Internet Engineering Task Force (IETF) W. Cheng
Request for Comments: 8185 L. Wang
Category: Standards Track H. Li
ISSN: 2070-1721 China Mobile
J. Dong
Huawei Technologies
A. D'Alessandro
Telecom Italia
June 2017
Internet Engineering Task Force (IETF) W. Cheng
Request for Comments: 8185 L. Wang
Category: Standards Track H. Li
ISSN: 2070-1721 China Mobile
J. Dong
Huawei Technologies
A. D'Alessandro
Telecom Italia
June 2017
Dual-Homing Coordination for MPLS Transport Profile (MPLS-TP) Pseudowires Protection
MPLS传输配置文件（MPLS-TP）伪线保护的双归宿协调
Abstract
摘要
In some scenarios, MPLS Transport Profile (MPLS-TP) pseudowires (PWs) (RFC 5921) may be statically configured when a dynamic control plane is not available. A fast protection mechanism for MPLS-TP PWs is needed to protect against the failure of an Attachment Circuit (AC), the failure of a Provider Edge (PE), or a failure in the Packet Switched Network (PSN). The framework and typical scenarios of dual-homing PW local protection are described in RFC 8184. This document proposes a dual-homing coordination mechanism for MPLS-TP PWs that is used for state exchange and switchover coordination between the dual-homing PEs for dual-homing PW local protection.
在某些场景中，当动态控制平面不可用时，可以静态配置MPLS传输配置文件（MPLS-TP）伪线（PWs）（RFC 5921）。MPLS-TP PWs需要一种快速保护机制来防止连接电路（AC）故障、提供商边缘（PE）故障或分组交换网络（PSN）故障。RFC 8184中描述了双归位PW局部保护的框架和典型场景。本文件提出了MPLS-TP PWs的双归宿协调机制，用于双归宿PEs之间的状态交换和切换协调，以实现双归宿PW本地保护。
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 7841.
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 7841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/rfc8185.
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/rfc8185.
Copyright Notice
版权公告
Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2017 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
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) 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.
(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 . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Overview of the Proposed Solution . . . . . . . . . . . . . . 4
4. Protocol Extensions for Dual-Homing MPLS-TP PW Protection . . 5
4.1. Information Exchange Between Dual-Homing PEs . . . . . . 5
4.2. Protection Procedures . . . . . . . . . . . . . . . . . . 9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
6. Security Considerations . . . . . . . . . . . . . . . . . . . 13
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.1. Normative References . . . . . . . . . . . . . . . . . . 14
7.2. Informative References . . . . . . . . . . . . . . . . . 15
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Overview of the Proposed Solution . . . . . . . . . . . . . . 4
4. Protocol Extensions for Dual-Homing MPLS-TP PW Protection . . 5
4.1. Information Exchange Between Dual-Homing PEs . . . . . . 5
4.2. Protection Procedures . . . . . . . . . . . . . . . . . . 9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
6. Security Considerations . . . . . . . . . . . . . . . . . . . 13
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.1. Normative References . . . . . . . . . . . . . . . . . . 14
7.2. Informative References . . . . . . . . . . . . . . . . . 15
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
[RFC6372], [RFC6378], and [RFC7771] describe the framework and mechanism of MPLS Transport Profile (MPLS-TP) linear protection, which can provide protection for the MPLS Label Switched Path (LSP) and pseudowires (PWs) between the edge nodes. These mechanisms cannot protect against the failure of the Attachment Circuit (AC) or the edge nodes. [RFC6718] and [RFC6870] specify the PW redundancy framework and mechanism for protecting the AC or edge node against failure by adding one or more edge nodes, but it requires PW switchover in case of an AC failure; also, PW redundancy relies on Packet Switched Network (PSN) protection mechanisms to protect against the failure of PW.
[RFC6372]、[RFC6378]和[RFC7771]描述了MPLS传输配置文件（MPLS-TP）线性保护的框架和机制，它可以为边缘节点之间的MPLS标签交换路径（LSP）和伪线（PWs）提供保护。这些机制无法防止连接电路（AC）或边缘节点发生故障。[RFC6718]和[RFC6870]通过添加一个或多个边缘节点来指定PW冗余框架和机制，以防止AC或边缘节点出现故障，但在AC故障时需要PW切换；此外，PW冗余依赖于分组交换网络（PSN）保护机制来防止PW故障。
In some scenarios such as mobile backhauling, the MPLS PWs are provisioned with dual-homing topology in which at least the Customer Edge (CE) node on one side is dual-homed to two Provider Edge (PE) nodes. If a failure occurs in the primary AC, operators usually prefer to perform local switchover in the dual-homing PE side and keep the working pseudowire unchanged, if possible. This is to avoid massive PW switchover in the mobile backhaul network due to AC failure in the mobile core site; such massive PW switchover may in turn lead to congestion caused by migrating traffic away from the preferred paths of network planners. Similarly, as multiple PWs share the physical AC in the mobile core site, it is preferable to keep using the working AC when one working PW fails in the PSN to potentially avoid unnecessary switchover for other PWs. To meet the above requirements, a fast dual-homing PW protection mechanism is needed to protect against failure in the AC, the PE node, and the PSN.
在诸如移动回送之类的一些场景中，MPLS pw被配置为双归宿拓扑，其中至少一侧的客户边缘（CE）节点被双归宿到两个提供商边缘（PE）节点。如果主交流发生故障，操作员通常倾向于在双归巢PE侧执行本地切换，并尽可能保持工作假线不变。这是为了避免移动回程网络中由于移动核心站点的交流故障而发生大规模PW切换；如此大规模的PW切换可能反过来导致拥塞，这是由于将流量从网络规划者的首选路径迁移而造成的。类似地，由于多个PW共享移动核心站点中的物理AC，因此当一个工作PW在PSN中发生故障时，最好继续使用工作AC，以潜在地避免其他PW的不必要切换。为了满足上述要求，需要一种快速双归宿PW保护机制来防止AC、PE节点和PSN中的故障。
[RFC8184] describes a framework and several scenarios of dual-homing PW local protection. This document proposes a dual-homing coordination mechanism for static MPLS-TP PWs; the mechanism is used for information exchange and switchover coordination between the dual-homing PEs for the dual-homing PW local protection. The proposed mechanism has been implemented and deployed in several mobile backhaul networks that use static MPLS-TP PWs for the backhauling of mobile traffic from the radio access sites to the core site.
