Internet Engineering Task Force (IETF) Y. Rekhter
Request for Comments: 7524 E. Rosen
Category: Standards Track Juniper Networks
ISSN: 2070-1721 R. Aggarwal
Arktan
T. Morin
I. Grosclaude
Orange
N. Leymann
Deutsche Telekom AG
S. Saad
AT&T
May 2015
Internet Engineering Task Force (IETF) Y. Rekhter
Request for Comments: 7524 E. Rosen
Category: Standards Track Juniper Networks
ISSN: 2070-1721 R. Aggarwal
Arktan
T. Morin
I. Grosclaude
Orange
N. Leymann
Deutsche Telekom AG
S. Saad
AT&T
May 2015
Inter-Area Point-to-Multipoint (P2MP) Segmented Label Switched Paths (LSPs)
区域间点对多点（P2MP）分段标签交换路径（LSP）
Abstract
摘要
This document describes procedures for building inter-area point-to-multipoint (P2MP) segmented service label switched paths (LSPs) by partitioning such LSPs into intra-area segments and using BGP as the inter-area routing and Label Distribution Protocol (LDP). Within each IGP area, the intra-area segments are either carried over intra-area P2MP LSPs, using P2MP LSP hierarchy, or instantiated using ingress replication. The intra-area P2MP LSPs may be signaled using P2MP RSVP-TE or P2MP multipoint LDP (mLDP). If ingress replication is used within an IGP area, then (multipoint-to-point) LDP LSPs or (point-to-point) RSVP-TE LSPs may be used in the IGP area. The applications/services that use such inter-area service LSPs may be BGP Multicast VPN, Virtual Private LAN Service (VPLS) multicast, or global table multicast over MPLS.
本文档描述了通过将区域间点对多点（P2MP）分段服务标签交换路径（LSP）划分为区域内段并使用BGP作为区域间路由和标签分发协议（LDP）来构建区域间点对多点（P2MP）分段服务标签交换路径（LSP）的过程。在每个IGP区域内，使用P2MP LSP层次结构通过区域内P2MP LSP携带区域内段，或者使用入口复制实例化区域内段。区域内P2MP lsp可使用P2MP RSVP-TE或P2MP多点LDP（mLDP）发信号。如果在IGP区域内使用入口复制，则可在IGP区域中使用（多点对点）LDP LSP或（点对点）RSVP-TE LSP。使用这种区域间服务lsp的应用/服务可以是BGP多播VPN、虚拟专用LAN服务（VPLS）多播或MPLS上的全局表多播。
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/rfc7524.
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/rfc7524.
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 ....................................................5
2. Specification of Requirements ...................................5
3. General Assumptions and Terminology .............................6
4. Inter-Area P2MP Segmented Next-Hop Extended Community ...........7
5. Discovering P2MP FEC of Inter-Area P2MP Service LSP .............8
5.1. BGP MVPN ...................................................8
5.1.1. Routes Originated by PE or ASBR .....................9
5.1.2. Routes Re-advertised by PE or ASBR ..................9
5.1.3. Inter-Area Routes ...................................9
5.2. LDP VPLS with BGP Auto-discovery or BGP VPLS ..............10
5.2.1. Routes Originated by PE or ASBR ....................10
5.2.2. Routes Re-advertised by PE or ASBR .................11
5.2.3. Inter-Area Routes ..................................11
5.3. Global Table Multicast over MPLS ..........................12
6. Egress PE/ASBR Signaling Procedures ............................13
6.1. Determining the Upstream ABR/PE/ASBR (Upstream Node) ......13
6.1.1. Upstream Node for MVPN or VPLS .....................13
6.1.2. Upstream Node for Global Table Multicast ...........14
6.2. Originating a Leaf A-D Route ..............................15
6.2.1. Leaf A-D Route for MVPN and VPLS ...................15
6.2.2. Leaf A-D Route for Global Table Multicast ..........15
6.2.3. Constructing the Rest of the Leaf A-D Route ........17
6.3. PIM-SM in ASM Mode for Global Table Multicast .............18
6.3.1. Option 1 ...........................................18
6.3.1.1. Originating Source Active A-D Routes ......18
6.3.1.2. Receiving BGP Source Active A-D
Route by PE ...............................19
6.3.1.3. Handling (S,G,rpt) State ..................19
6.3.2. Option 2 ...........................................19
6.3.2.1. Originating Source Active A-D Routes ......19
6.3.2.2. Receiving BGP Source Active A-D Route .....20
6.3.2.3. Pruning Sources Off the Shared Tree .......20
6.3.2.4. More on Handling (S,G,rpt) State ..........21
7. Egress ABR Procedures ..........................................21
7.1. Handling Leaf A-D Route on Egress ABR .....................21
7.2. P2MP LSP as the Intra-Area LSP in the Egress Area .........23
7.2.1. Received Leaf A-D Route Is for MVPN or VPLS ........23
7.2.2. Received Leaf A-D Route Is for Global Table
Multicast ..........................................24
7.2.2.1. Global Table Multicast and S-PMSI
A-D Routes ................................24
7.2.2.2. Global Table Multicast and
Wildcard S-PMSI A-D Routes ................25
7.2.3. Global Table Multicast and the Expected
Upstream Node ......................................25
1. Introduction ....................................................5
2. Specification of Requirements ...................................5
3. General Assumptions and Terminology .............................6
4. Inter-Area P2MP Segmented Next-Hop Extended Community ...........7
5. Discovering P2MP FEC of Inter-Area P2MP Service LSP .............8
5.1. BGP MVPN ...................................................8
5.1.1. Routes Originated by PE or ASBR .....................9
5.1.2. Routes Re-advertised by PE or ASBR ..................9
5.1.3. Inter-Area Routes ...................................9
5.2. LDP VPLS with BGP Auto-discovery or BGP VPLS ..............10
5.2.1. Routes Originated by PE or ASBR ....................10
5.2.2. Routes Re-advertised by PE or ASBR .................11
5.2.3. Inter-Area Routes ..................................11
5.3. Global Table Multicast over MPLS ..........................12
6. Egress PE/ASBR Signaling Procedures ............................13
6.1. Determining the Upstream ABR/PE/ASBR (Upstream Node) ......13
6.1.1. Upstream Node for MVPN or VPLS .....................13
6.1.2. Upstream Node for Global Table Multicast ...........14
6.2. Originating a Leaf A-D Route ..............................15
6.2.1. Leaf A-D Route for MVPN and VPLS ...................15
6.2.2. Leaf A-D Route for Global Table Multicast ..........15
6.2.3. Constructing the Rest of the Leaf A-D Route ........17
6.3. PIM-SM in ASM Mode for Global Table Multicast .............18
6.3.1. Option 1 ...........................................18
6.3.1.1. Originating Source Active A-D Routes ......18
6.3.1.2. Receiving BGP Source Active A-D
Route by PE ...............................19
6.3.1.3. Handling (S,G,rpt) State ..................19
6.3.2. Option 2 ...........................................19
6.3.2.1. Originating Source Active A-D Routes ......19
6.3.2.2. Receiving BGP Source Active A-D Route .....20
6.3.2.3. Pruning Sources Off the Shared Tree .......20
6.3.2.4. More on Handling (S,G,rpt) State ..........21
7. Egress ABR Procedures ..........................................21
7.1. Handling Leaf A-D Route on Egress ABR .....................21
7.2. P2MP LSP as the Intra-Area LSP in the Egress Area .........23
7.2.1. Received Leaf A-D Route Is for MVPN or VPLS ........23
7.2.2. Received Leaf A-D Route Is for Global Table
Multicast ..........................................24
7.2.2.1. Global Table Multicast and S-PMSI
A-D Routes ................................24
7.2.2.2. Global Table Multicast and
Wildcard S-PMSI A-D Routes ................25
7.2.3. Global Table Multicast and the Expected
Upstream Node ......................................25
7.2.4. P2MP LDP LSP as the Intra-Area P2MP LSP ............26
7.2.5. P2MP RSVP-TE LSP as the Intra-Area P2MP LSP ........26
7.3. Ingress Replication in the Egress Area ....................26
8. Ingress ABR Procedures .........................................27
8.1. P2MP LSP as the Intra-Area LSP in the Backbone Area .......27
8.2. Ingress Replication in the Backbone Area ..................27
9. Ingress PE/ASBR Procedures .....................................28
9.1. P2MP LSP as the Intra-Area LSP in the Ingress Area ........28
9.2. Ingress Replication in the Ingress Area ...................29
10. Common Tunnel Type in the Ingress and Egress Areas ............29
11. Placement of Ingress and Egress PEs ...........................30
12. MVPN with Virtual Hub-and-Spoke ...............................31
13. Data Plane ....................................................31
13.1. Data Plane Procedures on ABRs ............................31
13.2. Data Plane Procedures on Egress PEs ......................32
13.3. Data Plane Procedures on Ingress PEs .....................33
13.4. Data Plane Procedures on Transit Routers .................33
14. Support for Inter-Area Transport LSPs .........................33
14.1. "Transport Tunnel" Tunnel Type ...........................33
14.2. Discovering Leaves of the Inter-Area P2MP Service LSP ....34
14.3. Discovering P2MP FEC of P2MP Transport LSP ...............34
14.4. Egress PE Procedures for P2MP Transport LSP ..............35
14.5. ABRs and Ingress PE Procedures for P2MP Transport LSP ....35
14.6. Discussion ...............................................36
15. IANA Considerations ...........................................38
16. Security Considerations .......................................38
17. References ....................................................39
17.1. Normative References .....................................39
17.2. Informative References ...................................41
Acknowledgements ..................................................41
Authors' Addresses ................................................42
7.2.4. P2MP LDP LSP as the Intra-Area P2MP LSP ............26
7.2.5. P2MP RSVP-TE LSP as the Intra-Area P2MP LSP ........26
7.3. Ingress Replication in the Egress Area ....................26
8. Ingress ABR Procedures .........................................27
8.1. P2MP LSP as the Intra-Area LSP in the Backbone Area .......27
8.2. Ingress Replication in the Backbone Area ..................27
9. Ingress PE/ASBR Procedures .....................................28
9.1. P2MP LSP as the Intra-Area LSP in the Ingress Area ........28
9.2. Ingress Replication in the Ingress Area ...................29
10. Common Tunnel Type in the Ingress and Egress Areas ............29
11. Placement of Ingress and Egress PEs ...........................30
12. MVPN with Virtual Hub-and-Spoke ...............................31
13. Data Plane ....................................................31
13.1. Data Plane Procedures on ABRs ............................31
13.2. Data Plane Procedures on Egress PEs ......................32
13.3. Data Plane Procedures on Ingress PEs .....................33
13.4. Data Plane Procedures on Transit Routers .................33
14. Support for Inter-Area Transport LSPs .........................33
14.1. "Transport Tunnel" Tunnel Type ...........................33
14.2. Discovering Leaves of the Inter-Area P2MP Service LSP ....34
14.3. Discovering P2MP FEC of P2MP Transport LSP ...............34
14.4. Egress PE Procedures for P2MP Transport LSP ..............35
14.5. ABRs and Ingress PE Procedures for P2MP Transport LSP ....35
14.6. Discussion ...............................................36
15. IANA Considerations ...........................................38
16. Security Considerations .......................................38
17. References ....................................................39
17.1. Normative References .....................................39
17.2. Informative References ...................................41
Acknowledgements ..................................................41
Authors' Addresses ................................................42
This document describes procedures for building inter-area point-to-multipoint (P2MP) segmented service LSPs by partitioning such LSPs into intra-area segments and using BGP as the inter-area routing and label distribution protocol. Within each IGP area, the intra-area segments are either carried over intra-area P2MP LSPs, potentially using P2MP LSP hierarchy, or instantiated using ingress replication. The intra-area P2MP LSPs may be signaled using P2MP RSVP-TE [RFC4875] or P2MP mLDP [RFC6388]. If ingress replication is used in an IGP area, then (multipoint-to-point) LDP LSPs [RFC5036] or (point-to-point) RSVP-TE LSPs [RFC3209] may be used within the IGP area. The applications/services that use such inter-area service LSPs may be BGP Multicast VPN (BGP MVPN), VPLS multicast, or global table multicast over MPLS.
本文档描述了通过将区域间点对多点（P2MP）分段服务LSP划分为区域内段并使用BGP作为区域间路由和标签分发协议来构建区域间点对多点（P2MP）分段服务LSP的过程。在每个IGP区域内，区域内段或者通过区域内P2MP LSP携带，可能使用P2MP LSP层次结构，或者使用入口复制进行实例化。区域内P2MP LSP可使用P2MP RSVP-TE[RFC4875]或P2MP mLDP[RFC6388]发出信号。如果在IGP区域中使用入口复制，则（多点对点）LDP LSP[RFC5036]或（点对点）RSVP-TE LSP[RFC3209]可在IGP区域内使用。使用这种区域间服务lsp的应用/服务可以是BGP多播VPN（BGP MVPN）、VPLS多播或MPLS上的全局表多播。
The primary use case of such segmented P2MP service LSPs is when the Provider Edge (PE) routers are in different areas but in the same Autonomous System (AS) and thousands or more of PEs require P2MP connectivity. For instance, this may be the case when MPLS is pushed further to the metro edge and the metros are in different IGP areas. This may also be the case when a service provider's network comprises multiple IGP areas in a single AS, with a large number of PEs. Seamless MPLS is the industry term to address this case [SEAMLESS-MPLS]. Thus, one of the applicabilities of this document is that it describes the multicast procedures for seamless MPLS.
这种分段P2MP服务LSP的主要使用情况是，提供商边缘（PE）路由器位于不同区域，但位于同一自治系统（AS）中，并且数千个或更多的PE需要P2MP连接。例如，当MPLS被进一步推到地铁边缘并且地铁位于不同的IGP区域时，可能会出现这种情况。当服务提供商的网络包括单个AS中的多个IGP区域以及大量PE时，也可能出现这种情况。无缝MPLS是解决这种情况的行业术语[无缝MPLS]。因此，本文档的应用之一是描述无缝MPLS的多播过程。
It is to be noted that [RFC6514] and [RFC7117] already specify procedures for building segmented inter-AS P2MP service LSPs. This document complements those procedures, as it extends the segmented P2MP LSP model such that it is applicable to inter-area P2MP service LSPs as well. In fact, an inter-AS deployment could use inter-AS segmented P2MP LSPs as specified in [RFC6514] and [RFC7117] where each intra-AS segment is constructed using inter-area segmented P2MP LSPs, as specified in this document.
需要注意的是，[RFC6514]和[RFC7117]已经规定了构建分段的内部AS P2MP服务LSP的程序。本文件是对这些程序的补充，因为它扩展了分段P2MP LSP模型，因此也适用于区域间P2MP服务LSP。事实上，AS间部署可以使用[RFC6514]和[RFC7117]中规定的AS间分段P2MP LSP，其中每个AS内段都是使用本文件中规定的区域间分段P2MP LSP构建的。
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].
本文件中的关键词“必须”、“不得”、“必需”、“应”、“不应”、“应”、“不应”、“建议”、“可”和“可选”应按照[RFC2119]中所述进行解释。
The reader is assumed to be familiar with MVPN procedures and terminology [RFC6513] [RFC6514] and VPLS procedures and terminology [RFC7117].
假定读者熟悉MVPN程序和术语[RFC6513][RFC6514]和VPLS程序和术语[RFC7117]。
This document allows Area Border Routers (ABRs), acting as Route Reflectors, to follow the procedures specified in [SEAMLESS-MPLS] when handling the BGP Next Hop of the routes to the PEs. Specifically, when reflecting such routes from the non-backbone areas into the backbone area, the ABRs MUST set the BGP Next Hop to their own loopback addresses (next-hop-self), while when reflecting such routes from the backbone area into the non-backbone areas, the ABRs SHOULD NOT change the BGP Next Hop addresses (next-hop-unchanged).
本文件允许作为路由反射器的区域边界路由器（ABR）在处理通往PEs的路由的BGP下一跳时遵循[无缝MPLS]中规定的程序。具体来说，当将这些路由从非主干区域反射到主干区域时，ABR必须将BGP下一跳设置为其自己的环回地址（下一跳自），而当将这些路由从主干区域反射到非主干区域时，ABR不应更改BGP下一跳地址（下一跳不变）。
While this document allows ABRs to follow the procedures specified in [SEAMLESS-MPLS], procedures specified in this document are applicable even when ABRs do not follow the procedures specified in [SEAMLESS-MPLS].
虽然本文件允许ABR遵循[无缝-MPLS]中规定的程序，但即使ABR不遵循[无缝-MPLS]中规定的程序，本文件中规定的程序也适用。
This document specifies a particular way of supporting the global table multicast service. Although the document refers to this approach simply as "global table multicast", it does not mean to imply that there are no other ways to support global table multicast.
本文档指定了支持全局表多播服务的特定方式。尽管文档将这种方法简单地称为“全局表多播”，但这并不意味着没有其他方法支持全局表多播。
An alternative way to support global table multicast is to use the procedures for MVPN that are specified in [RFC6514] and in this document. That alternative is discussed in more detail in [GTM]. However, that alternative is not further considered in the current document.
支持全局表多播的另一种方法是使用[RFC6514]和本文档中指定的MVPN过程。[GTM]中更详细地讨论了该备选方案。然而，本文件没有进一步考虑这一备选方案。
This document assumes that, in the context of global table multicast, ABRs do not carry routes to the destinations external to their own AS. Furthermore, in the context of global table multicast, this document assumes that an Autonomous System Border Router (ASBR), when re-advertising into Internal BGP (IBGP) routes received from an external speaker (received via External BGP (EBGP)), may not change the BGP Next Hop to self.
本文档假设，在全局表多播上下文中，ABR不携带到其自身AS外部目的地的路由。此外，在全局表多播的上下文中，本文档假设自治系统边界路由器（ASBR）在向从外部扬声器接收（通过外部BGP（EBGP）接收）的内部BGP（IBGP）路由重新播发时，可能不会将BGP下一跳更改为自身。
Within an AS, a P2MP service LSP is partitioned into three segments: ingress area segment, backbone area segment, and egress area segment. Within each area, a segment is carried over an intra-area P2MP LSP or instantiated using ingress replication.
在AS中，P2MP服务LSP被划分为三个段：入口区段、主干区段和出口区段。在每个区域内，通过区域内P2MP LSP携带一个段，或使用入口复制进行实例化。
When intra-area P2MP LSPs are used to instantiate the intra-area segments, there could be either 1:1 or n:1 mapping between intra-area segments of the inter-area P2MP service LSP and a given intra-area P2MP LSP. The latter is realized using P2MP LSP hierarchy with
当使用区域内P2MP LSP来实例化区域内段时，区域间P2MP服务LSP的区域内段与给定的区域内P2MP LSP之间可能存在1:1或n:1映射。后者是使用P2MP LSP层次结构实现的
upstream-assigned labels [RFC5331]. For simplicity of presentation, we assume that P2MP LSP hierarchy is used even with 1:1 mapping; in which case, an Implicit NULL is used as the upstream-assigned label.
