = MUST Be Zero)
+-+-+-+-+-+-+-+-+
The 1-byte Flag field is mandatory. The following flags are defined:
1字节标志字段是必需的。定义了以下标志：
C-flag: Used to indicate the context of the PBB-VPLS component in which MAC flushing is required. For PBB-VPLS, there are two contexts of MAC flushing -- the Backbone VPLS (B-component VPLS) and the Customer VPLS (I-component VPLS). The C-flag MUST be ZERO (C = 0) when a MAC flush action for the B-VPLS is required and MUST be set (C = 1) when the MAC flush action for the I-component is required. In the regular H-VPLS case, the C-flag MUST be ZERO (C = 0) to indicate that the flush applies to the current VPLS context.
C-flag：用于指示需要MAC刷新的PBB-VPLS组件的上下文。对于PBB-VPL，MAC刷新有两种上下文——主干VPL（B组件VPL）和客户VPL（I组件VPL）。当需要对B-VPLS执行MAC刷新操作时，C标志必须为零（C=0），当需要对I组件执行MAC刷新操作时，C标志必须设置（C=1）。在常规的H-VPLS情况下，C标志必须为零（C=0），以指示刷新应用于当前VPLS上下文。
N-flag: Used to indicate whether a positive (N = 0, flush-all-but-mine) or negative (N = 1, flush-all-from-me) MAC flush action is required. The source (mine/me) is defined as the PW associated with either the LDP session on which the LDP MAC withdraw was received or the B-MAC(s) listed in the B-MAC Sub-TLV. For the optimized MAC flush procedure described in this section, the flag MUST be set (N = 1).
N-flag：用于指示是否需要正（N=0，除我外全部刷新）或负（N=1，从我开始全部刷新）MAC刷新操作。源（mine/me）被定义为与接收到LDP MAC撤回的LDP会话或B-MAC子TLV中列出的B-MAC相关联的PW。对于本节中描述的优化MAC刷新过程，必须设置标志（N=1）。
Detailed usage in the context of PBB-VPLS is explained in Section 5.2.
第5.2节解释了PBB-VPLS上下文中的详细用法。
MBZ flags: The rest of the flags SHOULD be set to zero on transmission and ignored on reception.
MBZ标志：其余标志在传输时应设置为零，在接收时忽略。
The MAC Flush TLV SHOULD be placed after the existing TLVs in the [RFC4762] MAC flush message.
MAC刷新TLV应置于[RFC4762]MAC刷新消息中现有TLV之后。
When optimized MAC flushing is supported, the MAC Flush TLV MUST be sent in an existing LDP address withdraw message with an empty MAC list but from the core PE-rs on detection of failure of its local/primary spoke PW. The N-bit in the TLV MUST be set to 1 to indicate flush-all-from-me. If the optimized MAC flush procedure is used in a Backbone VPLS or regular VPLS/H-VPLS context, the C-bit MUST be ZERO (C = 0). If it is used in an I-component context, the C-bit MUST be set (C = 1). See Section 5.2 for details of its usage in the context of PBB-VPLS.
当支持优化MAC刷新时，MAC刷新TLV必须在现有LDP地址撤回消息中发送，且MAC列表为空，但在检测到其本地/主分支PW故障时，必须从核心PE rs发送。TLV中的N位必须设置为1，以指示从me开始的全部刷新。如果在主干VPLS或常规VPLS/H-VPLS上下文中使用优化的MAC刷新过程，则C位必须为零（C=0）。如果在I组件上下文中使用，则必须设置C位（C=1）。有关其在PBB-VPLS环境中使用的详细信息，请参见第5.2节。
Note that the assumption is that the MAC Flush TLV is understood by all devices before it is turned on in any network. See Section 6 ("Operational Considerations").
注意，假设在任何网络中打开MAC刷新TLV之前，所有设备都能理解它。见第6节（“操作注意事项”）。
When optimized MAC flushing is not supported, the MAC withdraw procedures defined in [RFC4762], where either the MTU-s or PE2-rs sends the MAC withdraw message, SHOULD be used. This includes the case where the network is being changed to support optimized MAC flushing but not all devices are capable of understanding optimized MAC flush messages.
当不支持优化MAC刷新时，应使用[RFC4762]中定义的MAC撤回程序，其中MTU-s或PE2 rs发送MAC撤回消息。这包括以下情况：正在更改网络以支持优化的MAC刷新，但并非所有设备都能够理解优化的MAC刷新消息。
In the case of B-VPLS devices, the optimized MAC flush message SHOULD be supported.
对于B-VPLS设备，应支持优化的MAC刷新消息。
This section describes the processing rules of the MAC Flush TLV that MUST be followed in the context of optimized MAC flush procedures in VPLS.
本节描述了在VPLS中优化MAC刷新过程的上下文中必须遵循的MAC刷新TLV的处理规则。
When optimized MAC flushing is supported, a multi-homing PE-rs initiates a MAC flush message towards the other related VPLS PE-rs devices when it detects a transition (failure or a change to standby) in its active spoke PW. In such a case the MAC Flush TLV MUST be sent with N = 1. A PE-rs device receiving the MAC Flush TLV SHOULD follow the same processing rules as those described in this section.
当支持优化的MAC刷新时，多主PE rs在其活动分支PW中检测到转换（故障或更改为备用）时，会向其他相关VPLS PE rs设备发起MAC刷新消息。在这种情况下，MAC刷新TLV必须以N=1发送。接收MAC刷新TLV的PE rs设备应遵循与本节所述相同的处理规则。
Note that if a Multi-Segment Pseudowire (MS-PW) is used in VPLS, then a MAC flush message is processed only at the PW Terminating Provider Edge (T-PE) nodes, since PW Switching Provider Edge S-PE(s) traversed by the MS-PW propagates the MAC flush messages without any action. In this section, a PE-rs device signifies only a T-PE in the MS-PW case.
请注意，如果在VPLS中使用多段伪线（MS-PW），则MAC刷新消息仅在PW端接提供商边缘（T-PE）节点处处理，因为MS-PW穿过的PW交换提供商边缘S-PE传播MAC刷新消息而无需任何操作。在本节中，在MS-PW情况下，PE rs装置仅表示T-PE。
When a PE-rs device receives a MAC Flush TLV with N = 1, it SHOULD flush all the MAC addresses learned from the PW in the VPLS in the context on which the MAC flush message is received. It is assumed that when these procedures are used all nodes support the MAC flush message. See Section 6 ("Operational Considerations") for details.
当PE rs设备接收到N=1的MAC刷新TLV时，它应该在接收MAC刷新消息的上下文中刷新VPLS中从PW学习到的所有MAC地址。假设使用这些过程时，所有节点都支持MAC刷新消息。详情见第6节（“运营注意事项”）。
When optimized MAC flushing is not supported, a MAC Flush TLV is received with N = 0 in the MAC flush message; in such a case, the receiving PE-rs SHOULD flush the MAC addresses learned from all PWs in the VPLS instance, except the ones learned over the PW on which the message is received.
当不支持优化MAC刷新时，接收MAC刷新消息中N=0的MAC刷新TLV；在这种情况下，接收PE R应刷新从VPLS实例中的所有PW学习到的MAC地址，通过接收消息的PW学习到的MAC地址除外。
Regardless of whether optimized MAC flushing is supported, if a PE-rs device receives a MAC flush message with a MAC Flush TLV option (N = 0 or N = 1) and a valid MAC address list, it SHOULD ignore the option and deal with MAC addresses explicitly as per [RFC4762].
无论是否支持优化的MAC刷新，如果PE rs设备接收到带有MAC刷新TLV选项（N=0或N=1）和有效MAC地址列表的MAC刷新消息，则应忽略该选项，并根据[RFC4762]明确处理MAC地址。
This section expands on the optimized MAC flush procedure in the scenario shown in Figure 2.
本节将在图2所示的场景中展开优化的MAC刷新过程。
When optimized MAC flushing is being used, a PE-rs that is dual-homing aware SHOULD send MAC address messages with a MAC Flush TLV and N = 1, provided the other PEs understand the new messages. Upon receipt of the MAC flush message, PE2-rs identifies the VPLS instance that requires MAC flushing from the FEC element in the FEC TLV. On receiving N = 1, PE2-rs removes all MAC addresses learned from that PW over which the message is received. The same action is performed by PE3-rs and PE4-rs.
当使用优化的MAC刷新时，如果其他PE理解新消息，具有双重归位意识的PE rs应发送MAC地址消息，MAC刷新TLV和N=1。收到MAC刷新消息后，PE2 rs识别需要从FEC TLV中的FEC元素进行MAC刷新的VPLS实例。在接收到N=1时，PE2 rs删除从接收消息的PW中学习到的所有MAC地址。PE3 rs和PE4-rs执行相同的操作。
Figure 4 shows another redundant H-VPLS topology to protect against failure of the MTU-s device. In this case, since there is more than a single MTU-S, a protocol such as provider RSTP [IEEE.802.1Q-2011] may be used as the selection algorithm for active and backup PWs in order to maintain the connectivity between MTU-s devices and PE-rs devices at the edge. It is assumed that PE-rs devices can detect failure on PWs in either direction through OAM mechanisms (for instance, Virtual Circuit Connectivity Verification (VCCV) procedures).