[RFC8184]描述了双归宿PW本地保护的框架和几种场景。本文提出了一种用于静态MPLS-TP PWs的双归宿协调机制；该机制用于双归航PEs之间的信息交换和切换协调，用于双归航PW本地保护。所提出的机制已在多个移动回程网络中实施和部署，这些网络使用静态MPLS-TP PWs将移动通信量从无线接入站点回程到核心站点。
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.
本文件中的关键词“必须”、“不得”、“必需”、“应”、“不应”、“建议”、“不建议”、“可”和“可选”在所有大写字母出现时（如图所示）应按照BCP 14[RFC2119][RFC8174]所述进行解释。
Linear protection mechanisms for the MPLS-TP network are defined in [RFC6378], [RFC7271], and [RFC7324]. When such mechanisms are applied to PW linear protection [RFC7771], both the working PW and the protection PW are terminated on the same PE node. In order to provide dual-homing protection for MPLS-TP PWs, some additional mechanisms are needed.
[RFC6378]、[RFC7271]和[RFC7324]中定义了MPLS-TP网络的线性保护机制。当此类机制应用于PW线性保护[RFC7771]时，工作PW和保护PW都在同一PE节点上终止。为了为MPLS-TP PWs提供双归巢保护，需要一些额外的机制。
In MPLS-TP PW dual-homing protection, the linear protection mechanism (as defined in [RFC6378], [RFC7271], and [RFC7324]) on the single-homing PE (e.g., PE3 in Figure 1) is not changed, while on the dual-homing side, the working PW and protection PW are terminated on two dual-homing PEs (e.g., PE1 and PE2 in Figure 1), respectively, to protect against a failure occurring in a PE or a connected AC. As described in [RFC8184], a dedicated Dual-Node Interconnection (DNI) PW is used between the two dual-homing PE nodes to forward the traffic. In order to utilize the linear protection mechanism [RFC7771] in the dual-homing PEs scenario, coordination between the dual-homing PE nodes is needed so that the dual-homing PEs can switch the connection between the AC, the service PW, and the DNI-PW properly in a coordinated fashion by the forwarder.
在MPLS-TP PW双归位保护中，单归位PE（如图1中的PE3）上的线性保护机制（如[RFC6378]、[RFC7271]和[RFC7324]中所定义）不变，而在双归位侧，工作PW和保护PW分别在两个双归位PE（如图1中的PE1和PE2）上终止，如[RFC8184]所述，为了防止PE或连接的AC中发生故障，在两个双归宿PE节点之间使用专用双节点互连（DNI）PW来转发流量。为了在双归属PE场景中利用线性保护机制[RFC7771]，需要在双归属PE节点之间进行协调，以便双归属PE能够通过转发器以协调的方式正确切换AC、服务PW和DNI-PW之间的连接。
+----------------------------------+
| PE1 |
+----------------------------------+ +----+
| | | Working | |
X Forwarder + Service X-------------X |
/| | PW | Service PW1 | |
AC1 / +--------+--------+ | | |
/ | DNI-PW | | | |
+---* +--------X--------+----------------+ | | +---+
| | ^ | | | |
|CE1| | DNI-PW |PE3 +---|CE2|
| | | | | | |
| | V | | | |
+---* +--------X--------+----------------+ | | +---+
\ | DNI-PW | | | |
AC2 \ +--------+--------+ | Protection | |
\| | Service X-------------X |
X Forwarder + PW | Service PW2 | |
| | | +----+
+----------------------------------+
| PE2 |
+----------------------------------+
+----------------------------------+
| PE1 |
+----------------------------------+ +----+
| | | Working | |
X Forwarder + Service X-------------X |
/| | PW | Service PW1 | |
AC1 / +--------+--------+ | | |
/ | DNI-PW | | | |
+---* +--------X--------+----------------+ | | +---+
| | ^ | | | |
|CE1| | DNI-PW |PE3 +---|CE2|
| | | | | | |
| | V | | | |
+---* +--------X--------+----------------+ | | +---+
\ | DNI-PW | | | |
AC2 \ +--------+--------+ | Protection | |
\| | Service X-------------X |
X Forwarder + PW | Service PW2 | |
| | | +----+
+----------------------------------+
| PE2 |
+----------------------------------+
Figure 1: Dual-Homing Protection with DNI-PW
图1：带DNI-PW的双归巢保护
In dual-homing MPLS-TP PW local protection, the forwarding states of the dual-homing PEs are determined by the forwarding state machine in Table 1.
在双归位MPLS-TP PW本地保护中，双归位PEs的转发状态由表1中的转发状态机确定。
+-----------+---------+--------+---------------------+
|Service PW | AC | DNI-PW | Forwarding Behavior |
+-----------+---------+--------+---------------------+
| Active | Active | Up |Service PW <-> AC |
+-----------+---------+--------+---------------------+
| Active | Standby | Up |Service PW <-> DNI-PW|
+-----------+---------+--------+---------------------+
| Standby | Active | Up | DNI-PW <-> AC |
+-----------+---------+--------+---------------------+
| Standby | Standby | Up | Drop all packets |
+-----------+---------+--------+---------------------+
| Active | Active | Down |Service PW <-> AC |
+-----------+---------+--------+---------------------+
| Active | Standby | Down | Drop all packets |
+-----------+---------+--------+---------------------+
| Standby | Active | Down | Drop all packets |
+-----------+---------+--------+---------------------+
| Standby | Standby | Down | Drop all packets |
+-----------+---------+--------+---------------------+
+-----------+---------+--------+---------------------+
|Service PW | AC | DNI-PW | Forwarding Behavior |
+-----------+---------+--------+---------------------+
| Active | Active | Up |Service PW <-> AC |
+-----------+---------+--------+---------------------+
| Active | Standby | Up |Service PW <-> DNI-PW|
+-----------+---------+--------+---------------------+
| Standby | Active | Up | DNI-PW <-> AC |
+-----------+---------+--------+---------------------+
| Standby | Standby | Up | Drop all packets |
+-----------+---------+--------+---------------------+
| Active | Active | Down |Service PW <-> AC |
+-----------+---------+--------+---------------------+
| Active | Standby | Down | Drop all packets |
+-----------+---------+--------+---------------------+
| Standby | Active | Down | Drop all packets |
+-----------+---------+--------+---------------------+
| Standby | Standby | Down | Drop all packets |
+-----------+---------+--------+---------------------+
Table 1: Dual-Homing PE Forwarding State Machine
表1：双归宿PE转发状态机
In order to achieve dual-homing MPLS-TP PW protection, coordination between the dual-homing PE nodes is needed to exchange the PW status and protection coordination requests.
为了实现双归宿MPLS-TP PW保护，需要在双归宿PE节点之间进行协调，以交换PW状态和保护协调请求。
The coordination information will be sent on the DNI-PW over the Generic Associated Channel (G-ACh) as described in [RFC5586]. A new G-ACh channel type is defined for the dual-homing coordination between the dual-homing PEs of MPLS-TP PWs. This channel type can be used for the exchange of different types of information between the dual-homing PEs. This document uses this channel type for the exchange of PW status and switchover coordination between the dual-homing PEs. Other potential usages of this channel type are for further study and are out of the scope of this document.
协调信息将通过[RFC5586]中所述的通用相关信道（G-ACh）在DNI-PW上发送。定义了一种新的G-ACh信道类型，用于MPLS-TP PWs的双寻的PEs之间的双寻的协调。该信道类型可用于在双归巢PEs之间交换不同类型的信息。本文件使用该信道类型在双主引导PEs之间交换PW状态和切换协调。该通道类型的其他潜在用途有待进一步研究，不在本文件范围内。
The MPLS-TP Dual-Homing Coordination (DHC) message is sent on the DNI-PW between the dual-homing PEs. The format of the MPLS-TP DHC message is shown below:
MPLS-TP双寻的协调（DHC）消息在双寻的PEs之间的DNI-PW上发送。MPLS-TP DHC报文格式如下所示：
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1|Version| Reserved | DHC Channel Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Dual-Homing PEs Group ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ TLVs ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1|Version| Reserved | DHC Channel Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Dual-Homing PEs Group ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ TLVs ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: MPLS-TP Dual-Homing Coordination Message
图2:MPLS-TP双归宿协调消息
The first 4 octets is the common G-ACh header as specified in [RFC5586]. The DHC Channel Type is the G-ACh channel type code point assigned by IANA (0x0009).
前4个八位字节是[RFC5586]中规定的通用G-ACh报头。DHC信道类型是IANA分配的G-ACh信道类型代码点（0x0009）。
The Dual-Homing Group ID is a 4-octet unsigned integer to identify the dual-homing group to which the dual-homing PEs belong. It MUST be the same at both PEs in the same group.
双寻的组ID是一个4-octet无符号整数，用于标识双寻的PE所属的双寻的组。同一组中的两个PE必须相同。
The TLV Length field specifies the total length in octets of the subsequent TLVs.
TLV长度字段指定后续TLV的总长度（以八位字节为单位）。
In this document, two TLVs are defined in the MPLS-TP Dual-Homing Coordination message for dual-homing MPLS-TP PW protection:
在本文件中，MPLS-TP双归宿协调消息中定义了两个TLV，用于双归宿MPLS-TP PW保护：
Type Description Length 1 PW Status 20 bytes 2 Dual-Node Switching 16 bytes
类型描述长度1 PW状态20字节2双节点切换16字节
The PW Status TLV is used by a dual-homing PE to report its service PW status to the other dual-homing PE in the same dual-homing group.
PW Status TLV由一个双寻的PE用于向同一双寻的组中的另一个双寻的PE报告其维修PW状态。
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=1 (PW Status) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Dual-Homing PE Node_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Dual-Homing PE Node_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DNI-PW ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |P|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service PW Status |D|F|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=1 (PW Status) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Dual-Homing PE Node_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Dual-Homing PE Node_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DNI-PW ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |P|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service PW Status |D|F|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: PW Status TLV
图3:PW状态TLV
The Length field specifies the length in octets of the value field of the TLV.
长度字段指定TLV值字段的长度（以八位字节为单位）。
The Destination Dual-Homing PE Node_ID is the 32-bit identifier of the receiver PE [RFC6370], which supports both IPv4 and IPv6 environments. Usually it is the same as the Label Switching Router ID (LSR ID) of the receiver PE.
目标双主PE节点_ID是接收器PE[RFC6370]的32位标识符，它支持IPv4和IPv6环境。通常它与接收器PE的标签交换路由器ID（LSR ID）相同。
The Source Dual-Homing PE Node_ID is the 32-bit identifier of the sending PE [RFC6370], which supports both IPv4 and IPv6 environments. Usually it is the same as the LSR ID of the sending PE.
源双主PE节点_ID是发送PE[RFC6370]的32位标识符，它支持IPv4和IPv6环境。通常它与发送PE的LSR ID相同。
The DNI-PW ID field contains the 32-bit PW ID [RFC8077] of the DNI-PW.
DNI-PW ID字段包含DNI-PW的32位PW ID[RFC8077]。
The Flags field contains 32-bit flags, in which:
Flags字段包含32位标志，其中：
o The P (Protection) bit indicates whether the Source Dual-Homing PE is the working PE (P=0) or the protection PE (P=1).
o P（保护）位表示源双归位PE是工作PE（P=0）还是保护PE（P=1）。
o Other bits are reserved for future use, which MUST be set to 0 on transmission and MUST be ignored upon receipt.
o 其他位保留供将来使用，传输时必须设置为0，接收时必须忽略。
The Service PW Status field indicates the status of the service PW between the sending PE and the remote PE. Currently, two bits are defined in the Service PW Status field:
服务PW状态字段指示发送PE和远程PE之间的服务PW状态。目前，在维修PW状态字段中定义了两个位：
o F bit: If set, it indicates Signal Fail (SF) [RFC6378] on the service PW. It can be either a local request generated by the PE itself or a remote request received from the remote PE.
o F位：如果设置，则表示维修PW上的信号失败（SF）[RFC6378]。它可以是由PE本身生成的本地请求，也可以是从远程PE接收的远程请求。
o D bit: If set, it indicates Signal Degrade (SD) [RFC6378] on the service PW. It can be either a local request or a remote request received from the remote PE.
o D位：如果设置，则表示服务PW上的信号降级（SD）[RFC6378]。它可以是本地请求，也可以是从远程PE接收的远程请求。
o Other bits are reserved for future use, which MUST be set to 0 on transmission and MUST be ignored upon receipt.
o 其他位保留供将来使用，传输时必须设置为0，接收时必须忽略。
The Dual-Node Switching TLV is used by one dual-homing PE to send protection state coordination to the other PE in the same dual-homing group.
