Internet Engineering Task Force (IETF) D. Dhody
Request for Comments: 7897 U. Palle
Category: Experimental Huawei Technologies
ISSN: 2070-1721 R. Casellas
CTTC
June 2016
Internet Engineering Task Force (IETF) D. Dhody
Request for Comments: 7897 U. Palle
Category: Experimental Huawei Technologies
ISSN: 2070-1721 R. Casellas
CTTC
June 2016
Domain Subobjects for the Path Computation Element Communication Protocol (PCEP)
路径计算元素通信协议（PCEP）的域子对象
Abstract
摘要
The ability to compute shortest constrained Traffic Engineering Label Switched Paths (TE LSPs) in Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) networks across multiple domains has been identified as a key requirement. In this context, a domain is a collection of network elements within a common sphere of address management or path computational responsibility such as an Interior Gateway Protocol (IGP) area or an Autonomous System (AS). This document specifies a representation and encoding of a domain sequence, which is defined as an ordered sequence of domains traversed to reach the destination domain to be used by Path Computation Elements (PCEs) to compute inter-domain constrained shortest paths across a predetermined sequence of domains. This document also defines new subobjects to be used to encode domain identifiers.
在跨多个域的多协议标签交换（MPLS）和广义MPLS（GMPLS）网络中，计算最短约束流量工程标签交换路径（TE LSP）的能力已被确定为一项关键要求。在此上下文中，域是地址管理或路径计算责任的公共范围内的网络元素的集合，例如内部网关协议（IGP）区域或自治系统（as）。本文档规定了域序列的表示和编码，域序列定义为经过的域的有序序列，以到达目标域，路径计算元素（PCE）将使用该序列计算跨预定域序列的域间约束最短路径。本文档还定义了用于编码域标识符的新子对象。
Status of This Memo
关于下段备忘
This document is not an Internet Standards Track specification; it is published for examination, experimental implementation, and evaluation.
本文件不是互联网标准跟踪规范；它是为检查、实验实施和评估而发布的。
This document defines an Experimental Protocol for the Internet community. 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). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 7841.
本文档为互联网社区定义了一个实验协议。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。并非IESG批准的所有文件都适用于任何级别的互联网标准；见RFC 7841第2节。
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7897.
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/rfc7897.
Copyright Notice
版权公告
Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2016 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 . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Detail Description . . . . . . . . . . . . . . . . . . . . . 6
3.1. Domains . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Domain Sequence . . . . . . . . . . . . . . . . . . . . . 6
3.3. Domain Sequence Representation . . . . . . . . . . . . . 7
3.4. Include Route Object (IRO) . . . . . . . . . . . . . . . 8
3.4.1. Subobjects . . . . . . . . . . . . . . . . . . . . . 8
3.4.1.1. Autonomous System . . . . . . . . . . . . . . . . 8
3.4.1.2. IGP Area . . . . . . . . . . . . . . . . . . . . 9
3.4.2. Update in IRO Specification . . . . . . . . . . . . . 10
3.4.3. IRO for Domain Sequence . . . . . . . . . . . . . . . 11
3.4.3.1. PCC Procedures . . . . . . . . . . . . . . . . . 11
3.4.3.2. PCE Procedures . . . . . . . . . . . . . . . . . 11
3.5. Exclude Route Object (XRO) . . . . . . . . . . . . . . . 13
3.5.1. Subobjects . . . . . . . . . . . . . . . . . . . . . 13
3.5.1.1. Autonomous System . . . . . . . . . . . . . . . . 14
3.5.1.2. IGP Area . . . . . . . . . . . . . . . . . . . . 14
3.6. Explicit Exclusion Route Subobject (EXRS) . . . . . . . . 16
3.7. Explicit Route Object (ERO) . . . . . . . . . . . . . . . 16
4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.1. Inter-Area Path Computation . . . . . . . . . . . . . . . 17
4.2. Inter-AS Path Computation . . . . . . . . . . . . . . . . 19
4.2.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . 20
4.2.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . 22
4.3. Boundary Node and Inter-AS Link . . . . . . . . . . . . . 25
4.4. PCE Serving Multiple Domains . . . . . . . . . . . . . . 25
4.5. P2MP . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.6. Hierarchical PCE . . . . . . . . . . . . . . . . . . . . 27
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Detail Description . . . . . . . . . . . . . . . . . . . . . 6
3.1. Domains . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Domain Sequence . . . . . . . . . . . . . . . . . . . . . 6
3.3. Domain Sequence Representation . . . . . . . . . . . . . 7
3.4. Include Route Object (IRO) . . . . . . . . . . . . . . . 8
3.4.1. Subobjects . . . . . . . . . . . . . . . . . . . . . 8
3.4.1.1. Autonomous System . . . . . . . . . . . . . . . . 8
3.4.1.2. IGP Area . . . . . . . . . . . . . . . . . . . . 9
3.4.2. Update in IRO Specification . . . . . . . . . . . . . 10
3.4.3. IRO for Domain Sequence . . . . . . . . . . . . . . . 11
3.4.3.1. PCC Procedures . . . . . . . . . . . . . . . . . 11
3.4.3.2. PCE Procedures . . . . . . . . . . . . . . . . . 11
3.5. Exclude Route Object (XRO) . . . . . . . . . . . . . . . 13
3.5.1. Subobjects . . . . . . . . . . . . . . . . . . . . . 13
3.5.1.1. Autonomous System . . . . . . . . . . . . . . . . 14
3.5.1.2. IGP Area . . . . . . . . . . . . . . . . . . . . 14
3.6. Explicit Exclusion Route Subobject (EXRS) . . . . . . . . 16
3.7. Explicit Route Object (ERO) . . . . . . . . . . . . . . . 16
4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.1. Inter-Area Path Computation . . . . . . . . . . . . . . . 17
4.2. Inter-AS Path Computation . . . . . . . . . . . . . . . . 19
4.2.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . 20
4.2.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . 22
4.3. Boundary Node and Inter-AS Link . . . . . . . . . . . . . 25
4.4. PCE Serving Multiple Domains . . . . . . . . . . . . . . 25
4.5. P2MP . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.6. Hierarchical PCE . . . . . . . . . . . . . . . . . . . . 27
5. Other Considerations . . . . . . . . . . . . . . . . . . . . 27
5.1. Relationship to PCE Sequence . . . . . . . . . . . . . . 27
5.2. Relationship to RSVP-TE . . . . . . . . . . . . . . . . . 27
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
6.1. New Subobjects . . . . . . . . . . . . . . . . . . . . . 28
7. Security Considerations . . . . . . . . . . . . . . . . . . . 28
8. Manageability Considerations . . . . . . . . . . . . . . . . 29
8.1. Control of Function and Policy . . . . . . . . . . . . . 29
8.2. Information and Data Models . . . . . . . . . . . . . . . 29
8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 30
8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 30
8.5. Requirements on Other Protocols . . . . . . . . . . . . . 30
8.6. Impact on Network Operations . . . . . . . . . . . . . . 30
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 31
9.1. