Internet Engineering Task Force (IETF) E. Rosen
Request for Comments: 7582 Juniper Networks, Inc.
Updates: 6513, 6514, 6625 IJ. Wijnands
Category: Standards Track Cisco Systems, Inc.
ISSN: 2070-1721 Y. Cai
Microsoft
A. Boers
July 2015
Internet Engineering Task Force (IETF) E. Rosen
Request for Comments: 7582 Juniper Networks, Inc.
Updates: 6513, 6514, 6625 IJ. Wijnands
Category: Standards Track Cisco Systems, Inc.
ISSN: 2070-1721 Y. Cai
Microsoft
A. Boers
July 2015
Multicast Virtual Private Network (MVPN): Using Bidirectional P-Tunnels
多播虚拟专用网（MVPN）：使用双向P隧道
Abstract
摘要
A set of prior RFCs specify procedures for supporting multicast in BGP/MPLS IP VPNs. These procedures allow customer multicast data to travel across a service provider's backbone network through a set of multicast tunnels. The tunnels are advertised in certain BGP multicast auto-discovery routes, by means of a BGP attribute known as the "Provider Multicast Service Interface (PMSI) Tunnel" attribute. Encodings have been defined that allow the PMSI Tunnel attribute to identify bidirectional (multipoint-to-multipoint) multicast distribution trees. However, the prior RFCs do not provide all the necessary procedures for using bidirectional tunnels to support multicast VPNs. This document updates RFCs 6513, 6514, and 6625 by specifying those procedures. In particular, it specifies the procedures for assigning customer multicast flows (unidirectional or bidirectional) to specific bidirectional tunnels in the provider backbone, for advertising such assignments, and for determining which flows have been assigned to which tunnels.
一组先前的RFC指定了在BGP/MPLS IP VPN中支持多播的过程。这些过程允许客户多播数据通过一组多播隧道跨服务提供商的主干网络传输。隧道通过称为“提供商多播服务接口（PMSI）隧道”属性的BGP属性在某些BGP多播自动发现路由中进行广告。已经定义了允许PMSI隧道属性识别双向（多点到多点）多播分发树的编码。然而，先前的rfc没有提供使用双向隧道来支持多播vpn的所有必要过程。本文档通过指定这些程序来更新RFCs 6513、6514和6625。具体而言，它规定了将客户多播流（单向或双向）分配给提供商主干中的特定双向隧道、公布此类分配以及确定哪些流已分配给哪些隧道的过程。
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/rfc7582.
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/rfc7582.
Copyright Notice
版权公告
Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2015 IETF信托基金和确定为文件作者的人员。版权所有。
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(http://trustee.ietf.org/license-info)自本文件出版之日起生效。请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本，并提供简化BSD许可证中所述的无担保。
Table of Contents
目录
1. Introduction ....................................................4
1.1. Terminology ................................................4
1.2. Overview ...................................................9
1.2.1. Bidirectional P-Tunnel Technologies ................10
1.2.2. Reasons for Using Bidirectional P-Tunnels ..........11
1.2.3. Knowledge of Group-to-RP and/or
Group-to-RPA Mappings ..............................12
1.2.4. PMSI Instantiation Methods .........................12
2. The All BIDIR-PIM Wildcard .....................................15
3. Using Bidirectional P-Tunnels ..................................15
3.1. Procedures Specific to the Tunneling Technology ...........15
3.1.1. BIDIR-PIM P-Tunnels ................................16
3.1.2. MP2MP LSPs .........................................17
3.2. Procedures Specific to the PMSI Instantiation Method ......17
3.2.1. Flat Partitioning ..................................17
3.2.1.1. When an S-PMSI Is a 'Match for
Transmission' .............................19
3.2.1.2. When an I-PMSI Is a 'Match for
Transmission' .............................20
3.2.1.3. When an S-PMSI Is a 'Match for Reception' .21
3.2.1.4. When an I-PMSI Is a 'Match for Reception' .22
3.2.2. Hierarchical Partitioning ..........................23
3.2.2.1. Advertisement of PE Distinguisher Labels ..24
3.2.2.2. When an S-PMSI Is a 'Match for
Transmission' .............................25
3.2.2.3. When an I-PMSI Is a 'Match for
Transmission' .............................26
3.2.2.4. When an S-PMSI Is a 'Match for Reception' .27
3.2.2.5. When an I-PMSI Is a 'Match for Reception' .27
3.2.3. Unpartitioned ......................................28
3.2.3.1. When an S-PMSI Is a 'Match for
Transmission' .............................30
3.2.3.2. When an S-PMSI Is a 'Match for Reception' .30
3.2.4. Minimal Feature Set for Compliance .................31
4. Security Considerations ........................................32
5. References .....................................................32
5.1. Normative References ......................................32
5.2. Informative References ....................................33
Acknowledgments ...................................................34
Authors' Addresses ................................................34
1. Introduction ....................................................4
1.1. Terminology ................................................4
1.2. Overview ...................................................9
1.2.1. Bidirectional P-Tunnel Technologies ................10
1.2.2. Reasons for Using Bidirectional P-Tunnels ..........11
1.2.3. Knowledge of Group-to-RP and/or
Group-to-RPA Mappings ..............................12
1.2.4. PMSI Instantiation Methods .........................12
2. The All BIDIR-PIM Wildcard .....................................15
3. Using Bidirectional P-Tunnels ..................................15
3.1. Procedures Specific to the Tunneling Technology ...........15
3.1.1. BIDIR-PIM P-Tunnels ................................16
3.1.2. MP2MP LSPs .........................................17
3.2. Procedures Specific to the PMSI Instantiation Method ......17
3.2.1. Flat Partitioning ..................................17
3.2.1.1. When an S-PMSI Is a 'Match for
Transmission' .............................19
3.2.1.2. When an I-PMSI Is a 'Match for
Transmission' .............................20
3.2.1.3. When an S-PMSI Is a 'Match for Reception' .21
3.2.1.4. When an I-PMSI Is a 'Match for Reception' .22
3.2.2. Hierarchical Partitioning ..........................23
3.2.2.1. Advertisement of PE Distinguisher Labels ..24
3.2.2.2. When an S-PMSI Is a 'Match for
Transmission' .............................25
3.2.2.3. When an I-PMSI Is a 'Match for
Transmission' .............................26
3.2.2.4. When an S-PMSI Is a 'Match for Reception' .27
3.2.2.5. When an I-PMSI Is a 'Match for Reception' .27
3.2.3. Unpartitioned ......................................28
3.2.3.1. When an S-PMSI Is a 'Match for
Transmission' .............................30
3.2.3.2. When an S-PMSI Is a 'Match for Reception' .30
3.2.4. Minimal Feature Set for Compliance .................31
4. Security Considerations ........................................32
5. References .....................................................32
5.1. Normative References ......................................32
5.2. Informative References ....................................33
Acknowledgments ...................................................34
Authors' Addresses ................................................34
The RFCs that specify multicast support for BGP/MPLS IP VPNs ([RFC6513], [RFC6514], and [RFC6625]) allow customer multicast data to be transported across a service provider's network though a set of multicast tunnels. These tunnels are advertised in BGP multicast auto-discovery (A-D) routes, by means of a BGP attribute known as the "Provider Multicast Service Interface (PMSI) Tunnel" attribute. The base specifications allow the use of bidirectional (multipoint-to-multipoint) multicast distribution trees and describe how to encode the identifiers for bidirectional trees into the PMSI Tunnel attribute. However, those specifications do not provide all the necessary detailed procedures for using bidirectional tunnels; the full specification of these procedures was considered to be outside the scope of those documents. The purpose of this document is to provide all the necessary procedures for using bidirectional trees in a service provider's network to carry the multicast data of VPN customers.
指定BGP/MPLS IP VPN的多播支持的RFC（[RFC6513]、[RFC6514]和[RFC6625]）允许通过一组多播隧道跨服务提供商的网络传输客户多播数据。这些隧道通过称为“提供商多播服务接口（PMSI）隧道”属性的BGP属性在BGP多播自动发现（A-D）路由中公布。基本规范允许使用双向（多点到多点）多播分发树，并描述如何将双向树的标识符编码到PMSI隧道属性中。然而，这些规范并未提供使用双向隧道的所有必要详细程序；这些程序的完整规范被认为不在这些文件的范围之内。本文档旨在提供使用服务提供商网络中的双向树来承载VPN客户的多播数据的所有必要程序。
This document uses terminology from [RFC6513] and, in particular, uses the prefixes "C-" and "P-", as specified in Section 3.1 of [RFC6513], to distinguish addresses in the "customer address space" from addresses in the "provider address space". The following terminology and acronyms are particularly important in this document:
本文件使用[RFC6513]中的术语，尤其是[RFC6513]第3.1节中规定的前缀“C-”和“P-”，以区分“客户地址空间”中的地址与“提供商地址空间”中的地址。以下术语和首字母缩略词在本文件中尤为重要：
o MVPN
o MVPN
Multicast Virtual Private Network -- a VPN [RFC4364] in which multicast service is offered.
多播虚拟专用网——提供多播服务的VPN[RFC4364]。
o VRF
o VRF
VPN Routing and Forwarding table [RFC4364].
VPN路由和转发表[RFC4364]。
o PE
o 体育课
A Provider Edge router, as defined in [RFC4364].
提供程序边缘路由器，如[RFC4364]中所定义。
o SP
o 服务提供商
Service Provider.
服务提供商。
o LSP
o LSP
An MPLS Label Switched Path.
MPLS标签交换路径。
o P2MP
o P2MP
Point-to-Multipoint.
点对多点。
o MP2MP
o MP2MP
Multipoint-to-multipoint.
多点对多点。
o Unidirectional
o 单向的
Adjective for a multicast distribution tree in which all traffic travels downstream from the root of the tree. Traffic can enter a unidirectional tree only at the root. A P2MP LSP is one type of unidirectional tree. Multicast distribution trees set up by Protocol Independent Multicast - Sparse Mode (PIM-SM) [RFC4601] are also unidirectional trees. Data traffic traveling along a unidirectional multicast distribution tree is sometimes referred to in this document as "unidirectional traffic".
多播分发树的形容词，其中所有通信量从树的根向下游移动。流量只能在根节点进入单向树。P2MP LSP是一种单向树。由协议无关多播稀疏模式（PIM-SM）[RFC4601]建立的多播分布树也是单向树。在本文档中，沿单向多播分发树传输的数据流量有时称为“单向流量”。
o Bidirectional
o 双向的
Adjective for a multicast distribution tree in which traffic may travel both upstream (towards the root) and downstream (away from the root). Traffic may enter a bidirectional tree at any node. An MP2MP LSP is one type of bidirectional tree. Multicast distribution trees created by Bidirectional Protocol Independent Multicast (BIDIR-PIM) [RFC5015] are also bidirectional trees.
多播分发树的形容词，其中通信量可以向上游（朝向根）和下游（远离根）移动。流量可以在任何节点进入双向树。MP2MP LSP是一种双向树。由双向协议独立多播（BIDIR-PIM）[RFC5015]创建的多播分发树也是双向树。
Data traffic traveling along a bidirectional multicast distribution tree is sometimes referred to in this document as "bidirectional traffic".
在本文档中，沿双向多播分发树传输的数据流量有时称为“双向流量”。
o P-tunnel
o P型隧道
A tunnel through the network of one or more SPs. In this document, the P-tunnels we speak of are instantiated as bidirectional multicast distribution trees.
通过一个或多个SP的网络的隧道。在本文中，我们提到的P隧道被实例化为双向多播分发树。
o SSM
o SSM
Source-Specific Multicast. When SSM is being used, a multicast distribution tree carries traffic from only a single source.
源特定多播。当使用SSM时，多播分发树只承载来自单个源的流量。
o ASM
o ASM
Any Source Multicast. When ASM is being used, some multicast distribution trees ("share trees") carry traffic from multiple sources.
任何源多播。当使用ASM时，一些多播分发树（“共享树”）承载来自多个源的流量。
o C-S
o C-S
Multicast Source. A multicast source address, in the address space of a customer network.
多播源。客户网络地址空间中的多播源地址。
o C-G
o C-G
Multicast Group. A multicast group address (destination address) in the address space of a customer network. When used without qualification, "C-G" may refer to either a unidirectional group address or a bidirectional group address.
多播组。客户网络地址空间中的多播组地址（目标地址）。当在没有限定的情况下使用时，“C-G”可指单向组地址或双向组地址。
o C-G-BIDIR
o C-G-BIDIR
A bidirectional multicast group address (i.e., a group address whose IP multicast distribution tree is built by BIDIR-PIM).
双向多播组地址（即，其IP多播分发树由BIDIR-PIM构建的组地址）。
o C-multicast flow or C-flow
o C-多播流还是C-流
A customer multicast flow. A C-flow travels through VPN customer sites on a multicast distribution tree set up by the customer. These trees may be unidirectional or bidirectional, depending upon the multicast routing protocol used by the customer. A C-flow travels between VPN customer sites by traveling through P-tunnels.
客户多播流。C-flow在客户设置的多播分发树上通过VPN客户站点。这些树可以是单向的，也可以是双向的，这取决于客户使用的多播路由协议。C流通过P隧道在VPN客户站点之间移动。
A C-flow from a particular customer source is identified by the ordered pair (source address, group address), where each address is in the customer's address space. The identifier of such a C-flow is usually written as (C-S,C-G).
来自特定客户源的C流由有序对（源地址、组地址）标识，其中每个地址位于客户的地址空间中。这种C流的标识符通常写为（C-S，C-G）。
If a customer uses the ASM model, then some or all of the customer's C-flows may be traveling along the same "shared tree". In this case, we will speak of a "(C-*,C-G)" flow to refer to a set of C-flows that travel along the same shared tree in the customer sites.
如果客户使用ASM模型，则客户的部分或全部C流可能沿着同一“共享树”移动。在本例中，我们将使用“（C-*，C-G）”流来指代在客户站点中沿着同一共享树移动的一组C流。
o C-BIDIR flow or bidirectional C-flow
o C-BIDIR流或双向C-flow
A C-flow that, in the VPN customer sites, travels along a bidirectional multicast distribution tree. The term "C-BIDIR flow" indicates that the customer's bidirectional tree has been set up by BIDIR-PIM.
在VPN客户站点中，沿着双向多播分发树传播的C流。术语“C-BIDIR流”表示BIDIR-PIM已经建立了客户的双向树。
o RP
o 反相
A Rendezvous Point, as defined in [RFC4601].
[RFC4601]中定义的会合点。
o C-RP
o C-RP
A Rendezvous Point whose address is in the customer's address space.
地址在客户地址空间中的集合点。
o RPA
o RPA
A Rendezvous Point Address, as defined in [RFC5015].
[RFC5015]中定义的集合点地址。
o C-RPA
o C-RPA
An RPA in the customer's address space.
客户地址空间中的RPA。
o P-RPA
o P-RPA
An RPA in the SP's address space.
SP地址空间中的RPA。
o Selective P-tunnel
o 选择性P隧道
A P-tunnel that is joined only by PE routers that need to receive one or more of the C-flows that are traveling through that P-tunnel.