图4显示了另一个冗余H-VPLS拓扑，用于防止MTU-s设备出现故障。在这种情况下，由于存在多个MTU-S，因此可以使用诸如提供商RSTP[IEEE.802.1Q-2011]之类的协议作为活动和备份PW的选择算法，以维持MTU-S设备和边缘PE-rs设备之间的连接。假设PE-rs设备可以通过OAM机制（例如，虚拟电路连接验证（VCCV）程序）在任意方向上检测PWs上的故障。
MTU-1================PE1-rs==============PE3-rs
|| || \ /||
|| Redundancy || \ / ||
|| Provider RSTP || Full Mesh . ||
|| || / \ ||
|| || / \||
MTU-2----------------PE2-rs==============PE4-rs
Backup PW
MTU-1================PE1-rs==============PE3-rs
|| || \ /||
|| Redundancy || \ / ||
|| Provider RSTP || Full Mesh . ||
|| || / \ ||
|| || / \||
MTU-2----------------PE2-rs==============PE4-rs
Backup PW
Figure 4: Redundancy with Provider RSTP
图4：与提供程序RSTP的冗余
MTU-1, MTU-2, PE1-rs, and PE2-rs participate in provider RSTP. Configuration using RSTP ensures that the PW between MTU-1 and PE1-rs is active and the PW between MTU-2 and PE2-rs is blocked (made backup) at the MTU-2 end. When the active PW failure is detected by RSTP, it activates the PW between MTU-2 and PE2-rs. When PE1-rs detects the failing PW to MTU-1, it MAY trigger MAC flushing into the full mesh with a MAC Flush TLV that carries N = 1. Other PE-rs
MTU-1、MTU-2、PE1 rs和PE2 rs参与供应商RSTP。使用RSTP的配置确保MTU-1和PE1 rs之间的PW处于激活状态，并且MTU-2和PE2 rs之间的PW在MTU-2端被阻塞（备份）。当RSTP检测到激活的PW故障时，它会激活MTU-2和PE2-rs之间的PW。当PE1-rs检测到MTU-1的故障PW时，它可能会触发MAC刷新到带有N=1的MAC刷新TLV的完整网格中。其他体育
devices in the full mesh that receive the MAC flush message identify their respective PWs terminating on PE1-rs and flush all the MAC addresses learned from it.
接收MAC flush消息的完整网状网中的设备识别其各自的PW，终止于PE1 rs，并刷新从中获取的所有MAC地址。
[RFC4762] describes a multi-domain VPLS service where fully meshed VPLS networks (domains) are connected together by a single spoke PW per VPLS service between the VPLS "border" PE-rs devices. To provide redundancy against failure of the inter-domain spoke, full mesh of inter-domain spokes can be set up between border PE-rs devices, and provider RSTP may be used for selection of the active inter-domain spoke. In the case of inter-domain spoke PW failure, MAC withdrawal initiated by PE-rs MAY be used for optimized MAC flush procedures within individual domains.
[RFC4762]描述了一种多域VPLS服务，其中完全网状的VPLS网络（域）通过VPLS“边界”PE rs设备之间的每个VPLS服务的单分支PW连接在一起。为了针对域间辐条的故障提供冗余，可以在边界PE-rs设备之间建立域间辐条的完整网格，并且提供者RSTP可用于选择活动的域间辐条。在域间分支PW故障的情况下，PE rs发起的MAC撤回可用于各个域内的优化MAC刷新过程。
Further, the procedures are applicable to any native Ethernet access topologies multi-homed to two or more VPLS PE-rs devices. The text in this section applies for the native Ethernet case where active/standby PWs are replaced with the active/standby Ethernet endpoints. An optimized MAC flush message can be generated by the VPLS PE-rs that detects the failure in the primary Ethernet access.
此外，该过程适用于多宿到两个或多个VPLS-PE-rs设备的任何本机以太网接入拓扑。本节中的文本适用于本机以太网情况，即用主/备用以太网端点替换主/备用PW。VPLS PE rs可以生成优化的MAC刷新消息，用于检测主以太网访问中的故障。
The use of an address withdraw message with a MAC List TLV is proposed in [RFC4762] as a way to expedite removal of MAC addresses as the result of a topology change (e.g., failure of a primary link of a VPLS PE-rs device and, implicitly, the activation of an alternate link in a dual-homing use case). These existing procedures apply individually to B-VPLS and I-component domains.
[RFC4762]中建议将地址撤回消息与MAC列表TLV一起使用，作为拓扑变化（例如，VPLS PE rs设备的主链路故障，以及在双归宿用例中隐式激活备用链路）导致的加速MAC地址移除的方法。这些现有程序分别适用于B-VPLS和I-component域。
When it comes to reflecting topology changes in access networks connected to I-components across the B-VPLS domain, certain additions should be considered, as described below.
当涉及到在连接到B-VPLS域中的I组件的接入网络中反映拓扑变化时，应考虑某些添加，如下所述。
MAC switching in PBB is based on the mapping of Customer MACs (C-MACs) to one or more Backbone MACs (B-MACs). A topology change in the access (I-component domain) should just invoke the flushing of C-MAC entries in the PBB PEs' FIB(s) associated with the I-component(s) impacted by the failure. There is a need to indicate the PBB PE (B-MAC source) that originated the MAC flush message to selectively flush only the MACs that are affected.