上游指定标签[RFC5331]。为了简化表示，我们假设P2MP LSP层次结构即使与1:1映射一起使用；在这种情况下，隐式NULL用作上游指定的标签。
When intra-area segments of the inter-area P2MP service LSP are instantiated using ingress replication, multiple such segments may be carried in the same P2P RSVP-TE or MP2P LDP LSP. This can be achieved using downstream-assigned labels alone.
当使用入口复制实例化区域间P2MP服务LSP的区域内段时，可以在同一P2P RSVP-TE或MP2P LDP LSP中携带多个这样的段。这可以通过单独使用下游指定的标签来实现。
The ingress area segment of a P2MP service LSP is rooted at a PE (or at an ASBR in the case where the P2MP service LSP spans multiple ASes). The leaves of this segment are other PEs/ASBRs and ABRs in the same area as the root PE.
P2MP服务LSP的入口区域段以PE为根（如果P2MP服务LSP跨越多个ASE，则以ASBR为根）。该片段的叶是与根PE位于同一区域的其他PEs/ASBR和ABR。
The backbone area segment is rooted at either an ABR that is connected to the ingress area (ingress ABR), an ASBR if the ASBR is present in the backbone area, or a PE if the PE is present in the backbone area. The backbone area segment has its leaf ABRs that are connected to the egress area(s) or PEs in the backbone area, or ASBRs in the backbone area.
主干区域段根于连接到入口区域的ABR（入口ABR）、ASBR（如果ASBR存在于主干区域中）或PE（如果PE存在于主干区域中）。主干区域段具有连接到主干区域中的出口区域或PEs或主干区域中的ASBR的叶ABR。
The egress area segment is rooted at an ABR in the egress area (egress ABR), and has its leaf PEs and ASBR in that egress area (the latter covers the case where the P2MP service LSP spans multiple ASes). For a given P2MP service LSP, note that there may be more than one backbone segment, each rooted at its own ingress ABR, and more than one egress area segment, each rooted at its own egress ABR.
出口区域段植根于出口区域中的ABR（出口ABR），并且在该出口区域中具有其叶PEs和ASBR（后者涵盖P2MP服务LSP跨越多个ase的情况）。对于给定的P2MP服务LSP，请注意，可能存在多个主干段，每个主干段根在其自己的入口ABR，以及多个出口区域段，每个主干段根在其自己的出口ABR。
This document uses the term "A-D routes" for "auto-discovery routes".
本文档将术语“A-D路由”用于“自动查找路由”。
An implementation that supports this document MUST implement the procedures described in the following sections to support inter-area P2MP segmented service LSPs.
支持本文件的实施必须实施以下章节中描述的程序，以支持区域间P2MP分段服务LSP。
This document defines a new Transitive IPv4-Address-Specific Extended Community Sub-Type: "Inter-Area P2MP Next-Hop". This document also defines a new BGP Transitive IPv6-Address-Specific Extended Community Sub-Type: "Inter-Area P2MP Next-Hop".
本文档定义了一个新的可传递IPv4地址特定的扩展社区子类型：“区域间P2MP下一跳”。本文档还定义了一个新的BGP可传递IPv6地址特定的扩展社区子类型：“区域间P2MP下一跳”。
A PE, an ABR, or an ASBR constructs the Inter-Area P2MP Segmented Next-Hop Extended Community as follows:
PE、ABR或ASBR构建区域间P2MP分段下一跳扩展社区，如下所示：
- The Global Administrator field MUST be set to an IP address of the PE, ABR, or ASBR that originates or advertises the route carrying the P2MP Next-Hop Extended Community. For example this address may be the loopback address or the PE, ABR, or ASBR that advertises the route.
- “全局管理员”字段必须设置为PE、ABR或ASBR的IP地址，该PE、ABR或ASBR发起或播发承载P2MP下一跳扩展社区的路由。例如，该地址可以是环回地址，也可以是播发路由的PE、ABR或ASBR。
- The Local Administrator field MUST be set to 0.
- “本地管理员”字段必须设置为0。
If the Global Administrator field is an IPv4 address, the IPv4-Address-Specific Extended Community is used; if the Global Administrator field is an IPv6 address, the IPv6-Address-Specific Extended Community is used.
如果全局管理员字段是IPv4地址，则使用IPv4地址特定的扩展社区；如果全局管理员字段是IPv6地址，则使用特定于IPv6地址的扩展社区。
The detailed usage of these Extended Communities is described in the following sections.
这些扩展社区的详细用法将在以下部分中描述。
Each inter-area P2MP service LSP has associated with it P2MP Forwarding Equivalence Class (FEC). The egress PEs need to learn this P2MP FEC in order to initiate the creation of the egress area segment of the P2MP inter-area service LSP.
每个区域间P2MP服务LSP都与其P2MP转发等价类（FEC）相关联。出口PEs需要学习该P2MP FEC，以便开始创建P2MP区域间服务LSP的出口区域段。
The P2MP FEC of the inter-area P2MP LSP is learned by the egress PEs either by configuration or based on the application-specific procedures (e.g., MVPN-specific procedures or VPLS-specific procedures).
区域间P2MP LSP的P2MP FEC由出口PEs通过配置或基于应用特定程序（例如，MVPN特定程序或VPLS特定程序）学习。
Egress PEs and/or ASBRs discover the P2MP FEC of the service LSPs used by BGP MVPN using the Inclusive Provider Multicast Service Interface (I-PMSI) or Selective PMSI (S-PMSI) A-D routes that are originated by the ingress PEs or ASBRs following the procedures of [RFC6514], along with modifications as described in this document. The Network Layer Reachability Information (NLRI) of such routes encodes the P2MP FEC.
出口PEs和/或ASBR使用包含式提供商多播服务接口（I-PMSI）或选择性PMSI（S-PMSI）A-D路由发现BGP MVPN使用的服务LSP的P2MP FEC，该路由由入口PEs或ASBR按照[RFC6514]的程序发起，并进行本文档中所述的修改。这种路由的网络层可达性信息（NLRI）编码P2MP FEC。
The procedures in this document require that at least one ABR in a given IGP area act as a Route Reflector for MVPN A-D routes. Such a Router Reflector is responsible for re-advertising MVPN A-D routes across area boundaries. When re-advertising these routes across area boundaries, this Route Reflector MUST follow the procedures in this
本文件中的程序要求给定IGP区域中至少有一个ABR充当MVPN a-D路由的路由反射器。这种路由器反射器负责跨区域边界重新宣传MVPN a-D路由。当跨越区域边界重新宣传这些路线时，该路线反射器必须遵循本节中的程序
document. Note that such a Route Reflector may also re-advertise MVPN A-D routes within the same area; in which case, it follows the plain BGP Route Reflector procedures [RFC4456].
文件注意，这样的路由反射器还可以在相同区域内重新宣传MVPN a-D路由；在这种情况下，它遵循普通BGP路由反射器程序[RFC4456]。
The "Leaf Information Required" flag MUST be set in the PMSI Tunnel attribute carried in the MVPN A-D routes, when originated by the ingress PEs or ASBRs, except for the case where (a) as a matter of policy (provisioned on the ingress PEs or ASBRs) there is no aggregation of ingress area segments of the service LSPs and (b) mLDP is used as the protocol to establish intra-area transport LSPs in the ingress area. Before any Leaf A-D route is advertised by a PE or ABR in the same area, as described in the following sections, an I-PMSI/S-PMSI A-D route is advertised either with an explicit Tunnel Type and Tunnel Identifier in the PMSI Tunnel attribute, if the Tunnel Identifier has already been assigned, or with a special Tunnel Type of "No tunnel information present" otherwise.
当由入口PEs或ASBR发起时，必须在MVPN A-D路由中携带的PMSI隧道属性中设置“所需叶信息”标志，但以下情况除外：（A）根据策略（在入口PEs或ASBR上提供）不存在服务LSP的入口区域段的聚合和（b）mLDP用作在入口区域中建立区域内传输LSP的协议。在同一区域中的PE或ABR播发任何叶A-D路由之前，如以下各节所述，I-PMSI/S-PMSI A-D路由通过PMSI隧道属性中的显式隧道类型和隧道标识符播发（如果已分配隧道标识符），或者通过特殊的隧道类型播发否则，“不存在隧道信息”。
When the I-PMSI/S-PMSI A-D routes are re-advertised by an ingress ABR, the "Leaf Information Required" flag MUST be set in the PMSI Tunnel attribute present in the routes, except for the case where (a) as a matter of policy (provisioned on the ingress ABR) there is no aggregation of backbone area segments of the service LSPs and (b) mLDP is used as the protocol to establish intra-area transport LSPs in the backbone area. Likewise, when the I-PMSI/S-PMSI A-D routes are re-advertised by an egress ABR, the "Leaf Information Required" flag MUST be set in the PMSI Tunnel attribute present in the routes, except for the case where (a) as a matter of policy (provisioned on the egress ABR) there is no aggregation of egress area segments of the service LSPs and (b) mLDP is used as the protocol to establish intra-area transport LSPs in the egress area.
当I-PMSI/S-PMSI A-D路由由入口ABR重新通告时，必须在路由中存在的PMSI隧道属性中设置“所需叶信息”标志，除非（A）作为策略事项（在入口ABR上提供）没有服务lsp的主干区域段的聚合和（b）mLDP用作在主干区域中建立区域内传输LSP的协议。类似地，当I-PMSI/S-PMSI A-D路由由出口ABR重新通告时，必须在路由中存在的PMSI隧道属性中设置“所需叶信息”标志，除非（A）作为策略事项（在出口ABR上提供）不存在服务lsp的出口区域段的聚合和（b）mLDP用作在出口区域中建立区域内传输LSP的协议。
Note that the procedures in the above paragraph apply when intra-area segments are realized by either intra-area P2MP LSPs or by ingress replication.
注意，当通过区域内P2MP LSP或入口复制实现区域内段时，上述段落中的程序适用。
When BGP MVPN I-PMSI or S-PMSI A-D routes are advertised or propagated to signal inter-area P2MP service LSPs, to indicate that these LSPs should be segmented using the procedures specified in this document, these routes MUST carry the Inter-Area P2MP Segmented Next-Hop Extended Community. This Extended Community MUST be included in the I-PMSI/S-PMSI A-D route by the PE that originates such a route, or an ASBR that re-advertises such a route into its own
当BGP MVPN I-PMSI或S-PMSI A-D路由被播发或传播到区域间P2MP服务LSP信号时，为了指示这些LSP应使用本文件中规定的程序进行分段，这些路由必须承载区域间P2MP分段下一跳扩展社区。发起该路线的PE或将该路线重新发布到其自身的ASBR必须将该扩展社区包括在I-PMSI/S-PMSI A-D路线中
AS. The Global Administrator field in this Extended Community MUST be set to the advertising PE or ASBR's IP address. This Extended Community MUST also be included by ABRs as they re-advertise such routes. An ABR MUST set the Global Administrator field of the Inter-Area P2MP Segmented Next-Hop Extended Community to its own IP address. Presence of this Extended Community in the I-PMSI/S-PMSI A-D routes indicates to ABRs and PEs/ASBRs that they have to follow the procedures in this document when these procedures differ from those in [RFC6514].
像此扩展社区中的“全局管理员”字段必须设置为广告PE或ASBR的IP地址。ABR还必须包括这个扩展社区，因为他们重新宣传这些路线。ABR必须将区域间P2MP分段下一跳扩展社区的全局管理员字段设置为其自己的IP地址。I-PMSI/S-PMSI A-D路线中存在的扩展社区向ABR和PEs/ASBR表明，当这些程序与[RFC6514]中的程序不同时，他们必须遵循本文件中的程序。
If an ASBR receives from an IBGP peer an I-PMSI or S-PMSI A-D route that carries the Inter-Area P2MP Segmented Next-Hop Extended Community, then before re-advertising this route to an EBGP peer, the ASBR SHOULD remove this Extended Community from the route.
如果ASBR从IBGP对等方接收到携带区域间P2MP分段下一跳扩展社区的I-PMSI或S-PMSI A-D路由，则在向EBGP对等方重新公布该路由之前，ASBR应从路由中删除该扩展社区。
Suppose an ASBR receives an I-PMSI/S-PMSI A-D route from an EBGP peer, and this route carries the Inter-Area P2MP Segmented Next-Hop Extended Community. If the inter-area P2MP service LSP signaled by this route should not be segmented, then before re-advertising this route to its IBGP peers, the ASBR MUST remove this Extended Community from the route.
假设ASBR从EBGP对等方接收I-PMSI/S-PMSI A-D路由，该路由承载区域间P2MP分段下一跳扩展社区。如果此路由发出的区域间P2MP服务LSP不应分段，则在向其IBGP对等方重新发布此路由之前，ASBR必须从路由中删除此扩展社区。
To avoid requiring ABRs to participate in the propagation of C-multicast routes, this document requires that ABRs MUST NOT modify the BGP Next Hop when re-advertising Inter-AS I-PMSI A-D routes. For consistency, this document requires that ABRs MUST NOT modify the BGP Next Hop when re-advertising either Intra-AS or Inter-AS I-PMSI/S-PMSI A-D routes. The egress PEs may advertise the C-multicast routes to RRs that are different than the ABRs. However, ABRs can still be configured to be the Route Reflectors for C-multicast routes; in which case, they will participate in the propagation of C-multicast routes.
为了避免要求ABR参与C-多播路由的传播，本文件要求ABR在将Inter-AS I-PMSI A-D路由重新发布时不得修改BGP下一跳。为保持一致性，本文件要求ABR在重新公布AS内或AS间I-PMSI/S-PMSI A-D路由时不得修改BGP下一跳。出口PEs可以向不同于abr的RRs通告C多播路由。然而，abr仍然可以被配置为C多播路由的路由反射器；在这种情况下，它们将参与C多播路由的传播。
Egress PEs discover the P2MP FEC of the service LSPs used by VPLS, using the VPLS A-D routes that are originated by the ingress PEs [RFC4761] [RFC6074] or VPLS S-PMSI A-D routes that are originated by the ingress PEs [RFC7117]. The NLRI of such routes encodes the P2MP FEC.
出口PEs使用入口PEs[RFC4761][RFC6074]发起的VPLS A-D路由或入口PEs[RFC7117]发起的VPLS S-PMSI A-D路由发现VPLS使用的服务LSP的P2MP FEC。这些路由的NLRI编码P2MP FEC。
The "Leaf Information Required" flag MUST be set in the PMSI Tunnel attribute carried in the VPLS A-D routes or VPLS S-PMSI A-D routes, when originated by the ingress PEs or ASBRs, except for the case where (a) as a matter of policy (provisioned on the ingress PEs or ASBRs) there is no aggregation of ingress area segments of the
当由入口PEs或ASBR发起时，必须在VPLS A-D路由或VPLS S-PMSI A-D路由中携带的PMSI隧道属性中设置“所需叶信息”标志，但以下情况除外：（A）根据策略（在入口PEs或ASBR上提供）不存在入口区域段的聚合
service LSPs and (b) mLDP is used as the protocol to establish intra-area transport LSPs in the ingress area. Before any Leaf A-D route is advertised by a PE or ABR in the same area, as described in the following sections, a VPLS/S-PMSI A-D route is advertised either with an explicit Tunnel Type and Tunnel Identifier in the PMSI Tunnel attribute, if the Tunnel Identifier has already been assigned, or with a special Tunnel Type of "No tunnel information present" otherwise.
服务LSP和（b）mLDP用作在入口区域中建立区域内传输LSP的协议。在同一区域内的PE或ABR播发任何叶A-D路由之前，如以下各节所述，VPLS/S-PMSI A-D路由通过PMSI隧道属性中的显式隧道类型和隧道标识符播发（如果已分配隧道标识符），或者通过特殊的隧道类型播发否则，“不存在隧道信息”。
When the VPLS/S-PMSI A-D routes are re-advertised by an ingress ABR, the "Leaf Information Required" flag MUST be set in the PMSI Tunnel attribute present in the routes, except for the case where (a) as a matter of policy (provisioned on the ingress ABR) there is no aggregation of backbone area segments of the service LSPs and (b) mLDP is used as the protocol to establish intra-area transport LSPs in the backbone area. Likewise, when the VPLS/S-PMSI A-D routes are re-advertised by an egress ABR, the "Leaf Information Required" flag MUST be set in the PMSI Tunnel attribute present in the routes, except for the case where (a) as a matter of policy (provisioned on the egress ABR) there is no aggregation of egress area segments of the service LSPs and (b) mLDP is used as the protocol to establish intra-area transport LSPs in the egress area.
当入口ABR重新通告VPLS/S-PMSI A-D路由时，必须在路由中存在的PMSI隧道属性中设置“所需叶信息”标志，但以下情况除外：（A）作为策略（在入口ABR上提供）不存在服务LSP的主干区域段的聚合和（b）mLDP用作在主干区域中建立区域内传输LSP的协议。类似地，当出口ABR重新通告VPLS/S-PMSI A-D路由时，必须在路由中存在的PMSI隧道属性中设置“所需叶信息”标志，除非（A）作为策略事项（在出口ABR上提供）不存在服务lsp的出口区域段的聚合和（b）mLDP用作在出口区域中建立区域内传输LSP的协议。
When VPLS A-D routes or S-PMSI A-D routes are advertised or propagated to signal inter-area P2MP service LSPs, to indicate that these LSPs should be segmented using the procedures specified in this document, these routes MUST carry the Inter-Area P2MP Segmented Next-Hop Extended Community. This Extended Community MUST be included in the A-D route by the PE or ASBR that originates such a route, and the Global Administrator field MUST be set to the advertising PE or ASBR's IP address. This Extended Community MUST also be included by ABRs as they re-advertise such routes. An ABR MUST set the Global Administrator field of the Inter-Area P2MP Segmented Next-Hop Extended Community to its own IP address. Presence of this Extended Community in the I-PMSI/S-PMSI A-D routes indicates to ABRs and PEs/ASBRs that they have to follow the procedures in this document when these procedures differ from those in [RFC7117].
当VPLS A-D路由或S-PMSI A-D路由被广告或传播到区域间P2MP服务LSP的信号时，为了指示这些LSP应使用本文件中规定的程序进行分段，这些路由必须承载区域间P2MP分段下一跳扩展社区。发起此类路由的PE或ASBR必须将此扩展社区包括在A-D路由中，并且必须将“全局管理员”字段设置为广告PE或ASBR的IP地址。ABR还必须包括这个扩展社区，因为他们重新宣传这些路线。ABR必须将区域间P2MP分段下一跳扩展社区的全局管理员字段设置为其自己的IP地址。I-PMSI/S-PMSI A-D路线中存在的扩展社区向ABR和PEs/ASBR表明，当这些程序与[RFC7117]中的程序不同时，他们必须遵循本文件中的程序。
Note that the procedures in the above paragraph apply when intra-area segments are realized by either intra-area P2MP LSPs or by ingress replication.