仅由PE路由器连接的P隧道，需要接收通过该P隧道的一个或多个C流。
o Inclusive P-tunnel
o 包容性P隧道
A P-tunnel that is joined by all PE routers that attach to sites of a given MVPN.
由连接到给定MVPN站点的所有PE路由器连接的P隧道。
o PMSI
o PMSI
Provider Multicast Service Interface. A PMSI is a conceptual overlay on a Service Provider backbone, allowing a PE in a given MVPN to multicast to other PEs in the MVPN. PMSIs are instantiated by P-tunnels.
提供者多播服务接口。PMSI是服务提供商主干上的概念覆盖，允许给定MVPN中的PE多播到MVPN中的其他PE。PMSI由P-隧道实例化。
o I-PMSI
o I-PMSI
Inclusive PMSI. Traffic multicast by a PE on an I-PMSI is received by all other PEs in the MVPN. I-PMSIs are instantiated by Inclusive P-tunnels.
包括PMSI。I-PMSI上的PE的流量多播由MVPN中的所有其他PE接收。I-PMSI由包含的P-隧道实例化。
o S-PMSI
o S-PMSI
Selective PMSI. Traffic multicast by a PE on an S-PMSI is received by some (but not necessarily all) of the other PEs in the MVPN. S-PMSIs are instantiated by Selective P-tunnels.
选择性PMSI。S-PMSI上的PE的流量多播由MVPN中的一些（但不一定全部）其他PE接收。S-PMSI由选择性P隧道实例化。
o Intra-AS I-PMSI A-D route
o 内部AS I-PMSI A-D路由
Intra-AS (Autonomous System) Inclusive Provider Multicast Service Interface Auto-Discovery route. Carried in BGP Update messages, these routes can be used to advertise the use of Inclusive P-tunnels. See [RFC6514], Section 4.1.
内部AS（自治系统）包容性提供商多播服务接口自动发现路由。这些路由包含在BGP更新消息中，可用于宣传包容性P隧道的使用。见[RFC6514]，第4.1节。
o S-PMSI A-D route
o S-PMSI A-D路由
Selective Provider Multicast Service Interface Auto-Discovery route. Carried in BGP Update messages, these routes are used to advertise the fact that a particular C-flow or a particular set of C-flows is bound to (i.e., is traveling through) a particular P-tunnel. See [RFC6514], Section 4.3.
选择性提供者多播服务接口自动发现路由。在BGP更新消息中，这些路由用于通告特定C流或特定C流集绑定到（即，正在通过）特定P隧道的事实。见[RFC6514]，第4.3节。
o (C-S,C-G) S-PMSI A-D route
o （C-S，C-G）S-PMSI A-D路线
An S-PMSI A-D route whose NLRI (Network Layer Reachability Information) contains C-S in its "Multicast Source" field and C-G in its "Multicast Group" field.
一种S-PMSI A-D路由，其NLRI（网络层可达性信息）在其“多播源”字段中包含C-S，在其“多播组”字段中包含C-G。
o (C-*,C-G) S-PMSI A-D route
o （C-*，C-G）S-PMSI A-D路线
An S-PMSI A-D route whose NLRI contains the wildcard (C-*) in its "Multicast Source" field and C-G in its "Multicast Group" field. See [RFC6625].
一种S-PMSI A-D路由，其NLRI在其“多播源”字段中包含通配符（C-*），在其“多播组”字段中包含C-G。见[RFC6625]。
o (C-*,C-G-BIDIR) S-PMSI A-D route
o （C-*，C-G-BIDIR）S-PMSI A-D路线
An S-PMSI A-D route whose NLRI contains the wildcard (C-*) in its "Multicast Source" field and C-G-BIDIR in its "Multicast Group" field. See [RFC6625].
一种S-PMSI A-D路由，其NLRI在其“多播源”字段中包含通配符（C-*），在其“多播组”字段中包含C-G-BIDIR。见[RFC6625]。
o (C-*,C-*) S-PMSI A-D route
o （C-*，C-*）S-PMSI A-D路线
An S-PMSI A-D route whose NLRI contains the wildcard C-* in its "Multicast Source" field and the wildcard C-* in its "Multicast Group" field. See [RFC6625].
一种S-PMSI A-D路由，其NLRI在其“多播源”字段中包含通配符C-*，在其“多播组”字段中包含通配符C-*。见[RFC6625]。
o (C-*,C-*-BIDIR) S-PMSI A-D route
o （C-*，C-*-BIDIR）S-PMSI A-D路线
An S-PMSI A-D route whose NLRI contains the wildcard C-* in its "Multicast Source" field and the wildcard "C-*-BIDIR" in its "Multicast Group" field. See Section 2 of this document.
一种S-PMSI A-D路由，其NLRI在其“多播源”字段中包含通配符C-*，在其“多播组”字段中包含通配符“C-*-BIDIR”。见本文件第2节。
o (C-S,C-*) S-PMSI A-D route
o （C-S，C-*）S-PMSI A-D路线
An S-PMSI A-D route whose NLRI contains C-S in its "Multicast Source" field and the wildcard C-* in its "Multicast Group" field. See [RFC6625].
一种S-PMSI A-D路由，其NLRI在其“多播源”字段中包含C-S，在其“多播组”字段中包含通配符C-*。见[RFC6625]。
o Wildcard S-PMSI A-D route
o 通配符S-PMSI A-D路由
A (C-*,C-G) S-PMSI A-D route, a (C-*,C-*) S-PMSI A-D route, a (C-S,C-*) S-PMSI A-D route, or a (C-*,C-*-BIDIR) S-PMSI A-D route.
A（C-*，C-G）S-PMSI A-D路线，A（C-*，C-*）S-PMSI A-D路线，A（C-S，C-*）S-PMSI A-D路线，或A（C-*，C-*-BIDIR）S-PMSI A-D路线。
o PTA
o 精对苯二甲酸
PMSI Tunnel attribute, a BGP attribute that identifies a P-tunnel. See [RFC6514], Section 8.
PMSI隧道属性，标识P隧道的BGP属性。见[RFC6514]，第8节。
The terminology used for categorizing S-PMSI A-D routes will also be used for categorizing the S-PMSIs advertised by those routes. For example, the S-PMSI advertised by a (C-*,C-G) S-PMSI A-D route will be known as a "(C-*,C-G) S-PMSI".
用于对S-PMSI A-D路线进行分类的术语也将用于对这些路线宣传的S-PMSI进行分类。例如，由（C-*，C-G）S-PMSI a-D路线公布的S-PMSI将被称为“（C-*，C-G）S-PMSI”。
Familiarity with multicast concepts and terminology [RFC4601] is also presupposed.
还需要熟悉多播概念和术语[RFC4601]。
This specification uses the terms "match for transmission" and "match for reception" as they are defined in [RFC6625]. When it is clear from the context whether we are talking of transmission or reception, we will sometimes talk simply of a C-flow "matching" an I-PMSI or S-PMSI A-D route.
本规范使用[RFC6625]中定义的术语“传输匹配”和“接收匹配”。当我们从上下文中清楚地知道是在谈论传输还是接收时，我们有时会简单地谈论C流“匹配”I-PMSI或S-PMSI a-D路由。
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document, when and only when appearing in all caps, are to be interpreted as described in [RFC2119].
当且仅当出现在所有大写字母中时，本文件中的关键词“必须”、“不得”、“必需”、“应”、“不应”、“建议”、“可”和“可选”应按照[RFC2119]中的说明进行解释。
The base documents for MVPN ([RFC6513] and [RFC6514]) define a "PMSI Tunnel attribute" (PTA). This is a BGP Path attribute that may be attached to the BGP "I-PMSI A-D routes" and "S-PMSI A-D routes" that are defined in those documents. The base documents define the way in which the identifier of a bidirectional P-tunnel is to be encoded in the PTA. However, those documents do not contain the full set of specifications governing the use of bidirectional P-tunnels; rather, those documents declare the full set of specifications for using bidirectional P-tunnels to be outside their scope. Similarly, the
MVPN的基础文档（[RFC6513]和[RFC6514]）定义了“PMSI隧道属性”（PTA）。这是一个BGP路径属性，可附加到这些文档中定义的BGP“I-PMSI a-D路由”和“S-PMSI a-D路由”。基本文档定义了双向P隧道的标识符在PTA中的编码方式。然而，这些文件不包含管理双向P型隧道使用的全套规范；相反，这些文件声明使用双向P型隧道的全套规范超出其范围。同样地
use of bidirectional P-tunnels advertised in wildcard S-PMSI A-D routes is declared by [RFC6625] to be "outside the scope" of that document.
[RFC6625]宣布在通配符S-PMSI A-D路由中公布的双向P隧道的使用“超出该文件的范围”。
This document provides the specifications governing the use of bidirectional P-tunnels to provide MVPN support. This includes the procedures for assigning C-flows to specific bidirectional P-tunnels, for advertising the fact that a particular C-flow has been assigned to a particular bidirectional P-tunnel, and for determining the bidirectional P-tunnel on which a given C-flow may be expected.
本文件提供了双向P隧道用于提供MVPN支持的规范。这包括用于将C流分配给特定双向P-隧道、用于宣传特定C流已分配给特定双向P-隧道的事实以及用于确定可能期望给定C流的双向P-隧道的过程。
The C-flows carried on bidirectional P-tunnels may, themselves, be either unidirectional or bidirectional. Procedures are provided for both cases.
双向P型隧道上的C型流本身可以是单向的，也可以是双向的。这两种情况都提供了程序。
This document does not specify any new data encapsulations for bidirectional P-tunnels. Section 12 ("Encapsulations") of [RFC6513] applies unchanged.
本文档没有为双向P隧道指定任何新的数据封装。[RFC6513]第12节（“封装”）适用，未作修改。
With regard to the procedures for using bidirectional P-tunnels to instantiate PMSIs, if there is any conflict between the procedures specified in this document and the procedures of [RFC6513], [RFC6514], or [RFC6625], the procedures of this document take precedence.
关于使用双向P隧道实例化PMSI的程序，如果本文件中规定的程序与[RFC6513]、[RFC6514]或[RFC6625]中的程序存在任何冲突，则以本文件中的程序为准。
The use of bidirectional P-tunnels to support extranets [MVPN-XNET] is outside the scope of this document. The use of bidirectional P-tunnels as "segmented P-tunnels" (see Section 8 of [RFC6513] and various sections of [RFC6514]) is also outside the scope of this document.
使用双向P隧道来支持外部网[MVPN-XNET]不在本文档的范围之内。将双向P隧道用作“分段P隧道”（见[RFC6513]第8节和[RFC6514]各节）也不在本文件范围内。
This document supports two different technologies for creating and maintaining bidirectional P-tunnels:
本文档支持创建和维护双向P隧道的两种不同技术：
o Multipoint-to-multipoint Label Switched Paths (MP2MP LSPs) that are created through the use of the Label Distribution Protocol (LDP) Multipoint-to-Multipoint extensions [RFC6388].
o 通过使用标签分发协议（LDP）多点到多点扩展创建的多点到多点标签交换路径（MP2MP LSP）[RFC6388]。
o Multicast distribution trees that are created through the use of BIDIR-PIM [RFC5015].
o 通过使用BIDIR-PIM[RFC5015]创建的多播分发树。
Other bidirectional tunnel technologies are outside the scope of this document.
其他双向隧道技术不在本文件范围内。
Bidirectional P-tunnels can be used to instantiate I-PMSIs and/or S-PMSIs.
双向P隧道可用于实例化I-PMSI和/或S-PMSI。
An SP may decide to use bidirectional P-tunnels to instantiate certain I-PMSIs and/or S-PMSIs in order to provide its customers with C-BIDIR support, using the "Partitioned Set of PEs" technique discussed in Section 11.2 of [RFC6513] and Section 3.6 of [RFC6517]. This technique can be used whether the C-BIDIR flows are being carried on an I-PMSI or an S-PMSI.
SP可能决定使用双向P隧道来实例化某些I-PMSI和/或S-PMSI，以便使用[RFC6513]第11.2节和[RFC6517]第3.6节中讨论的“PEs分区集”技术为其客户提供C-BIDIR支持。无论C-BIDIR流是在I-PMSI还是S-PMSI上进行，都可以使用该技术。
Even if an SP does not need to provide C-BIDIR support, it may still decide to use bidirectional P-tunnels, in order to save state in the network's transit nodes. For example, if an MVPN has n PEs attached to sites with multicast sources, and there is an I-PMSI for that MVPN, instantiating the I-PMSI with unidirectional P-tunnels (i.e., with P2MP multicast distribution trees) requires n multicast distribution trees, each one rooted at a different PE. If the I-PMSI is instantiated by a bidirectional P-tunnel, a single multicast distribution tree can be used, assuming appropriate support by the provisioning system.
即使SP不需要提供C-BIDIR支持，它仍然可以决定使用双向P隧道，以保存网络传输节点中的状态。例如，如果一个MVPN有n个PE连接到具有多播源的站点，并且该MVPN有一个I-PMSI，则使用单向P隧道（即，具有P2MP多播分发树）实例化I-PMSI需要n个多播分发树，每个树都根于不同的PE。如果I-PMSI由双向P隧道实例化，则可以使用单个多播分发树，前提是供应系统提供适当的支持。
An SP may decide to use bidirectional P-tunnels for either or both of these reasons. Note that even if the reason for using bidirectional P-tunnels is to provide C-BIDIR support, the same P-tunnels can also be used to carry unidirectional C-flows, if that is the choice of the SP.
SP可能出于以下任一或两个原因决定使用双向P隧道。请注意，即使使用双向P隧道的原因是为了提供C-BIDIR支持，如果SP选择了单向C流，也可以使用相同的P隧道来承载单向C流。
These two reasons for using bidirectional P-tunnels may appear to be somewhat in conflict with each other, since (as will be seen in subsequent sections) the use of bidirectional P-tunnels for C-BIDIR support may require multiple bidirectional P-tunnels per VPN. Each such P-tunnel is associated with a particular "distinguished PE", and can only carry those C-BIDIR flows whose C-RPAs are reachable through its distinguished PE. However, on platforms that support MPLS upstream-assigned labels ([RFC5331]), PE Distinguisher Labels (Section 4 of [RFC6513] and Section 8 of [RFC6514]) can be used to aggregate multiple bidirectional P-tunnels onto a single outer bidirectional P-tunnel, thereby allowing one to provide C-BIDIR support with minimal state at the transit nodes.