PBB中的MAC交换基于客户MAC（C-MAC）到一个或多个骨干MAC（B-MAC）的映射。访问（I组件域）中的拓扑更改应仅调用与受故障影响的I组件相关联的PBB PEs FIB中C-MAC项的刷新。需要指示发起MAC flush消息的PBB-PE（B-MAC源），以便仅选择性地刷新受影响的MAC。
These goals can be achieved by including the MAC Flush Parameters TLV in the LDP address withdraw message to indicate the particular domain(s) requiring MAC flushing. On the other end, the receiving PEs SHOULD use the information from the new TLV to flush only the related FIB entry/entries in the I-component instance(s).
这些目标可以通过在LDP地址撤回消息中包含MAC刷新参数TLV来实现，以指示需要MAC刷新的特定域。另一方面，接收PE应使用来自新TLV的信息，仅刷新I-component实例中的相关FIB条目。
At least one of the following sub-TLVs MUST be included in the MAC Flush Parameters TLV if the C-flag is set to 1:
如果C标志设置为1，则MAC刷新参数TLV中必须至少包括以下子TLV之一：
o PBB B-MAC List Sub-TLV:
o PBB-MAC列表子TLV：
Type: 0x0407
类型：0x0407
Length: Value length in octets. At least one B-MAC address MUST be present in the list.
长度：以八位字节为单位的值长度。列表中必须至少有一个B-MAC地址。
Value: One or a list of 48-bit B-MAC addresses. These are the source B-MAC addresses associated with the B-VPLS instance that originated the MAC withdraw message. It will be used to identify the C-MAC(s) mapped to the B-MAC(s) listed in the sub-TLV.
值：一个或48位B-MAC地址列表。这些是与发起MAC撤回消息的B-VPLS实例关联的源B-MAC地址。它将用于识别映射到子TLV中列出的B-MAC的C-MAC。
o PBB I-SID List Sub-TLV:
o PBB I-SID列表子TLV：
Type: 0x0408
类型：0x0408
Length: Value length in octets. Zero indicates an empty I-SID list. An empty I-SID list means that the flushing applies to all the I-SIDs mapped to the B-VPLS indicated by the FEC TLV.
长度：以八位字节为单位的值长度。零表示I-SID列表为空。空的I-SID列表意味着刷新应用于映射到FEC TLV指示的B-VPL的所有I-SID。
Value: One or a list of 24-bit I-SIDs that represent the I-component FIB(s) where the MAC flushing needs to take place.
值：一个或24位I-SID列表，表示需要进行MAC刷新的I分量FIB。
The following steps describe the details of the processing rules for the MAC Flush TLV in the context of PBB-VPLS. In general, these procedures are similar to the VPLS case but are tailored to PBB, which may have a large number of MAC addresses. In PBB, there are two sets of MAC addresses: Backbone (outer) MACs (B-MACs) and Customer (inner) MACs (C-MACs). C-MACs are associated to remote B-MACs by learning. There are also I-SIDs in PBB; I-SIDs are similar to VLANs for the purposes of the discussion in this section. In order to achieve behavior that is similar to the Regular VPLS case, there are some differences in the interpretation of the optimized MAC flush message.
以下步骤描述了PBB-VPLS上下文中MAC刷新TLV的处理规则的详细信息。一般来说，这些过程与VPLS类似，但是针对PBB定制的，PBB可能有大量MAC地址。在PBB中，有两组MAC地址：主干（外部）MAC（B-MAC）和客户（内部）MAC（C-MAC）。C-MAC通过学习与远程B-MAC相关联。PBB中也有I-SID；在本节讨论中，I-SID与VLAN类似。为了实现与常规VPLS类似的行为，对优化MAC刷新消息的解释存在一些差异。
1. Positive flush of C-MACs. This is equivalent to [RFC4762] MAC flushing in a PBB context. In this case, the N-bit is set to 0; the C-bit is set to 1, and C-MACs are to be flushed. However, since C-MACs are related to B-MACs in an I-SID context, further refinement of the flushing scope is possible.
1. C-MAC的正冲洗。这相当于PBB上下文中的[RFC4762]MAC刷新。在这种情况下，N位被设置为0；C位设置为1，C-MAC将被刷新。然而，由于C-MAC与I-SID上下文中的B-MAC相关，因此可以进一步细化刷新范围。
- If an I-SID needs to be flushed (all C-MACs within that I-SID), then I-SIDs are listed in the appropriate TLV. If all I-SIDs are to have the C-MACs flushed, then the I-SID TLV can be empty. It is typical to flush a single I-SID only, since each I-SID is associated with one or more interfaces (typically one, in the case of dual-homing). In the PBB case, flushing the I-SID is equivalent to the empty MAC list discussed in [RFC4762].