注意，当通过区域内P2MP LSP或入口复制实现区域内段时，上述段落中的程序适用。
The procedures in this document require that at least one ABR in a given area act as a Route Reflector for VPLS A-D routes. Such a Router Reflector is responsible for re-advertising VPLS A-D routes across areas boundaries. When re-advertising these routes across areas boundaries, this Route Reflector MUST follow the procedures in this document. Note that such a Route Reflector may also re-advertise VPLS A-D routes within the same area; in which case, it follows plain BGP Route Reflector procedures [RFC4456].
本文件中的程序要求给定区域中至少有一个ABR充当VPLS a-D路由的路由反射器。这种路由器反射器负责跨区域边界重新宣传VPLS a-D路由。当跨越区域边界重新宣传这些路线时，该路线必须遵循本文件中的程序。注意，这样的路由反射器还可以在同一区域内重新通告VPLS a-D路由；在这种情况下，它遵循普通BGP路由反射器程序[RFC4456]。
When re-advertising VPLS A-D routes, a Route Reflector MUST NOT modify the BGP Next Hop of these routes.
当重新公布VPLS A-D路由时，路由反射器不得修改这些路由的BGP下一跳。
This section describes how the egress PEs discover the P2MP FEC when the application is global table multicast over an MPLS-capable infrastructure. In the rest of the document, we will refer to this application as "global table multicast".
本节描述了当应用程序在支持MPLS的基础设施上进行全局表多播时，出口PEs如何发现P2MP FEC。在文档的其余部分中，我们将此应用程序称为“全局表多播”。
When Protocol Independent Multicast - Sparse Mode (PIM-SM) is used for non-bidirectional ASM ("Any Source Multicast") group addresses, this document refers to this as "PIM-SM in ASM mode".
当协议独立多播稀疏模式（PIM-SM）用于非双向ASM（“任何源多播”）组地址时，本文档将其称为“ASM模式下的PIM-SM”。
In the case where global table multicast uses PIM-SM in ASM mode, the following assumes that an inter-area P2MP service LSP could be used to carry traffic either on a shared (*,G) or a source (S,G) tree.
在全局表多播在ASM模式下使用PIM-SM的情况下，以下假设区域间P2MP服务LSP可用于在共享（*，G）树或源（S，G）树上承载流量。
An egress PE learns the (S/*,G) of a multicast stream as a result of receiving IGMP or PIM messages on one of its IP multicast interfaces. This (S/*,G) forms the P2MP FEC of the inter-area P2MP service LSP. For each such P2MP FEC, there MAY exist a distinct inter-area P2MP service LSP, or multiple such FECs MAY be carried over a single P2MP service LSP using a wildcard (*,*) S-PMSI [RFC6625].
出口PE通过在其一个IP多播接口上接收IGMP或PIM消息来学习多播流的（S/*，G）。这（S/*，G）形成区域间P2MP服务LSP的P2MP FEC。对于每个这样的P2MP FEC，可能存在不同的区域间P2MP服务LSP，或者可以使用通配符（*，*）S-PMSI[RFC6625]在单个P2MP服务LSP上携带多个这样的FEC。
Note that this document does not require the use of (*,G) inter-area P2MP service LSPs when global table multicast uses PIM-SM in ASM mode. In fact, PIM-SM in ASM mode may be supported entirely by using only (S,G) inter-area P2MP service LSPs.
请注意，当全局表多播在ASM模式下使用PIM-SM时，本文档不要求使用（*，G）区域间P2MP服务LSP。事实上，ASM模式下的PIM-SM可以通过仅使用（S，G）区域间P2MP服务LSP完全得到支持。
This section describes the egress PE/ASBR procedures for constructing segmented inter-area P2MP LSPs. The procedures in this section apply irrespective of whether the egress PE/ASBR is in a leaf IGP area, the backbone area, or even in the same IGP area as the ingress PE/ASBR.
本节描述了构建分段区域间P2MP LSP的出口PE/ASBR程序。无论出口PE/ASBR是否位于叶IGP区域、主干区域或甚至与入口PE/ASBR位于同一IGP区域，本节中的程序均适用。
An egress PE/ASBR applies procedures specified in this section to MVPN I-PMSI or S-PMSI A-D routes only if these routes carry the Inter-Area P2MP Segmented Next-Hop Extended Community. An egress PE applies procedures specified in this section to VPLS A-D routes or VPLS S-PMSI A-D routes only if these routes carry the Inter-Area P2MP Segmented Next-Hop Extended Community.
出口PE/ASBR仅当MVPN I-PMSI或S-PMSI A-D路由承载区域间P2MP分段下一跳扩展社区时，才将本节规定的程序应用于MVPN I-PMSI或S-PMSI A-D路由。出口PE仅当VPLS A-D路由或VPLS S-PMSI A-D路由承载区域间P2MP分段下一跳扩展社区时，才将本节规定的程序应用于这些路由。
In order to support global table multicast, an egress PE MUST be auto-configured to import routes that carry an AS-specific Route Target Extended Community ([RFC4360]) with the Global Administrator field set to the AS of the PE and the Local Administrator field set to 0.
为了支持全局表多播，出口PE必须自动配置为导入带有AS特定路由目标扩展社区（[RFC4360]）的路由，全局管理员字段设置为PE的AS，本地管理员字段设置为0。
Once an egress PE/ASBR discovers the P2MP FEC of an inter-area segmented P2MP service LSP, it MUST propagate this P2MP FEC in BGP in order to construct the segmented inter-area P2MP service LSP. This propagation uses BGP Leaf A-D routes.
一旦出口PE/ASBR发现区域间分段P2MP服务LSP的P2MP FEC，它必须在BGP中传播该P2MP FEC，以便构建区域间分段P2MP服务LSP。此传播使用BGP叶A-D路由。
An egress PE/ASBR discovers the P2MP FEC of an inter-area P2MP segmented service LSP as described in Section 5. Once the egress PE/ASBR discovers this P2MP FEC, it MUST determine the upstream node to reach such a FEC. If the egress PE/ASBR and the ingress PE/ASBR are not in the same area, and the egress PE/ASBR is not in the backbone IGP area, then this upstream node would be an egress ABR. If the egress PE/ASBR is in the backbone area and the ingress PE/ASBR is not in the backbone area, then this upstream node would be an ingress ABR. If the egress PE/ASBR is in the same area as the ingress PE/ASBR, then this upstream node would be the ingress PE/ASBR.
出口PE/ASBR发现区域间P2MP分段服务LSP的P2MP FEC，如第5节所述。一旦出口PE/ASBR发现该P2MP FEC，它必须确定上游节点以到达该FEC。如果出口PE/ASBR和入口PE/ASBR不在同一区域中，并且出口PE/ASBR不在主干IGP区域中，则该上游节点将是出口ABR。如果出口PE/ASBR在主干区域，而入口PE/ASBR不在主干区域，则该上游节点将是入口ABR。如果出口PE/ASBR与入口PE/ASBR位于同一区域，则该上游节点将是入口PE/ASBR。
If the application is MVPN or VPLS, then the upstream node's IP address is the IP address determined from the Global Administrator field of the Inter-Area P2MP Segmented Next-Hop Extended Community. As described in Section 5, this Extended Community MUST be carried in the MVPN or VPLS A-D route from which the P2MP FEC of the inter-area P2MP segmented service LSP is determined.
如果应用程序是MVPN或VPLS，则上游节点的IP地址是根据区域间P2MP分段下一跳扩展社区的全局管理员字段确定的IP地址。如第5节所述，该扩展社区必须在MVPN或VPLS A-D路线中承载，从该路线确定区域间P2MP分段服务LSP的P2MP FEC。
If the application is global table multicast, then the unicast routes to multicast sources/RPs SHOULD carry the "VRF Route Import" Extended Community [RFC6514] where the IP address in the Global Administrator field is set to the IP address of the PE or ASBR advertising the unicast route. The Local Administrator field of this Extended Community MUST be set to 0 (note that this is in contrast to the case of MVPN, where the Local Administrator field carries a non-zero value that identifies a particular VRF on a PE that originates VPN-IP routes). If it is not desirable to advertise the VRF Route Import Extended Community in unicast routes, then unicast routes to multicast sources/RPs MUST be advertised using the multicast Subsequent Address Family Identifier (SAFI), i.e., SAFI 2, and such routes MUST carry the VRF Route Import Extended Community.
如果应用程序是全局表多播，则到多播源/RP的单播路由应带有“VRF路由导入”扩展社区[RFC6514]，其中全局管理员字段中的IP地址设置为宣传单播路由的PE或ASBR的IP地址。此扩展社区的本地管理员字段必须设置为0（请注意，这与MVPN的情况相反，MVPN的本地管理员字段带有非零值，该值标识发起VPN-IP路由的PE上的特定VRF）。如果不希望在单播路由中播发VRF路由导入扩展社区，则必须使用多播后续地址族标识符（SAFI），即SAFI 2，播发到多播源/RP的单播路由，并且此类路由必须携带VRF路由导入扩展社区。
Further, if the application is global table multicast, then the BGP unicast routes that advertise the routes to the IP addresses of PEs/ASBRs/ABRs SHOULD carry the Inter-Area P2MP Segmented Next-Hop Extended Community. The IP address in the Global Administrator field of this Extended Community MUST be set to the IP address of the PE, ASBR, or ABR advertising the unicast route. The Local Administrator field of this Extended Community MUST be set to 0. If it is not desirable to advertise the Inter-Area P2MP Segmented Next-Hop Extended Community in BGP unicast routes, then the BGP unicast routes to the IP addresses of PEs/ASBRs/ABRs MUST be advertised using the multicast SAFI, i.e., SAFI 2, and such routes MUST carry the Inter-Area P2MP Segmented Next-Hop Extended Community. The procedures for handling the BGP Next Hop attribute of SAFI 2 routes are the same as those of handling regular unicast routes and MAY follow [SEAMLESS-MPLS].
此外，如果应用程序是全局表多播，则向PEs/ASBR/ABR的IP地址播发路由的BGP单播路由应携带区域间P2MP分段下一跳扩展社区。此扩展社区的“全局管理员”字段中的IP地址必须设置为播发单播路由的PE、ASBR或ABR的IP地址。此扩展社区的本地管理员字段必须设置为0。如果不希望在BGP单播路由中通告区域间P2MP分段下一跳扩展社区，则必须使用多播SAFI（即SAFI 2）通告到PEs/ASBR/ABR的IP地址的BGP单播路由，并且此类路由必须承载区域间P2MP分段下一跳扩展社区。处理SAFI 2路由的BGP下一跳属性的过程与处理常规单播路由的过程相同，可以遵循[无缝-MPLS]。
If the application is global table multicast, then in order to determine the upstream node address, the egress PE first determines the ingress PE. In order to determine the ingress PE, the egress PE determines the best route to reach the S/RP. The ingress PE address is the IP address determined from the Global Administrator field of the VRF Route Import Extended Community that is carried in this route. Then, the egress PE finds the best unicast route to reach the ingress PE. The upstream node address is the IP address determined from the Global Administrator field of the Inter-Area P2MP Segmented Next-Hop Extended Community that is carried in this route.
如果应用程序是全局表多播，则为了确定上游节点地址，出口PE首先确定入口PE。为了确定入口PE，出口PE确定到达S/RP的最佳路由。入口PE地址是从该路由中携带的VRF路由导入扩展社区的全局管理员字段确定的IP地址。然后，出口PE找到到达入口PE的最佳单播路由。上游节点地址是根据该路由中承载的区域间P2MP分段下一跳扩展社区的全局管理员字段确定的IP地址。
If the P2MP FEC was derived from an MVPN or VPLS A-D route, and if the route carries a PMSI Tunnel attribute with the "Leaf Information Required" flag set, then the egress PE MUST originate a Leaf A-D route.
如果P2MP FEC来自MVPN或VPLS A-D路由，并且如果该路由带有设置了“需要叶信息”标志的PMSI隧道属性，则出口PE必须发起叶A-D路由。
If the P2MP FEC was derived from a global table multicast (S/*,G), and the upstream node's address is not the same as the egress PE, then the egress PE MUST originate a Leaf A-D route.
如果P2MP FEC来自全局表多播（S/*，G），并且上游节点的地址与出口PE不同，则出口PE必须发起一个叶a-D路由。
If the P2MP FEC was derived from MVPN or VPLS A-D routes, then the Route Key field of the Leaf A-D route contains the NLRI of the A-D route from which the P2MP FEC was derived. This follows procedures for constructing Leaf A-D routes described in [RFC6514] [RFC7117].
如果P2MP FEC源于MVPN或VPLS A-D路由，则叶A-D路由的路由键字段包含源于P2MP FEC的A-D路由的NLRI。这遵循[RFC6514][RFC7117]中描述的构建叶A-D路由的过程。
If the application is global table multicast, then the MCAST-VPN NLRI of the Leaf A-D route is constructed as follows.
如果应用程序是全局表多播，则叶A-D路由的MCAST-VPN NLRI构造如下。
The Route Key field of the MCAST-VPN NLRI has the following format:
MCAST-VPN NLRI的路由密钥字段具有以下格式：
+-----------------------------------+
| RD (8 octets) |
+-----------------------------------+
| Multicast Source Length (1 octet) |
+-----------------------------------+
| Multicast Source (Variable) |
+-----------------------------------+
| Multicast Group Length (1 octet) |
+-----------------------------------+
| Multicast Group (Variable) |
+-----------------------------------+
| Ingress PE's IP Address |
+-----------------------------------+
+-----------------------------------+
| RD (8 octets) |
+-----------------------------------+
| Multicast Source Length (1 octet) |
+-----------------------------------+
| Multicast Source (Variable) |
+-----------------------------------+
| Multicast Group Length (1 octet) |
+-----------------------------------+
| Multicast Group (Variable) |
+-----------------------------------+
| Ingress PE's IP Address |
+-----------------------------------+
RD is set to 0 for (S,G) state and all ones for (*,G) state, Multicast Source is set to S for (S,G) state or RP for (*,G) state, Multicast Group is set to G, and Multicast Source Length and Multicast Group Length are set to either 4 or 16 (depending on whether S/RP and G are IPv4 or IPv6 addresses).
对于（S，G）状态，RD设置为0，对于（*，G）状态，所有值都设置为0；对于（S，G）状态，多播源设置为S；对于（*，G）状态，多播组设置为G；多播源长度和多播组长度设置为4或16（取决于S/RP和G是IPv4地址还是IPv6地址）。
The Ingress PE's IP address is determined as described in Section 6.1.
入口PE的IP地址如第6.1节所述确定。
The Originating Router's IP Address field of the MCAST-VPN NLRI is set to the address of the local PE (the PE that originates the route).
MCAST-VPN NLRI的发起路由器IP地址字段设置为本地PE（发起路由的PE）的地址。
Thus, the entire MCAST-VPN NLRI of the route has the following format:
因此，路由的整个MCAST-VPN NLRI具有以下格式：
+-----------------------------------+
| Route Type = 4 (1 octet) |
+-----------------------------------+
| Length (1 octet) |
+-----------------------------------+
| RD (8 octets) |
+-----------------------------------+
| Multicast Source Length (1 octet) |
+-----------------------------------+
| Multicast Source (Variable) |
+-----------------------------------+
| Multicast Group Length (1 octet) |
+-----------------------------------+
| Multicast Group (Variable) |
+-----------------------------------+
| Ingress PE's IP Address |
+-----------------------------------+
| Originating Router's IP Address |
+-----------------------------------+
+-----------------------------------+
| Route Type = 4 (1 octet) |
+-----------------------------------+
| Length (1 octet) |
+-----------------------------------+
| RD (8 octets) |
+-----------------------------------+
| Multicast Source Length (1 octet) |
+-----------------------------------+
| Multicast Source (Variable) |
+-----------------------------------+
| Multicast Group Length (1 octet) |
+-----------------------------------+
| Multicast Group (Variable) |
+-----------------------------------+
| Ingress PE's IP Address |
+-----------------------------------+
| Originating Router's IP Address |
+-----------------------------------+
Note that the encoding of the MCAST-VPN NLRI for the Leaf A-D routes used for global table multicast is different from the encoding used by the Leaf A-D routes originated in response to S-PMSI or I-PMSI A-D routes. A router that receives a Leaf A-D route can distinguish between these two cases by examining the third octet of the MCAST-VPN NLRI of the route. If the value of this octet is 0x01, 0x02, or 0x03, then this Leaf A-D route was originated in response to an S-PMSI or I-PMSI A-D route. If the value of this octet is either 0x00 or 0xff, and octets 3 through 10 contain either all 0x00 or all 0xff, then this is a Leaf A-D route used for global table multicast.
请注意，用于全局表多播的叶A-D路由的MCAST-VPN NLRI编码不同于源于响应S-PMSI或I-PMSI A-D路由的叶A-D路由所使用的编码。接收叶子A-D路由的路由器可以通过检查路由的MCAST-VPN NLRI的第三个八位组来区分这两种情况。如果此八位组的值为0x01、0x02或0x03，则此叶A-D路由源自对S-PMSI或I-PMSI A-D路由的响应。如果此八位字节的值为0x00或0xff，并且八位字节3到10包含所有0x00或所有0xff，则这是用于全局表多播的叶a-D路由。
When the PE deletes (S,G)/(*,G) state that was created as a result of receiving PIM or IGMP messages on one of its IP multicast interfaces, if the PE previously originated a Leaf A-D route for that state, the PE SHOULD withdraw that route.
当PE删除由于在其一个IP多播接口上接收PIM或IGMP消息而创建的（S，G）/（*，G）状态时，如果PE先前为该状态发起了叶a-D路由，则PE应撤回该路由。
An AS with an IPv4 network may provide global table multicast service for customers that use IPv6, and an AS with an IPv6 network may provide global table multicast service for customers that use IPv4. Therefore, the address family of the Ingress PE's IP Address field and the Originating Router's IP Address field in the Leaf A-D routes
具有IPv4网络的AS可以为使用IPv6的客户提供全局表多播服务，而具有IPv6网络的AS可以为使用IPv4的客户提供全局表多播服务。因此，在叶A-D路由中，入口PE的IP地址字段和发起路由器的IP地址字段的地址族
used for global table multicast MUST NOT be inferred from the AFI field of the associated MP_REACH_NLRI/MP_UNREACH_NLRI attribute of these routes. The address family is determined from the length of the address (a length of 4 octets for IPv4 addresses or a length of 16 octets for IPv6 addresses).
不能从这些路由的关联MP_REACH_NLRI/MP_UNREACH_NLRI属性的AFI字段推断用于全局表多播。地址族由地址的长度确定（IPv4地址的长度为4个八位字节，IPv6地址的长度为16个八位字节）。
For example, if an AS with an IPv4 network is providing IPv6 multicast service to a customer, the Ingress PE's IP Address and Originating Router's IP Address in the Leaf A-D routes used for IPv6 global table multicast will be a 4-octet IPv4 address, even though the AFI of those routes will have the value 2.