双节点切换TLV由一个双归宿PE使用，以向同一双归宿组中的另一个PE发送保护状态协调。
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=2 (Dual-Node Switching) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Dual-Homing PE Node_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Dual-Homing PE Node_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DNI-PW ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |S|P|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=2 (Dual-Node Switching) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Dual-Homing PE Node_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Dual-Homing PE Node_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DNI-PW ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |S|P|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Dual-Node Switching TLV
图4：双节点切换TLV
The Length field specifies the length in octets of the value field of the TLV.
长度字段指定TLV值字段的长度（以八位字节为单位）。
The Destination Dual-Homing PE Node_ID is the 32-bit identifier of the receiver PE [RFC6370]. Usually it is the same as the LSR ID of the receiver PE.
目的地双归宿PE节点_ID是接收机PE[RFC6370]的32位标识符。通常它与接收器PE的LSR ID相同。
The Source Dual-Homing PE Node_ID is the 32-bit identifier of the sending PE [RFC6370]. Usually it is the same as the LSR ID of the sending PE.
源双归宿PE节点_ID是发送PE[RFC6370]的32位标识符。通常它与发送PE的LSR ID相同。
The DNI-PW ID field contains the 32-bit PW-ID [RFC8077] of the DNI-PW.
DNI-PW ID字段包含DNI-PW的32位PW-ID[RFC8077]。
The Flags field contains 32-bit flags, in which:
Flags字段包含32位标志，其中：
o The P (Protection) bit indicates whether the Source Dual-Homing PE is the working PE (P=0) or the protection PE (P=1).
o P（保护）位表示源双归位PE是工作PE（P=0）还是保护PE（P=1）。
o The S (PW Switching) bit indicates which service PW is used for forwarding traffic. It is set to 0 when traffic will be transported on the working PW, and it is set to 1 if traffic will be transported on the protection PW. The value of the S bit is determined by the protection coordination mechanism between the dual-homing PEs and the remote PE.
o S（PW交换）位指示哪个服务PW用于转发流量。当在工作PW上传输流量时，设置为0；如果在保护PW上传输流量，设置为1。S位的值由双归位PE和远程PE之间的保护协调机制确定。
o Other bits are reserved for future use, which MUST be set to 0 on transmission and MUST be ignored upon receipt.
o 其他位保留供将来使用，传输时必须设置为0，接收时必须忽略。
When a change of service PW status is detected by one of the dual-homing PEs, it MUST be reflected in the PW Status TLV and sent to the other dual-homing PE as quickly as possible to allow for fast protection switching using three consecutive DHC messages. This set of three messages allows for fast protection switching even if one or two of these packets are lost or corrupted. After the transmission of the three rapid messages, the dual-homing PE MUST send the most recently transmitted service PW status periodically to the other dual-homing PE on a continual basis using the DHC message.
当其中一个双归位PE检测到维修PW状态变化时，必须将其反映在PW状态TLV中，并尽快发送到另一个双归位PE，以允许使用三条连续DHC消息进行快速保护切换。这组三条消息允许快速保护切换，即使其中一个或两个数据包丢失或损坏。在传输三条快速消息后，双归属PE必须使用DHC消息连续定期向另一双归属PE发送最近传输的服务PW状态。
When one dual-homing PE determines that the active service PW needs to be switched from the working PW to the protection PW, it MUST send the Dual-Node Switching TLV to the other dual-homing PE as quickly as possible to allow for fast protection switching using three consecutive DHC messages. After the transmission of the three messages, the protection PW would become the active service PW, and the dual-homing PE MUST send the most recently transmitted Dual-Node Switching TLV periodically to the other dual-homing PE on a continual basis using the DHC message.
当一个双主PE确定需要将活动服务PW从工作PW切换到保护PW时，它必须尽快将双节点切换TLV发送到另一个双主PE，以允许使用三个连续的DHC消息进行快速保护切换。在传输三条消息之后，保护PW将成为主动服务PW，并且双归属PE必须使用DHC消息连续地周期性地向另一双归属PE发送最近传输的双节点切换TLV。
It is RECOMMENDED that the default interval of the first three rapid DHC messages be 3.3 ms, similar to [RFC6378], and the default interval of the subsequent messages is 1 second. Both the default interval of the three consecutive messages as well as the default interval of the periodic messages SHALL be configurable by the operator.
建议前三条快速DHC消息的默认间隔为3.3 ms，类似于[RFC6378]，后续消息的默认间隔为1秒。操作员应可配置三条连续消息的默认间隔以及定期消息的默认间隔。
The dual-homing MPLS-TP PW protection mechanism can be deployed with the existing AC redundancy mechanisms. On the PSN side, a PSN tunnel protection mechanism is not required, as the dual-homing PW protection can also protect if a failure occurs in the PSN.
双归宿MPLS-TP PW保护机制可以与现有的交流冗余机制一起部署。在PSN侧，不需要PSN隧道保护机制，因为如果PSN发生故障，双归位PW保护也可以保护。
This section uses the one-side dual-homing scenario as an example to describe the dual-homing PW protection procedures; the procedures for a two-side dual-homing scenario would be similar.
本节以单侧双归航场景为例，描述双归航PW保护程序；双面双归航方案的程序类似。
On the dual-homing PE side, the role of working and protection PE are set by the management system or local configuration. The service PW connecting to the working PE is the working PW, and the service PW connecting to the protection PE is called the protection PW.
在双归位PE侧，工作和保护PE的角色由管理系统或本地配置设置。连接到工作PE的维修PW称为工作PW，连接到保护PE的维修PW称为保护PW。
On the single-homing PE side, it treats the working PW and protection PW as if they terminate on the same remote PE node, thus normal MPLS-TP protection coordination procedures still apply on the single-homing PE.