- 如果需要刷新I-SID（该I-SID中的所有C-MAC），则I-SID将列在相应的TLV中。如果所有I-SID都要刷新C-MAC，则I-SID TLV可以为空。通常只刷新单个I-SID，因为每个I-SID都与一个或多个接口关联（在双归位的情况下，通常是一个接口）。在PBB情况下，刷新I-SID相当于[RFC4762]中讨论的空MAC列表。
- If only a set of B-MAC-to-C-MAC associations needs to be flushed, then a B-MAC list can be included to further refine the list. This can be the case if an I-SID component has more than one interface and a B-MAC is used to refine the granularity. Since this is a positive MAC flush message, the intended behavior is to flush all C-MACs except those that are associated with B-MACs in the list.
- 如果只需要刷新一组B-MAC-to-C-MAC关联，那么可以包括一个B-MAC列表以进一步细化该列表。如果I-SID组件具有多个接口，并且使用B-MAC细化粒度，则可能出现这种情况。由于这是一个积极的MAC刷新消息，因此预期的行为是刷新列表中与B-MAC关联的所有C-MAC。
Positive flush of B-MACs is also useful for propagating flush from other protocols such as RSTP.
B-MAC的正刷新也有助于从其他协议（如RSTP）传播刷新。
2. Negative flush of C-MACs. This is equivalent to optimized MAC flushing. In this case, the N-bit is set to 1; the C-bit is set to 1, and a list of B-MACs is provided so that the respective C-MACs can be flushed.
2. C-MAC的负冲洗。这相当于优化的MAC刷新。在这种情况下，N位被设置为1；C位设置为1，并提供B-MAC列表，以便可以刷新相应的C-MAC。
- The I-SID list SHOULD be specified. If it is absent, then all I-SIDs require that the C-MACs be flushed.
- 应指定I-SID列表。如果没有，则所有I-SID都要求冲洗C-MAC。
- A set of B-MACs SHOULD be listed, since B-MAC-to-C-MAC associations need to be flushed and listing B-MACs scopes the flush to just those B-MACs. Again, this is typical usage, because a PBB VPLS I-component interface will have one associated I-SID and typically one (but possibly more than one) B-MAC, each with multiple remotely learned C-MACs. The B-MAC list is included to further refine the list for the remote receiver. Since this is a negative MAC flush message, the intended behavior is to flush all remote C-MACs that are associated with any B-MACs in the list (in other words, from the affected interface).
- 应该列出一组B-MAC，因为B-MAC到C-MAC的关联需要刷新，并且列出B-MAC将刷新范围仅限于这些B-MAC。同样，这是典型的用法，因为PBB VPLS I组件接口将有一个关联的I-SID，通常有一个（但可能不止一个）B-MAC，每个都有多个远程学习的C-MAC。包括B-MAC列表以进一步细化用于远程接收器的列表。由于这是一条消极的MAC刷新消息，因此预期的行为是刷新与列表中任何B-MAC关联的所有远程C-MAC（换句话说，从受影响的接口）。
The processing rules on reception of the MAC flush message are:
接收MAC刷新消息的处理规则如下：
- On Backbone Core Bridges (BCBs), if the C-bit is set to 1, then the PBB-VPLS SHOULD NOT flush their B-MAC FIBs. The B-VPLS control plane SHOULD propagate the MAC flush message following the data-plane split-horizon rules to the established B-VPLS topology.
- 在主干核心网桥（BCB）上，如果C位设置为1，则PBB-VPL不应刷新其B-MAC FIB。B-VPLS控制平面应按照数据平面拆分地平线规则将MAC刷新消息传播到已建立的B-VPLS拓扑。
- On Backbone Edge Bridges (BEBs), the following actions apply:
- 在主干边缘网桥（BEB）上，以下操作适用：
- The PBB I-SID list is used to determine the particular I-SID FIBs (I-component) that need to be considered for flushing action. If the PBB I-SID List Sub-TLV is not included in a received message, then all the I-SID FIBs associated with the receiving B-VPLS SHOULD be considered for flushing action.
- PBB I-SID列表用于确定冲洗操作需要考虑的特定I-SID FIB（I组件）。如果接收到的消息中未包含PBB I-SID List子TLV，则应考虑与接收到的B-VPL关联的所有I-SID FIB进行刷新操作。
- The PBB B-MAC list is used to identify from the I-SID FIBs in the previous step to selectively flush B-MAC-to-C-MAC associations, depending on the N-flag specified below. If the PBB B-MAC List Sub-TLV is not included in a received message, then all B-MAC-to-C-MAC associations in all I-SID FIBs (I-component) as specified by the I-SID List are considered for required flushing action, again depending on the N-flag specified below.
- PBB B-MAC列表用于根据上一步骤中的I-SID FIB进行识别，以根据下面指定的N标志选择性地刷新B-MAC到C-MAC的关联。如果PBB B-MAC列表子TLV未包含在接收到的消息中，则所有I-SID FIB（I-component）中由I-SID列表指定的所有B-MAC到C-MAC关联将被视为所需的刷新操作，这同样取决于下面指定的N标志。
- Next, depending on the N-flag value, the following actions apply:
- 接下来，根据N标志值，应用以下操作：
- N = 0: all the C-MACs in the selected I-SID FIBs SHOULD be flushed, with the exception of the resultant C-MAC list from the B-MAC list mentioned in the message ("flush all but the C-MACs associated with the B-MAC(s) in the B-MAC List Sub-TLV from the FIBs associated with the I-SID list").