例如，如果具有IPv4网络的AS向客户提供IPv6多播服务，则用于IPv6全局表多播的叶a-D路由中的入口PE的IP地址和发起路由器的IP地址将是4-octet IPv4地址，即使这些路由的AFI将具有值2。
Note that the Ingress PE's IP Address and the Originating Router's IP Address must be either both IPv4 or both IPv6 addresses; thus, they must be of the same length. Since the two variable-length fields (Multicast Source and Multicast Group) in the Leaf A-D routes used for global table multicast have their own Length field, from these two Length fields, and the Length field of the MCAST-VPN NLRI, one can compute the length of the Ingress PE's IP Address field and the Originating Router's IP Address field. If the computed length of these fields is neither 4 nor 16, the MP_REACH_NLRI attribute MUST be considered to be "incorrect", and MUST be handled as specified in Section 7 of [RFC4760].
注意，入口PE的IP地址和发起路由器的IP地址必须同时为IPv4或IPv6地址；因此，它们必须具有相同的长度。由于用于全局表多播的叶A-D路由中的两个可变长度字段（多播源和多播组）有自己的长度字段，从这两个长度字段和MCAST-VPN NLRI的长度字段中，可以计算入口PE的IP地址字段和原始路由器的IP地址字段的长度。如果这些字段的计算长度既不是4也不是16，则MP_REACH_NLRI属性必须被视为“不正确”，并且必须按照[RFC4760]第7节的规定进行处理。
The Next Hop field of the MP_REACH_NLRI attribute of the route SHOULD be set to the same IP address as the one carried in the Originating Router's IP Address field of the route.
路由的MP_REACH_NLRI属性的下一跳字段应设置为与路由的原始路由器IP地址字段中携带的IP地址相同的IP地址。
When ingress replication is used to instantiate the egress area segment, the Leaf A-D route MUST carry a downstream-assigned label in the PMSI Tunnel attribute where the PMSI Tunnel Type is set to ingress replication. A PE MUST assign a distinct MPLS label for each Leaf A-D route originated by the PE.
当入口复制用于实例化出口区域段时，叶A-D路由必须在PMSI隧道属性中携带下游分配的标签，其中PMSI隧道类型设置为入口复制。PE必须为PE发起的每个叶A-D路由分配不同的MPLS标签。
To constrain distribution of this route, the originating PE constructs an IP-based Route Target Extended Community by placing the IP address of the upstream node in the Global Administrator field of the Extended Community, with the Local Administrator field of this community set to 0. The originating PE then adds this Route Target Extended Community to this Leaf A-D route. The upstream node's address is determined as specified in Section 6.1.
为了约束此路由的分发，发起PE通过将上游节点的IP地址放置在扩展社区的全局管理员字段中，并将此社区的本地管理员字段设置为0，来构建基于IP的路由目标扩展社区。然后，发起PE将此路由目标扩展社区添加到此叶A-D路由。上游节点的地址按照第6.1节的规定确定。
The PE then advertises this route to the upstream node.
PE然后向上游节点播发该路由。
This specification allows two options for supporting global table multicast that are initiated using PIM-SM in ASM mode. The first option does not carry IP multicast shared trees over the MPLS network. The second option does carry shared trees over the MPLS network and provides support for switching from shared trees to source trees.
此规范允许两个选项来支持在ASM模式下使用PIM-SM启动的全局表多播。第一个选项不在MPLS网络上承载IP多播共享树。第二个选项通过MPLS网络承载共享树，并支持从共享树切换到源树。
This option does not carry IP multicast shared trees over the MPLS network. Therefore, when an (egress) PE creates (*,G) state (as a result of receiving PIM or IGMP messages on one of its IP multicast interfaces), the PE does not propagate this state using Leaf A-D routes.
此选项不在MPLS网络上承载IP多播共享树。因此，当（出口）PE创建（*，G）状态时（作为在其一个IP多播接口上接收PIM或IGMP消息的结果），PE不会使用叶a-D路由传播该状态。
Whenever an RP that is co-located with a PE discovers a new multicast source (as a result of receiving PIM Register or MSDP messages), the RP/PE SHOULD originate a BGP Source Active A-D route. Similarly, whenever, as a result of receiving MSDP messages, a PE that is not configured as an RP discovers a new multicast source, the PE SHOULD originate a BGP Source Active A-D route. The BGP Source Active A-D route carries a single MCAST-VPN NLRI constructed as follows:
每当与PE共存的RP发现新的多播源时（由于接收PIM寄存器或MSDP消息），RP/PE应发起BGP源活动a-D路由。类似地，无论何时，作为接收MSDP消息的结果，未配置为RP的PE发现新的多播源，PE都应发起BGP源活动a-D路由。BGP源活动A-D路由承载单个MCAST-VPN NLRI，其构造如下：
+ The RD in this NLRI is set to 0.
+ 此NLRI中的RD设置为0。
+ The Multicast Source field MUST be set to S. The Multicast Source Length field is set appropriately to reflect this.
+ “多播源”字段必须设置为S。多播源长度字段已适当设置以反映这一点。
+ The Multicast Group field MUST be set to G. The Multicast Group Length field is set appropriately to reflect this.
+ 多播组字段必须设置为G。多播组长度字段的设置应适当反映这一点。
The Route Target of this Source Active A-D route is an AS-specific Route Target Extended Community with the Global Administrator field set to the AS of the advertising RP/PE and the Local Administrator field set to 0.
此源活动A-D路由的路由目标是特定于AS的路由目标扩展社区，全局管理员字段设置为广告RP/PE的AS，本地管理员字段设置为0。
To constrain distribution of the Source Active A-D route to the AS of the advertising RP, this route SHOULD carry the NO_EXPORT Community ([RFC1997]).
为了将源活动A-D路由的分布限制到广告RP的AS，此路由应包含NO_导出社区（[RFC1997]）。
Using the normal BGP procedures, the Source Active A-D route is propagated to all other PEs within the AS.
使用正常BGP程序，源活动A-D路由被传播到AS内的所有其他PE。
Whenever the RP/PE discovers that the source is no longer active, the RP MUST withdraw the Source Active A-D route, if such a route was previously advertised by the RP.
每当RP/PE发现源不再处于活动状态时，RP必须撤回源活动A-D路由，前提是RP之前已公布该路由。
As a result of receiving PIM or IGMP messages on one of its IP multicast interfaces, when an egress PE creates in its Tree Information Base (TIB) a new (*,G) entry with a non-empty outgoing interface list that contains one or more IP multicast interfaces, the PE MUST check if it has any Source Active A-D routes for that G. If there is such a route, S of that route is reachable via an MPLS interface, and the PE does not have (S,G) state in its TIB for (S,G) carried in the route, then the PE originates a Leaf A-D route carrying that (S,G), as specified in Section 6.2.2.
作为在其一个IP多播接口上接收PIM或IGMP消息的结果，当出口PE在其树信息库（TIB）中创建一个包含一个或多个IP多播接口的非空输出接口列表的新（*，G）条目时，PE必须检查其是否有该G的任何源活动a-D路由。如果有这样的路由，该路由的S可通过MPLS接口访问，且PE在其TIB中没有（S，G）状态，用于路由中承载的（S，G），则PE根据第6.2.2节的规定，发起承载该（S，G）的叶a-D路由。
When an egress PE receives a new Source Active A-D route, the PE MUST check if its TIB contains an (*,G) entry with the same G as carried in the Source Active A-D route. If such an entry is found, S is reachable via an MPLS interface, and the PE does not have (S,G) state in its TIB for (S,G) carried in the route, then the PE originates a Leaf A-D route carrying that (S,G), as specified in Section 6.2.2.
当出口PE接收到新的源活动a-D路由时，PE必须检查其TIB是否包含与源活动a-D路由中携带的G相同的（*，G）条目。如果发现这样一个条目，则可以通过MPLS接口访问S，并且PE在其TIB中没有（S，G）状态用于路由中携带的（S，G），则PE根据第6.2.2节的规定发起一个携带（S，G）的叶a-D路由。
Creation and deletion of (S,G,rpt) state on a PE that resulted from receiving PIM messages on one of its IP multicast interfaces do not result in any BGP actions by the PE.
在PE的一个IP多播接口上接收PIM消息后，在PE上创建和删除（S、G、rpt）状态不会导致PE执行任何BGP操作。
This option does carry IP multicast shared trees over the MPLS network. Therefore, when an egress PE creates (*,G) state (as a result of receiving PIM or IGMP messages on one of its IP multicast interfaces), the PE does propagate this state using Leaf A-D routes.
此选项在MPLS网络上承载IP多播共享树。因此，当出口PE创建（*，G）状态时（由于在其一个IP多播接口上接收PIM或IGMP消息），该PE确实使用叶a-D路由传播该状态。
Whenever a PE creates an (S,G) state as a result of receiving Leaf A-D routes associated with the global table multicast service, if S is reachable via one of the IP multicast-capable interfaces, and the PE determines that G is in the PIM-SM in ASM mode range, the PE MUST originate a BGP Source Active A-D route. The route carries a single MCAST-VPN NLRI constructed as follows:
每当PE由于接收与全局表多播服务相关联的叶a-D路由而创建（S，G）状态时，如果可以通过其中一个支持IP多播的接口访问S，并且PE确定G处于ASM模式范围内的PIM-SM中，则PE必须发起BGP源活动a-D路由。该路由承载单个MCAST-VPN NLRI，其构造如下：
+ The RD in this NLRI is set to 0.
+ 此NLRI中的RD设置为0。
+ The Multicast Source field MUST be set to S. The Multicast Source Length field is set appropriately to reflect this.
+ “多播源”字段必须设置为S。多播源长度字段已适当设置以反映这一点。
+ The Multicast Group field MUST be set to G. The Multicast Group Length field is set appropriately to reflect this.
+ 多播组字段必须设置为G。多播组长度字段的设置应适当反映这一点。
The Route Target of this Source Active A-D route is an AS-specific Route Target Extended Community with the Global Administrator field set to the AS of the advertising PE and the Local Administrator field set to 0.
此源活动A-D路由的路由目标是特定于AS的路由目标扩展社区，全局管理员字段设置为广告PE的AS，本地管理员字段设置为0。
To constrain distribution of the Source Active A-D route to the AS of the advertising PE, this route SHOULD carry the NO_EXPORT Community [RFC1997].
为了将源活动A-D路由的分发限制到广告PE的AS，此路由应包含NO_导出社区[RFC1997]。
Using the normal BGP procedures, the Source Active A-D route is propagated to all other PEs within the AS.
使用正常BGP程序，源活动A-D路由被传播到AS内的所有其他PE。
Whenever the PE deletes the (S,G) state that was previously created as a result of receiving a Leaf A-D route for (S,G), the PE that deletes the state MUST also withdraw the Source Active A-D route, if such a route was advertised when the state was created.
每当PE删除之前由于接收（S，G）的叶a-D路由而创建的（S，G）状态时，删除该状态的PE还必须撤回源活动a-D路由（如果在创建状态时通告了该路由）。
Procedures for receiving BGP Source Active A-D routes are the same as with Option 1.
接收BGP源活动A-D路由的步骤与选项1相同。
After receiving a new Source Active A-D route for (S,G), if a PE determines that (a) it has the (*,G) entry in its TIB, (b) the incoming interface (iif) list for that entry contains one of the IP interfaces, (c) an MPLS LSP is in the outgoing interface (oif) list for that entry, and (d) the PE does not originate a Leaf A-D route for (S,G), then the PE MUST transition the (S,G,rpt) downstream state to the Prune state. [Conceptually the PIM state machine on the PE will act "as if" it had received Prune(S,G,Rpt) from some other PE, without actually having received one.] Depending on the (S,G,rpt) state on the iifs, this may result in the PE using PIM procedures to prune S off the Shared (*,G) tree.
在接收到（S，G）的新源活动a-D路由后，如果PE确定（a）其TIB中有（*，G）条目，（b）该条目的传入接口（iif）列表包含一个IP接口，（c）MPLS LSP在该条目的传出接口（oif）列表中，并且（D）PE没有为（S，G）发起叶a-D路由，然后PE必须将（S、G、rpt）下游状态转换为修剪状态。[从概念上讲，PE上的PIM状态机将“好像”它从其他PE收到了修剪（S，G，Rpt），而实际上没有收到修剪。]根据iifs上的（S，G，Rpt）状态，这可能导致PE使用PIM过程修剪共享（*，G）树上的修剪。
Transitioning the state machine to the Prune state SHOULD be done after a delay that is controlled by a timer. The value of the timer MUST be configurable. The purpose of this timer is to ensure that S is not pruned off the shared tree until all PEs have had time to receive the Source Active A-D route for (S,G).
将状态机转换到Prune状态应该在计时器控制的延迟之后完成。计时器的值必须是可配置的。此计时器的目的是确保在所有PE都有时间接收（S，G）的源活动A-D路由之前，不会从共享树中删除S。
The PE MUST keep the (S,G,rpt) downstream state machine in the Prune state for as long as (a) the outgoing interface list (oif) for (*,G) contains an MPLS LSP, (b) the PE has at least one Source Active A-D route for (S,G), and (c) the PE does not originate the Leaf A-D route for (S,G). Once any of these conditions become no longer valid, the PE MUST transition the (S,G,rpt) downstream state machine to the NoInfo state.
只要（a）用于（*，G）的传出接口列表（oif）包含MPLS LSP，（b）PE至少有一个用于（S，G）的源活动a-D路由，以及（c）PE不发起用于（S，G）的叶a-D路由，PE就必须将（S，G，rpt）下游状态机保持在修剪状态。一旦这些条件中的任何一个不再有效，PE必须将（S、G、rpt）下游状态机转换为NoInfo状态。
Note that, except for the scenario described in the first paragraph of this section, in all scenarios relying solely on PIM procedures on the PE is sufficient to ensure the correct behavior when pruning sources off the shared tree.
请注意，除了本节第一段中描述的场景外，在所有场景中，仅依赖PE上的PIM过程就足以确保在从共享树上修剪源时的正确行为。
Creation and deletion of (S,G,rpt) state on a PE that resulted from receiving PIM messages on one of its IP multicast interfaces do not result in any BGP actions by the PE.
在PE的一个IP多播接口上接收PIM消息后，在PE上创建和删除（S、G、rpt）状态不会导致PE执行任何BGP操作。
This section describes the egress ABR procedures for constructing segmented inter-area P2MP LSPs.
本节描述用于构建分段区域间P2MP LSP的出口ABR程序。
When an egress ABR receives a Leaf A-D route and the Route Target Extended Community carried by the route contains the IP address of this ABR, the following procedures will be executed.
当出口ABR接收到叶a-D路由并且该路由携带的路由目标扩展社区包含该ABR的IP地址时，将执行以下过程。
If the value of the third octet of the MCAST-VPN NLRI of the received Leaf A-D route is either 0x01, 0x02, or 0x03, this indicates that the Leaf A-D route was originated in response to an S-PMSI or I-PMSI A-D route (see Section 6.2.2). In this case, the egress ABR MUST find an S-PMSI or I-PMSI route whose NLRI has the same value as the Route Key field of the received Leaf A-D route. If such a matching route is found, then the Leaf A-D route MUST be accepted. If the Leaf A-D route is accepted and if it is the first Leaf A-D route update for the Route Key field in the route, or the withdrawal of the last Leaf A-D route for the Route Key field, then the following procedures will be executed.
如果接收到的叶A-D路由的MCAST-VPN NLRI的第三个八位组的值为0x01、0x02或0x03，则表示叶A-D路由是响应S-PMSI或I-PMSI A-D路由而产生的（见第6.2.2节）。在这种情况下，出口ABR必须找到其NLRI与所接收的叶A-D路由的路由密钥字段具有相同值的S-PMSI或I-PMSI路由。如果找到这样的匹配路由，则必须接受叶a-D路由。如果叶A-D路由被接受，并且如果它是路由中路由密钥字段的第一个叶A-D路由更新，或者是路由密钥字段的最后一个叶A-D路由的退出，则将执行以下程序。
If the RD of the received Leaf A-D route is set to all zeros or all ones, then the received Leaf A-D route is for the global table multicast service.
如果接收到的叶A-D路由的RD设置为全零或全1，则接收到的叶A-D路由用于全局表多播服务。
If the received Leaf A-D route is the first Leaf A-D route update for the Route Key field carried in the route, then the egress ABR originates a Leaf A-D route, whose MCAST-VPN NLRI is constructed as follows.
如果接收到的叶A-D路由是路由中携带的路由密钥字段的第一个叶A-D路由更新，则出口ABR发起叶A-D路由，其MCAST-VPN NLRI构造如下。
The Route Key field of the MCAST-VPN NLRI is the same as the Route Key field of the MCAST-VPN NLRI of the received Leaf A-D route. The Originating Router's IP Address field of the MCAST-VPN NLRI is set to the address of the local ABR (the ABR that originates the route).
MCAST-VPN NLRI的路由密钥字段与接收到的叶A-D路由的MCAST-VPN NLRI的路由密钥字段相同。MCAST-VPN NLRI的发起路由器IP地址字段设置为本地ABR（发起路由的ABR）的地址。
The Next Hop field of the MP_REACH_NLRI attribute of the route SHOULD be set to the same IP address as the one carried in the Originating Router's IP Address field of the route.
路由的MP_REACH_NLRI属性的下一跳字段应设置为与路由的原始路由器IP地址字段中携带的IP地址相同的IP地址。
To constrain distribution of this route, the originating egress ABR constructs an IP-based Route Target Extended Community by placing the IP address of the upstream node in the Global Administrator field of the Extended Community, with the Local Administrator field of this Extended Community set to 0, and sets the Extended Communities attribute of this Leaf A-D route to that Extended Community.
为了约束此路由的分布，发起出口ABR通过将上游节点的IP地址放置在扩展社区的全局管理员字段中，并将此扩展社区的本地管理员字段设置为0，来构建基于IP的路由目标扩展社区，并将此叶A-D路由的“扩展社区”属性设置为该扩展社区。
The upstream node's IP address is the IP address determined from the Global Administrator field of the Inter-Area P2MP Segmented Next-Hop Extended Community, where this Extended Community is obtained as follows. When the Leaf A-D route is for MVPN or VPLS, this Extended Community is the one carried in the I-PMSI/S-PMSI A-D route that matches the Leaf A-D route. When the Leaf A-D route is for global table multicast, this Extended Community is the one carried in the best unicast route to the Ingress PE. The Ingress PE address is determined from the received Leaf A-D route. The best unicast route MUST first be determined from multicast SAFI, i.e., SAFI 2 routes, if present.
上游节点的IP地址是根据区域间P2MP分段下一跳扩展社区的全局管理员字段确定的IP地址，其中该扩展社区的获得如下。当叶A-D路由用于MVPN或VPLS时，此扩展社区是与叶A-D路由匹配的I-PMSI/S-PMSI A-D路由中承载的社区。当叶A-D路由用于全局表多播时，此扩展社区是到入口PE的最佳单播路由中承载的社区。入口PE地址由接收到的叶A-D路由确定。最好的单播路由必须首先从多播SAFI确定，即SAFI 2路由（如果存在）。
The ABR then advertises this Leaf A-D route to the upstream node in the backbone area.