在单归属PE侧，它将工作PW和保护PW视为在同一远程PE节点上终止，因此正常的MPLS-TP保护协调程序仍然适用于单归属PE。
The forwarding behavior of the dual-homing PEs is determined by the components shown in the figure below:
双归位PEs的转发行为由下图所示的组件决定：
+---------------------------------+ +-----+
| PE1 (Working PE) | | |
+---------------------------------+ PW1 | |
| | | Working | |
+ Forwarder + Service X<-------->X |
/| | PW | | |
/ +--------+--------+ | | |
AC1 / | DNI-PW | | | |
/ +--------X--------+---------------+ | |
+-----+/ AC ^ DNI-PW | | +---+
| CE1 |redundancy | | PE3 +--|CE2|
+-----+ mechanism | DHC message | | +---+
\ V exchange | |
AC2 \ +--------X--------+---------------+ | |
\ | DNI-PW | | | |
\ +--------+--------+ | PW2 | |
\| | Service |Protection| |
+ Forwarder + PW X<-------->X |
| | | PSC | |
+---------------------------------+ message | |
| PE2 (Protection PE) | exchange | |
+---------------------------------+ +-----+
+---------------------------------+ +-----+
| PE1 (Working PE) | | |
+---------------------------------+ PW1 | |
| | | Working | |
+ Forwarder + Service X<-------->X |
/| | PW | | |
/ +--------+--------+ | | |
AC1 / | DNI-PW | | | |
/ +--------X--------+---------------+ | |
+-----+/ AC ^ DNI-PW | | +---+
| CE1 |redundancy | | PE3 +--|CE2|
+-----+ mechanism | DHC message | | +---+
\ V exchange | |
AC2 \ +--------X--------+---------------+ | |
\ | DNI-PW | | | |
\ +--------+--------+ | PW2 | |
\| | Service |Protection| |
+ Forwarder + PW X<-------->X |
| | | PSC | |
+---------------------------------+ message | |
| PE2 (Protection PE) | exchange | |
+---------------------------------+ +-----+
Figure 5: Components of One-Side Dual-Homing PW Protection
图5：单侧双归位PW保护的组件
In Figure 5, for each dual-homing PE, the service PW is the PW used to carry service between the dual-homing PE and the remote PE. The state of the service PW is determined by the Operation, Administration, and Maintenance (OAM) mechanisms between the dual-homing PEs and the remote PE.
在图5中，对于每个双归属PE，服务PW是用于在双归属PE和远程PE之间承载服务的PW。服务PW的状态由双主PE和远程PE之间的操作、管理和维护（OAM）机制确定。
The DNI-PW is provisioned between the two dual-homing PE nodes. It is used to bridge traffic when a failure occurs in the PSN or in the ACs. The state of the DNI-PW is determined by the OAM mechanism between the dual-homing PEs. Since the DNI-PW is used to carry both
DNI-PW在两个双归属PE节点之间提供。它用于在PSN或ACs中发生故障时桥接通信量。DNI-PW的状态由双归巢PEs之间的OAM机制确定。因为DNI-PW用于承载两个
the DHC messages and the service traffic during protection switching, it is important to ensure the robustness of the DNI-PW. In order to avoid the DNI-PW failure due to the failure of a particular link, it is RECOMMENDED that multiple diverse links be deployed between the dual-homing PEs and the underlying Label Switched Path (LSP) protection mechanism SHOULD be enabled.
在保护切换期间，DHC消息和服务流量对于确保DNI-PW的健壮性非常重要。为了避免由于特定链路故障而导致的DNI-PW故障，建议在双归属PEs之间部署多个不同的链路，并且应启用底层标签交换路径（LSP）保护机制。
The AC is the link that connects a dual-homing PE to the dual-homed CE. The status of AC is determined by the existing AC redundancy mechanisms; this is out of the scope of this document.
AC是连接双主PE和双主CE的链路。AC的状态由现有AC冗余机制决定；这超出了本文件的范围。
In order to perform dual-homing PW local protection, the service PW status and Dual-Node Switching coordination requests are exchanged between the dual-homing PEs using the DHC message defined in Section 4.1.
为了执行双归位PW本地保护，使用第4.1节中定义的DHC消息在双归位PEs之间交换服务PW状态和双节点切换协调请求。
Whenever a change of service PW status is detected by a dual-homing PE, it MUST be reflected in the PW Status TLV and sent to the other dual-homing PE immediately using the three consecutive DHC messages. After the transmission of the three rapid messages, the dual-homing PE MUST send the most recently transmitted service PW status periodically to the other dual-homing PE on a continual basis using the DHC message. This way, both dual-homing PEs have the status of the working and protection PW consistently.
每当双主PE检测到服务PW状态变化时，必须将其反映在PW状态TLV中，并立即使用三条连续的DHC消息发送给另一个双主PE。在传输三条快速消息后，双归属PE必须使用DHC消息连续定期向另一双归属PE发送最近传输的服务PW状态。这样，两个双归位PEs都具有一致的工作和保护PW状态。
When there is a switchover request either generated locally or received on the protection PW from the remote PE, based on the status of the working and protection service PW along with the local and remote request of the protection coordination between the dual-homing PEs and the remote PE, the active/standby state of the service PW can be determined by the dual-homing PEs. As the remote protection coordination request is transmitted over the protection path, in this case the active/standby status of the service PW is determined by the protection PE in the dual-homing group.
当根据工作和保护服务PW的状态以及双归位PEs和远程PE之间保护协调的本地和远程请求，在本地生成或在保护PW上从远程PE接收到切换请求时，服务PW的主/备用状态可由双归位PEs确定。由于远程保护协调请求通过保护路径传输，在这种情况下，服务PW的活动/备用状态由双归宿组中的保护PE确定。
If it is determined on one dual-homing PE that switchover of the service PW is needed, this dual-homing PE MUST set the S bit in the Dual-Node Switching TLV and send it to the other dual-homing PE immediately using the three consecutive DHC messages. With the exchange of service PW status and the switching request, both dual-homing PEs are consistent on the active/standby forwarding status of the working and protection service PWs. The status of the DNI-PW is determined by PW OAM mechanism as defined in [RFC5085], and the status of ACs is determined by existing AC redundancy mechanisms: both are out of the scope of this document. The forwarding behavior on the dual-homing PE nodes is determined by the forwarding state machine as shown in Table 1.
如果在一个双归属PE上确定需要切换服务PW，则该双归属PE必须在双节点切换TLV中设置S位，并使用三个连续的DHC消息立即将其发送给另一个双归属PE。通过交换服务PW状态和切换请求，两个双归位PE在工作和保护服务PW的主/备用转发状态上保持一致。DNI-PW的状态由[RFC5085]中定义的PW OAM机制确定，ACs的状态由现有的AC冗余机制确定：两者均不在本文件的范围内。双归属PE节点上的转发行为由转发状态机确定，如表1所示。
Using the topology in Figure 5 as an example, in normal state, the working PW (PW1) is in active state, the protection PW (PW2) is in standby state, the DNI-PW is up, and AC1 is in active state according to the AC redundancy mechanism. According to the forwarding state machine in Table 1, traffic will be forwarded through the working PW (PW1) and the primary AC (AC1). No traffic will go through the protection PE (PE2) or the DNI-PW, as both the protection PW (PW2) and the AC connecting to PE2 are in standby state.