使用双向P隧道的这两个原因似乎相互冲突，因为（将在后续章节中看到）使用双向P隧道支持C-BIDIR可能需要每个VPN有多个双向P隧道。每个这样的P隧道都与特定的“区分的PE”相关联，并且只能承载其C-rpa可通过其区分的PE到达的那些C-BIDIR流。然而，在支持MPLS上游分配标签（[RFC5331]）的平台上，PE识别标签（RFC6513]的第4节和[RFC6514]的第8节）可用于将多个双向P隧道聚合到单个外部双向P隧道上，从而允许在传输节点以最小状态提供C-BIDIR支持。
Since there are two fundamentally different reasons for using bidirectional P-tunnels, and since many deployed router platforms do not support upstream-assigned labels at the current time, this document specifies several different methods of using bidirectional P-tunnels to instantiate PMSIs. We refer to these as "PMSI Instantiation Methods". The method or methods deployed by any
由于使用双向P隧道有两个根本不同的原因，并且由于许多部署的路由器平台目前不支持上游分配的标签，因此本文档指定了几种使用双向P隧道实例化PMSI的不同方法。我们称之为“PMSI实例化方法”。由任何
particular SP will depend upon that SP's goals and engineering trade-offs and upon the set of platforms deployed by that SP.
特定SP将取决于该SP的目标、工程权衡以及该SP部署的平台集。
The rules for using bidirectional P-tunnels in I-PMSI or S-PMSI A-D routes are not exactly the same as the rules for using unidirectional P-tunnels, and the rules are also different for the different PMSI instantiation methods. Subsequent sections of this document specify the rules in detail.
在I-PMSI或S-PMSI A-D路由中使用双向P隧道的规则与使用单向P隧道的规则不完全相同，对于不同的PMSI实例化方法，规则也不同。本文件后续章节详细说明了规则。
If a VPN customer is making use of a particular ASM group address, the PEs of that VPN generally need to know the group-to-RP mappings that are used within the VPN. If a VPN customer is making use of BIDIR-PIM group addresses, the PEs need to know the group-to-RPA mappings that are used within the VPN. Commonly, the PEs obtain this knowledge either through provisioning or by participating in a dynamic "group-to-RP(A) mapping discovery protocol" that runs within the VPN. However, the way in which this knowledge is obtained is outside the scope of this document.
如果VPN客户正在使用特定的ASM组地址，则该VPN的PE通常需要知道VPN中使用的组到RP的映射。如果VPN客户使用BIDIR-PIM组地址，则PEs需要知道VPN中使用的组到RPA的映射。通常，PEs通过提供或参与VPN内运行的动态“组到RP（a）映射发现协议”来获取此知识。然而，获取这些知识的方式超出了本文件的范围。
The PEs also need to be able to forward traffic towards the C-RPs and/or C-RPAs and to determine whether the next-hop interface of the route to a particular C-RP(A) is a VRF interface or a PMSI. This is done by applying the procedures of [RFC6513], Section 5.1.
PEs还需要能够将业务转发到C-RP和/或C-RPA，并确定到特定C-RP（a）的路由的下一跳接口是VRF接口还是PMSI。这是通过应用[RFC6513]第5.1节中的程序完成的。
This document specifies three methods for using bidirectional P-tunnels to instantiate PMSIs: two partitioned methods (the Flat Partitioned Method and the Hierarchical Partitioned Method) and the Unpartitioned Method.
本文件规定了使用双向P隧道实例化PMSI的三种方法：两种分区方法（平面分区方法和分层分区方法）和未分区方法。
o Partitioned Methods
o 分区方法
In the Partitioned Methods, a particular PMSI is instantiated by a set of bidirectional P-tunnels. These P-tunnels may be aggregated (as inner P-tunnels) into a single outer bidirectional P-tunnel ("Hierarchical Partitioning"), or they may be unaggregated ("Flat Partitioning"). Any PE that joins one of these P-tunnels can transmit a packet on it, and the packet will be received by all the other PEs that have joined the P-tunnel. For each such P-tunnel (each inner P-tunnel, in the case of Hierarchical Partitioning) there is one PE that is its distinguished PE. When a PE receives a packet from a given P-tunnel, the PE can determine from the packet's encapsulation the P-tunnel it has arrived on, and it can thus infer the identity of the distinguished PE associated with the packet. This association plays an important
在分区方法中，特定的PMSI由一组双向P隧道实例化。这些P-隧道可以聚合（作为内部P-隧道）为单个外部双向P-隧道（“分层分区”），也可以是未聚合的（“平面分区”）。加入其中一个P隧道的任何PE都可以在其上传输数据包，并且该数据包将被加入P隧道的所有其他PE接收。对于每个这样的P-隧道（在分层分区的情况下，每个内部P-隧道）有一个PE是其区别的PE。当PE从给定的P-隧道接收到分组时，PE可以从分组的封装确定其到达的P-隧道，并且由此可以推断与分组相关联的可分辨PE的身份。这个协会起着重要的作用
role in the treatment of the packet, as specified later on in this document.
在数据包处理中的角色，如本文件后面所述。
The number of P-tunnels needed (the number of inner P-tunnels needed, if Hierarchical Partitioning is used) depends upon a number of factors that are described later in this document.
所需的P-隧道数量（如果使用分层分区，则所需的内部P-隧道数量）取决于本文档后面描述的许多因素。
The Hierarchical Partitioned Method requires the use of upstream-assigned MPLS labels (PE Distinguisher Labels) and requires the use of the PE Distinguisher Labels attribute in BGP. The Flat Partitioned Method requires neither of these.
分层分区方法要求使用上游分配的MPLS标签（PE区分器标签），并要求在BGP中使用PE区分器标签属性。平面分区方法不需要这两种方法。
The Partitioned Method (either Flat or Hierarchical) is a prerequisite for implementing the "Partitioned Sets of PEs" technique of supporting C-BIDIR, as discussed in [RFC6513], Section 11.2. The Partitioned Method (either Flat or Hierarchical) is also a prerequisite for applying the "Discarding Packets from Wrong PE" technique, discussed in [RFC6513], Section 9.1.1, to a PMSI that is instantiated by a bidirectional P-tunnel.
如[RFC6513]第11.2节所述，分区方法（平面或层次）是实现支持C-BIDIR的“PEs分区集”技术的先决条件。分区方法（平面或分层）也是将[RFC6513]第9.1.1节中讨论的“从错误PE丢弃数据包”技术应用于由双向P隧道实例化的PMSI的先决条件。
The Flat Partitioned Method is a prerequisite for implementing the "Partial Mesh of MP2MP P-Tunnels" technique for carrying customer bidirectional (C-BIDIR) traffic, as discussed in [RFC6513], Section 11.2.3.
如[RFC6513]第11.2.3节所述，平面分区方法是实施“MP2MP P隧道部分网格”技术以承载客户双向（C-BIDIR）流量的先决条件。
The Hierarchical Partitioned Method is a prerequisite for implementing the "Using PE Distinguisher Labels" technique of carrying customer bidirectional (C-BIDIR) traffic, as discussed in [RFC6513], Section 11.2.2.
如[RFC6513]第11.2.2节所述，分层分区方法是实现承载客户双向（C-BIDIR）流量的“使用PE识别器标签”技术的先决条件。
Note that a particular deployment may choose to use the Partitioned Methods for carrying the C-BIDIR traffic on bidirectional P-tunnels, while carrying other traffic either on unidirectional P-tunnels or on bidirectional P-tunnels using the Unpartitioned Method. Routers in a given deployment must be provisioned to know which PMSI instantiation method to use for which PMSIs.
注意，特定部署可以选择使用分区方法在双向P隧道上承载C-BIDIR业务，同时在单向P隧道或使用未分区方法的双向P隧道上承载其他业务。必须对给定部署中的路由器进行配置，以了解将哪个PMSI实例化方法用于哪个PMSI。
There may be ways of implementing the Partitioned Methods with PMSIs that are instantiated by unidirectional P-tunnels. (See, e.g., [MVPN-BIDIR-IR].) However, that is outside the scope of the current document.
可能存在通过单向P隧道实例化的PMSI实现分区方法的方法。（例如，参见[MVPN-BIDIR-IR]）但是，这超出了当前文档的范围。
o Unpartitioned Method
o 非分割法
In the Unpartitioned Method, a particular PMSI can be instantiated by a single bidirectional P-tunnel. Any PE that joins the tunnel can transmit a packet on it, and the packet will be received by
在Unpartitioned方法中，特定的PMSI可以通过单个双向P隧道实例化。加入隧道的任何PE都可以在其上传输数据包，并且数据包将由用户接收
all the other PEs that have joined the tunnel. The receiving PEs can determine the tunnel on which the packet was transmitted, but they cannot determine which PE transmitted the packet, nor can they associate the packet with any particular distinguished PE.
所有其他加入隧道的PEs。接收PEs可以确定在其上发送分组的隧道，但是它们不能确定哪个PE发送分组，也不能将分组与任何特定的可分辨PE相关联。
When the Unpartitioned Method is used, this document does not mandate that only one bidirectional P-tunnel be used to instantiate each PMSI. It allows for the case where more than one P-tunnel is used. In this case, the transmitting PEs will have a choice of which such P-tunnel to use when transmitting, and the receiving PEs must be prepared to receive from any of those P-tunnels. The use of multiple P-tunnels in this case provides additional robustness, but it does not provide additional functionality.
当使用未分区方法时，本文件不要求仅使用一个双向P隧道来实例化每个PMSI。它允许使用多个P型隧道的情况。在这种情况下，发射PEs可以选择在发射时使用哪种P隧道，并且接收PEs必须准备好从这些P隧道中的任何一个接收。在这种情况下，多个P通道的使用提供了额外的健壮性，但不提供额外的功能。
If bidirectional P-tunnels are being used to instantiate the PMSIs of a given MVPN, one of these methods must be chosen for that MVPN. All the PEs of that MVPN must be provisioned to know the method that is being used for that MVPN.
如果双向P隧道用于实例化给定MVPN的PMSI，则必须为该MVPN选择其中一种方法。必须设置该MVPN的所有PE，以了解用于该MVPN的方法。
I-PMSIs may be instantiated by bidirectional P-tunnels using either the Partitioned (either Flat or Hierarchical) Methods or the Unpartitioned Method. The method used for a given MVPN is determined by provisioning. It SHOULD be possible to provision this on a per-MVPN basis, but all the VRFs of a single MVPN MUST be provisioned to use the same method for the given MVPN's I-PMSI.
I-PMSI可通过使用分区（平面或层次）方法或非分区方法的双向P隧道实例化。用于给定MVPN的方法由配置决定。应该可以在每个MVPN的基础上提供此功能，但是必须提供单个MVPN的所有VRF，以便对给定MVPN的I-PMSI使用相同的方法。
If a bidirectional P-tunnel is used to instantiate an S-PMSI (including the case of a (C-*,C-*) S-PMSI), either the Partitioned Methods (either Flat or Hierarchical) or the Unpartitioned Method may be used. The method used by a given VRF is determined by provisioning. It is desirable to be able to provision this on a per-MVPN basis. All the VRFs of a single MVPN MUST be provisioned to use the same method for those of their S-PMSIs that are instantiated by bidirectional P-tunnels.
如果双向P隧道用于实例化S-PMSI（包括（C-*，C-*）S-PMSI的情况），则可以使用分区方法（平面或层次）或未分区方法。给定VRF使用的方法由配置决定。希望能够在每个MVPN的基础上提供这一点。单个MVPN的所有VRF必须配置为对其S-PMSI（由双向P隧道实例化）使用相同的方法。
If one of the Partitioned Methods is used, all the VRFs of a single MVPN MUST be provisioned to use the same variant of the Partitioned Methods, i.e., either they must all use the Flat Partitioned Method or they must all use the Hierarchical Partitioned Method.
如果使用其中一种分区方法，则必须将单个MVPN的所有VRF配置为使用分区方法的相同变体，即，它们必须全部使用平面分区方法或全部使用分层分区方法。
It is valid to use the Unpartitioned Method to instantiate the I-PMSIs, while using one of the Partitioned Methods to instantiate the S-PMSIs.
使用未分区方法实例化I-PMSI是有效的，而使用分区方法之一实例化S-PMSI是有效的。
It is valid to instantiate some S-PMSIs by unidirectional P-tunnels and others by bidirectional P-tunnels.
用单向P-隧道实例化一些S-PMSIs是有效的，而用双向P-隧道实例化另一些S-PMSIs是有效的。
The procedures for the use of bidirectional P-tunnels, specified in subsequent sections of this document, depend on both the tunnel technology and the PMSI instantiation method. Note that this document does not specify procedures for every possible combination of tunnel technology and PMSI instantiation method.
本文件后续章节中规定的双向P隧道使用程序取决于隧道技术和PMSI实例化方法。请注意，本文件并未规定隧道技术和PMSI实例化方法的每种可能组合的程序。
[RFC6514] specifies the method of encoding C-multicast source and group addresses into the NLRI of certain BGP routes. [RFC6625] extends that specification by allowing the source and/or group address to be replaced by a wildcard. When an MVPN customer is using BIDIR-PIM, it is useful to be able to advertise an S-PMSI A-D route whose semantics are "by default, all BIDIR-PIM C-multicast traffic (within a given VPN) that has not been bound to any other P-tunnel is bound to the bidirectional P-tunnel identified by the PTA of this route". This can be especially useful if one is using a bidirectional P-tunnel to carry the C-BIDIR flows while using unidirectional P-tunnels to carry other C-flows. To do this, it is necessary to have a way to encode a (C-*,C-*) wildcard that is restricted to BIDIR-PIM C-groups.
[RFC6514]指定将C多播源地址和组地址编码到某些BGP路由的NLRI中的方法。[RFC6625]通过允许用通配符替换源和/或组地址来扩展该规范。当MVPN客户使用BIDIR-PIM时，能够公布语义为“默认情况下，所有未绑定到任何其他P隧道的BIDIR-PIM C多播流量（在给定VPN内）都绑定到该路由的PTA标识的双向P隧道”的S-PMSI A-D路由是有用的。如果使用双向P隧道来承载C-BIDIR流，而使用单向P隧道来承载其他C-BIDIR流，则这可能特别有用。要做到这一点，必须有一种方法来编码（C-*，C-*）通配符，该通配符仅限于BIDIR-PIM C-组。
Therefore, we define a special value of the group wildcard, whose meaning is "all BIDIR-PIM groups". The "BIDIR-PIM groups wildcard" is encoded as a group field whose length is 8 bits and whose value is zero. That is, the "multicast group length" field contains the value 0x08, and the "multicast group" field is a single octet containing the value 0x00. (This encoding is distinct from the group wildcard encoding defined in [RFC6625]). We will use the notation (C-*,C-*-BIDIR) to refer to the "all BIDIR-PIM groups" wildcard.
因此，我们定义了组通配符的一个特殊值，其含义是“所有BIDIR-PIM组”。“BIDIR-PIM组通配符”被编码为长度为8位且值为零的组字段。也就是说，“多播组长度”字段包含值0x08，“多播组”字段是包含值0x00的单个八位字节。（此编码不同于[RFC6625]中定义的组通配符编码）。我们将使用符号（C-*，C-*-BIDIR）来表示“所有BIDIR-PIM组”通配符。
A bidirectional P-tunnel may be advertised in the PTA of an Intra-AS I-PMSI A-D route or in the PTA of an S-PMSI A-D route. The advertisement of a bidirectional P-tunnel in the PTA of an Inter-AS I-PMSI A-D route is outside the scope of this document.