然后，ABR将该叶A-D路由播发到主干区域中的上游节点。
Mechanisms specified in [RFC4684] for constrained BGP route distribution can be used along with this specification to ensure that only the needed PE/ABR will have to process a said Leaf A-D route.
[RFC4684]中规定的约束BGP路由分配机制可与本规范一起使用，以确保只有所需的PE/ABR必须处理所述叶a-D路由。
When ingress replication is used to instantiate the backbone area segment, the Leaf A-D route originated by the egress ABR MUST carry a downstream-assigned label in the PMSI Tunnel attribute where the Tunnel Type is set to ingress replication. The ABR MUST assign a distinct MPLS label for each Leaf A-D route that it originates.
当入口复制用于实例化主干区域段时，由出口ABR发起的叶A-D路由必须在PMSI隧道属性中携带下游分配的标签，其中隧道类型设置为入口复制。ABR必须为其发起的每个叶a-D路由分配不同的MPLS标签。
In order to support global table multicast, an egress ABR MUST auto-configure an import AS-based Route Target Extended Community with the Global Administrator field set to the AS of the ABR and the Local Administrator field set to 0.
为了支持全局表多播，出口ABR必须自动配置基于导入AS的路由目标扩展社区，全局管理员字段设置为ABR的AS，本地管理员字段设置为0。
If the received Leaf A-D route is the withdrawal of the last Leaf A-D route for the Route Key carried in the route, then the egress ABR must withdraw the Leaf A-D route associated with that Route Key that has been previously advertised by the egress ABR in the backbone area.
如果接收到的叶A-D路由是对路由中携带的路由密钥的最后一个叶A-D路由的撤回，则出口ABR必须撤回与该路由密钥相关联的叶A-D路由，该路由密钥先前已由出口ABR在主干区域中通告。
This section describes procedures for using intra-area P2MP LSPs in the egress area. The procedures that are common to both P2MP RSVP-TE and P2MP LDP are described first, followed by procedures that are specific to the signaling protocol.
本节描述在出口区域中使用区域内P2MP LSP的过程。首先描述P2MP RSVP-TE和P2MP LDP通用的过程，然后描述特定于信令协议的过程。
When P2MP LSPs are used as the intra-area LSPs, note that an existing intra-area P2MP LSP may be used solely for a particular inter-area P2MP service LSP or for other inter-area P2MP service LSPs as well.
当P2MP LSP用作区域内LSP时，请注意，现有区域内P2MP LSP可仅用于特定区域间P2MP服务LSP或其他区域间P2MP服务LSP。
The choice between the two options is purely local to the egress ABR. The first option provides one-to-one mapping between inter-area P2MP service LSPs and intra-area P2MP LSPs; the second option provides many-to-one mapping, thus allowing the aggregation of forwarding state.
这两个选项之间的选择完全取决于出口ABR。第一个选项提供区域间P2MP服务LSP和区域内P2MP LSP之间的一对一映射；第二个选项提供多对一映射，从而允许聚合转发状态。
If the value of the third octet of the MCAST-VPN NLRI of the received Leaf A-D route is either 0x01, 0x02, or 0x03, this indicates that the Leaf A-D route was originated in response to an MVPN or VPLS S-PMSI or I-PMSI A-D route (see Section 6.2.2). In this case, the ABR MUST re-advertise in the egress area the MVPN/VPLS A-D route that matches the Leaf A-D route to signal the binding of the intra-area P2MP LSP to the inter-area P2MP service LSP. This must be done if and only if (a) such a binding hasn't already been advertised or (b) the binding has changed. The re-advertised route MUST carry the Inter-area P2MP Segmented Next-Hop Extended Community.
如果接收到的叶A-D路由的MCAST-VPN NLRI的第三个八位组的值为0x01、0x02或0x03，则表示叶A-D路由是响应MVPN或VPLS S-PMSI或I-PMSI A-D路由而产生的（参见第6.2.2节）。在这种情况下，ABR必须在出口区域中重新通告与叶A-D路由匹配的MVPN/VPLS A-D路由，以发出区域内P2MP LSP到区域间P2MP服务LSP的绑定的信号。当且仅当（a）此类绑定尚未发布或（b）绑定已更改时，才必须执行此操作。重新公布的路线必须承载区域间P2MP分段下一跳扩展社区。
The PMSI Tunnel attribute of the re-advertised route specifies either an intra-area P2MP RSVP-TE LSP or an intra-area P2MP LDP LSP rooted at the ABR and MUST also carry an upstream-assigned MPLS label. The upstream-assigned MPLS label MUST be set to Implicit NULL if the mapping between the inter-area P2MP service LSP and the intra-area P2MP LSP is one-to-one. If the mapping is many-to-one, the intra-area segment of the inter-area P2MP service LSP (referred to as the
重新播发的路由的PMSI隧道属性指定以ABR为根的区域内P2MP RSVP-TE LSP或区域内P2MP LDP LSP，并且还必须携带上游分配的MPLS标签。如果区域间P2MP服务LSP和区域内P2MP LSP之间的映射为一对一，则上游分配的MPLS标签必须设置为隐式NULL。如果映射为多对一，则区域间P2MP服务LSP的区域内段（称为
"inner" P2MP LSP) is constructed by nesting the inter-area P2MP service LSP in an intra-area P2MP LSP (referred to as the "outer" intra-area P2MP LSP), by using P2MP LSP hierarchy based on upstream-assigned MPLS labels [RFC5332].
“内部”P2MP LSP）是通过使用基于上游分配的MPLS标签的P2MP LSP层次结构，将区域间P2MP服务LSP嵌套在区域内P2MP LSP（称为“外部”区域内P2MP LSP）中而构建的[RFC5332]。
If segments of multiple MVPN or VPLS S-PMSI service LSPs are carried over a given intra-area P2MP LSP, each of these segments MUST carry a distinct upstream-assigned label, even if all these service LSPs are for (C-S/*,C-G/*)s from the same MVPN/VPLS. Therefore, an ABR maintains a Label Forwarding Information Base (LFIB) state for each such S-PMSI traversing the ABR (that applies to both the ingress and the egress ABRs).
如果多个MVPN或VPLS S-PMSI服务LSP的段承载在给定的区域内P2MP LSP上，则这些段中的每一个都必须承载一个不同的上游分配标签，即使所有这些服务LSP都是来自同一MVPN/VPL的（C-S/*，C-G/*）。因此，ABR为穿过ABR的每个这样的S-PMSI（适用于入口和出口ABR两者）维持标签转发信息基（LFIB）状态。
When the RD of the received Leaf A-D route is set to all zeros or all ones, this is the case of inter-area P2MP service LSP being associated with the global table multicast service. The procedures for this are described below.
当接收到的叶A-D路由的RD被设置为全零或全1时，这是区域间P2MP服务LSP与全局表多播服务相关联的情况。下文介绍了这方面的程序。
This section applies only if it is desired to send a particular (S,G) or (*,G) global table multicast flow to only those egress PEs that have receivers for that multicast flow.
仅当需要将特定（S，G）或（*，G）全局表多播流仅发送给具有该多播流接收器的出口PE时，本节才适用。
If the egress ABR has not previously received (and re-advertised) an S-PMSI A-D route for (S,G) or (*,G) that has been originated by an ingress PE/ASBR (see Section 9.1), then the egress ABR MUST originate an S-PMSI A-D route. The PMSI Tunnel attribute of the route MUST contain the identity of the intra-area P2MP LSP and an upstream-assigned MPLS label (although this label may be an Implicit NULL -- see Section 3). The RD, Multicast Source Length, Multicast Source, Multicast Group Length (1 octet), and Multicast Group fields of the NLRI of this route are the same as those of the received Leaf A-D route. The Originating Router's IP Address field in the S-PMSI A-D route is the same as the Ingress PE's IP Address field in the received Leaf A-D route. The Route Target of this route is an AS-specific Route Target Extended Community with the Global Administrator field set to the AS of the advertising ABR and the Local Administrator field set to 0. The route MUST carry the Inter-Area P2MP Segmented Next-Hop Extended Community. This Extended Community is constructed following the procedures in Section 4.
如果出口ABR之前没有收到（并重新通告）由入口PE/ASBR发起的（S，G）或（*，G）的S-PMSI A-D路由（见第9.1节），则出口ABR必须发起S-PMSI A-D路由。路由的PMSI隧道属性必须包含区域内P2MP LSP的标识和上游分配的MPLS标签（尽管该标签可能是隐式空的——请参见第3节）。此路由的NLRI的RD、多播源长度、多播源、多播组长度（1个八位字节）和多播组字段与接收到的叶A-D路由的字段相同。s-PMSI A-D路由中发起路由器的IP地址字段与接收到的叶A-D路由中的入口PE的IP地址字段相同。此路由的路由目标是特定于AS的路由目标扩展社区，全局管理员字段设置为广告ABR的AS，本地管理员字段设置为0。该路线必须承载区域间P2MP分段下一跳扩展社区。该扩展社区按照第4节中的程序构建。
The egress ABR MUST advertise this route into the egress area. PEs in the egress area that participate in the global table multicast will import this route based on the Route Target carried by the route.
出口ABR必须向出口区域宣传该路线。参与全局表多播的出口区域中的PE将基于路由携带的路由目标导入该路由。
A PE in the egress area that originated the Leaf A-D route SHOULD join the P2MP LSP advertised in the PMSI Tunnel attribute of the S-PMSI A-D route.
发起叶A-D路由的出口区域中的PE应加入S-PMSI A-D路由的PMSI隧道属性中公布的P2MP LSP。
It may be desirable for an ingress PE to carry multiple multicast flows associated with the global table multicast over the same inter-area P2MP service LSP. This can be achieved using wildcard, i.e., (*,*) S-PMSI A-D routes [RFC6625]. An ingress PE MAY advertise a wildcard S-PMSI A-D route as described in Section 9.
入口PE可能希望在同一区域间P2MP服务LSP上承载与全局表组播相关联的多个组播流。这可以使用通配符实现，即（*，*）S-PMSI A-D路由[RFC6625]。如第9节所述，入口PE可公布通配符S-PMSI a-D路由。
If the ingress PE originates a wildcard S-PMSI A-D route, and the egress ABR receives this route from the ingress ABR, then the egress ABR either (a) MUST re-advertise this route into the egress area with the PMSI Tunnel attribute containing the identifier of the intra-area P2MP LSP in the egress area and an upstream-assigned label (note that this label may be an Implicit NULL -- see Section 3) assigned to the inter-area wildcard S-PMSI or (b) MUST be able to disaggregate traffic carried over the wildcard S-PMSI onto the egress area (S,G) or (*,G) S-PMSIs. The procedures for such disaggregation require IP processing on the egress ABRs.
如果入口PE发起通配符S-PMSI a-D路由，并且出口ABR从入口ABR接收该路由，则出口ABR（a）必须使用包含出口区域中的区域内P2MP LSP的标识符和上游分配的标签的PMSI隧道属性将该路由重新播发到出口区域中（注意，该标签可能是一个隐式空值——参见第3节）分配给区域间通配符S-PMSI或（b）必须能够将通过通配符S-PMSI携带的流量分解到出口区域（S，G）或（*，G）S-PMSI上。这种分解过程需要出口ABR上的IP处理。
If the egress ABR advertises a wildcard S-PMSI A-D route into the egress area, this route MUST carry an AS-specific Route Target Extended Community with the Global Administrator field set to the AS of the advertising ABR and the Local Administrator field set to 0. PEs in the egress area that participate in the global table multicast will import this route.
如果出口ABR向出口区域播发通配符S-PMSI a-D路由，则该路由必须携带AS-specific route Target Extended Community，全局管理员字段设置为广告ABR的AS，本地管理员字段设置为0。参与全局表多播的出口区域中的PE将导入此路由。
A PE in the egress area SHOULD join the P2MP LSP advertised in the PMSI Tunnel attribute of the wildcard S-PMSI A-D route if (a) the Originating Router's IP Address field in the S-PMSI A-D route has the same value as the Ingress PE's IP Address in at least one of the Leaf A-D routes for global table multicast originated by the PE and (b) the upstream ABR for the Ingress PE's IP address in that Leaf A-D route is the egress ABR that advertises the wildcard S-PMSI A-D route.
如果（A）S-PMSI A-D路由中的始发路由器的IP地址字段与PE发起的全局表多播的至少一个叶A-D路由中的入口PE的IP地址具有相同的值，则出口区域中的PE应加入通配符S-PMSI A-D路由的PMSI隧道属性中公布的P2MP LSP，并且（b）该叶A-D路由中入口PE的IP地址的上游ABR是播发通配符s-PMSI A-D路由的出口ABR。
If the mapping between the inter-area P2MP service LSP for global table multicast service and the intra-area P2MP LSP is many-to-one, then an egress PE must be able to determine whether a given multicast packet for a particular (S,G) is received from the "expected" upstream node. The expected node is the node towards which the Leaf A-D route is sent by the egress PE. Packets received from another upstream node for that (S,G) MUST be dropped. To allow the egress PE
如果用于全局表多播服务的区域间P2MP服务LSP与区域内P2MP LSP之间的映射是多对一的，则出口PE必须能够确定是否从“预期”上游节点接收到特定（S，G）的给定多播分组。预期节点是由出口PE向其发送叶A-D路由的节点。必须丢弃从另一个上游节点接收的（S，G）数据包。允许出口PE
to determine the sender upstream node, the intra-area P2MP LSP MUST be signaled with no Penultimate Hop Popping (PHP), when the mapping between the inter-area P2MP service LSP for global table multicast service and the intra-area P2MP LSP is many-to-one.
要确定发送方上游节点，当全局表多播服务的区域间P2MP服务LSP和区域内P2MP LSP之间的映射为多对一时，必须以无倒数第二跳弹出（PHP）的方式通知区域内P2MP LSP。
Further, the egress ABR MUST first push onto the label stack the upstream-assigned label advertised in the S-PMSI A-D route, if the label is not the Implicit NULL.
此外，如果标签不是隐式NULL，则出口ABR必须首先将在S-PMSI A-D路由中通告的上游分配标签推送到标签堆栈上。
The above procedures are sufficient if P2MP LDP LSPs are used as the intra-area P2MP LSP in the egress area.
如果将P2MP LDP LSP用作出口区域中的区域内P2MP LSP，则上述步骤就足够了。
If P2MP RSVP-TE LSP is used as the intra-area LSP in the egress area, then the egress ABR can either (a) graft the leaf (whose IP address is specified in the received Leaf A-D route) into an existing P2MP LSP rooted at the egress ABR, and use that LSP for carrying traffic for the inter-area segmented P2MP service LSP or (b) originate a new P2MP LSP to be used for carrying (S,G).
如果P2MP RSVP-TE LSP用作出口区域中的区域内LSP，则出口ABR可以（a）将叶（其IP地址在接收到的叶a-D路由中指定）嫁接到根在出口ABR的现有P2MP LSP中，并使用该LSP来承载区域间分段P2MP服务LSP的业务，或者（b）创建一个新的P2MP LSP，用于承载（S，G）。
When the RD of the received Leaf A-D route is all zeros or all ones, the procedures are as described in Section 7.2.2.
当接收到的叶A-D路由的RD为全零或全一时，程序如第7.2.2节所述。
Note also that the SESSION object that the egress ABR would use for the intra-area P2MP LSP need not encode the P2MP FEC from the received Leaf A-D route.
还注意，出口ABR将用于区域内P2MP LSP的会话对象不需要对来自所接收的叶A-D路由的P2MP FEC进行编码。
When ingress replication is used to instantiate the egress area segment, the Leaf A-D route advertised by the egress PE MUST carry a downstream-assigned label in the PMSI Tunnel attribute where the Tunnel Type is set to ingress replication. We will call this label the egress PE downstream-assigned label.
当入口复制用于实例化出口区域段时，出口PE播发的叶A-D路由必须在PMSI隧道属性中携带下游分配的标签，其中隧道类型设置为入口复制。我们将此标签称为出口PE下游指定标签。
The egress ABR MUST forward packets received from the backbone area intra-area segment, for a particular inter-area P2MP LSP, to all the egress PEs from which the egress ABR has imported a Leaf A-D route for the inter-area P2MP LSP. A packet to a particular egress PE is encapsulated, by the egress ABR, using an MPLS label stack the bottom label of which is the egress PE downstream-assigned label. The top label is the P2P RSVP-TE or the MP2P LDP label to reach the egress PE.
出口ABR必须将针对特定区域间P2MP LSP从骨干区域内段接收到的分组转发到出口ABR已经为区域间P2MP LSP导入叶a-D路由的所有出口pe。到特定出口PE的分组由出口ABR使用MPLS标签栈封装，MPLS标签栈的底部标签是出口PE下游分配的标签。顶部标签是P2P RSVP-TE或MP2P LDP标签，以到达出口PE。
Note that these procedures ensure that an egress PE always receives packets only from the upstream node expected by the egress PE.
注意，这些过程确保出口PE始终仅从出口PE预期的上游节点接收分组。
When an ingress ABR receives a Leaf A-D route and the Route Target Extended Community carried by the route contains the IP address of this ABR, the ingress ABR follows the same procedures as in Section 7, with egress ABR replaced by ingress ABR, backbone area replaced by ingress area, and backbone area segment replaced by ingress area segment.
当入口ABR接收到叶a-D路由且该路由承载的路由目标扩展社区包含该ABR的IP地址时，入口ABR遵循与第7节相同的程序，出口ABR替换为入口ABR，主干区域替换为入口区域，主干区域段替换为入口区域段。
In order to support global table multicast, the ingress ABR MUST be auto-configured with an import AS-based Route Target Extended Community whose Global Administrator field is set to the AS of the ABR and whose Local Administrator field is set to 0.
为了支持全局表多播，入口ABR必须自动配置一个基于导入AS的路由目标扩展社区，其全局管理员字段设置为ABR的AS，本地管理员字段设置为0。
The procedures for binding the backbone area segment of an inter-area P2MP LSP to the intra-area P2MP LSP in the backbone area are the same as in Sections 7 and 7.2, with egress PE being replaced by egress ABR, egress ABR being replaced by ingress ABR, and egress area being replaced by backbone area. This applies to the inter-area P2MP LSPs associated with either MVPN, VPLS, or global table multicast.
将区域间P2MP LSP的主干区域段绑定到主干区域中的区域内P2MP LSP的程序与第7节和第7.2节中的程序相同，出口PE替换为出口ABR，出口ABR替换为入口ABR，出口区域替换为主干区域。这适用于与MVPN、VPLS或全局表多播相关联的区域间P2MP LSP。
It is to be noted that, in the case of global table multicast, if the backbone area uses wildcard S-PMSI, then the egress area also SHOULD use wildcard S-PMSI for global table multicast, or the egress ABRs MUST be able to disaggregate traffic carried over the wildcard S-PMSI onto the egress area (S,G) or (*,G) S-PMSIs. The procedures for such disaggregation require IP processing on the egress ABRs.