- N=0：应刷新所选I-SID FIB中的所有C-MAC，消息中提到的B-MAC列表中的结果C-MAC列表除外（“从与I-SID列表相关联的FIB中刷新除与B-MAC列表子TLV中的B-MAC相关联的C-MAC之外的所有C-MAC”）。
- N = 1: all the resultant C-MACs SHOULD be flushed ("flush all the C-MACs associated with the B-MAC(s) in the B-MAC List Sub-TLV from the FIBs associated with the I-SID list").
- N=1：应刷新所有生成的C-MAC（“从与I-SID列表关联的FIB中刷新与B-MAC列表子TLV中的B-MAC关联的所有C-MAC”）。
If the MAC Flush Parameters TLV is received by a Backbone Edge Bridge (BEB) in a PBB-VPLS that does not understand the TLV, then an undesirable MAC flushing action may result. It is RECOMMENDED that all PE-rs devices participating in PBB-VPLS support the MAC Flush Parameters TLV. If this is not possible, the MAC Flush Parameters TLV SHOULD be disabled, as mentioned in Section 6 ("Operational Considerations").
如果不理解TLV的PBB-VPLS中的主干边缘网桥（BEB）接收到MAC刷新参数TLV，则可能导致不希望的MAC刷新操作。建议所有参与PBB-VPLS的PE rs设备支持MAC刷新参数TLV。如果不可能，应禁用MAC刷新参数TLV，如第6节（“操作注意事项”）所述。
"Mac Flush TLV" and its formal name -- "MAC Flush Parameters TLV" -- are synonymous. The MAC Flush TLV is applicable to the regular VPLS context as well, as explained in Section 3.1.1. To achieve negative MAC flushing (flush-all-from-me) in a regular VPLS context, the MAC Flush Parameters TLV SHOULD be encoded with C = 0 and N = 1 without
“Mac刷新TLV”及其正式名称——“Mac刷新参数TLV”是同义词。MAC刷新TLV也适用于常规VPLS上下文，如第3.1.1节所述。要在常规VPLS上下文中实现负MAC刷新（从me全部刷新），MAC刷新参数TLV应使用C=0和N=1编码，而不使用
inclusion of any Sub-TLVs. A negative MAC flush message is highly desirable in scenarios where VPLS access redundancy is provided by Ethernet ring protection as specified in the ITU-T G.8032 [ITU.G8032] specification.
包括任何子TLV。按照ITU-T G.8032[ITU.G8032]规范的规定，在通过以太网环保护提供VPLS访问冗余的情况下，负面MAC刷新消息是非常理想的。
As mentioned earlier, if the MAC Flush Parameters TLV is not understood by a receiver, then an undesirable MAC flushing action would result. To avoid this, one possible solution is to develop an LDP-based capability negotiation mechanism to negotiate support of various MAC flushing capabilities between PE-rs devices in a VPLS instance. A negotiation mechanism was discussed previously and was considered outside the scope of this document. Negotiation is not required to deploy this optimized MAC flushing as described in this document.
如前所述，如果接收机不理解MAC刷新参数TLV，则将导致不希望的MAC刷新动作。为了避免这种情况，一种可能的解决方案是开发基于LDP的能力协商机制，以协商VPLS实例中PE-rs设备之间对各种MAC刷新能力的支持。先前讨论了谈判机制，认为该机制不属于本文件的范围。如本文档所述，部署此优化的MAC刷新不需要协商。
VPLS may be used with or without the optimization. If an operator wants the optimization for VPLS, it is the operator's responsibility to make sure that the VPLS devices that are capable of supporting the optimization are properly configured. From an operational standpoint, it is RECOMMENDED that implementations of the solution provide administrative control to select the desired MAC flushing action towards a PE-rs device in the VPLS. Thus, in the topology described in Figure 2, an implementation could support PE1-rs, sending optimized MAC flush messages towards the PE-rs devices that support the solution and the PE2-rs device initiating the [RFC4762] style of MAC flush messages towards the PE-rs devices that do not support the optimized solution during upgrades. The PE-rs that supports the MAC Flush Parameters TLV MUST support the RFC 4762 MAC flushing procedures, since this document only augments them.
VPLS可在有优化或无优化的情况下使用。如果运营商希望优化VPLS，则运营商有责任确保能够支持优化的VPLS设备正确配置。从操作角度来看，建议解决方案的实施提供管理控制，以选择针对VPLS中的PE rs设备的所需MAC刷新操作。因此，在图2中描述的拓扑中，实现可以支持PE1 rs，向支持该解决方案的PE rs设备发送优化的MAC刷新消息，并向升级期间不支持该优化解决方案的PE rs设备发送[RFC4762]风格的MAC刷新消息。支持MAC刷新参数TLV的PE rs必须支持RFC 4762 MAC刷新过程，因为本文档仅对其进行了补充。
In the case of PBB-VPLS, this operation is the only method supported for specifying I-SIDs, and the optimization is assumed to be supported or should be turned off, reverting to flushing using [RFC4762] at the Backbone MAC level.