双向P隧道可以在AS-I-PMSI A-D路由的PTA或S-PMSI A-D路由的PTA中进行广告。Inter-AS I-PMSI a-D路线PTA中的双向P隧道广告不在本文件范围内。
This section discusses the procedures that are specific to a given tunneling technology (BIDIR-PIM or the MP2MP procedures of mLDP (Multipoint LDP)) but that are independent of the method (Unpartitioned, Flat Partitioned, or Hierarchical Partitioned) used to instantiate a PMSI.
本节讨论特定于给定隧道技术（BIDIR-PIM或mLDP（多点LDP）的MP2MP过程）但独立于用于实例化PMSI的方法（未分区、平分区或分层分区）的过程。
Each BIDIR-PIM P-tunnel is identified by a unique P-group address ([RFC6513], Section 3.1). (The P-group address is called a "P-Multicast Group" in [RFC6514]). Section 5 of [RFC6514] specifies the way to identify a particular BIDIR-PIM P-tunnel in the PTA of an I-PMSI or S-PMSI A-D route.
每个BIDIR-PIM P隧道由唯一的P组地址标识（[RFC6513]，第3.1节）。（P组地址在[RFC6514]中称为“P多播组”）。[RFC6514]第5节规定了识别I-PMSI或S-PMSI a-D路线PTA中特定BIDIR-PIM P-隧道的方法。
Ordinary BIDIR-PIM procedures are used to set up the BIDIR-PIM P-tunnels. A BIDIR-PIM P-group address is always associated with a unique Rendezvous Point Address (RPA) in the SP's address space. We will refer to this as the "P-RPA". Every PE needing to join a particular BIDIR-PIM P-tunnel must be able to determine the P-RPA that corresponds to the P-tunnel's P-group address. To construct the P-tunnel, PIM Join/Prune messages are sent along the path from the PE to the P-RPA. Any P routers along that path must also be able to determine the P-RPA, so that they too can send PIM Join/Prune messages towards it. The method of mapping a P-group address to an RPA may be static configuration, or some automated means of RPA discovery that is outside the scope of this specification.
普通BIDIR-PIM程序用于设置BIDIR-PIM P-隧道。BIDIR-PIM P组地址始终与SP地址空间中的唯一集合点地址（RPA）关联。我们将其称为“P-RPA”。每个需要加入特定BIDIR-PIM P-隧道的PE必须能够确定对应于P-隧道的P-组地址的P-RPA。为了构建P-tunnel，将沿着从PE到P-RPA的路径发送PIM Join/Prune消息。沿着该路径的任何P路由器也必须能够确定P-RPA，以便它们也可以向其发送PIM加入/删减消息。将P组地址映射到RPA的方法可以是静态配置，也可以是本规范范围之外的一些RPA自动发现方法。
If a BIDIR-PIM P-tunnel is used to instantiate an I-PMSI or an S-PMSI, it is RECOMMENDED that the path from each PE in the tunnel to the RPA consist entirely of point-to-point links. On a point-to-point link, there is no ambiguity in determining which router is upstream towards a particular RPA, so the BIDIR-PIM "Designated Forwarder Election" is very quick and simple. Use of a BIDIR-PIM P-tunnel containing multiaccess links is possible, but considerably more complex.
如果BIDIR-PIM P隧道用于实例化I-PMSI或S-PMSI，建议隧道中每个PE到RPA的路径完全由点对点链路组成。在点到点链路上，确定哪个路由器向特定RPA上游是没有歧义的，因此BIDIR-PIM“指定转发器选择”非常快速和简单。使用包含多址链路的BIDIR-PIM P隧道是可能的，但要复杂得多。
The use of BIDIR-PIM P-tunnels to support the Hierarchical Partitioned Method is outside the scope of this document.
使用BIDIR-PIM P-tunnels支持分层分区方法不在本文件范围内。
When the PTA of an Intra-AS I-PMSI A-D route or an S-PMSI A-D route identifies a BIDIR-PIM tunnel, the originator of the route SHOULD NOT include a PE Distinguisher Labels attribute. If it does, that attribute MUST be ignored. When we say the attribute is "ignored", we do not mean that its normal BGP processing is not done, but that the attribute has no effect on the data plane. However, it MUST be treated by BGP as if it were an unsupported optional transitive attribute. (PE Distinguisher Labels are used for the Hierarchical Partitioning Method, but this document does not provide support for the Hierarchical Partitioning Method with BIDIR-PIM P-tunnels.)
当内部AS I-PMSI A-D路由或S-PMSI A-D路由的PTA识别BIDIR-PIM隧道时，该路由的发起人不应包括PE识别标签属性。如果是，则必须忽略该属性。当我们说属性被“忽略”时，我们并不是说它的正常BGP处理没有完成，而是说该属性对数据平面没有影响。但是，BGP必须将其视为不受支持的可选传递属性。（PE识别器标签用于分层分区方法，但本文档不支持BIDIR-PIM P-tunnels的分层分区方法。）
Each MP2MP LSP is identified by a unique "MP2MP FEC (Forwarding Equivalence Class) element" [RFC6388]. The FEC element contains the IP address of the root node, followed by an opaque value that identifies the MP2MP LSP uniquely in the context of the root node's IP address. This opaque value may be configured or autogenerated; there is no need for different root nodes to use the same opaque value for a given MVPN.
每个MP2MP LSP由唯一的“MP2MP FEC（转发等价类）元素”[RFC6388]标识。FEC元素包含根节点的IP地址，后跟一个不透明值，该值在根节点的IP地址上下文中唯一标识MP2MP LSP。此不透明值可以配置或自动生成；对于给定的MVPN，不同的根节点不需要使用相同的不透明值。
The mLDP specification supports the use of several different ways of constructing the tunnel identifiers. The current specification does not place any restriction on the type or types of tunnel identifier that is used in a given deployment. A given implementation is not expected to be able to advertise (in the PTAs of I-PMSI or S-PMSI A-D routes) tunnel identifiers of every possible type. However, an implementation SHOULD be able to accept and properly process a PTA that uses any legal type of tunnel identifier.
mLDP规范支持使用几种不同的方法构造隧道标识符。当前规范对给定部署中使用的隧道标识符的类型没有任何限制。预期给定的实现不能够公布（在I-PMSI或S-PMSI A-D路由的PTA中）每种可能类型的隧道标识符。但是，实现应该能够接受并正确处理使用任何合法类型的隧道标识符的PTA。
Section 5 of [RFC6514] specifies the way to identify a particular MP2MP P-tunnel in the PTA of an I-PMSI or S-PMSI A-D route.
[RFC6514]第5节规定了识别I-PMSI或S-PMSI a-D路线PTA中特定MP2MP P隧道的方法。
Ordinary mLDP procedures for MP2MP LSPs are used to set up the MP2MP LSP.
MP2MP LSP的普通mLDP程序用于设置MP2MP LSP。
When either the Flat Partitioned Method or the Hierarchical Partitioned Method is used to implement the "Partitioned Sets of PEs" method of supporting C-BIDIR, as discussed in Section 11.2 of [RFC6513] and Section 3.6 of [RFC6517], a C-BIDIR flow MUST be carried only on an I-PMSI or on a (C-*,C-G-BIDIR), (C-*,C-*-BIDIR), or (C-*,C-*) S-PMSI. A PE MUST NOT originate any (C-S,C-G-BIDIR) S-PMSI A-D routes. (Though it may, of course, originate (C-S,C-G) S-PMSI A-D routes for C-G's that are not C-BIDIR groups.) Packets of a C-BIDIR flow MUST NOT be carried on a (C-S,C-*) S-PMSI.
如[RFC6513]第11.2节和[RFC6517]第3.6节所述，当使用平面分区方法或分层分区方法来实现支持C-BIDIR的“PEs分区集”方法时，C-BIDIR流必须仅在I-PMSI或（C-*，C-G-BIDIR），（C-*，C-*-BIDIR）或（C-*，C-*）S-PMSI上进行。PE不得发起任何（C-S、C-G-BIDIR）S-PMSI A-D路由。（当然，它可能为非C-BIDIR组的C-G发起（C-S，C-G）S-PMSI A-D路由。）C-BIDIR流的数据包不得携带在（C-S，C-*）S-PMSI上。
Sections 3.2.1 and 3.2.2 specify additional details of the two Partitioned Methods.
第3.2.1节和第3.2.2节规定了两种分区方法的附加细节。
The procedures of this section and its subsections apply when (and only when) the Flat Partitioned Method is used. This method is introduced in [RFC6513], Section 11.2.3, where it is called "Partial Mesh of MP2MP P-Tunnels". This method can be used with MP2MP LSPs or with BIDIR-PIM P-tunnels.
当（且仅当）使用平面分区方法时，本节及其小节的程序适用。[RFC6513]第11.2.3节介绍了该方法，其中称为“MP2MP P隧道的部分网格”。此方法可用于MP2MP LSP或BIDIR-PIM P隧道。
When a PE originates an I-PMSI or S-PMSI A-D route whose PTA specifies a bidirectional P-tunnel, the PE MUST be the root node of the specified P-tunnel.
当PE发起其PTA指定双向P隧道的I-PMSI或S-PMSI a-D路由时，PE必须是指定P隧道的根节点。
If BIDIR-PIM P-tunnels are used, each advertised P-tunnel MUST have a distinct P-group address. The PE advertising the tunnel will be considered to be the root node of the tunnel. Note that this creates a unique mapping from P-group address to root node. The assignment of P-group addresses to MVPNs is by provisioning.
如果使用BIDIR-PIM P-隧道，则每个公布的P-隧道必须具有不同的P-组地址。隧道的PE将被视为隧道的根节点。请注意，这将创建从P组地址到根节点的唯一映射。P组地址分配给MVPN是通过配置实现的。
If MP2MP LSPs are used, each P-tunnel MUST have a distinct MP2MP FEC (i.e., a distinct combination of root node and opaque value). The PE advertising the tunnel MUST be the same PE identified in the root node field of the MP2MP FEC that is encoded in the PTA.
如果使用MP2MP LSP，则每个P隧道必须具有不同的MP2MP FEC（即根节点和不透明值的不同组合）。播发隧道的PE必须是在PTA中编码的MP2MP FEC的根节点字段中标识的相同PE。
It follows that two different PEs may not advertise the same bidirectional P-tunnel. Any PE that receives a packet from the P-tunnel can infer the identity of the P-tunnel from the packet's encapsulation. Once the identity of the P-tunnel is known, the root node of the P-tunnel is also known. The root node of the P-tunnel on which the packet arrived is treated as the distinguished PE for that packet.
因此，两个不同的PE可能不会宣传相同的双向P隧道。从P隧道接收数据包的任何PE都可以从数据包的封装推断P隧道的身份。一旦P隧道的标识已知，P隧道的根节点也已知。数据包到达的P隧道的根节点被视为该数据包的可分辨PE。
The Flat Partitioned Method does not use upstream-assigned labels in the data plane, and hence does not use the BGP PE Distinguisher Labels attribute. When this method is used, I-PMSI and/or S-PMSI A-D routes SHOULD NOT contain a PE Distinguisher Labels attribute; if such an attribute is present in a received I-PMSI or S-PMSI A-D route, it MUST be ignored. (When we say the attribute is "ignored", we do not mean that its normal BGP processing is not done, but that the attribute has no effect on the data plane. It MUST, however, be treated by BGP as if it were an unsupported optional transitive attribute.)
平面分区方法在数据平面中不使用上游指定的标签，因此不使用BGP PE Discriminator labels属性。使用此方法时，I-PMSI和/或S-PMSI A-D路由不应包含PE Discriminator Labels属性；如果接收到的I-PMSI或S-PMSI a-D路由中存在此类属性，则必须忽略该属性。（当我们说属性被“忽略”时，并不是说它的正常BGP处理没有完成，而是说该属性对数据平面没有影响。但是，BGP必须将其视为不受支持的可选传递属性。）
When the Flat Partitioned Method is used to instantiate the I-PMSIs of a given MVPN, every PE in that MVPN that originates an Intra-AS I-PMSI A-D route MUST include a PTA that specifies a bidirectional P-tunnel. If the intention is to carry C-BIDIR traffic on the I-PMSI, a PE MUST originate an Intra-AS I-PMSI A-D route if one of its VRF interfaces is the next-hop interface on its best path to the C-RPA of any bidirectional C-group of the MVPN.
当使用平面分区方法实例化给定MVPN的I-PMSI时，该MVPN中发起内部AS I-PMSI a-D路由的每个PE必须包括指定双向P隧道的PTA。如果意图是在I-PMSI上承载C-BIDIR业务，则如果PE的一个VRF接口是其到MVPN的任何双向C组的C-RPA的最佳路径上的下一跳接口，则PE必须发起内部AS I-PMSI a-D路由。
When the Flat Partitioned Method is used to instantiate a (C-*,C-*) S-PMSI, a (C-*,C-*-BIDIR) S-PMSI, or a (C-*,C-G-BIDIR) S-PMSI, a PE that originates the corresponding S-PMSI A-D route MUST include in that route a PTA specifying a bidirectional P-tunnel. Per the procedures of [RFC6513] and [RFC6514], a PE will originate such an S-PMSI A-D route only if one of the PE's VRF interfaces is the next-
当使用扁平分区方法实例化（C-*，C-*）S-PMSI，（C-*，C-*-BIDIR）S-PMSI或（C-*，C-G-BIDIR）S-PMSI时，发起相应S-PMSI a-D路由的PE必须在该路由中包含指定双向P隧道的PTA。根据[RFC6513]和[RFC6514]的程序，只有当PE的一个VRF接口是下一个接口时，PE才会发起这样的S-PMSI a-D路由-
hop interface of the PE's best path to the C-RPA of a C-BIDIR group that is to be carried on the specified S-PMSI.
PE到C-BIDIR组的C-RPA的最佳路径的跃点接口，该C-RPA将在指定的s-PMSI上进行。
PMSIs that are instantiated via the Flat Partitioned Method may carry customer bidirectional traffic AND customer unidirectional traffic. The rules of Sections 3.2.1.1 and 3.2.1.2 determine when a given customer multicast packet is a match for transmission to a given PMSI. However, if the "Partitioned Set of PEs" method of supporting C-BIDIR traffic is being used for a given MVPN, the PEs must be provisioned in such a way that packets from a C-BIDIR flow of that MVPN never match any PMSI that is not instantiated by a bidirectional P-tunnel. (For example, if the given MVPN's (C-*,C-*) S-PMSI were not instantiated by a bidirectional P-tunnel, one could meet this requirement by carrying all C-BIDIR traffic of that MVPN on a (C-*,C-*-BIDIR) S-PMSI.)