需要注意的是，在全局表组播的情况下，如果主干区域使用通配符S-PMSI，那么出口区域也应该使用通配符S-PMSI进行全局表组播，或者出口abr必须能够将通过通配符S-PMSI携带的业务分解到出口区域（S，G）或（*，G）S-PMSI。这种分解过程需要在出口abr上进行IP处理。
When ingress replication is used to instantiate the backbone area segment, the Leaf A-D route advertised by the egress ABR MUST carry a downstream-assigned label in the PMSI Tunnel attribute where the Tunnel Type is set to ingress replication. We will call this the egress ABR downstream-assigned label. The egress ABR MUST assign a distinct MPLS label for each Leaf A-D route originated by the ABR.
当入口复制用于实例化主干区域段时，出口ABR播发的叶A-D路由必须在PMSI隧道属性中携带下游分配的标签，其中隧道类型设置为入口复制。我们将其称为出口ABR下游指定标签。出口ABR必须为ABR发起的每个叶a-D路由分配不同的MPLS标签。
The ingress ABR MUST forward packets received from the ingress area intra-area segment, for a particular inter-area P2MP LSP, to all the egress ABRs from which the ingress ABR has imported a Leaf A-D route for the inter-area P2MP LSP. A packet to a particular egress ABR is encapsulated, by the ingress ABR, using an MPLS label stack the bottom label of which is the egress ABR downstream-assigned label.
对于特定的区域间P2MP LSP，入口ABR必须将从入口区域内段接收的分组转发到入口ABR已经为区域间P2MP LSP导入了叶a-D路由的所有出口ABR。到特定出口ABR的分组由入口ABR使用MPLS标签栈封装，MPLS标签栈的底部标签是出口ABR下游分配的标签。
The top label is the P2P RSVP-TE or the MP2P LDP label to reach the egress ABR.
顶部标签是用于到达出口ABR的P2P RSVP-TE或MP2P LDP标签。
This section describes the ingress PE/ASBR procedures for constructing segmented inter-area P2MP LSPs.
本节介绍用于构建分段区域间P2MP LSP的入口PE/ASBR程序。
When an ingress PE/ASBR receives a Leaf A-D route and the Route Target Extended Community carried by the route contains the IP address of this PE/ASBR, the following procedures will be executed.
当入口PE/ASBR接收到叶a-D路由，且该路由携带的路由目标扩展社区包含该PE/ASBR的IP地址时，将执行以下过程。
If the value of the third octet of the MCAST-VPN NLRI of the received Leaf A-D route is either 0x01, 0x02, or 0x03, this indicates that the Leaf A-D route was originated in response to an S-PMSI or I-PMSI A-D route (see Section 6.2.2). In this case, the ingress PE/ASBR MUST find an S-PMSI or I-PMSI route whose NLRI has the same value as the Route Key field of the received Leaf A-D route. If such a matching route is found, then the Leaf A-D route MUST be accepted or else it MUST be discarded. If the Leaf A-D route is accepted, then it MUST be processed as per MVPN or VPLS procedures.
如果接收到的叶A-D路由的MCAST-VPN NLRI的第三个八位组的值为0x01、0x02或0x03，则表示叶A-D路由是响应S-PMSI或I-PMSI A-D路由而产生的（见第6.2.2节）。在这种情况下，入口PE/ASBR必须找到一个S-PMSI或I-PMSI路由，其NLRI值与所接收的叶A-D路由的路由键字段值相同。如果找到这样一个匹配的路由，那么必须接受叶a-D路由，否则必须丢弃它。如果叶A-D路由被接受，则必须按照MVPN或VPLS程序进行处理。
If the RD of the received A-D route is set to all zeros or all ones, then the received Leaf A-D route is for the global table multicast service. If this is the first Leaf A-D route for the Route Key carried in the route, the PIM implementation MUST set its upstream (S/RP,G) state machine to Joined state for the (S/RP,G) received via a Leaf A-D route update. Likewise, if this is the withdrawal of the last Leaf A-D route whose Route Key matches a particular (S/RP,G) state, the PIM implementation MUST set its upstream (S/RP,G) state machine to Prune state for the (S/RP,G).
如果接收到的A-D路由的RD设置为全零或全1，则接收到的叶A-D路由用于全局表多播服务。如果这是路由中携带的路由密钥的第一个叶A-D路由，则PIM实现必须将其上游（S/RP，G）状态机设置为通过叶A-D路由更新接收的（S/RP，G）的连接状态。同样，如果这是最后一个叶A-D路由的退出，其路由密钥与特定（S/RP，G）状态匹配，则PIM实现必须将其上游（S/RP，G）状态机设置为（S/RP，G）的修剪状态。
If the value of the third octet of the MCAST-VPN NLRI of the received Leaf A-D route is either 0x01, 0x02, or 0x03 (which indicates that the Leaf A-D route was originated in response to an S-PMSI or I-PMSI A-D route), and P2MP LSP is used as the intra-area LSP in the ingress area, then the procedures for binding the ingress area segment of the inter-area P2MP LSP to the intra-area P2MP LSP in the ingress area are the same as in Sections 7 and 7.2.
如果接收到的叶A-D路由的MCAST-VPN NLRI的第三个八位组的值为0x01、0x02或0x03（这表示叶A-D路由是响应于S-PMSI或I-PMSI A-D路由而发起的），并且P2MP LSP用作入口区域中的区域内LSP，然后，将区域间P2MP LSP的入口区域段绑定到入口区域内的区域内P2MP LSP的步骤与第7节和第7.2节中的步骤相同。
When the RD of the received Leaf A-D route is all zeros or all ones, as is the case where the inter-area service P2MP LSP is associated with the global table multicast service, the ingress PE MAY originate an S-PMSI A-D route with the RD, multicast source, and multicast group fields being the same as those in the received Leaf A-D route.
当接收到的叶A-D路由的RD为全零或全1时，如区域间服务P2MP LSP与全局表多播服务相关联的情况，入口PE可以发起S-PMSI A-D路由，其中RD、多播源和多播组字段与接收到的叶A-D路由中的字段相同。
Further, in the case of global table multicast, an ingress PE MAY originate a wildcard S-PMSI A-D route as per the procedures in [RFC6625] with the RD set to 0. This route may be originated by the ingress PE based on configuration or based on the import of a Leaf A-D route with the RD set to 0. If an ingress PE originates such a route, then the ingress PE MAY decide not to originate (S,G) or (*,G) S-PMSI A-D routes.
此外，在全局表多播的情况下，入口PE可以根据[RFC6625]中的过程发起通配符S-PMSI a-D路由，并且RD设置为0。该路由可由入口PE基于配置或基于RD设置为0的叶a-D路由的导入发起。如果入口PE发起这样的路由，则入口PE可决定不发起（S，G）或（*，G）S-PMSI a-D路由。
The wildcard S-PMSI A-D route MUST carry the Inter-Area P2MP Segmented Next-Hop Extended Community. This Extended Community is constructed following the procedures in Section 4.
通配符S-PMSI A-D路由必须承载区域间P2MP分段下一跳扩展社区。该扩展社区按照第4节中的程序构建。
It is to be noted that, in the case of global table multicast, if the ingress area uses wildcard S-PMSI, then the backbone area also SHOULD use wildcard S-PMSI for global table multicast, or the ingress ABRs MUST be able to disaggregate traffic carried over the wildcard S-PMSI onto the backbone area (S,G) or (*,G) S-PMSIs. The procedures for such disaggregation require IP processing on the ingress ABRs.
需要注意的是，在全局表多播的情况下，如果入口区域使用通配符S-PMSI，那么主干区域也应该使用通配符S-PMSI进行全局表多播，或者入口ABR必须能够将通过通配符S-PMSI携带的业务分解到主干区域（S，G）或（*，G）S-PMSI上。这种分解的程序需要在入口ABR上进行IP处理。
When ingress replication is used to instantiate the ingress area segment, the Leaf A-D route advertised by the ingress ABR MUST carry a downstream-assigned label in the PMSI Tunnel attribute where the Tunnel Type is set to ingress replication. We will call this the ingress ABR downstream-assigned label. The ingress ABR MUST assign a distinct MPLS label for each Leaf A-D route originated by the ABR.
当入口复制用于实例化入口区域段时，入口ABR播发的叶A-D路由必须在PMSI隧道属性中携带下游分配的标签，其中隧道类型设置为入口复制。我们将其称为入口ABR下游分配标签。入口ABR必须为ABR发起的每个叶a-D路由分配不同的MPLS标签。
The ingress PE/ASBR MUST forward packets received from the CE, for a particular inter-area P2MP LSP, to all the ingress ABRs from which the ingress PE/ASBR has imported a Leaf A-D route for the inter-area P2MP LSP. A packet to a particular ingress ABR is encapsulated, by the ingress PE/ASBR, using an MPLS label stack the bottom label of which is the ingress ABR downstream-assigned label. The top label is the P2P RSVP-TE or the MP2P LDP label to reach the ingress ABR.
入口PE/ASBR必须将从CE接收到的用于特定区域间P2MP LSP的数据包转发到入口PE/ASBR已从中为区域间P2MP LSP导入叶a-D路由的所有入口ABR。到特定入口ABR的分组由入口PE/ASBR使用MPLS标签栈进行封装，MPLS标签栈的底部标签是入口ABR下游分配的标签。顶部标签是P2P RSVP-TE或MP2P LDP标签，用于到达入口ABR。
For a given inter-area service P2MP LSP, the PE/ASBR that is the root of that LSP controls the type of the intra-area P-tunnel that carries the ingress area segment of that LSP. However, the type of the intra-area P-tunnel that carries the backbone area segment of that LSP may be different from the type of the intra-area P-tunnels that carry the ingress area segment and the egress area segment of that LSP. In that situation, if, for a given inter-area P2MP LSP, it is desirable/necessary to use the same type of tunnel for the intra-area P-tunnels that carry the ingress area segment and for the intra-area
对于给定的区域间服务P2MP LSP，作为该LSP根的PE/ASBR控制承载该LSP的入口区域段的区域内P隧道的类型。然而，承载该LSP的主干区域段的区域内P隧道的类型可能不同于承载该LSP的入口区域段和出口区域段的区域内P隧道的类型。在这种情况下，如果对于给定的区域间P2MP LSP，希望/有必要为承载入口区域段的区域内P-隧道和区域内P-隧道使用相同类型的隧道
P-tunnels that carry the egress area segment of that LSP, then the following procedures on the ingress ABR and egress ABR provide this functionality.
P-承载该LSP的出口区域段的隧道，然后入口ABR和出口ABR上的以下程序提供此功能。
When an ingress ABR re-advertises into the backbone area a BGP MVPN I-PMSI, S-PMSI A-D route, or VPLS A-D route, the ingress ABR places the PMSI Tunnel attribute of this route into the ATTR_SET BGP attribute [RFC6368], adds this attribute to the re-advertised route, and then replaces the original PMSI Tunnel attribute with a new one (note that the Tunnel Type of the new attribute may be different from the Tunnel Type of the original attribute).
当入口ABR向主干区域重新播发BGP MVPN I-PMSI、S-PMSI a-D路由或VPLS a-D路由时，入口ABR将该路由的PMSI隧道属性放入属性集BGP属性[RFC6368]，将该属性添加到重新播发的路由，然后用新属性替换原始PMSI隧道属性（请注意，新属性的隧道类型可能不同于原始属性的隧道类型）。
When an egress ABR re-advertises into the egress area a BGP MVPN I-PMSI or S-PMSI A-D route, or VPLS A-D route, if the route carries the ATTR_SET BGP attribute [RFC6368], the ABR sets the Tunnel Type of the PMSI Tunnel attribute in the re-advertised route to the Tunnel Type of the PMSI Tunnel attribute carried in the ATTR_SET BGP attribute, and removes the ATTR_SET from the route.
当出口ABR将BGP MVPN I-PMSI或S-PMSI a-D路由或VPLS a-D路由重新播发到出口区域时，如果该路由携带ATTR_SET BGP属性[RFC6368]，则ABR将重新播发路由中的PMSI隧道属性的隧道类型设置为ATTR_SET BGP属性中携带的PMSI隧道属性的隧道类型，并从路由中删除属性集。
As described in the earlier sections, procedures in this document allow the placement of ingress and egress PEs in the backbone area. They also allow the placement of egress PEs in the ingress area or the placement of ingress PEs in the egress area.
如前几节所述，本文件中的程序允许在主干区域中放置入口和出口PE。它们还允许在入口区域放置出口PE或在出口区域放置入口PE。
For instance, suppose that in the ingress and egress areas, a global table multicast service is being provided, and the data is being sent over PIM-based IP/GRE P-tunnels. Suppose also that it is desired to carry that data over the backbone area through MPLS P-tunnels. This can be done if the ABR connecting the ingress area to the backbone follows the procedures that this document specifies for ingress PEs providing the global table multicast service, and if the ABR connecting the egress area to the backbone follows the procedures that this document specifies for egress PEs providing the global table multicast service.
例如，假设在入口和出口区域中，正在提供全局表多播服务，并且正在通过基于PIM的IP/grep-tunnels发送数据。还假设希望通过MPLS P隧道在主干区域上传输该数据。如果将入口区域连接到主干网的ABR遵循本文档为提供全局表多播服务的入口PE指定的程序，则可以执行此操作，以及如果将出口区域连接到主干的ABR遵循本文档为提供全局表多播服务的出口PEs指定的过程。
If MVPN service is being provided in the ingress and egress areas, with the MVPN data carried in PIM-based IP/GRE P-tunnels, this same technique enables the MVPN data to be carried over the backbone in MPLS P-tunnels. The PIM-based IP/GRE P-tunnels in the ingress and egress areas are treated as global table multicasts, and the ABRs provide the ingress and egress PE functionality.
如果在入口和出口区域中提供MVPN服务，并且MVPN数据在基于PIM的IP/GRE P隧道中承载，则该相同技术使得MVPN数据能够在MPLS P隧道中的主干上承载。入口和出口区域中基于PIM的IP/GRE P隧道被视为全局表多播，ABR提供入口和出口PE功能。
Procedures described in this document could be used in conjunction with the Virtual Hub-and-Spoke procedures [RFC7024].
本文档中描述的过程可与虚拟中心辐射过程结合使用[RFC7024]。
This document does not place any restrictions on the placement of Virtual Hubs and Virtual Spokes.
本文档对虚拟轮毂和虚拟辐条的放置没有任何限制。
In addition to I-PMSI/S-PMSI A-D routes, the procedures described in this document are applicable to Associated-V-spoke-only I-PMSI A-D routes.
除I-PMSI/S-PMSI A-D路由外，本文件中所述的程序适用于相关的V-spoke-only I-PMSI A-D路由。
In the scenario where a V-hub, as a result of importing an S-PMSI A-D route in its VRF, originates an S-PMSI A-D route targeted to its V-spokes (as specified in Section 7.8.2 of [RFC7024]), the V-hub SHOULD be able to control via configuration whether the Inter-Area P2MP Segmented Next-Hop Extended Community, if present in the received S-PMSI A-D route, should also be carried in the originated S-PMSI A-D route. By default, if the received S-PMSI A-D route carries the Inter-Area P2MP Segmented Next-Hop Extended Community, then the originated S-PMSI A-D route SHOULD also carry this Extended Community.
在V-hub由于在其VRF中导入S-PMSI a-D路由而发起针对其V-Spoke的S-PMSI a-D路由（如[RFC7024]第7.8.2节所述）的场景中，V-hub应能够通过配置控制区域间P2MP分段下一跳扩展社区，如果存在于接收到的S-PMSI A-D路由中，则也应在原始S-PMSI A-D路由中携带。默认情况下，如果接收到的S-PMSI A-D路由承载区域间P2MP分段下一跳扩展社区，则原始S-PMSI A-D路由也应承载该扩展社区。
This section describes the data plane procedures on the ABRs, ingress PEs, egress PEs, and transit routers.
本节描述了ABR、入口PEs、出口PEs和传输路由器上的数据平面程序。
When procedures in this document are followed to signal inter-area P2MP segmented LSPs, ABRs are required to perform only MPLS switching. When an ABR receives an MPLS packet from an "incoming" intra-area segment of the inter-area P2MP segmented LSP, it forwards the packet, based on MPLS switching, on to another "outgoing" intra-area segment of the inter-area P2MP segmented LSP.
当遵循本文件中的程序向区域间P2MP分段LSP发送信号时，ABR只需执行MPLS交换。当ABR从区域间P2MP分段LSP的“传入”区域内段接收到MPLS分组时，它基于MPLS交换将该分组转发到区域间P2MP分段LSP的另一个“传出”区域内段。
If the outgoing intra-area segment is instantiated using a P2MP LSP, and if there is a one-to-one mapping between the outgoing intra-area segment and the P2MP LSP, then the ABR MUST pop the incoming segment's label stack and push the label stack of the outgoing P2MP LSP. If there is a many-to-one mapping between outgoing intra-area segments and the P2MP LSP, then the ABR MUST pop the incoming segment's label stack and first push the upstream-assigned label corresponding to the outgoing intra-area segment, if such a label has been assigned, and then push the label stack of the outgoing P2MP LSP.
如果使用P2MP LSP实例化传出区域内段，并且传出区域内段和P2MP LSP之间存在一对一映射，则ABR必须弹出传入段的标签堆栈并推送传出P2MP LSP的标签堆栈。如果传出区域内段和P2MP LSP之间存在多对一映射，则ABR必须弹出传入段的标签堆栈，并首先推送与传出区域内段对应的上游分配标签（如果已分配此类标签），然后推送传出P2MP LSP的标签堆栈。
If the outgoing intra-area segment is instantiated using ingress replication, then the ABR must pop the incoming segment's label stack and replicate the packet once to each leaf ABR or PE of the outgoing intra-area segment. The label stack of the packet sent to each such leaf MUST first include a downstream-assigned label assigned by the leaf to the segment, followed by the label stack of the P2P or MP2P LSP to the leaf.
如果使用入口复制实例化传出区域内段，则ABR必须弹出传入段的标签堆栈，并将数据包复制一次到传出区域内段的每个叶ABR或PE。发送到每个这样的叶的分组的标签堆栈必须首先包括由该叶分配给该段的下游分配的标签，然后是P2P或MP2P LSP分配给该叶的标签堆栈。
An egress PE must first identify the inter-area P2MP segmented LSP based on the incoming label stack. After this identification, the egress PE must forward the packet using the application that is bound to the inter-area P2MP segmented LSP.
出口PE必须首先基于传入标签堆栈识别区域间P2MP分段LSP。在该识别之后，出口PE必须使用绑定到区域间P2MP分段LSP的应用转发分组。
Note that the application-specific forwarding for MVPN service may require the egress PE to determine whether the packets were received from the expected sender PE. When the application is MVPN, the FEC of an inter-area P2MP segmented LSP is at the granularity of the sender PE. Note that MVPN intra-AS I-PMSI A-D routes and S-PMSI A-D routes both carry the Originating Router's IP Address. Thus, an egress PE could associate the data arriving on P-tunnels advertised by these routes with the Originating Router's IP Address carried by these routes, which is the same as the ingress PE. Since a unique label stack is associated with each such FEC, the egress PE can determine the sender PE from the label stack.