在PBB-VPLS的情况下，此操作是指定I-SID所支持的唯一方法，假设支持或应关闭优化，在主干MAC级别恢复为使用[RFC4762]刷新。
IANA maintains a registry called "Label Distribution Protocol (LDP) Parameters" with a sub-registry called "TLV Type Name Space".
IANA维护一个名为“标签分发协议（LDP）参数”的注册表和一个名为“TLV类型名称空间”的子注册表。
IANA has allocated three new code points as follows:
IANA分配了三个新代码点，如下所示：
Value | Description | Reference | Notes
-------+---------------------------+------------+-----------
0x0406 | MAC Flush Parameters TLV | [RFC7361] |
0x0407 | PBB B-MAC List Sub-TLV | [RFC7361] |
0x0408 | PBB I-SID List Sub-TLV | [RFC7361] |
Value | Description | Reference | Notes
-------+---------------------------+------------+-----------
0x0406 | MAC Flush Parameters TLV | [RFC7361] |
0x0407 | PBB B-MAC List Sub-TLV | [RFC7361] |
0x0408 | PBB I-SID List Sub-TLV | [RFC7361] |
IANA has created a new sub-registry under "Label Distribution Protocol (LDP) Parameters" called "MAC Flush Flags".
IANA在“标签分发协议（LDP）参数”下创建了一个名为“MAC刷新标志”的新子注册表。
IANA has populated the registry as follows:
IANA已填充注册表，如下所示：
Bit Number | Hex | Abbreviation | Description | Reference
-----------+------+--------------+-----------------------+-----------
0 | 0x80 | C | Context | [RFC7361]
1 | 0x40 | N | Negative MAC flushing | [RFC7361]
2-7 | | | Unassigned |
Bit Number | Hex | Abbreviation | Description | Reference
-----------+------+--------------+-----------------------+-----------
0 | 0x80 | C | Context | [RFC7361]
1 | 0x40 | N | Negative MAC flushing | [RFC7361]
2-7 | | | Unassigned |
Other new bits are to be assigned by Standards Action [RFC5226].
其他新位将由标准行动[RFC5226]分配。
Control-plane aspects:
控制平面方面：
LDP security (authentication) methods as described in [RFC5036] are applicable here. Further, this document implements security considerations as discussed in [RFC4447] and [RFC4762]. The extensions defined here optimize the MAC flushing action, and so the risk of security attacks is reduced. However, in the event that the configuration of support for the new TLV can be spoofed, sub-optimal behavior will be seen.
[RFC5036]中描述的LDP安全（认证）方法适用于此处。此外，本文档实现了[RFC4447]和[RFC4762]中讨论的安全注意事项。这里定义的扩展优化了MAC刷新操作，从而降低了安全攻击的风险。然而，如果新TLV的支持配置可能被欺骗，则会出现次优行为。
Data-plane aspects:
数据平面方面：
This specification does not have any impact on the VPLS forwarding plane but can improve MAC flushing behavior.
此规范对VPLS转发平面没有任何影响，但可以改进MAC刷新行为。
The authors would like to thank Marc Lasserre, who made a major contribution to the development of this document.
作者要感谢Marc Lasserre，他为本文件的编写做出了重大贡献。
Marc Lasserre Alcatel-Lucent EMail: marc.lasserre@alcatel-lucent.com
马克·拉塞尔·阿尔卡特·朗讯电子邮件：马克。lasserre@alcatel-朗讯网
The authors would like to thank the following people who have provided valuable comments, feedback, and review on the topics discussed in this document: Dimitri Papadimitriou, Jorge Rabadan, Prashanth Ishwar, Vipin Jain, John Rigby, Ali Sajassi, Wim Henderickx, Paul Kwok, Maarten Vissers, Daniel Cohn, Nabil Bitar, Giles Heron, Adrian Farrel, Ben Niven-Jenkins, Robert Sparks, Susan Hares, and Stephen Farrell.
作者要感谢以下人士，他们就本文件中讨论的主题提供了宝贵的意见、反馈和评论：迪米特里·帕帕迪米特里欧、豪尔赫·拉巴丹、普拉尚特·伊什瓦尔、维平·贾因、约翰·里格比、阿里·萨贾西、维姆·亨德里克斯、保罗·郭、马丁·维瑟斯、丹尼尔·科恩、纳比尔·比塔、吉尔斯·赫隆、阿德里安·法雷尔、，本·尼文·詹金斯、罗伯特·斯帕克斯、苏珊·哈尔斯和斯蒂芬·法雷尔。
[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。
[RFC4762] Lasserre, M., Ed., and V. Kompella, Ed., "Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling", RFC 4762, January 2007.