通过扁平分区方法实例化的PMSI可承载客户双向通信量和客户单向通信量。第3.2.1.1节和第3.2.1.2节的规则确定给定的客户多播数据包何时与传输到给定的PMSI相匹配。然而，如果支持C-BIDIR业务的“PEs的分区集”方法正用于给定MVPN，则必须以这样的方式来供应PEs，即来自该MVPN的C-BIDIR流的分组永远不会匹配未由双向P隧道实例化的任何PMSI。（例如，如果给定的MVPN（C-*，C-*）s-PMSI没有被双向P隧道实例化，则可以通过在（C-*，C-*-BIDIR）s-PMSI上承载该MVPN的所有C-BIDIR流量来满足此要求。）
When a PE receives a customer multicast data packet from a bidirectional P-tunnel, it associates that packet with a distinguished PE. The distinguished PE for a given packet is the root node of the tunnel from which the packet is received. The rules of Sections 3.2.1.1 and 3.2.1.2 ensure that:
当PE从双向P隧道接收到客户多播数据包时，它将该数据包与可分辨PE相关联。给定数据包的可分辨PE是从中接收数据包的隧道的根节点。第3.2.1.1节和第3.2.1.2节的规则确保：
o If the received packet is part of a unidirectional C-flow, its distinguished PE is the PE that transmitted the packet onto the P-tunnel.
o 如果接收到的分组是单向C流的一部分，则其可分辨的PE是将分组传输到P隧道的PE。
o If the received packet is part of a bidirectional C-flow, its distinguished PE is not necessarily the PE that transmitted it, but rather the transmitter's upstream PE [RFC6513] for the C-RPA of the bidirectional C-group.
o 如果接收到的分组是双向C流的一部分，则其可分辨PE不一定是发送它的PE，而是用于双向C组的C-RPA的发送器的上游PE[RFC6513]。
The rules of Sections 3.2.1.3 and 3.2.1.4 allow the receiving PEs to determine the expected distinguished PE for each C-flow, and ensure that a packet will be discarded if its distinguished PE is not the expected distinguished PE for the C-flow to which the packet belongs. This prevents duplication of data for both bidirectional and unidirectional C-flows.
第3.2.1.3节和第3.2.1.4节的规则允许接收PE确定每个C流的预期可分辨PE，并确保如果数据包的可分辨PE不是该数据包所属C流的预期可分辨PE，则该数据包将被丢弃。这可以防止双向和单向C流的数据重复。
Suppose a given PE, say PE1, needs to transmit multicast data packets of a particular C-flow. Section 3.1 of [RFC6625] gives a four-step algorithm for determining the S-PMSI A-D route, if any, that matches that C-flow for transmission.
假设一个给定的PE，比如PE1，需要传输特定C流的多播数据包。[RFC6625]第3.1节给出了确定S-PMSI a-D路由（如有）的四步算法，该路由与传输的C-flow相匹配。
If the C-flow is not a BIDIR-PIM C-flow, those rules apply unchanged; the remainder of this section applies only to C-BIDIR flows. If a C-BIDIR flow has group address C-G-BIDIR, the rules applied by PE1 are given below:
如果C-flow不是BIDIR-PIM C-flow，则这些规则不变；本节其余部分仅适用于C-BIDIR流。如果C-BIDIR流具有组地址C-G-BIDIR，则PE1应用的规则如下所示：
o If the C-RPA for C-G-BIDIR is a C-address of PE1, or if PE1's route to the C-RPA is via a VRF interface, then:
o 如果C-G-BIDIR的C-RPA是PE1的C地址，或者如果PE1到C-RPA的路由是通过VRF接口，则：
* If there is a (C-*,C-G-BIDIR) S-PMSI A-D route currently originated by PE1, then the C-flow matches that route.
* 如果PE1当前发起了（C-*，C-G-BIDIR）S-PMSI a-D路由，则C-flow与该路由匹配。
* Otherwise, if there is a (C-*,C-*-BIDIR) S-PMSI A-D route currently originated by PE1, then the C-flow matches that route.
* 否则，如果PE1当前发起了（C-*，C-*-BIDIR）S-PMSI a-D路由，则C-flow与该路由匹配。
* Otherwise, if there is a (C-*,C-*) S-PMSI A-D route currently originated by PE1, then the C-flow matches that route.
* 否则，如果PE1当前发起了（C-*，C-*）S-PMSI a-D路由，则C-flow与该路由匹配。
o If PE1 determines the upstream PE for C-G-BIDIR's C-RPA to be some other PE, say PE2, then:
o 如果PE1确定C-G-BIDIR的C-RPA的上游PE为其他PE，如PE2，则：
* If there is an installed (C-*,C-G-BIDIR) S-PMSI A-D route originated by PE2, then the C-flow matches that route.
* 如果存在由PE2发起的已安装（C-*，C-G-BIDIR）S-PMSI A-D路由，则C-flow与该路由匹配。
* Otherwise, if there is an installed (C-*,C-*-BIDIR) S-PMSI A-D route originated by PE2, then the C-flow matches that route.
* 否则，如果存在由PE2发起的已安装（C-*，C-*-BIDIR）S-PMSI A-D路由，则C-flow与该路由匹配。
* Otherwise, if there is an installed (C-*,C-*) S-PMSI A-D route originated by PE2, then the C-flow matches that route.
* 否则，如果存在由PE2发起的已安装（C-*，C-*）S-PMSI A-D路由，则C-flow与该路由匹配。
If there is an S-PMSI A-D route that matches a given C-flow, and if PE1 needs to transmit packets of that C-flow or other PEs, then it MUST transmit those packets on the bidirectional P-tunnel identified in the PTA of the matching S-PMSI A-D route.
如果存在与给定C-flow匹配的S-PMSI A-D路由，并且如果PE1需要传输该C-flow或其他pe的分组，则其必须在匹配S-PMSI A-D路由的PTA中标识的双向P隧道上传输这些分组。
Suppose a given PE, say PE1, needs to transmit packets of a given C-flow (of a given MVPN) to other PEs, but according to the conditions of Section 3.2.1.1 and/or Section 3.1 of [RFC6625], that C-flow does not match any S-PMSI A-D route. Then, the packets of the C-flow need to be transmitted on the MVPN's I-PMSI.
假设一个给定的PE，例如PE1，需要将给定C流（给定MVPN）的数据包传输到其他PE，但根据[RFC6625]第3.2.1.1节和/或第3.1节的条件，C流与任何S-PMSI a-D路由都不匹配。然后，C流的分组需要在MVPN的I-PMSI上传输。
If the C-flow is not a BIDIR-PIM C-flow, the P-tunnel on which the C-flow MUST be transmitted is the one identified in the PTA of the Intra-AS I-PMSI A-D route originated by PE1 for the given MVPN.
如果C-flow不是BIDIR-PIM C-flow，则必须在其上传输C-flow的P-tunnel是由PE1针对给定MVPN发起的内部AS I-PMSI a-D路由的PTA中标识的P-tunnel。
If the C-flow is a BIDIR-PIM C-flow with group address C-G-BIDIR, the rules applied by PE1 are:
如果C-flow是组地址为C-G-BIDIR的BIDIR-PIM C-flow，则PE1应用的规则为：
o Suppose that the C-RPA for C-G-BIDIR is a C-address of PE1, or that PE1's route to the C-RPA is via a VRF interface. Then, if there is an I-PMSI A-D route currently originated by PE1, the C-flow MUST be transmitted on the P-tunnel identified in the PTA of that I-PMSI A-D route.
o 假设C-G-BIDIR的C-RPA是PE1的C地址，或者PE1到C-RPA的路由是通过VRF接口。然后，如果存在当前由PE1发起的I-PMSI A-D路由，则必须在该I-PMSI A-D路由的PTA中标识的P隧道上传输C流。
o If PE1 determines the upstream PE for C-G-BIDIR's C-RPA to be some other PE, say PE2, then if there is an installed I-PMSI A-D route originated by PE2, the C-flow MUST be transmitted on the P-tunnel identified in the PTA of that route.
o 如果PE1确定C-G-BIDIR的C-RPA的上游PE为其他PE，如PE2，则如果存在由PE2发起的已安装I-PMSI A-D路由，则必须在该路由的PTA中标识的P隧道上传输C流。
If there is no I-PMSI A-D route meeting the above conditions, the C-flow MUST NOT be transmitted.
如果没有满足上述条件的I-PMSI A-D路由，则不得传输C-flow。
Suppose a given PE, say PE1, needs to receive multicast data packets of a particular C-flow. Section 3.2 of [RFC6625] specifies procedures for determining the S-PMSI A-D route, if any, that matches that C-flow for reception. Those rules apply unchanged for C-flows that are not BIDIR-PIM C-flows. The remainder of this section applies only to C-BIDIR flows.
假设给定的PE（比如PE1）需要接收特定C流的多播数据包。[RFC6625]第3.2节规定了确定S-PMSI A-D路线（如有）的程序，该路线与接收的C-flow相匹配。这些规则适用于非BIDIR-PIM C-flows的C-flows，但不适用于BIDIR-PIM C-flows。本节其余部分仅适用于C-BIDIR流。
The rules of [RFC6625], Section 3.2.1, are not applicable to C-BIDIR flows. The rules of [RFC6625], Section 3.2.2, are replaced by the following rules.
[RFC6625]第3.2.1节的规则不适用于C-BIDIR流。[RFC6625]第3.2.2节的规则替换为以下规则。
Suppose PE1 needs to receive (C-*,C-G-BIDIR) traffic. Suppose also that PE1 has determined that PE2 is the upstream PE [RFC6513] for the C-RPA of C-G-BIDIR. Then:
假设PE1需要接收（C-*，C-G-BIDIR）流量。还假设PE1已确定PE2是C-G-BIDIR的C-RPA的上游PE[RFC6513]。然后：
o If PE1 is not the same as PE2, and PE1 has an installed (C-*,C-G-BIDIR) S-PMSI A-D route originated by PE2, then (C-*,C-G-BIDIR) matches this route.
o 如果PE1与PE2不同，且PE1已安装由PE2发起的（C-*，C-G-BIDIR）S-PMSI A-D路由，则（C-*，C-G-BIDIR）与该路由匹配。
o Otherwise, if PE1 is the same as PE2, and PE1 has currently originated a (C-*,C-G-BIDIR) S-PMSI A-D route, then (C-*,C-G-BIDIR) matches this route.
o 否则，如果PE1与PE2相同，并且PE1当前已发起（C-*，C-G-BIDIR）S-PMSI a-D路由，则（C-*，C-G-BIDIR）匹配此路由。
o Otherwise, if PE1 is not the same as PE2, and PE1 has an installed (C-*,C-*-BIDIR) S-PMSI A-D route originated by PE2, then (C-*,C-G-BIDIR) matches this route.
o 否则，如果PE1与PE2不同，并且PE1安装了由PE2发起的（C-*，C-*-BIDIR）S-PMSI A-D路由，则（C-*，C-G-BIDIR）与该路由匹配。
o Otherwise, if PE1 is the same as PE2, and PE1 has currently originated a (C-*,C-*-BIDIR) S-PMSI A-D route, then (C-*,C-G-BIDIR) matches this route.
o 否则，如果PE1与PE2相同，并且PE1当前已发起（C-*，C-*-BIDIR）S-PMSI a-D路由，则（C-*，C-G-BIDIR）匹配此路由。
o Otherwise, if PE1 is not the same as PE2, and PE1 has an installed (C-*,C-*) S-PMSI A-D route originated by PE2, then (C-*,C-G-BIDIR) matches this route.
o 否则，如果PE1与PE2不同，并且PE1安装了由PE2发起的（C-*，C-*）S-PMSI A-D路由，则（C-*，C-G-BIDIR）与该路由匹配。
o Otherwise, if PE1 is the same as PE2, and PE1 has currently originated a (C-*,C-*) S-PMSI A-D route, then (C-*,C-G-BIDIR) matches this route.
o 否则，如果PE1与PE2相同，并且PE1当前已发起（C-*，C-*）S-PMSI a-D路由，则（C-*，C-G-BIDIR）匹配此路由。
If there is an S-PMSI A-D route matching (C-*,C-G-BIDIR), according to these rules, the root node of that P-tunnel is considered to be the distinguished PE for that (C-*,C-G-BIDIR) flow. If a (C-*,C-G-BIDIR) packet is received on a P-tunnel whose root node is not the distinguished PE for the C-flow, the packet MUST be discarded.
如果存在S-PMSI A-D路由匹配（C-*，C-G-BIDIR），则根据这些规则，该P隧道的根节点被视为该（C-*，C-G-BIDIR）流的可分辨PE。如果在根节点不是C流的可分辨PE的P隧道上接收到（C-*，C-G-BIDIR）数据包，则必须丢弃该数据包。
Suppose a given PE, say PE1, needs to receive packets of a given C-flow (of a given MVPN) from another PE, but according to the conditions of Section 3.2.1.3 and/or Section 3.2 of [RFC6625], that C-flow does not match any S-PMSI A-D route. Then, the packets of the C-flow need to be received on the MVPN's I-PMSI.
假设一个给定的PE，例如PE1，需要从另一个PE接收给定C流（给定MVPN）的数据包，但根据[RFC6625]第3.2.1.3节和/或第3.2节的条件，该C流不匹配任何S-PMSI a-D路由。然后，需要在MVPN的I-PMSI上接收C流的分组。
If the C-flow is not a BIDIR-PIM C-flow, the rules for determining the P-tunnel on which packets of the C-flow are expected are given in [RFC6513]. The remainder of this section applies only to C-BIDIR flows.
如果C-flow不是BIDIR-PIM C-flow，则在[RFC6513]中给出了用于确定预期C-flow的数据包所在的P隧道的规则。本节其余部分仅适用于C-BIDIR流。
Suppose that PE1 needs to receive (C-*,C-G-BIDIR) traffic from other PEs. Suppose also that PE1 has determined that PE2 is the upstream PE [RFC6513] for the C-RPA of C-G-BIDIR. Then, PE1 considers PE2 to be the distinguished PE for (C-*,C-G-BIDIR). If PE1 has an installed Intra-AS I-PMSI A-D route originated by PE2, PE1 will expect to receive packets of the C-flow from the tunnel specified in that route's PTA. (If all VRFs of the MVPN have been properly provisioned to use the Flat Partitioned Method for the I-PMSI, the PTA will specify a bidirectional P-tunnel.) Note that if PE1 is the same as PE2, then the relevant Intra-AS I-PMSI A-D route is the one currently originated by PE1.
假设PE1需要从其他PE接收（C-*，C-G-BIDIR）流量。还假设PE1已确定PE2是C-G-BIDIR的C-RPA的上游PE[RFC6513]。然后，PE1认为PE2是（C-*，C-G-BIDIR）的区别PE。如果PE1安装了由PE2发起的内部AS I-PMSI A-D路由，则PE1将期望从该路由的PTA中指定的隧道接收C流的数据包。（如果MVPN的所有VRF已正确设置为使用I-PMSI的平面分区方法，PTA将指定双向P隧道。）注意，如果PE1与PE2相同，则相关的内部as I-PMSI a-D路由是PE1当前发起的路由。
If a (C-*,C-G-BIDIR) packet is received on a P-tunnel other than the expected one, the packet MUST be discarded.
如果（C-*，C-G-BIDIR）数据包在P隧道上接收到，而不是预期的，则必须丢弃该数据包。
The procedures of this section and its subsections apply when (and only when) the Hierarchical Partitioned Method is used. This method is introduced in [RFC6513], Section 11.2.2. This document only provides procedures for using this method when using MP2MP LSPs as the P-tunnels.