注意，MVPN服务的应用特定转发可能需要出口PE来确定是否从预期发送方PE接收到分组。当应用是MVPN时，区域间P2MP分段LSP的FEC处于发送方PE的粒度。请注意，MVPN内部AS I-PMSI A-D路由和S-PMSI A-D路由都携带发起路由器的IP地址。因此，出口PE可以将到达这些路由所通告的P隧道上的数据与这些路由携带的发起路由器的IP地址相关联，这与入口PE相同。由于唯一标签堆栈与每个这样的FEC相关联，因此出口PE可以从标签堆栈确定发送方PE。
Likewise for VPLS service, for the purposes of Media Access Control (MAC) learning the egress, the PE must be able to determine the "VE-ID" (VPLS Edge Device Identifier) from which the packets have been received. The FEC of the VPLS A-D routes carries the VE-ID. Thus, an egress PE could associate the data arriving on P-tunnels advertised by these routes with the VE-ID carried by these routes. Since a unique label stack is associated with each such FEC, the egress PE can perform MAC learning for packets received from a given VE-ID.
同样，对于VPLS服务，为了媒体访问控制（MAC）学习出口，PE必须能够确定从其接收分组的“VE-ID”（VPLS边缘设备标识符）。VPLS A-D路由的FEC携带VE-ID。因此，出口PE可以将到达这些路由广告的P隧道上的数据与这些路由携带的VE-ID相关联。由于唯一标签堆栈与每个这样的FEC相关联，因此出口PE可以对从给定VE-ID接收的分组执行MAC学习。
When the application is global table multicast, it is sufficient for the label stack to include identification of the sender upstream node. When P2MP LSPs are used, this requires that PHP MUST be turned off. When ingress replication is used, the egress PE knows the incoming downstream-assigned label to which it has bound a particular (S/*,G) and must accept packets with only that label for that (S/*,G).
当应用程序是全局表多播时，标签堆栈包含发送方上游节点的标识就足够了。当使用P2MP LSP时，这要求必须关闭PHP。当使用入口复制时，出口PE知道其绑定了特定（S/*，G）的传入下游分配标签，并且必须只接受带有该标签的数据包（S/*，G）。
An Ingress PE must perform application-specific forwarding procedures to identify the outgoing intra-area segment of an incoming packet.
入口PE必须执行特定于应用程序的转发过程，以识别传入数据包的传出区域内段。
If the outgoing intra-area segment is instantiated using a P2MP LSP, and if there is a one-to-one mapping between the outgoing intra-area segment and the P2MP LSP, then the ingress PE MUST encapsulate the packet in the label stack of the outgoing P2MP LSP. If there is a many-to-one mapping between outgoing intra-area segments and the P2MP LSP, then the PE MUST first push the upstream-assigned label corresponding to the outgoing intra-area segment, if such a label has been assigned, and then push the label stack of the outgoing P2MP LSP.
如果使用P2MP LSP实例化出站区域内段，并且如果出站区域内段与P2MP LSP之间存在一对一映射，则入口PE必须将该数据包封装在出站P2MP LSP的标签堆栈中。如果传出区域内段和P2MP LSP之间存在多对一映射，则PE必须首先推送与传出区域内段对应的上游分配标签（如果已分配此类标签），然后推送传出P2MP LSP的标签堆栈。
If the outgoing intra-area segment is instantiated using ingress replication, then the PE must replicate the packet once to each leaf ABR or PE of the outgoing intra-area segment. The label stack of the packet sent to each such leaf MUST first include a downstream-assigned label assigned by the leaf to the segment, followed by the label stack of the P2P or MP2P LSP to the leaf.
如果使用入口复制实例化传出的区域内段，则PE必须将该分组复制一次到传出区域内段的每个叶ABR或PE。发送到每个这样的叶的分组的标签堆栈必须首先包括由该叶分配给该段的下游分配的标签，然后是P2P或MP2P LSP分配给该叶的标签堆栈。
When procedures in this document are followed to signal inter-area P2MP segmented LSPs, transit routers in each area perform only MPLS switching.
当遵循本文件中的程序向区域间P2MP分段LSP发送信号时，每个区域中的中转路由器仅执行MPLS交换。
This section describes OPTIONAL procedures that allow multiple (inter-area) P2MP LSPs to be aggregated into a single inter-area P2MP "transport LSP". The segmentation procedures, as specified in this document, are then applied to these inter-area P2MP transport LSPs, rather than being applied directly to the individual LSPs that are aggregated into the transport. In the following, the individual LSPs that are aggregated into a single transport LSP will be known as "service LSPs".
本节描述了允许将多个（区域间）P2MP LSP聚合为单个区域间P2MP“传输LSP”的可选过程。本文件中规定的分段程序随后应用于这些区域间P2MP传输LSP，而不是直接应用于聚合到传输中的单个LSP。在下文中，聚合为单个传输LSP的各个LSP将被称为“服务LSP”。
For the PMSI Tunnel attribute, we define a new Tunnel Type, called "Transport Tunnel", whose Tunnel Identifier is a tuple <Source PE Address, Local Number>. This Tunnel Type is assigned a value of 8. The Source PE Address is the address of the PE that originates the (service) A-D route that carries this attribute, and the Local Number is a number that is unique to the Source PE. The length of the Local Number part is the same as the length of the Source PE Address.
对于PMSI隧道属性，我们定义了一种新的隧道类型，称为“传输隧道”，其隧道标识符是元组<源PE地址，本地编号>。此隧道类型的指定值为8。源PE地址是发起承载此属性的（服务）A-D路由的PE的地址，本地号码是源PE唯一的号码。本地号码部分的长度与源PE地址的长度相同。
Thus, if the Source PE Address is an IPv4 address, then the Local Number part is 4 octets; if the Source PE Address is an IPv6 address, then the Local Number part is 16 octets.
因此，如果源PE地址是IPv4地址，则本地数字部分是4个八位字节；如果源PE地址是IPv6地址，则本地号码部分为16个八位字节。
When aggregating multiple P2MP LSPs using P2MP LSP hierarchy, determining the leaf nodes of the LSPs being aggregated is essential for being able to trade-off the overhead due to the P2MP LSPs versus suboptimal use of bandwidth due to the partial congruency of the LSPs being aggregated.
当使用P2MP LSP层次结构聚合多个P2MP LSP时，确定正在聚合的LSP的叶节点对于能够权衡由于P2MP LSP而产生的开销与由于正在聚合的LSP的部分一致性而导致的带宽的次优使用是至关重要的。
Therefore, if a PE that is a root of a given service P2MP LSP wants to aggregate this LSP with other (service) P2MP LSPs rooted at the same PE into an inter-area P2MP transport LSP, the PE should first determine all the leaf nodes of that service LSP, as well as those of the other service LSPs being aggregated.
因此，如果作为给定服务P2MP LSP的根的PE希望将该LSP与在同一PE上根的其他（服务）P2MP LSP聚合到区域间P2MP传输LSP中，则PE应首先确定该服务LSP的所有叶节点以及正在聚合的其他服务LSP的叶节点。
To accomplish this, the PE sets the PMSI Tunnel attribute of the service A-D route (an I-PMSI or S-PMSI A-D route for MVPN or VPLS service) associated with that LSP as follows. The Tunnel Type is set to "No tunnel information present", and the "Leaf Information Required" flag is set to 1. The route MUST NOT carry the Inter-Area P2MP Segmented Next-Hop Extended Community. In contrast to the procedures for the MVPN and VPLS A-D routes described so far, the Route Reflectors that participate in the distribution of this route need not be ABRs.
为此，PE设置与该LSP关联的服务A-D路由（MVPN或VPLS服务的I-PMSI或S-PMSI A-D路由）的PMSI隧道属性，如下所示。隧道类型设置为“无隧道信息存在”，且“需要叶信息”标志设置为1。路线不得承载区域间P2MP分段下一跳扩展社区。与目前描述的MVPN和VPLS A-D路由程序不同，参与该路由分布的路由反射器不需要是ABR。
Once the ingress PE determines all the leaves of a given P2MP service LSP, the PE (using some local criteria) selects a particular inter-area transport P2MP LSP to be used for carrying the (inter-area) service P2MP LSP.
一旦入口PE确定给定P2MP服务LSP的所有叶子，PE（使用一些本地标准）选择要用于承载（区域间）服务P2MP LSP的特定区域间传输P2MP LSP。
Once the PE selects the transport P2MP LSP, the PE (re-)originates the service A-D route. The PMSI Tunnel attribute of this route now carries the Tunnel Identifier of the selected transport LSP, with the Tunnel Type set to "Transport Tunnel". If the transport LSP carries multiple P2MP service LSPs, then the MPLS Label field in the attribute carries an upstream-assigned label assigned by the PE that is bound to the P2MP FEC of the inter-area P2MP service LSP. Otherwise, this field is set to Implicit NULL.
一旦PE选择传输P2MP LSP，PE（重新）发起服务A-D路由。此路由的PMSI Tunnel属性现在携带所选传输LSP的隧道标识符，隧道类型设置为“传输隧道”。如果传输LSP携带多个P2MP服务LSP，则属性中的MPLS标签字段携带由绑定到区域间P2MP服务LSP的P2MP FEC的PE分配的上游分配标签。否则，此字段设置为隐式NULL。
As described earlier, this service A-D route MUST NOT carry the Inter-Area P2MP Segmented Next-Hop Extended Community, and the Route Reflectors that participate in the distribution of this route need not be ABRs.
如前所述，该服务A-D路由不得承载区域间P2MP分段下一跳扩展社区，并且参与该路由分配的路由反射器不需要是abr。
When an egress PE receives and accepts an MVPN or VPLS service A-D route, if the "Leaf Information Required" flag in the PMSI Tunnel attribute of the received A-D route is set to 1, and the route does not carry the Inter-Area P2MP Segmented Next-Hop Extended Community, then the egress PE, following the "regular" MVPN or VPLS procedures associated with the received A-D route (as specified in [RFC6514] and [RFC7117]), originates a Leaf A-D route.
当出口PE接收并接受MVPN或VPLS服务A-D路由时，如果接收到的A-D路由的PMSI隧道属性中的“所需叶信息”标志设置为1，并且该路由不携带区域间P2MP分段下一跳扩展社区，则出口PE将遵循“常规”与接收到的A-D路由相关联的MVPN或VPLS程序（如[RFC6514]和[RFC7117]中所述）发起一个叶A-D路由。
In addition, if the Tunnel Type in the PMSI Tunnel attribute of the received service A-D route is set to "Transport Tunnel", the egress PE originates yet another Leaf A-D route.
此外，如果接收到的服务A-D路由的PMSI Tunnel属性中的隧道类型被设置为“传输隧道”，则出口PE发起另一个叶A-D路由。
The format of the Route Key field of the MCAST-VPN NLRI of this additional Leaf A-D route is the same as defined in Section 6.2.2. The Route Key field of the MCAST-VPN NLRI of this route is constructed as follows:
此附加叶A-D路由的MCAST-VPN NLRI的路由密钥字段格式与第6.2.2节中的定义相同。该路由的MCAST-VPN NLRI的路由密钥字段构造如下：
RD (8 octets) - set to 0
RD（8个八位字节）-设置为0
Multicast Source Length, Multicast Source - constructed from the Source PE Address part of the Tunnel Identifier carried in the PMSI Tunnel attribute of the received service S-PMSI A-D route.
多播源长度，多播源-由接收服务S-PMSI A-D路由的PMSI隧道属性中携带的隧道标识符的源PE地址部分构成。
Multicast Group Length, Multicast Group - constructed from the Local Number part of the Tunnel Identifier carried in the PMSI Tunnel attribute of the received service S-PMSI A-D route.
多播组长度，多播组-由接收服务S-PMSI A-D路由的PMSI隧道属性中携带的隧道标识符的本地编号部分构造。
Ingress PE IP Address - set to the Source PE Address part of the Tunnel Identifier carried in the PMSI Tunnel attribute of the received service S-PMSI A-D route.
入口PE IP地址-设置为接收服务S-PMSI A-D路由的PMSI隧道属性中携带的隧道标识符的源PE地址部分。
The egress PE, when determining the upstream ABR, follows the procedures specified in Section 6.1 for global table multicast.
出口PE在确定上游ABR时，遵循第6.1节中针对全局表多播规定的程序。
The egress PE constructs the rest of the Leaf A-D route following the procedures specified in Section 6.2.3.
出口PE按照第6.2.3节规定的程序建造剩余的叶片A-D路线。
From that point on we follow the procedures used for the Leaf A-D routes for global table multicast, as outlined below.
从那时起，我们将遵循用于全局表多播的叶A-D路由的过程，如下所述。
In this section, we specify ingress and egress ABRs, as well as ingress PE procedures for P2MP transport LSPs.
在本节中，我们指定了入站和出站ABR，以及P2MP传输LSP的入站PE程序。
When an egress ABR receives the Leaf A-D route, and P2MP LSP is used to instantiate the egress area segment of the inter-area transport LSP, the egress ABR will advertise into the egress area an S-PMSI A-D route. This route is constructed following the procedures in Section 7.2.2.1. The egress PE(s) will import this route.
当出口ABR接收到叶A-D路由，并且P2MP LSP用于实例化区域间传输LSP的出口区域段时，出口ABR将向出口区域播发S-PMSI A-D路由。该路线按照第7.2.2.1节中的程序建造。出口PE将导入此路由。
The egress ABR will also propagate, with appropriate modifications, the received Leaf A-D route into the backbone area. This is irrespective of whether the egress area segment is instantiated using P2MP LSP or ingress replication.
通过适当的修改，出口ABR还将把接收到的叶A-D路由传播到主干区域。这与是否使用P2MP LSP或入口复制实例化出口区域段无关。
If P2MP LSP is used to instantiate the backbone area segment of the inter-area transport LSP, then an ingress ABR will advertise into the backbone area an S-PMSI A-D route. This route is constructed following the procedures in Section 7.1.2.1. The egress ABR(s) will import this route.
如果P2MP LSP用于实例化区域间传输LSP的主干区域段，则入口ABR将向主干区域播发S-PMSI A-D路由。该路线按照第7.1.2.1节中的程序建造。出口ABR将导入该路线。
The ingress ABR will also propagate, with appropriate modifications, the received Leaf A-D route into the ingress area towards the ingress/root PE. This is irrespective of whether the backbone area segment is instantiated using P2MP LSP or ingress replication.
入口ABR还将通过适当的修改，将接收到的叶A-D路由传播到入口区域，朝向入口/根PE。这与是否使用P2MP LSP或入口复制实例化主干区域段无关。
Finally, if P2MP LSP is used to instantiate the ingress area segment, the ingress PE will advertise into the ingress area an S-PMSI A-D route with the RD, multicast source, and multicast group fields being the same as those in the received Leaf A-D route. The PMSI Tunnel attribute of this route contains the identity of the intra-area P2MP LSP used to instantiate the ingress area segment, and an upstream-assigned MPLS label. The ingress ABR(s) and other PE(s) in the ingress area, if any, will import this route. The ingress PE will use the (intra-area) P2MP LSP advertised in this route for carrying traffic associated with the original service A-D route advertised by the PE.
最后，如果使用P2MP LSP来实例化入口区域段，则入口PE将向入口区域播发S-PMSI A-D路由，其中RD、多播源和多播组字段与接收到的叶A-D路由中的字段相同。此路由的PMSI隧道属性包含用于实例化入口区域段的区域内P2MP LSP的标识和上游分配的MPLS标签。入口区域内的入口ABR和其他PE（如有）将导入该路由。入口PE将使用在该路由中通告的（区域内）P2MP LSP来承载与PE通告的原始服务A-D路由相关联的业务。
Use of inter-area transport P2MP LSPs, as described in this section, creates a level of indirection between (inter-area) P2MP service LSPs, and intra-area transport LSPs that carry the service LSPs. Rather than segmenting (inter-area) service P2MP LSPs, and then aggregating (intra-area) segments of these service LSPs into intra-area transport LSPs, this approach first aggregates multiple (inter-area) service P2MP LSPs into a single inter-area transport P2MP LSP, then segments such inter-area transport P2MP LSPs, and then aggregates (intra-area) segments of these inter-area transport LSPs into intra-area transport LSPs.
如本节所述，使用区域间传输P2MP LSP会在（区域间）P2MP服务LSP和承载服务LSP的区域内传输LSP之间创建一个间接级别。这种方法不是将（区域间）服务P2MP LSP分段，然后将这些服务LSP的（区域内）分段聚合为区域内传输LSP，而是首先将多个（区域间）服务P2MP LSP聚合为单个区域间传输P2MP LSP，然后将此类区域间传输P2MP LSP分段，然后聚合这些区域间传输LSP的（区域内）段转换为区域内传输LSP。
On one hand, this approach could result in reducing the state (and the overhead associated with maintaining the state) on ABRs. This is because instead of requiring ABRs to maintain state for individual P2MP service LSPs, ABRs would need to maintain state only for the inter-area P2MP transport LSPs. Note, however, that this reduction is possible only if a single inter-area P2MP transport LSP aggregates more than one (inter-area) service LSP. In the absence of such aggregation, use of inter-area transport LSPs provides no benefits, yet results in extra overhead. And while such aggregation does allow reduced state on ABRs, it comes at a price, as described below.
一方面，这种方法可以减少abr上的状态（以及与维护状态相关的开销）。这是因为ABR不需要维护单个P2MP服务LSP的状态，而只需要维护区域间P2MP传输LSP的状态。然而，请注意，仅当单个区域间P2MP传输LSP聚合了多个（区域间）服务LSP时，才可能实现此减少。在没有这种聚合的情况下，使用区域间传输LSP不会带来任何好处，但会导致额外的开销。虽然这种聚合确实允许ABR上的状态减少，但它是有代价的，如下所述。
As we mentioned before, aggregating multiple P2MP service LSPs into a single inter-area P2MP transport LSP requires the PE rooted at these LSPs to determine all the leaf nodes of the service LSPs to be aggregated. This means that the root PE has to track all the leaf PEs of these LSPs. In contrast, when one applies segmentation procedures directly to the P2MP service LSPs, the root PE has to track only the leaf PEs in its own IGP area, plus the ingress ABR(s). Likewise, an ingress ABR has to track only the egress ABRs. Finally, an egress ABR has to track only the leaf PEs in its own area. Therefore, while the total overhead of leaf tracking due to the P2MP service LSPs is about the same in both approaches, the distribution of this overhead is different. Specifically, when one uses inter-area P2MP transport LSPs, this overhead is concentrated on the ingress PE. When one applies segmentation procedures directly to the P2MP service LSPs, this overhead is distributed among the ingress PE and ABRs.