[RFC4762]Lasserre，M.，Ed.，和V.Kompella，Ed.，“使用标签分发协议（LDP）信令的虚拟专用LAN服务（VPLS）”，RFC 4762，2007年1月。
[RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed., "LDP Specification", RFC 5036, October 2007.
[RFC5036]Andersson，L.，Ed.，Minei，I.，Ed.，和B.Thomas，Ed.，“LDP规范”，RFC 5036，2007年10月。
[IEEE.802.1Q-2011] IEEE, "IEEE Standard for Local and metropolitan area networks -- Media Access Control (MAC) Bridges and Virtual Bridged Local Area Networks", IEEE Std 802.1Q, 2011.
[IEEE.802.1Q-2011]IEEE，“局域网和城域网的IEEE标准——媒体访问控制（MAC）网桥和虚拟桥接局域网”，IEEE标准802.1Q，2011年。
[ITU.G8032] International Telecommunication Union, "Ethernet ring protection switching", ITU-T Recommendation G.8032, February 2012.
[ITU.G8032]国际电信联盟，“以太网环保护交换”，ITU-T建议G.8032，2012年2月。
[RFC4664] Andersson, L., Ed., and E. Rosen, Ed., "Framework for Layer 2 Virtual Private Networks (L2VPNs)", RFC 4664, September 2006.
[RFC4664]Andersson，L.，Ed.，和E.Rosen，Ed.，“第二层虚拟专用网络（L2VPN）框架”，RFC 4664，2006年9月。
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008.
[RFC5226]Narten，T.和H.Alvestrand，“在RFCs中编写IANA注意事项部分的指南”，BCP 26，RFC 5226，2008年5月。
[RFC6073] Martini, L., Metz, C., Nadeau, T., Bocci, M., and M. Aissaoui, "Segmented Pseudowire", RFC 6073, January 2011.
[RFC6073]Martini，L.，Metz，C.，Nadeau，T.，Bocci，M.和M.Aissaoui，“分段伪线”，RFC 60732011年1月。
[RFC6718] Muley, P., Aissaoui, M., and M. Bocci, "Pseudowire Redundancy", RFC 6718, August 2012.
[RFC6718]Muley，P.，Aissaoui，M.和M.Bocci，“伪线冗余”，RFC 67182012年8月。
[RFC7041] Balus, F., Ed., Sajassi, A., Ed., and N. Bitar, Ed., "Extensions to the Virtual Private LAN Service (VPLS) Provider Edge (PE) Model for Provider Backbone Bridging", RFC 7041, November 2013.
[RFC7041]Balus，F.，Ed.，Sajassi，A.，Ed.，和N.Bitar，Ed.，“虚拟专用LAN服务（VPLS）提供商边缘（PE）模型的扩展，用于提供商主干网桥”，RFC 7041，2013年11月。
[VPLS-MH] Kothari, B., Kompella, K., Henderickx, W., Balus, F., Uttaro, J., Palislamovic, S., and W. Lin, "BGP based Multi-homing in Virtual Private LAN Service", Work in Progress, July 2014.
[VPLS-MH]Kothari，B.，Kompella，K.，Henderickx，W.，Balus，F.，Uttaro，J.，Palislamovic，S.，和W.Lin，“虚拟专用局域网服务中基于BGP的多主服务”，正在进行中，2014年7月。
Authors' Addresses
作者地址
Pranjal Kumar Dutta Alcatel-Lucent 701 E Middlefield Road Mountain View, CA 94043 USA
Pranjal Kumar Dutta Alcatel-Lucent 701 E Middlefield Road Mountain View，加利福尼亚州94043
EMail: pranjal.dutta@alcatel-lucent.com
EMail: pranjal.dutta@alcatel-lucent.com
Florin Balus Alcatel-Lucent 701 E Middlefield Road Mountain View, CA 94043 USA
美国加利福尼亚州米德尔菲尔德山景路东701号弗罗林巴卢斯阿尔卡特朗讯94043
EMail: florin.balus@alcatel-lucent.com
EMail: florin.balus@alcatel-lucent.com
Olen Stokes Extreme Networks 2121 RDU Center Drive Suite 300 Morrisville, NC 27650 USA
美国北卡罗来纳州莫里斯维尔奥伦斯托克斯极限网络2121 RDU中心大道套房300号，邮编27650
EMail: ostokes@extremenetworks.com
EMail: ostokes@extremenetworks.com
Geraldine Calvignac Orange 2, avenue Pierre-Marzin Lannion Cedex, 22307 France
Geraldine Calvignac Orange 2号，皮埃尔·马津·拉尼翁·塞德克斯大道，22307法国
EMail: geraldine.calvignac@orange.com
EMail: geraldine.calvignac@orange.com
Don Fedyk Hewlett-Packard Company USA
美国唐·费迪克惠普公司
EMail: don.fedyk@hp.com
EMail: don.fedyk@hp.com