当（且仅当）使用分层分区方法时，本节及其小节中的程序适用。[RFC6513]第11.2.2节介绍了该方法。本文件仅提供将MP2MP LSP用作P隧道时使用此方法的程序。
The Hierarchical Partitioned Method provides the same functionality as the Flat Partitioned Method, but it requires a smaller amount of state to be maintained in the core of the network. However, it requires the use of upstream-assigned MPLS labels ("PE Distinguisher Labels"), which are not necessarily supported by all hardware platforms. The upstream-assigned labels are used to provide an LSP hierarchy, in which an outer MP2MP LSP carries multiple inner MP2MP LSPs. Transit routers along the path between PE routers then only need to maintain state for the outer MP2MP LSP.
分层分区方法提供了与平面分区方法相同的功能，但它需要在网络核心中维护较少的状态。然而，它需要使用上游分配的MPLS标签（“PE识别标签”），并非所有硬件平台都必须支持这些标签。上游分配的标签用于提供LSP层次结构，其中外部MP2MP LSP承载多个内部MP2MP LSP。沿着PE路由器之间的路径传输路由器只需维护外部MP2MP LSP的状态。
When this method is used to instantiate a particular PMSI, the bidirectional P-tunnel advertised in the PTA of the corresponding I-PMSI or S-PMSI A-D route is the outer P-tunnel. When a packet is received from a P-tunnel, the PE that receives it can infer the identity of the outer P-tunnel from the MPLS label that has risen to the top of the packet's label stack. However, the packet's distinguished PE is not necessarily the root node of the outer P-tunnel. Rather, the identity of the packet's distinguished PE is inferred from the PE Distinguisher Label further down in the label stack. (See [RFC6513], Section 12.3.) The PE Distinguisher Label may be thought of as identifying an inner MP2MP LSP whose root is the PE corresponding to that label.
当使用该方法实例化特定PMSI时，在对应I-PMSI或S-PMSI a-D路由的PTA中广告的双向P隧道是外部P隧道。当从P隧道接收到分组时，接收该分组的PE可以从上升到分组标签栈顶部的MPLS标签推断外部P隧道的标识。然而，分组的可分辨PE不一定是外部P隧道的根节点。相反，数据包的可分辨PE的标识是从标签堆栈中较低的PE区分器标签推断出来的。（参见[RFC6513]，第12.3节。）PE识别器标签可被视为识别内部MP2MP LSP，其根是对应于该标签的PE。
In the context of a given MVPN, if it is desired to use the Hierarchical Partitioned Method to instantiate an I-PMSI, a (C-*,C-*) S-PMSI, or a (C-*,C-*-BIDIR) S-PMSI, the corresponding A-D routes MUST be originated by some of the PEs that attach to that MVPN. The PEs that are REQUIRED to originate these routes are those that satisfy one of the following conditions:
在给定MVPN的上下文中，如果希望使用分层分区方法来实例化I-PMSI、（C-*，C-*）S-PMSI或（C-*，C-*-BIDIR）S-PMSI，则相应的a-D路由必须由附加到该MVPN的一些PE发起。发起这些路线所需的PEs是满足以下条件之一的PEs：
o There is a C-BIDIR group for which the best path from the PE to the C-RPA of that C-group is via a VRF interface.
o 有一个C-BIDIR组，从PE到该C组的C-RPA的最佳路径是通过VRF接口。
o The PE might have to transmit unidirectional customer multicast traffic on the PMSI identified in the route (of course this condition does not apply to (C-*,C-*-BIDIR) or to (C-*,C-G-BIDIR) S-PMSIs).
o PE可能必须在路由中标识的PMSI上传输单向客户多播流量（当然，此条件不适用于（C-*，C-*-BIDIR）或（C-*，C-G-BIDIR）S-PMSI）。
o The PE is the root node of the MP2MP LSP that is used to instantiate the PMSI.
o PE是用于实例化PMSI的MP2MP LSP的根节点。
When the Hierarchical Partitioned method is used to instantiate a (C-*,C-G-BIDIR) S-PMSI, the corresponding (C-*,C-G-BIDIR) S-PMSI route MUST NOT be originated by a given PE unless either (a) that PE's best path to the C-RPA for C-G-BIDIR is via a VRF interface, or (b) the C-RPA is a C-address of the PE. Further, that PE MUST be the root node of the MP2MP LSP identified in the PTA of the S-PMSI A-D route.
当使用分层分区方法实例化（C-*，C-G-BIDIR）S-PMSI时，相应的（C-*，C-G-BIDIR）S-PMSI路由不得由给定PE发起，除非（a）PE到C-G-BIDIR的C-RPA的最佳路径是通过VRF接口，或者（b）C-RPA是PE的C地址。此外，该PE必须是在S-PMSI A-D路由的PTA中标识的MP2MP LSP的根节点。
If any VRF of a given MVPN uses this method to instantiate an S-PMSI with a bidirectional P-tunnel, all VRFs of that MVPN must use this method.
如果给定MVPN的任何VRF使用此方法实例化具有双向P隧道的S-PMSI，则该MVPN的所有VRF必须使用此方法。
Suppose that for a given MVPN, the Hierarchical Partitioned Method is used to instantiate the I-PMSI. In general, more than one of the PEs in the MVPN will originate an Intra-AS I-PMSI A-D route for that MVPN. This document allows the PTAs of those routes to all specify the same MP2MP LSP as the "outer tunnel". However, it does not require that those PTAs all specify the same MP2MP LSP as the outer tunnel. By having all the PEs specify the same outer tunnel for the I-PMSI, one can minimize the amount of state in the transit nodes. By allowing them to specify different outer tunnels, one uses more state, but may increase the robustness of the system.
假设对于给定的MVPN，使用分层分区方法实例化I-PMSI。通常，MVPN中的多个PE将为该MVPN发起一个内部AS I-PMSI A-D路由。本文件允许这些路线的PTA指定与“外部隧道”相同的MP2MP LSP。但是，它不要求这些PTA都指定与外部隧道相同的MP2MP LSP。通过让所有PE为I-PMSI指定相同的外部隧道，可以最小化传输节点中的状态量。通过允许它们指定不同的外部通道，可以使用更多的状态，但可以提高系统的健壮性。
The considerations of the previous paragraph apply as well when the Hierarchical Partitioned Method is used to instantiate an S-PMSI.
当使用分层分区方法实例化S-PMSI时，上一段的注意事项也适用。
A PE Distinguisher Label is an upstream-assigned MPLS label [RFC5331] that can be used, in the context of an MP2MP LSP, to denote a particular PE that either has joined or may in the future join that LSP.
PE识别标签是上游分配的MPLS标签[RFC5331]，可在MP2MP LSP的上下文中用于表示已加入或将来可能加入该LSP的特定PE。
In order to use upstream-assigned MPLS labels in the context of an outer MP2MP LSP, there must be a convention that identifies a particular router as the router that is responsible for allocating the labels and for advertising the labels to the PEs that may join the MP2MP LSP. This document REQUIRES that the PE Distinguisher Labels used in the context of a given MP2MP LSP be allocated and advertised by the router that is the root node of the LSP.
为了在外部MP2MP LSP的上下文中使用上游分配的MPLS标签，必须有一个约定，将特定路由器标识为负责分配标签并向可能加入MP2MP LSP的PE发布标签的路由器。本文件要求在给定MP2MP LSP上下文中使用的PE识别器标签由作为LSP根节点的路由器分配和公布。
This convention accords with the rules of Section 7 of [RFC5331]. Note that according to Section 7 of [RFC5331], upstream-assigned labels are unique in the context of the IP address of the root node; if two MP2MP LSPs have the same root node IP address, the upstream-assigned labels used within the two LSPs come from the same label space.
本公约符合[RFC5331]第7节的规则。注意，根据[RFC5331]第7节，上游分配的标签在根节点的IP地址上下文中是唯一的；如果两个MP2MP LSP具有相同的根节点IP地址，则两个LSP内使用的上游分配标签来自相同的标签空间。
This document assumes that the root node address of an MP2MP LSP is an IP address that is uniquely assigned to the node. The use of an "anycast address" as the root node address is outside the scope of this document.
本文档假定MP2MP LSP的根节点地址是唯一分配给该节点的IP地址。使用“选播地址”作为根节点地址超出了本文档的范围。
A PE Distinguisher Labels attribute SHOULD NOT be attached to an I-PMSI or S-PMSI A-D route unless that route also contains a PTA that specifies an MP2MP LSP. (While PE Distinguisher Labels could in theory also be used if the PTA specifies a BIDIR-PIM P-tunnel, such use is outside the scope of this document.)
PE识别器标签属性不应附加到I-PMSI或S-PMSI A-D路由，除非该路由还包含指定MP2MP LSP的PTA。（如果PTA规定了BIDIR-PIM P-隧道，理论上也可以使用PE识别标签，但此类使用不在本文件范围内。）
The PE Distinguisher Labels attribute specifies a set of <MPLS label, IP address> bindings. Within a given PE Distinguisher Labels attribute, each such IP address MUST appear at most once, and each MPLS label MUST appear only once. Otherwise, the attribute is considered to be malformed, and the "treat-as-withdraw" error-handling approach described in Section 2 of [BGP-ERROR] MUST be used.
PE Discriminator Labels属性指定一组<MPLS label，IP address>绑定。在给定的PE Discriminator Labels属性中，每个这样的IP地址最多只能出现一次，而每个MPLS标签只能出现一次。否则，该属性将被视为格式错误，必须使用[BGP-error]第2节中描述的“视为撤回”错误处理方法。
When a PE Distinguisher Labels attribute is included in a given I-PMSI or S-PMSI A-D route, it MUST assign a label to the IP address of each of the following PEs:
当PE Discriminator Labels属性包含在给定的I-PMSI或S-PMSI a-D路由中时，它必须将标签分配给以下每个PE的IP地址：
o The root node of the MP2MP LSP identified in the PTA of the route.
o 路由的PTA中标识的MP2MP LSP的根节点。
o Any PE that is possibly the ingress PE for a C-RPA of any C-BIDIR group.
o 可能是任何C-BIDIR组的C-RPA的入口PE的任何PE。
o Any PE that may need to transmit non-C-BIDIR traffic on the MP2MP LSP identified in the PTA of the route.
o 可能需要在路由的PTA中标识的MP2MP LSP上传输非C-BIDIR流量的任何PE。
One simple way to meet these requirements is to assign a PE Distinguisher label to every PE that has originated an Intra-AS I-PMSI A-D route.
满足这些要求的一个简单方法是为每个发起内部AS I-PMSI a-D路由的PE分配一个PE识别器标签。
Suppose a given PE, say PE1, needs to transmit multicast data packets of a particular C-flow. Section 3.1 of [RFC6625] gives a four-step algorithm for determining the S-PMSI A-D route, if any, that matches that C-flow for transmission.
假设一个给定的PE，比如PE1，需要传输特定C流的多播数据包。[RFC6625]第3.1节给出了确定S-PMSI a-D路由（如有）的四步算法，该路由与传输的C-flow相匹配。
If the C-flow is not a BIDIR-PIM C-flow, those rules apply unchanged. If there is a matching S-PMSI A-D route, the P-tunnel on which the C-flow MUST be transmitted is the one identified in the PTA of the matching route. Each packet of the C-flow MUST carry the PE Distinguisher Label assigned by the root node of that P-tunnel to the IP address of PE1. See Section 12.3 of [RFC6513] for encapsulation details.
如果C-flow不是BIDIR-PIM C-flow，则这些规则不变。如果存在匹配的S-PMSI a-D路由，则必须在其上传输C流的P隧道是在匹配路由的PTA中标识的P隧道。C-flow的每个数据包必须携带由该P-tunnel的根节点分配到PE1的IP地址的PE识别器标签。封装细节见[RFC6513]第12.3节。
The remainder of this section applies only to C-BIDIR flows. If a C-BIDIR flow has group address C-G-BIDIR, the rules applied by PE1 are the same as the rules given in Section 3.2.1.1.
本节其余部分仅适用于C-BIDIR流。如果C-BIDIR流具有组地址C-G-BIDIR，则PE1应用的规则与第3.2.1.1节中给出的规则相同。
If there is a matching S-PMSI A-D route, PE1 MUST transmit the C-flow on the P-tunnel identified in its PTA. Suppose PE1 has determined that PE2 is the upstream PE for the C-RPA of the given C-flow. In constructing the packet's MPLS label stack, PE1 must use the PE Distinguisher Label that was assigned by the P-tunnel's root node to the IP address of "PE2", not the label assigned to the IP address of "PE1" (unless, of course, PE1 is the same as PE2). See Section 12.3 of [RFC6513] for encapsulation details. Note that the root of the P-tunnel might be a PE other than PE1 or PE2.
如果存在匹配的S-PMSI a-D路由，PE1必须在其PTA中确定的P隧道上传输C流。假设PE1已确定PE2是给定C流C-RPA的上游PE。在构造数据包的MPLS标签堆栈时，PE1必须使用由P隧道的根节点分配给“PE2”IP地址的PE识别器标签，而不是分配给“PE1”IP地址的标签（当然，除非PE1与PE2相同）。封装细节见[RFC6513]第12.3节。请注意，P隧道的根部可能是PE1或PE2以外的PE。
Suppose a given PE, say PE1, needs to transmit packets of a given C-flow (of a given MVPN) to other PEs, but according to the conditions of Section 3.2.2.2 and/or Section 3.1 of [RFC6625], that C-flow does not match any S-PMSI A-D route. Then the packets of the C-flow need to be transmitted on the MVPN's I-PMSI.
假设一个给定的PE，例如PE1，需要将给定C流（给定MVPN）的数据包传输到其他PE，但根据[RFC6625]第3.2.2.2节和/或第3.1节的条件，C流与任何S-PMSI a-D路由都不匹配。然后，需要在MVPN的I-PMSI上传输C流的数据包。
If the C-flow is not a BIDIR-PIM C-flow, the P-tunnel on which the C-flow MUST be transmitted is the one identified in the PTA of the Intra-AS I-PMSI A-D route originated by PE1 for the given MVPN. Each packet of the C-flow MUST carry the PE Distinguisher Label assigned by the root node of that P-tunnel to the IP address of PE1.
如果C-flow不是BIDIR-PIM C-flow，则必须在其上传输C-flow的P-tunnel是由PE1针对给定MVPN发起的内部AS I-PMSI a-D路由的PTA中标识的P-tunnel。C-flow的每个数据包必须携带由该P-tunnel的根节点分配到PE1的IP地址的PE识别器标签。
If the C-flow is a BIDIR-PIM C-flow with group address C-G-BIDIR, the rules as applied by PE1 are the same as those given in Section 3.2.1.2.