以图5中的拓扑为例，根据交流冗余机制，在正常状态下，工作PW（PW1）处于激活状态，保护PW（PW2）处于待机状态，DNI-PW处于启动状态，AC1处于激活状态。根据表1中的转发状态机，流量将通过工作PW（PW1）和主AC（AC1）进行转发。由于保护PW（PW2）和连接至PE2的AC均处于待机状态，因此没有流量通过保护PE（PE2）或DNI-PW。
If a failure occurs in AC1, the state of AC2 changes to active according to the AC redundancy mechanism, while there is no change in the state of the working and protection PWs. According to the forwarding state machine in Table 1, PE1 starts to forward traffic between the working PW and the DNI-PW, and PE2 starts to forward traffic between AC2 and the DNI-PW. It should be noted that in this case only AC switchover takes place; in the PSN, traffic is still forwarded using the working PW.
如果AC1发生故障，AC2的状态将根据交流冗余机制变为激活状态，而工作和保护PWs的状态没有变化。根据表1中的转发状态机，PE1开始转发工作PW和DNI-PW之间的流量，PE2开始转发AC2和DNI-PW之间的流量。应注意的是，在这种情况下，仅发生交流切换；在PSN中，仍然使用工作PW转发通信量。
If a failure in the PSN brings PW1 down, the failure can be detected by PE1 or PE3 using existing OAM mechanisms. If PE1 detects the failure of PW1, it MUST inform PE2 of the state of the working PW using the PW Status TLV in the DHC messages and change the forwarding status of PW1 to standby. On receipt of the DHC message, PE2 SHOULD change the forwarding status of PW2 to active. Then, according to the forwarding state machine in Table 1, PE1 SHOULD set up the connection between the DNI-PW and AC1, and PE2 SHOULD set up the connection between PW2 and the DNI-PW. According to the linear protection mechanism [RFC6378], PE2 also sends an appropriate protection coordination message [RFC6378] over the protection PW (PW2) to PE3 for the remote side to switchover from PW1 to PW2. If PE3 detects the failure of PW1, according to the linear protection mechanism [RFC6378], it sends a protection coordination message on the protection PW (PW2) to inform PE2 of the failure on the working PW. Upon receipt of the message, PE2 SHOULD change the forwarding status of PW2 to active and set up the connection according to the forwarding state machine in Table 1. PE2 SHOULD send a DHC message to PE1 with the S bit set in the Dual-Node Switching TLV to coordinate the switchover on PE1 and PE2. This is useful for a unidirectional failure that cannot be detected by PE1.
如果PSN中的故障导致PW1停机，则PE1或PE3可以使用现有OAM机制检测故障。如果PE1检测到PW1故障，则必须使用DHC消息中的PW状态TLV通知PE2工作PW的状态，并将PW1的转发状态更改为待机状态。收到DHC消息后，PE2应将PW2的转发状态更改为活动。然后，根据表1中的转发状态机，PE1应设置DNI-PW和AC1之间的连接，PE2应设置PW2和DNI-PW之间的连接。根据线性保护机制[RFC6378]，PE2还通过保护PW（PW2）向PE3发送适当的保护协调消息[RFC6378]，以便远程侧从PW1切换到PW2。如果PE3检测到PW1的故障，根据线性保护机制[RFC6378]，它会在保护PW（PW2）上发送保护协调消息，通知PE2工作PW的故障。收到消息后，PE2应将PW2的转发状态更改为active，并根据表1中的转发状态机建立连接。PE2应向PE1发送DHC消息，并在双节点切换TLV中设置S位，以协调PE1和PE2上的切换。这对于PE1无法检测到的单向故障非常有用。
If a failure brings the working PE (PE1) down, the failure can be detected by both PE2 and PE3 using existing OAM mechanisms. Both PE2 and PE3 SHOULD change the forwarding status of PW2 to active and send a protection coordination message [RFC6378] on the protection PW (PW2) to inform the remote side to switchover. According to the existing AC redundancy mechanisms, the status of AC1 changes to
如果故障导致工作PE（PE1）停机，则PE2和PE3都可以使用现有的OAM机制检测到故障。PE2和PE3都应将PW2的转发状态更改为激活状态，并在保护PW（PW2）上发送保护协调消息[RFC6378]，通知远程侧进行切换。根据现有的交流冗余机制，AC1的状态更改为
standby and the state of AC2 changes to active. According to the forwarding state machine in Table 1, PE2 starts to forward traffic between the PW2 and AC2.
待机状态，AC2的状态变为活动状态。根据表1中的转发状态机，PE2开始转发PW2和AC2之间的通信量。
IANA has assigned a new channel type for the "MPLS-TP Dual-Homing Coordination Message" from the "MPLS Generalized Associated Channel (G-ACh) Types (including Pseudowire Associated Channel Types)" subregistry within the "Generic Associated Channel (G-ACh) Parameters" registry.
IANA已从“通用关联信道（G-ACh）参数”注册表中的“MPLS通用关联信道（G-ACh）类型（包括伪线关联信道类型）”子区为“MPLS-TP双归巢协调消息”分配了新的信道类型。
Value Description Reference 0x0009 MPLS-TP Dual-Homing Coordination message RFC 8185
值说明参考0x0009 MPLS-TP双归宿协调消息RFC 8185
IANA has created a new subregistry called "MPLS-TP DHC TLVs" within the "Generic Associated Channel (G-ACh) Parameters" registry. The registry has the following fields and initial allocations:
IANA在“通用关联通道（G-ACh）参数”注册表中创建了一个新的子区域，名为“MPLS-TP DHC TLV”。注册表具有以下字段和初始分配：
Type Description Length Reference 0x0000 Reserved 0x0001 PW Status 20 Bytes RFC 8185 0x0002 Dual-Node Switching 16 Bytes RFC 8185
类型描述长度参考0x0000保留0x0001 PW状态20字节RFC 8185 0x0002双节点切换16字节RFC 8185
The allocation policy for this registry is IETF Review, as specified in [RFC8126].
按照[RFC8126]中的规定，此注册表的分配策略为IETF Review。
MPLS-TP is a subset of MPLS and so builds upon many of the aspects of the MPLS security model. Please refer to [RFC5920] for generic MPLS security issues and methods for securing traffic privacy and integrity.
MPLS-TP是MPLS的一个子集，因此建立在MPLS安全模型的许多方面之上。请参考[RFC5920]了解通用MPLS安全问题以及保护流量隐私和完整性的方法。
The DHC message defined in this document contains control information. If it is injected or modified by an attacker, the dual-homing PEs might not agree on which PE should be used to deliver the CE traffic, and this could be used as a denial-of-service attack against the CE. It is important that the DHC message be used within a trusted MPLS-TP network domain as described in [RFC6941].