如前所述，将多个P2MP服务LSP聚合到单个区域间P2MP传输LSP需要根在这些LSP上的PE确定要聚合的服务LSP的所有叶节点。这意味着根PE必须跟踪这些LSP的所有叶PE。相反，当将分段过程直接应用于P2MP服务LSP时，根PE必须仅跟踪其自身IGP区域中的叶PE，以及入口ABR。同样，入口ABR必须仅跟踪出口ABR。最后，出口ABR必须仅跟踪其自身区域内的叶片PEs。因此，虽然两种方法中由于P2MP服务lsp而产生的叶跟踪的总开销大致相同，但该开销的分布是不同的。具体地说，当使用区域间P2MP传输lsp时，该开销集中在入口PE上。当将分段过程直接应用于P2MP服务lsp时，该开销分布在入口PE和abr之间。
Moreover, when one uses inter-area P2MP transport LSPs, ABRs have to bear the overhead of leaf tracking for inter-area P2MP transport LSPs. In contrast, when one applies segmentation procedures directly to the P2MP service LSPs, there is no such overhead (as there are no inter-area P2MP transport LSPs).
此外，当使用区域间P2MP传输lsp时，abr必须承担区域间P2MP传输lsp的叶跟踪开销。相反，当将分段过程直接应用于P2MP服务lsp时，没有这样的开销（因为没有区域间P2MP传输lsp）。
Use of inter-area P2MP transport LSPs may also result in more bandwidth inefficiency, as compared to applying segmentation procedures directly to the P2MP service LSPs. This is because with inter-area P2MP transport LSPs the ABRs aggregate segments of inter-area P2MP transport LSPs, rather than segments of (inter-area) P2MP service LSPs. To illustrate this, consider the following example.
与直接将分段过程应用于P2MP服务lsp相比，使用区域间P2MP传输lsp还可能导致更多的带宽效率低下。这是因为对于区域间P2MP传输LSP，ABR聚合区域间P2MP传输LSP的段，而不是（区域间）P2MP服务LSP的段。为了说明这一点，请考虑下面的例子。
Assume PE1 in Area 1 is an ingress PE, with two multicast streams, (C-S1, C-G1) and (C-S2, C-G2), originated by an MVPN site connected to PE1. Assume that PE2 in Area 2 has an MVPN site with receivers for (C-S1, C-G1), PE3 and PE4 in Area 3 have an MVPN site with receivers for both (C-S1, C-G1) and (C-S2, C-G2). Finally, assume that PE5 in Area 4 has an MVPN site with receivers for (C-S2, C-G2).
假设区域1中的PE1是入口PE，具有两个多播流（C-S1、C-G1）和（C-S2、C-G2），由连接到PE1的MVPN站点发起。假设区域2的PE2有一个MVPN站点，其中接收器用于（C-S1，C-G1），区域3的PE3和PE4有一个MVPN站点，接收器用于（C-S1，C-G1）和（C-S2，C-G2）。最后，假设4区的PE5有一个MVPN站点，该站点具有（C-S2、C-G2）的接收器。
When segmentation applies directly to the P2MP service LSPs, Area 2 would have just one intra-area transport LSP that would carry the egress area segment of the P2MP service LSP for (C-S1, C-G1); Area 3 would have just one intra-area transport LSP that would carry the egress area segments of both the P2MP service LSP for (C-S1, C-G1) and the P2MP service LSP for (C-S2, C-G2); Area 4 would have just one intra-area transport LSP that would carry the egress area segment of the P2MP service LSP for (C-S2, C-G2). Note that there is no bandwidth inefficiency in this case at all.
当分段直接应用于P2MP服务LSP时，区域2将仅有一个区域内传输LSP，该LSP将承载（C-S1、C-G1）的P2MP服务LSP的出口区域分段；区域3将只有一个区域内传输LSP，该LSP将承载（C-S1，C-G1）的P2MP服务LSP和（C-S2，C-G2）的P2MP服务LSP的出口区域段；区域4将只有一个区域内传输LSP，该LSP将承载（C-S2、C-G2）的P2MP服务LSP的出口区域段。请注意，在这种情况下根本不存在带宽效率低下的问题。
When using inter-area P2MP transport LSPs, to achieve the same state overhead on the routers within each of the egress areas (except for egress ABRs), PE1 would need to aggregate the P2MP service LSP for (C-S1, C-G1) and the P2MP service LSP for (C-S2, C-G2) into the same inter-area P2MP transport LSP. While such aggregation would reduce state on ABRs, it would also result in bandwidth inefficiency, as (C-S1, C-G1) will be delivered not just to PE2, PE3, and PE4, but also to PE5, which has no receivers for this stream. Likewise, (C-S2, C-G2) will be delivered not just to PE3, PE4, and PE5, but also to PE2, which has no receivers for this stream.
当使用区域间P2MP传输LSP时，为了在每个出口区域（出口abr除外）内的路由器上实现相同的状态开销，PE1需要将（C-S1，C-G1）的P2MP服务LSP和（C-S2，C-G2）的P2MP服务LSP聚合到相同的区域间P2MP传输LSP中。虽然这种聚合会减少ABR上的状态，但也会导致带宽效率低下，因为（C-S1、C-G1）将不仅传送到PE2、PE3和PE4，而且也传送到PE5，因为PE5没有此流的接收器。同样，（C-S2、C-G2）将不仅交付给PE3、PE4和PE5，还将交付给PE2，该流没有接收器。
This document defines a new BGP Extended Community called "Inter-Area P2MP Segmented Next-Hop" (see Section 4). This may be either a Transitive IPv4-Address-Specific Extended Community or a Transitive IPv6-Address-Specific Extended Community. IANA has assigned the value 0x12 in the "Transitive IPv4-Address-Specific Extended Community Sub-Types" registry, and IANA has assigned the value 0x0012 in the "Transitive IPv6-Address-Specific Extended Community Types" registry. This document is the reference for both code points.
本文件定义了一个新的BGP扩展社区，称为“区域间P2MP分段下一跳”（见第4节）。这可以是特定于IPv4地址的可传递扩展社区，也可以是特定于IPv6地址的可传递扩展社区。IANA已在“特定于IPv4地址的可传递扩展社区子类型”注册表中分配了值0x12，IANA已在“特定于IPv6地址的可传递扩展社区子类型”注册表中分配了值0x0012。本文档是两个代码点的参考。
IANA has assigned the value 0x08 in the "P-Multicast Service Interface Tunnel (PMSI Tunnel) Tunnel Types" registry [RFC7385] as "Transport Tunnel" (see Section 14).
IANA已将“P-多播服务接口隧道（PMSI隧道）隧道类型”注册表[RFC7385]中的值0x08指定为“传输隧道”（见第14节）。
This document makes use of a Route Distinguisher whose value is all ones. The two-octet type field of this Route Distinguisher thus has the value 65535. IANA has assigned this value in the "Route Distinguisher Type Field" registry as "For Use Only in Certain Leaf A-D Routes", with this document as the reference.
本文档使用了一个值为“全1”的路由标识符。因此，该路由识别器的两个八位组类型字段的值为65535。IANA已将“路由识别器类型字段”注册表中的该值指定为“仅用于某些叶A-D路由”，并将本文件作为参考。
Procedures described in this document are subject to security threats similar to those experienced by any MPLS deployment. It is recommended that baseline security measures are considered as described in "Security Framework for MPLS and GMPLS Networks"
本文档中描述的过程会受到与任何MPLS部署类似的安全威胁。建议按照“MPLS和GMPLS网络安全框架”中的说明考虑基线安全措施
[RFC5920], in the mLDP specification [RFC6388], and in the P2MP RSVP-TE specification [RFC3209]. The security considerations of [RFC6513] are also applicable.
[RFC5920]，在mLDP规范[RFC6388]和P2MP RSVP-TE规范[RFC3209]中。[RFC6513]的安全注意事项也适用。
[RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996, <http://www.rfc-editor.org/info/rfc1997>.
[RFC1997]Chandra，R.，Traina，P.，和T.Li，“BGP社区属性”，RFC 1997，DOI 10.17487/RFC1997，1996年8月<http://www.rfc-editor.org/info/rfc1997>.
[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>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, <http://www.rfc-editor.org/info/rfc3209>.
[RFC3209]Awduche，D.，Berger，L.，Gan，D.，Li，T.，Srinivasan，V.，和G.Swallow，“RSVP-TE：LSP隧道RSVP的扩展”，RFC 3209，DOI 10.17487/RFC3209，2001年12月<http://www.rfc-editor.org/info/rfc3209>.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended Communities Attribute", RFC 4360, DOI 10.17487/RFC4360, February 2006, <http://www.rfc-editor.org/info/rfc4360>.
[RFC4360]Sangli，S.，Tappan，D.和Y.Rekhter，“BGP扩展社区属性”，RFC 4360，DOI 10.17487/RFC4360，2006年2月<http://www.rfc-editor.org/info/rfc4360>.
[RFC4456] Bates, T., Chen, E., and R. Chandra, "BGP Route Reflection: An Alternative to Full Mesh Internal BGP (IBGP)", RFC 4456, DOI 10.17487/RFC4456, April 2006, <http://www.rfc-editor.org/info/rfc4456>.
[RFC4456]Bates，T.，Chen，E.和R.Chandra，“BGP路由反射：全网格内部BGP（IBGP）的替代方案”，RFC 4456，DOI 10.17487/RFC4456，2006年4月<http://www.rfc-editor.org/info/rfc4456>.
[RFC4684] Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk, R., Patel, K., and J. Guichard, "Constrained Route Distribution for Border Gateway Protocol/MultiProtocol Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual Private Networks (VPNs)", RFC 4684, DOI 10.17487/RFC4684, November 2006, <http://www.rfc-editor.org/info/rfc4684>.
[RFC4684]Marques，P.，Bonica，R.，Fang，L.，Martini，L.，Raszuk，R.，Patel，K.，和J.Guichard，“边界网关协议/多协议标签交换（BGP/MPLS）互联网协议（IP）虚拟专用网络（VPN）的受限路由分布”，RFC 4684，DOI 10.17487/RFC4684，2006年11月<http://www.rfc-editor.org/info/rfc4684>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, "Multiprotocol Extensions for BGP-4", RFC 4760, DOI 10.17487/RFC4760, January 2007, <http://www.rfc-editor.org/info/rfc4760>.
[RFC4760]Bates，T.，Chandra，R.，Katz，D.，和Y.Rekhter，“BGP-4的多协议扩展”，RFC 4760，DOI 10.17487/RFC4760，2007年1月<http://www.rfc-editor.org/info/rfc4760>.
[RFC4761] Kompella, K., Ed., and Y. Rekhter, Ed., "Virtual Private LAN Service (VPLS) Using BGP for Auto-Discovery and Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007, <http://www.rfc-editor.org/info/rfc4761>.
[RFC4761]Kompella，K.，Ed.，和Y.Rekhter，Ed.，“使用BGP进行自动发现和信令的虚拟专用LAN服务（VPLS）”，RFC 4761，DOI 10.17487/RFC4761，2007年1月<http://www.rfc-editor.org/info/rfc4761>.
[RFC4875] Aggarwal, R., Ed., Papadimitriou, D., Ed., and S. Yasukawa, Ed., "Extensions to Resource Reservation Protocol - Traffic Engineering (RSVP-TE) for Point-to-Multipoint TE Label Switched Paths (LSPs)", RFC 4875, DOI 10.17487/RFC4875, May 2007, <http://www.rfc-editor.org/info/rfc4875>.
[RFC4875]Aggarwal，R.，Ed.，Papadimitriou，D.，Ed.，和S.Yasukawa，Ed.，“资源预留协议的扩展-点对多点TE标签交换路径（LSP）的流量工程（RSVP-TE）”，RFC 4875，DOI 10.17487/RFC4875，2007年5月<http://www.rfc-editor.org/info/rfc4875>.
[RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed., "LDP Specification", RFC 5036, DOI 10.17487/RFC5036, October 2007, <http://www.rfc-editor.org/info/rfc5036>.
[RFC5036]Andersson，L.，Ed.，Minei，I.，Ed.，和B.Thomas，Ed.“LDP规范”，RFC 5036，DOI 10.17487/RFC5036，2007年10月<http://www.rfc-editor.org/info/rfc5036>.
[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>.
[RFC5332] Eckert, T., Rosen, E., Ed., Aggarwal, R., and Y. Rekhter, "MPLS Multicast Encapsulations", RFC 5332, DOI 10.17487/RFC5332, August 2008, <http://www.rfc-editor.org/info/rfc5332>.
[RFC5332]Eckert，T.，Rosen，E.，Ed.，Aggarwal，R.，和Y.Rekhter，“MPLS多播封装”，RFC 5332，DOI 10.17487/RFC5332，2008年8月<http://www.rfc-editor.org/info/rfc5332>.
[RFC6074] Rosen, E., Davie, B., Radoaca, V., and W. Luo, "Provisioning, Auto-Discovery, and Signaling in Layer 2 Virtual Private Networks (L2VPNs)", RFC 6074, DOI 10.17487/RFC6074, January 2011, <http://www.rfc-editor.org/info/rfc6074>.
[RFC6074]Rosen，E.，Davie，B.，Radoaca，V.，和W.Luo，“第二层虚拟专用网络（L2VPN）中的资源调配、自动发现和信令”，RFC 6074，DOI 10.17487/RFC6074，2011年1月<http://www.rfc-editor.org/info/rfc6074>.
[RFC6368] Marques, P., Raszuk, R., Patel, K., Kumaki, K., and T. Yamagata, "Internal BGP as the Provider/Customer Edge Protocol for BGP/MPLS IP Virtual Private Networks (VPNs)", RFC 6368, DOI 10.17487/RFC6368, September 2011, <http://www.rfc-editor.org/info/rfc6368>.
[RFC6368]Marques，P.，Raszuk，R.，Patel，K.，Kumaki，K.，和T.Yamagata，“内部BGP作为BGP/MPLS IP虚拟专用网络（VPN）的提供商/客户边缘协议”，RFC 6368，DOI 10.17487/RFC6368，2011年9月<http://www.rfc-editor.org/info/rfc6368>.
[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>.
[RFC7117] Aggarwal, R., Ed., Kamite, Y., Fang, L., Rekhter, Y., and C. Kodeboniya, "Multicast in Virtual Private LAN Service (VPLS)", RFC 7117, DOI 10.17487/RFC7117, February 2014, <http://www.rfc-editor.org/info/rfc7117>.
[RFC7117]Aggarwal，R.，Ed.，Kamite，Y.，Fang，L.，Rekhter，Y.，和C.Kodeboniya，“虚拟专用局域网服务（VPLS）中的多播”，RFC 7117，DOI 10.17487/RFC71172014年2月<http://www.rfc-editor.org/info/rfc7117>.
[RFC7385] Andersson, L. and G. Swallow, "IANA Registry for P-Multicast Service Interface (PMSI) Tunnel Type Code Points", RFC 7385, DOI 10.17487/RFC7385, October 2014, <http://www.rfc-editor.org/info/rfc7385>.
[RFC7385]Andersson，L.和G.Swallow，“P-多播服务接口（PMSI）隧道类型代码点的IANA注册”，RFC 7385，DOI 10.17487/RFC7385，2014年10月<http://www.rfc-editor.org/info/rfc7385>.
[GTM] Zhang, J, Giuliano, L, Rosen, E., Ed., Subramanian, K., Pacella, D., and J. Schiller, "Global Table Multicast with BGP-MVPN Procedures", Work in Progress, draft-ietf-bess-mvpn-global-table-mcast-00, November 2014.
[GTM]Zhang，J，Giuliano，L，Rosen，E.，Ed.，Subramanian，K.，Pacella，D.，和J.Schiller，“使用BGP-MVPN程序的全局表多播”，正在进行的工作，草稿-ietf-bess-MVPN-Global-Table-mcast-00，2014年11月。
[RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010, <http://www.rfc-editor.org/info/rfc5920>.
[RFC5920]方，L.，编辑，“MPLS和GMPLS网络的安全框架”，RFC 5920，DOI 10.17487/RFC5920，2010年7月<http://www.rfc-editor.org/info/rfc5920>.
[RFC7024] Jeng, H., Uttaro, J., Jalil, L., Decraene, B., Rekhter, Y., and R. Aggarwal, "Virtual Hub-and-Spoke in BGP/MPLS VPNs", RFC 7024, DOI 10.17487/RFC7024, October 2013, <http://www.rfc-editor.org/info/rfc7024>.
[RFC7024]Jeng，H.，Uttaro，J.，Jalil，L.，Decraene，B.，Rekhter，Y.，和R.Aggarwal，“BGP/MPLS VPN中的虚拟中心和辐射”，RFC 7024DOI 10.17487/RFC70242013年10月<http://www.rfc-editor.org/info/rfc7024>.
[SEAMLESS-MPLS] Leymann, N., Ed., Decraene, B., Filsfils, C., Konstantynowicz, M., Ed., and D. Steinberg, "Seamless MPLS Architecture", Work in Progress, draft-ietf-mpls-seamless-mpls-07, June 2014.
[SEAMLESS-MPLS]莱曼，N.，Ed.，德雷恩，B.，菲尔斯菲尔斯，C.，康斯坦蒂诺维奇，M.，Ed.，和D.斯坦伯格，“无缝MPLS体系结构”，在建工程，草案-ietf-MPLS-SEAMLESS-MPLS-072014年6月。
Acknowledgements
致谢
We would like to thank Loa Andersson and Qin Wu for their review and comments.
我们要感谢Loa Andersson和秦武的审查和评论。
Authors' Addresses
作者地址
Yakov Rekhter Juniper Networks 1194 North Mathilda Ave. Sunnyvale, CA 94089 United States
美国加利福尼亚州桑尼维尔北马蒂尔达大道1194号雅科夫·雷克特·朱尼珀网络公司，邮编94089
Eric C Rosen Juniper Networks 10 Technology Park Drive Westford, MA 01886 United States EMail: erosen@juniper.net
Eric C Rosen Juniper Networks 10 Technology Park Drive Westford，马萨诸塞州01886美国电子邮件：erosen@juniper.net
Rahul Aggarwal EMail: raggarwa_1@yahoo.com
Rahul Aggarwal电子邮件：raggarwa_1@yahoo.com
Thomas Morin Orange 2, avenue Pierre-Marzin 22307 Lannion Cedex France EMail: thomas.morin@orange.com
Thomas Morin Orange 2，Pierre Marzin大街22307 Lannion Cedex法国电子邮件：Thomas。morin@orange.com
Irene Grosclaude Orange 2, avenue Pierre-Marzin 22307 Lannion Cedex France EMail: irene.grosclaude@orange.com
艾琳·格罗斯克劳德·奥兰治2号，皮埃尔·马津大街22307拉尼翁·塞德克斯法国电子邮件：艾琳。grosclaude@orange.com
Nicolai Leymann Deutsche Telekom AG Winterfeldtstrasse 21 Berlin 10781 Germany EMail: n.leymann@telekom.de
Nicolai Leymann Deutsche Telekom AG Winterfeldtstrasse 21 Berlin 10781德国电子邮件：n。leymann@telekom.de
Samir Saad AT&T EMail: samirsaad1@outlook.com
萨米尔·萨阿德AT&T电子邮件：samirsaad1@outlook.com