如果C-flow是组地址为C-G-BIDIR的BIDIR-PIM C-flow，则PE1应用的规则与第3.2.1.2节中给出的规则相同。
If there is a matching I-PMSI A-D route, PE1 MUST transmit the C-flow on the P-tunnel identified in its PTA. In constructing the packet's MPLS label stack, it must use the PE Distinguisher Label that was assigned by the P-tunnel's root node to the IP address of "PE2", not the label assigned to the IP address of "PE1" (unless, of course, PE1 is the same as PE2). (Section 3.2.1.2 specifies the difference between PE1 and PE2.) See Section 12.3 of [RFC6513] for encapsulation details. Note that the root of the P-tunnel might be a PE other than PE1 or PE2.
如果存在匹配的I-PMSI a-D路由，PE1必须在其PTA中确定的P隧道上传输C流。在构造数据包的MPLS标签堆栈时，它必须使用由P隧道的根节点分配给“PE2”IP地址的PE识别器标签，而不是分配给“PE1”IP地址的标签（当然，除非PE1与PE2相同）。（第3.2.1.2节规定了PE1和PE2之间的差异。）有关封装细节，请参见[RFC6513]第12.3节。请注意，P隧道的根部可能是PE1或PE2以外的PE。
If, for a packet of a particular C-flow, there is no S-PMSI A-D route or I-PMSI A-D route that is a match for transmission, the packet MUST NOT be transmitted.
如果对于特定C流的数据包，不存在与传输匹配的S-PMSI a-D路由或I-PMSI a-D路由，则不得传输该数据包。
Suppose a given PE, say PE1, needs to receive multicast data packets of a particular C-flow. Section 3.2 of [RFC6625] specifies procedures for determining the S-PMSI A-D route, if any, that matches that C-flow for reception. Those rules require that the matching S-PMSI A-D route has been originated by the upstream PE for the C-flow. The rules are modified in this section, as follows:
假设给定的PE（比如PE1）需要接收特定C流的多播数据包。[RFC6625]第3.2节规定了确定S-PMSI A-D路线（如有）的程序，该路线与接收的C-flow相匹配。这些规则要求匹配的S-PMSI A-D路由由上游PE为C-flow发起。本节对规则进行了如下修改：
Consider a particular C-flow. Suppose either:
考虑一个特定的C流。假设：
o the C-flow is unidirectional, and PE1 determines that its upstream PE is PE2, or
o C流是单向的，PE1确定其上游PE为PE2，或
o the C-flow is bidirectional, and PE1 determines that the upstream PE for its C-RPA is PE2
o C流是双向的，PE1确定其C-RPA的上游PE为PE2
Then, the C-flow may match an installed S-PMSI A-D route that was not originated by PE2, as long as:
然后，C-flow可能与安装的S-PMSI A-D路线匹配，该路线不是由PE2发起的，只要：
1. the PTA of that A-D route identifies an MP2MP LSP,
1. 该A-D路线的PTA识别MP2MP LSP，
2. there is an installed S-PMSI A-D route originated by the root node of that LSP, or PE1 itself is the root node of the LSP and there is a currently originated S-PMSI A-D route from PE1 whose PTA identifies that LSP, and
2. 存在由该LSP的根节点发起的已安装的S-PMSI A-D路由，或者PE1本身是该LSP的根节点，并且存在来自PE1的当前发起的S-PMSI A-D路由，其PTA识别该LSP，以及
3. the latter S-PMSI A-D route (the one identified in 2 just above) contains a PE Distinguisher Labels attribute that assigned an MPLS label to the IP address of PE2.
3. 后一个S-PMSI A-D路由（上面2中标识的路由）包含一个PE Discriminator Labels属性，该属性将MPLS标签分配给PE2的IP地址。
However, a bidirectional C-flow never matches an S-PMSI A-D route whose NLRI contains (C-S,C-G).
然而，双向C流从不匹配NLRI包含（C-S，C-G）的S-PMSI a-D路由。
If a multicast data packet is received over a matching P-tunnel, but does not carry the value of the PE Distinguisher Label that has been assigned to the upstream PE for its C-flow, then the packet MUST be discarded.
如果通过匹配的P隧道接收到多播数据分组，但没有携带已为其C流分配给上游PE的PE区分器标签的值，则必须丢弃该分组。
If a PE needs to receive packets of a given C-flow (of a given MVPN) from another PE, and if, according to the conditions of Section 3.2.2.4, that C-flow does not match any S-PMSI A-D route, then the packets of the C-flow need to be received on the MVPN's I-PMSI. The P-tunnel on which the packets are expected to arrive is determined by the Intra-AS I-PMSI A-D route originated by the distinguished PE for the given C-flow. The PTA of that route specifies the "outer
如果一个PE需要从另一个PE接收给定C流（给定MVPN）的数据包，并且根据第3.2.2.4节的条件，如果该C流不匹配任何S-PMSI a-D路由，则需要在MVPN的I-PMSI上接收C流的数据包。分组预期到达的P隧道由给定C流的可分辨PE发起的内部AS I-PMSI A-D路由确定。该路线的PTA规定了“外部
P-tunnel" and thus determines the top label that packets of that C-flow will be carrying when received. A PE that needs to receive packets of a given C-flow must determine the expected value of the second label for packets of that C-flow. This will be the value of a PE Distinguisher Label, taken from the PE Distinguisher Labels attribute of the Intra-AS I-PMSI A-D route of the root node of that outer tunnel. The expected value of the second label on received packets (corresponding to the "inner tunnel") of a given C-flow is determined according to the following rules.
P型隧道从而确定接收到该C流的数据包时将携带的顶部标签。需要接收给定C流数据包的PE必须确定该C流数据包的第二个标签的预期值。这将是PE识别器标签的值，取自该外部隧道根节点的Intra AS I-PMSI a-D路由的PE识别器标签属性。根据以下规则确定给定C流的接收分组（对应于“内部隧道”）上的第二标签的期望值。
First, the distinguished PE for the C-flow is determined:
首先，确定C流的可分辨PE：
o If the C-flow is not a BIDIR-PIM C-flow, the distinguished PE for the C-flow is its upstream PE, as determined by the rules of [RFC6513].
o 如果C-flow不是BIDIR-PIM C-flow，则C-flow的可分辨PE是其上游PE，由[RFC6513]的规则确定。
o If the C-flow is a BIDIR-PIM C-flow, the distinguished PE for the C-flow is its upstream PE of the C-flow's C-RPA, as determined by the rules of [RFC6513].
o 如果C-flow是BIDIR-PIM C-flow，则C-flow的区分PE是C-flow的C-RPA的上游PE，由[RFC6513]的规则确定。
The expected value of the second label is the value that the root PE of the outer tunnel has assigned, in the PE Distinguisher Labels attribute of its Intra-AS I-PMSI A-D route, to the IP address of the distinguished PE.
第二个标签的期望值是外部隧道的根PE在其内部AS I-PMSI A-D路由的PE Discriminator Labels属性中分配给可分辨PE的IP地址的值。
Packets addressed to C-G that arrive on other than the expected inner and outer P-tunnels (i.e., that arrive with unexpected values of the top two labels) MUST be discarded.
发往C-G的数据包到达预期的内部和外部P隧道之外的地方（即到达时带有前两个标签的意外值），必须丢弃。
When a particular MVPN uses the Unpartitioned Method of instantiating an I-PMSI with a bidirectional P-tunnel, it MUST be the case that at least one VRF of that MVPN originates an Intra-AS I-PMSI A-D route that includes a PTA specifying a bidirectional P-tunnel. The conditions under which an Intra-AS I-PMSI A-D route must be originated from a given VRF are as specified in [RFC6514]. This document allows all but one of such routes to omit the PTA. However, each such route MAY contain a PTA. If the PTA is present, it MUST specify a bidirectional P-tunnel. As specified in [RFC6513] and [RFC6514], every PE that imports such an Intra-AS I-PMSI A-D route into one of its VRFs MUST, if the route has a PTA, join the P-tunnel specified in the route's PTA.
当特定MVPN使用实例化具有双向P隧道的I-PMSI的未分割方法时，必须是该MVPN的至少一个VRF发起包括指定双向P隧道的PTA的AS内I-PMSI a-D路由的情况。[RFC6514]中规定了必须从给定VRF发起内部AS I-PMSI A-D路由的条件。本文件允许除一条路线外的所有路线省略PTA。然而，每条此类路线可能包含PTA。如果存在PTA，则必须指定双向P隧道。按照[RFC6513]和[RFC6514]中的规定，如果路由具有PTA，则将As内I-PMSI A-D路由导入其一个VRF的每个PE必须加入路由PTA中规定的P隧道。
Packets received on any of these P-tunnels are treated as having been received over the I-PMSI. The disposition of a received packet MUST NOT depend upon the particular P-tunnel over which it has been received.
在这些P隧道中的任何一个上接收的分组被视为已经通过I-PMSI接收。接收到的数据包的处理不能依赖于接收它的特定P隧道。
When a PE needs to transmit a packet on such an I-PMSI, then if that PE advertised a P-tunnel in the PTA of an Intra-AS I-PMSI A-D route that it originated, the PE SHOULD transmit the on that P-tunnel. However, any PE that transmits a packet on the I-PMSI MAY transmit it on any of the P-tunnels advertised in any of the currently installed Intra-AS I-PMSI A-D routes for its VPN.
当PE需要在这样的I-PMSI上发送分组时，如果该PE在其发起的帧内AS I-PMSI a-D路由的PTA中通告P隧道，则该PE应在该P隧道上发送分组。然而，在I-PMSI上传输分组的任何PE可以在其VPN的任何当前安装的帧内AS I-PMSI a-D路由中公布的任何P隧道上传输分组。
This allows a single bidirectional P-tunnel to be used to instantiate the I-PMSI, but also allows the use of multiple bidirectional P-tunnels. There may be a robustness advantage in having multiple P-tunnels available for use, but the number of P-tunnels used does not impact the functionality in any way. If there are, e.g., two P-tunnels available, these procedures allow each P-tunnel to be advertised by a single PE, but they also allow each P-tunnel to be advertised by multiple PEs. Note that the PE advertising a given P-tunnel does not have to be the root node of the tunnel. The root node might not even be a PE router, and it might not originate any BGP routes at all.
这允许使用单个双向P隧道来实例化I-PMSI，但也允许使用多个双向P隧道。使用多个P通道可能具有健壮性优势，但使用的P通道数量不会以任何方式影响功能。例如，如果有两个P-隧道可用，这些程序允许每个P-隧道由单个PE播发，但也允许每个P-隧道由多个PE播发。请注意，为给定P隧道播发广告的PE不必是隧道的根节点。根节点甚至可能不是PE路由器，也可能根本不发起任何BGP路由。
In the Unpartitioned Method, packets received on the I-PMSI cannot be associated with a distinguished PE, so duplicate detection using the techniques of Section 9.1.1 of [RFC6513] is not possible; the techniques of Sections 9.1.2 or 9.1.3 of [RFC6513] would have to be used instead. Support for C-BIDIR using the "Partitioned set of PEs" technique (Section 11.2 of [RFC6513] and Section 3.6 of [RFC6517]) is not possible when the Unpartitioned Method is used. If it is desired to use that technique to support C-BIDIR, but also to use the Unpartitioned Method to instantiate the I-PMSI, then all the C-BIDIR traffic would have to be carried on an S-PMSI, where the S-PMSI is instantiated using one of the Partitioned Methods.
在非分区方法中，I-PMSI上接收的数据包不能与可分辨PE相关联，因此不可能使用[RFC6513]第9.1.1节的技术进行重复检测；必须使用[RFC6513]第9.1.2节或第9.1.3节中的技术。使用未分区方法时，不可能使用“PEs分区集”技术（RFC6513第11.2节和RFC6517第3.6节）支持C-BIDIR。如果希望使用该技术来支持C-BIDIR，但也希望使用未分区方法来实例化I-PMSI，那么所有C-BIDIR通信量都必须在S-PMSI上进行，其中S-PMSI使用分区方法之一进行实例化。
When a PE, say PE1, needs to transmit multicast data packets of a particular C-flow to other PEs, and PE1 does not have an S-PMSI that is a match for transmission for that C-flow (see Section 3.2.3.1), PE1 transmits the packets on one of the P-tunnel(s) that instantiates the I-PMSI. When a PE, say PE1, needs to receive multicast data packets of a particular C-flow from another PE, and PE1 does not have an S-PMSI that is a match for reception for that C-flow (see Section 3.2.3.2), PE1 expects to receive the packets on any of the P-tunnels that instantiate the I-PMSI.
当PE（例如PE1）需要将特定C流的多播数据包传输到其他PE，并且PE1没有与该C流的传输相匹配的S-PMSI（参见第3.2.3.1节）时，PE1在实例化I-PMSI的P隧道之一上传输包。当一个PE，例如PE1，需要从另一个PE接收特定C流的多播数据包，并且PE1没有与该C流的接收相匹配的S-PMSI时（参见第3.2.3.2节），PE1期望在实例化I-PMSI的任何P隧道上接收包。
When a particular MVPN uses the Unpartitioned Method to instantiate a (C-*,C-*) S-PMSI or a (C-*,C-*-BIDIR) S-PMSI using a bidirectional P-tunnel, the same conditions apply as when an I-PMSI is instantiated via the Unpartitioned Method. The only difference is that a PE need not join a P-tunnel that instantiates the S-PMSI unless that PE needs to receive multicast packets on the S-PMSI.
当特定MVPN使用未分区方法实例化（C-*，C-*）S-PMSI或使用双向P隧道实例化（C-*，C-*-BIDIR）S-PMSI时，适用的条件与通过未分区方法实例化I-PMSI时相同。唯一的区别是PE不需要加入实例化S-PMSI的P隧道，除非该PE需要在S-PMSI上接收多播数据包。
When a particular MVPN uses bidirectional P-tunnels to instantiate other S-PMSIs, different S-PMSI A-D routes that do not contain (C-*,C-*) or (C-*,C-*-BIDIR), originated by the same or by different PEs, MAY have PTAs that identify the same bidirectional tunnel, and they MAY have PTAs that do not identify the same bidirectional tunnel.
当特定MVPN使用双向P隧道实例化其他S-PMSI时，不包含（C-*，C-*）或（C-*，C-*-BIDIR）的不同S-PMSI a-D路由（由相同或不同PE发起）可能具有标识相同双向隧道的PTA，并且它们可能具有不标识相同双向隧道的PTA。
While the Unpartitioned Method MAY be used to instantiate an S-PMSI to which one or more C-BIDIR flows are bound, it must be noted that the "Partitioned Set of PEs" method discussed in Section 11.2 of [RFC6513] and Section 3.6 of [RFC6517] cannot be supported using the Unpartitioned Method. C-BIDIR support would have to be provided by the procedures of [RFC6513], Section 11.1.
虽然未分区方法可用于实例化一个或多个C-BIDIR流绑定到的S-PMSI，但必须注意，[RFC6513]第11.2节和[RFC6517]第3.6节中讨论的“PEs分区集”方法不能使用未分区方法支持。必须按照[RFC6513]第11.1节的程序提供C-BIDIR支持。
Suppose a PE needs to transmit multicast data packets of a particular customer C-flow. [RFC6625], Section 3.1, gives a four-step algorithm for determining the S-PMSI A-D route, if any, that matches that C-flow for transmission. When referring to that section, please recall that BIDIR-PIM groups are also ASM groups.