本文档中定义的DHC消息包含控制信息。如果它被攻击者注入或修改，双主PE可能不同意使用哪个PE来传递CE流量，这可能被用作针对CE的拒绝服务攻击。如[RFC6941]所述，在可信MPLS-TP网络域内使用DHC消息非常重要。
The DHC message is carried in the G-ACh [RFC5586], so it is dependent on the security of the G-ACh itself. The G-ACh is a generalization of the Associated Channel defined in [RFC4385]. Thus, this document relies on the security mechanisms provided for the Associated Channel as described in those two documents.
DHC消息在G-ACh[RFC5586]中传输，因此它取决于G-ACh本身的安全性。G-ACh是[RFC4385]中定义的相关信道的推广。因此，本文档依赖于为相关通道提供的安全机制，如这两个文档中所述。
As described in the Security Considerations section of [RFC6378], the G-ACh is essentially connection oriented, so injection or modification of control messages requires the subversion of a transit node. Such subversion is generally considered hard in connection-oriented MPLS networks and impossible to protect against at the protocol level. Management-level techniques are more appropriate. The procedures and protocol extensions defined in this document do not affect the security model of MPLS-TP linear protection as defined in [RFC6378].
如[RFC6378]的安全注意事项部分所述，G-ACh本质上是面向连接的，因此控制消息的注入或修改需要对传输节点进行颠覆。在面向连接的MPLS网络中，这种颠覆通常被认为是很难实现的，并且不可能在协议级别进行保护。管理层技术更合适。本文件中定义的程序和协议扩展不影响[RFC6378]中定义的MPLS-TP线性保护的安全模型。
Uniqueness of the identifiers defined in this document is guaranteed by the assigner (e.g., the operator). Failure by an assigner to use unique values within the specified scoping for any of the identifiers defined herein could result in operational problems. Please refer to [RFC6370] for more details about the uniqueness of the identifiers.
本文件中定义的标识符的唯一性由转让人（如运营商）保证。转让人未能在此处定义的任何标识符的指定范围内使用唯一值可能会导致操作问题。有关标识符唯一性的更多详细信息，请参阅[RFC6370]。
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>.
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，DOI 10.17487/RFC2119，1997年3月<http://www.rfc-editor.org/info/rfc2119>.
[RFC5085] Nadeau, T., Ed. and C. Pignataro, Ed., "Pseudowire Virtual Circuit Connectivity Verification (VCCV): A Control Channel for Pseudowires", RFC 5085, DOI 10.17487/RFC5085, December 2007, <http://www.rfc-editor.org/info/rfc5085>.
[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，DOI 10.17487/RFC5085，2007年12月<http://www.rfc-editor.org/info/rfc5085>.
[RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed., "MPLS Generic Associated Channel", RFC 5586, DOI 10.17487/RFC5586, June 2009, <http://www.rfc-editor.org/info/rfc5586>.
[RFC5586]Bocci，M.，Ed.，Vigoureux，M.，Ed.，和S.Bryant，Ed.，“MPLS通用关联信道”，RFC 5586，DOI 10.17487/RFC55862009年6月<http://www.rfc-editor.org/info/rfc5586>.
[RFC6370] Bocci, M., Swallow, G., and E. Gray, "MPLS Transport Profile (MPLS-TP) Identifiers", RFC 6370, DOI 10.17487/RFC6370, September 2011, <http://www.rfc-editor.org/info/rfc6370>.
[RFC6370]Bocci，M.，Swallow，G.和E.Gray，“MPLS传输配置文件（MPLS-TP）标识符”，RFC 6370，DOI 10.17487/RFC6370，2011年9月<http://www.rfc-editor.org/info/rfc6370>.
[RFC6378] Weingarten, Y., Ed., Bryant, S., Osborne, E., Sprecher, N., and A. Fulignoli, Ed., "MPLS Transport Profile (MPLS-TP) Linear Protection", RFC 6378, DOI 10.17487/RFC6378, October 2011, <http://www.rfc-editor.org/info/rfc6378>.
[RFC6378]Y.Weingarten，Ed.，Bryant，S.，Osborne，E.，Sprecher，N.，和A.Fulignoli，Ed.，“MPLS传输模式（MPLS-TP）线性保护”，RFC 6378，DOI 10.17487/RFC6378，2011年10月<http://www.rfc-editor.org/info/rfc6378>.
[RFC7271] Ryoo, J., Ed., Gray, E., Ed., van Helvoort, H., D'Alessandro, A., Cheung, T., and E. Osborne, "MPLS Transport Profile (MPLS-TP) Linear Protection to Match the Operational Expectations of Synchronous Digital Hierarchy, Optical Transport Network, and Ethernet Transport Network Operators", RFC 7271, DOI 10.17487/RFC7271, June 2014, <http://www.rfc-editor.org/info/rfc7271>.
[RFC7271]Ryoo，J.，Ed.，Gray，E.，Ed.，van Helvoort，H.，D'Alessandro，A.，Cheung，T.，和E.Osborne，“MPLS传输配置文件（MPLS-TP）线性保护，以满足同步数字体系、光传输网络和以太网传输网络运营商的运营期望”，RFC 7271，DOI 10.17487/RFC72712014年6月， <http://www.rfc-editor.org/info/rfc7271>.
[RFC7324] Osborne, E., "Updates to MPLS Transport Profile Linear Protection", RFC 7324, DOI 10.17487/RFC7324, July 2014, <http://www.rfc-editor.org/info/rfc7324>.
[RFC7324]Osborne，E.“MPLS传输配置文件线性保护的更新”，RFC 7324，DOI 10.17487/RFC73242014年7月<http://www.rfc-editor.org/info/rfc7324>.
[RFC8077] Martini, L., Ed. and G. Heron, Ed., "Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)", STD 84, RFC 8077, DOI 10.17487/RFC8077, February 2017, <http://www.rfc-editor.org/info/rfc8077>.
[RFC8077]Martini，L.，Ed.和G.Heron，Ed.，“使用标签分发协议（LDP）的伪线设置和维护”，STD 84，RFC 8077，DOI 10.17487/RFC8077，2017年2月<http://www.rfc-editor.org/info/rfc8077>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <http://www.rfc-editor.org/info/rfc8174>.
[RFC8174]Leiba，B.，“RFC 2119关键词中大写与小写的歧义”，BCP 14，RFC 8174，DOI 10.17487/RFC8174，2017年5月<http://www.rfc-editor.org/info/rfc8174>.
[RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson, "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for Use over an MPLS PSN", RFC 4385, DOI 10.17487/RFC4385, February 2006, <http://www.rfc-editor.org/info/rfc4385>.
[RFC4385]Bryant，S.，Swallow，G.，Martini，L.，和D.McPherson，“用于MPLS PSN的伪线仿真边到边（PWE3）控制字”，RFC 4385，DOI 10.17487/RFC4385，2006年2月<http://www.rfc-editor.org/info/rfc4385>.
[RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010, <http://www.rfc-editor.org/info/rfc5920>.
[RFC5920]方，L.，编辑，“MPLS和GMPLS网络的安全框架”，RFC 5920，DOI 10.17487/RFC5920，2010年7月<http://www.rfc-editor.org/info/rfc5920>.
[RFC6372] Sprecher, N., Ed. and A. Farrel, Ed., "MPLS Transport Profile (MPLS-TP) Survivability Framework", RFC 6372, DOI 10.17487/RFC6372, September 2011, <http://www.rfc-editor.org/info/rfc6372>.
[RFC6372]Sprecher，N.，Ed.和A.Farrel，Ed.，“MPLS传输配置文件（MPLS-TP）生存能力框架”，RFC 6372，DOI 10.17487/RFC6372，2011年9月<http://www.rfc-editor.org/info/rfc6372>.
[RFC6718] Muley, P., Aissaoui, M., and M. Bocci, "Pseudowire Redundancy", RFC 6718, DOI 10.17487/RFC6718, August 2012, <http://www.rfc-editor.org/info/rfc6718>.
[RFC6718]Muley，P.，Aissaoui，M.和M.Bocci，“伪线冗余”，RFC 6718，DOI 10.17487/RFC6718，2012年8月<http://www.rfc-editor.org/info/rfc6718>.
[RFC6870] Muley, P., Ed. and M. Aissaoui, Ed., "Pseudowire Preferential Forwarding Status Bit", RFC 6870, DOI 10.17487/RFC6870, February 2013, <http://www.rfc-editor.org/info/rfc6870>.
[RFC6870]Muley，P.，Ed.和M.Aissaoui，Ed.，“伪线优先转发状态位”，RFC 6870，DOI 10.17487/RFC6870，2013年2月<http://www.rfc-editor.org/info/rfc6870>.
[RFC6941] Fang, L., Ed., Niven-Jenkins, B., Ed., Mansfield, S., Ed., and R. Graveman, Ed., "MPLS Transport Profile (MPLS-TP) Security Framework", RFC 6941, DOI 10.17487/RFC6941, April 2013, <http://www.rfc-editor.org/info/rfc6941>.
[RFC6941]Fang，L.，Ed.，Niven Jenkins，B.，Ed.，Mansfield，S.，Ed.，和R.Graveman，Ed.，“MPLS传输配置文件（MPLS-TP）安全框架”，RFC 6941，DOI 10.17487/RFC69411913年4月<http://www.rfc-editor.org/info/rfc6941>.
[RFC7771] Malis, A., Ed., Andersson, L., van Helvoort, H., Shin, J., Wang, L., and A. D'Alessandro, "Switching Provider Edge (S-PE) Protection for MPLS and MPLS Transport Profile (MPLS-TP) Static Multi-Segment Pseudowires", RFC 7771, DOI 10.17487/RFC7771, January 2016, <http://www.rfc-editor.org/info/rfc7771>.
[RFC7771]Malis，A.，Ed.，Andersson，L.，van Helvoort，H.，Shin，J.，Wang，L.，和A.D'Alessandro，“MPLS和MPLS传输配置文件（MPLS-TP）静态多段伪线的交换提供商边缘（S-PE）保护”，RFC 7771，DOI 10.17487/RFC7771，2016年1月<http://www.rfc-editor.org/info/rfc7771>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, <http://www.rfc-editor.org/info/rfc8126>.
[RFC8126]Cotton，M.，Leiba，B.，和T.Narten，“在RFC中编写IANA考虑事项部分的指南”，BCP 26，RFC 8126，DOI 10.17487/RFC8126，2017年6月<http://www.rfc-editor.org/info/rfc8126>.
[RFC8184] Cheng, W., Wang, L., Li, H., Davari, S., and J. Dong, "Dual-Homing Protection for MPLS and the MPLS Transport Profile (MPLS-TP) Pseudowires", RFC 8184, DOI 10.17487/RFC8184, June 2017.
[RFC8184]Cheng，W.，Wang，L.，Li，H.，Davari，S.，和J.Dong，“MPLS的双归宿保护和MPLS传输配置文件（MPLS-TP）伪线”，RFC 8184，DOI 10.17487/RFC8184，2017年6月。
Contributors
贡献者
The following individuals substantially contributed to the content of this document:
以下个人对本文件的内容做出了重大贡献：
Kai Liu Huawei Technologies Email: alex.liukai@huawei.com
刘凯华为技术电子邮件：alex。liukai@huawei.com
Shahram Davari Broadcom Corporation Email: davari@broadcom.com
Shahram Davari Broadcom Corporation电子邮件：davari@broadcom.com
Authors' Addresses
作者地址
Weiqiang Cheng China Mobile No.32 Xuanwumen West Street Beijing 100053 China
中国移动北京宣武门西街32号威强城100053
Email: chengweiqiang@chinamobile.com
Email: chengweiqiang@chinamobile.com
Lei Wang China Mobile No.32 Xuanwumen West Street Beijing 100053 China
雷王中国移动北京宣武门西街32号100053
Email: Wangleiyj@chinamobile.com
Email: Wangleiyj@chinamobile.com
Han Li China Mobile No.32 Xuanwumen West Street Beijing 100053 China
中国移动北京宣武门西街32号汉力100053
Email: Lihan@chinamobile.com
Email: Lihan@chinamobile.com
Jie Dong Huawei Technologies Huawei Campus, No. 156 Beiqing Rd. Beijing 100095 China
中国北京市北青路156号华为校园华为技术有限公司，邮编：100095
Email: jie.dong@huawei.com
Email: jie.dong@huawei.com
Alessandro D'Alessandro Telecom Italia via Reiss Romoli, 274 Torino 10148 Italy
Alessandro D'Alessandro Telecom Italia via Reiss Romoli，274都灵10148意大利
Email: alessandro.dalessandro@telecomitalia.it
Email: alessandro.dalessandro@telecomitalia.it