假设PE需要传输特定客户C-flow的多播数据包。[RFC6625]第3.1节给出了确定S-PMSI a-D路由（如果有）的四步算法，该路由与传输的C-flow相匹配。参考该部分时，请记住BIDIR-PIM组也是ASM组。
When bidirectional P-tunnels are used in the Unpartitioned Method, the same algorithm applies, with one modification, when the PTA of an S-PMSI A-D route identifies a bidirectional P-tunnel. One additional step is added to the algorithm. This new step occurs before the fourth step of the algorithm, and is as follows:
当在非分区方法中使用双向P-隧道时，当S-PMSI A-D路由的PTA识别双向P-隧道时，相同的算法适用（经过一次修改）。算法中增加了一个附加步骤。此新步骤发生在算法的第四步之前，如下所示：
o Otherwise, if there is a (C-*,C-*-BIDIR) S-PMSI A-D route currently originated by PE1, and if C-G is a BIDIR group, the C-flow matches that route.
o 否则，如果PE1当前发起了（C-*，C-*-BIDIR）S-PMSI a-D路由，并且如果C-G是BIDIR组，则C-flow与该路由匹配。
When the Unpartitioned Method is used, the PE SHOULD transmit the C-flow on the P-tunnel advertised in the in the matching S-PMSI A-D route, but it MAY transmit the C-flow on any P-tunnel that is advertised in the PTA of any installed S-PMSI A-D route that contains the same (C-S,C-G) as the matching S-PMSI A-D route.
当使用非分区方法时，PE应在匹配的S-PMSI A-D路由中的P-tunnel上发送C-flow，但它可以在任何已安装的S-PMSI A-D路由的PTA中所发布的P-tunnel上发送C-flow，该P-tunnel包含与匹配的S-PMSI A-D路由相同的（C-S，C-G）。
Suppose a PE needs to receive multicast data packets of a particular customer C-flow. Section 3.2 of [RFC6625] specifies the procedures for determining the S-PMSI A-D route, if any, that advertised the P-tunnel on which the PE should expect to receive that C-flow.
假设PE需要接收特定客户C-flow的多播数据包。[RFC6625]第3.2节规定了确定S-PMSI A-D路线（如有）的程序，该路线公布了PE预计接收C-flow的P-tunnel。
When bidirectional P-tunnels are used in the Unpartitioned Method, the same procedures apply, with one modification.
当双向P型隧道用于非分区方法时，同样的程序适用，只需一次修改。
The last paragraph of Section 3.2.2 of [RFC6625] begins:
[RFC6625]第3.2.2节的最后一段开始：
If (C-*,C-G) does not match a (C-*,C-G) S-PMSI A-D route from PE2, but PE1 has an installed (C-*,C-*) S-PMSI A-D route from PE2, then (C-*,C-G) matches the (C-*,C-*) route if one of the following conditions holds:
如果（C-*，C-G）与来自PE2的（C-*，C-G）S-PMSI a-D路线不匹配，但PE1已安装了来自PE2的（C-*，C-*）S-PMSI a-D路线，则如果以下条件之一成立，则（C-*，C-G）与（C-*，C-*）路线匹配：
This is changed to:
更改为：
If (C-*,C-G) does not match a (C-*,C-G) S-PMSI A-D route from PE2, but C-G is a BIDIR group and PE1 has an installed (C-*,C-*-BIDIR) S-PMSI A-D route, then (C-*,C-G) matches that route. Otherwise, if PE1 has an installed (C-*,C-*) S-PMSI A-D route from PE2, then (C-*,C-G) matches the (C-*,C-*) route if one of the following conditions holds:
如果（C-*，C-G）与PE2的（C-*，C-G）S-PMSI a-D路由不匹配，但C-G是BIDIR组，且PE1已安装（C-*，C-*-BIDIR）S-PMSI a-D路由，则（C-*，C-G）与该路由匹配。否则，如果PE1从PE2安装了（C-*，C-*）S-PMSI A-D路由，则如果以下条件之一成立，则（C-*，C-G）与（C-*，C-*）路由匹配：
When the Unpartitioned Method is used, the PE MUST join the P-tunnel that is advertised in the matching S-PMSI A-D route, and it MUST also join the P-tunnels that are advertised in other installed S-PMSI A-D routes that contain the same (C-S,C-G) as the matching S-PMSI A-D route.
使用未分区方法时，PE必须加入在匹配的S-PMSI A-D路由中播发的P隧道，还必须加入在其他已安装的S-PMSI A-D路由中播发的P隧道，这些路由包含与匹配的S-PMSI A-D路由相同的（C-S，C-G）。
Implementation of bidirectional P-tunnels is OPTIONAL. If bidirectional P-tunnels are not implemented, the issue of compliance to this specification does not arise. However, for the case where bidirectional P-tunnels ARE implemented, this section specifies the minimal set of features that MUST be implemented in order to claim compliance to this specification.
双向P隧道的实施是可选的。如果未实施双向P隧道，则不会出现符合本规范的问题。但是，对于实施双向P隧道的情况，本节规定了必须实施的最小功能集，以声明符合本规范。
In order to be compliant with this specification, an implementation that provides bidirectional P-tunnels MUST support at least one of the two P-tunnel technologies mentioned in Section 1.2.1.
为了符合本规范，提供双向P隧道的实施必须支持第1.2.1节中提到的两种P隧道技术中的至少一种。
A PE that does not provide C-BIDIR support using the "partitioned set of PEs" method is deemed compliant to this specification if it supports the Unpartitioned Method, using either MP2MP LSPs or BIDIR-PIM multicast distribution trees as P-tunnels.
如果PE支持未分区方法（使用MP2MP LSP或BIDIR-PIM多播分发树作为P隧道），则不使用“PEs分区集”方法提供C-BIDIR支持的PE被视为符合本规范。
A PE that does provide C-BIDIR support using the "partitioned set of PEs" method MUST, at a minimum, be able to provide C-BIDIR support using the "Partial Mesh of MP2MP P-tunnels" variant of this method (see Section 11.2 of [RFC6513]). An implementation will be deemed compliant to this minimum requirement if it can carry all of a VPN's C-BIDIR traffic on a (C-*,C-*-BIDIR) S-PMSI that is instantiated by a bidirectional P-tunnel, using the Flat Partitioned Method.
使用“PEs分区集”方法提供C-BIDIR支持的PE必须至少能够使用该方法的“MP2MP P隧道部分网格”变体提供C-BIDIR支持（见[RFC6513]第11.2节）。如果一个实现可以在（C-*，C-*-BIDIR）s-PMSI上承载VPN的所有C-BIDIR流量，则该实现将被视为符合该最低要求，该s-PMSI由双向P隧道使用平面分区方法实例化。
There are no additional security considerations beyond those of [RFC6513] and [RFC6514], or any that may apply to the particular protocol used to set up the bidirectional tunnels ([RFC5015], [RFC6388]).
除了[RFC6513]和[RFC6514]的安全注意事项外，没有其他安全注意事项，也没有任何其他安全注意事项适用于用于设置双向隧道的特定协议（[RFC5015]、[RFC6388]）。
[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>.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 2006, <http://www.rfc-editor.org/info/rfc4364>.
[RFC4364]Rosen，E.和Y.Rekhter，“BGP/MPLS IP虚拟专用网络（VPN）”，RFC 4364，DOI 10.17487/RFC4364，2006年2月<http://www.rfc-editor.org/info/rfc4364>.
[RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, "Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)", RFC 4601, DOI 10.17487/RFC4601, August 2006, <http://www.rfc-editor.org/info/rfc4601>.
[RFC4601]Fenner，B.，Handley，M.，Holbrook，H.，和I.Kouvelas，“协议独立多播-稀疏模式（PIM-SM）：协议规范（修订版）”，RFC 4601，DOI 10.17487/RFC4601，2006年8月<http://www.rfc-editor.org/info/rfc4601>.
[RFC5015] Handley, M., Kouvelas, I., Speakman, T., and L. Vicisano, "Bidirectional Protocol Independent Multicast (BIDIR-PIM)", RFC 5015, DOI 10.17487/RFC5015, October 2007, <http://www.rfc-editor.org/info/rfc5015>.
[RFC5015]Handley，M.，Kouvelas，I.，Speakman，T.，和L.Vicisano，“双向协议独立多播（BIDIR-PIM）”，RFC 5015，DOI 10.17487/RFC5015，2007年10月<http://www.rfc-editor.org/info/rfc5015>.
[RFC6388] Wijnands, IJ., Ed., Minei, I., Ed., Kompella, K., and B. Thomas, "Label Distribution Protocol Extensions for Point-to-Multipoint and Multipoint-to-Multipoint Label Switched Paths", RFC 6388, DOI 10.17487/RFC6388, November 2011, <http://www.rfc-editor.org/info/rfc6388>.
[RFC6388]Wijnands，IJ.，Ed.，Minei，I.，Ed.，Kompella，K.和B.Thomas，“点对多点和多点对多点标签交换路径的标签分发协议扩展”，RFC 6388，DOI 10.17487/RFC6388，2011年11月<http://www.rfc-editor.org/info/rfc6388>.
[RFC6513] Rosen, E., Ed., and R. Aggarwal, Ed., "Multicast in MPLS/BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513, February 2012, <http://www.rfc-editor.org/info/rfc6513>.
[RFC6513]Rosen，E.，Ed.，和R.Aggarwal，Ed.，“MPLS/BGP IP VPN中的多播”，RFC 6513，DOI 10.17487/RFC6513，2012年2月<http://www.rfc-editor.org/info/rfc6513>.
[RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP Encodings and Procedures for Multicast in MPLS/BGP IP VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012, <http://www.rfc-editor.org/info/rfc6514>.
[RFC6514]Aggarwal，R.，Rosen，E.，Morin，T.，和Y.Rekhter，“MPLS/BGP IP VPN中的BGP编码和多播过程”，RFC 6514，DOI 10.17487/RFC6514，2012年2月<http://www.rfc-editor.org/info/rfc6514>.
[RFC6625] Rosen, E., Ed., Rekhter, Y., Ed., Hendrickx, W., and R. Qiu, "Wildcards in Multicast VPN Auto-Discovery Routes", RFC 6625, DOI 10.17487/RFC6625, May 2012, <http://www.rfc-editor.org/info/rfc6625>.
[RFC6625]Rosen，E.，Ed.，Rekhter，Y.，Ed.，Hendrickx，W.，和R.Qiu，“多播VPN自动发现路由中的通配符”，RFC 6625，DOI 10.17487/RFC6625，2012年5月<http://www.rfc-editor.org/info/rfc6625>.
[BGP-ERROR] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K. Patel, "Revised Error Handling for BGP UPDATE Messages", Work in Progress, draft-ietf-idr-error-handling-19, April 2015.
[BGP-ERROR]Chen，E.，Ed.，Scudder，J.，Ed.，Mohapatra，P.，和K.Patel，“BGP更新消息的修订错误处理”，正在进行的工作，草案-ietf-idr-ERROR-HANDING-19，2015年4月。
[MVPN-BIDIR-IR] Zhang, Z., Rekhter, Y., and A. Dolganow, "Simulating 'Partial Mesh of MP2MP P-Tunnels' with Ingress Replication", Work in Progress, draft-ietf-bess-mvpn-bidir-ingress-replication-00, January 2015.
[MVPN-BIDIR-IR]Zhang，Z.，Rekhter，Y.，和A.Dolganow，“使用入口复制模拟“MP2MP P隧道的部分网格”，正在进行的工作，草稿-ietf-bess-MVPN-BIDIR-Ingress-Replication-00，2015年1月。
[MVPN-XNET] Rekhter, Y., Ed., Rosen, E., Ed., Aggarwal, R., Cai, Y., and T. Morin, "Extranet Multicast in BGP/IP MPLS VPNs", Work in Progress, draft-ietf-bess-mvpn-extranet-02, May 2015.
[MVPN-XNET]Rekhter，Y.，Ed.，Rosen，E.，Ed.，Aggarwal，R.，Cai，Y.，和T.Morin，“BGP/IP MPLS VPN中的外联网多播”，正在进行的工作，草案-ietf-bess-MVPN-Extranet-02，2015年5月。
[RFC5331] Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream Label Assignment and Context-Specific Label Space", RFC 5331, DOI 10.17487/RFC5331, August 2008, <http://www.rfc-editor.org/info/rfc5331>.
[RFC5331]Aggarwal，R.，Rekhter，Y.，和E.Rosen，“MPLS上游标签分配和上下文特定标签空间”，RFC 5331，DOI 10.17487/RFC5331，2008年8月<http://www.rfc-editor.org/info/rfc5331>.
[RFC6517] Morin, T., Ed., Niven-Jenkins, B., Ed., Kamite, Y., Zhang, R., Leymann, N., and N. Bitar, "Mandatory Features in a Layer 3 Multicast BGP/MPLS VPN Solution", RFC 6517, DOI 10.17487/RFC6517, February 2012, <http://www.rfc-editor.org/info/rfc6517>.
[RFC6517]Morin，T.，Ed.，Niven Jenkins，B.，Ed.，Kamite，Y.，Zhang，R.，Leymann，N.，和N.Bitar，“第三层多播BGP/MPLS VPN解决方案中的强制功能”，RFC 6517，DOI 10.17487/RFC6517，2012年2月<http://www.rfc-editor.org/info/rfc6517>.
Acknowledgments
致谢
The authors wish to thank Karthik Subramanian, Rajesh Sharma, and Apoorva Karan for their input. We also thank Yakov Rekhter for his valuable critique.
作者希望感谢Karthik Subramanian、Rajesh Sharma和Apoorva Karan的投入。我们也感谢亚科夫·雷克特的宝贵评论。
Special thanks go to Jeffrey (Zhaohui) Zhang for his careful review, probing questions, and useful suggestions.
特别感谢Jeffrey（赵辉）Zhang的仔细回顾、探究性问题和有用的建议。
Authors' Addresses
作者地址
Eric C. Rosen Juniper Networks, Inc. 10 Technology Park Drive Westford, MA 01886 United States
Eric C.Rosen Juniper Networks，Inc.美国马萨诸塞州韦斯特福德科技园大道10号01886
Email: erosen@juniper.net
Email: erosen@juniper.net
IJsbrand Wijnands Cisco Systems, Inc. De kleetlaan 6a Diegem 1831 Belgium
IJsbrand Wijlands Cisco Systems，Inc.De kleetlaan 6a Diegem 1831比利时
Email: ice@cisco.com
Email: ice@cisco.com
Yiqun Cai Microsoft 1065 La Avenida Mountain View, CA 94043 United States
美国加利福尼亚州拉阿维尼达山景大道1065号，邮编94043
Email: yiqunc@microsoft.com
Email: yiqunc@microsoft.com
Arjen Boers
阿尔扬·波尔斯
Email: arjen@boers.com
Email: arjen@boers.com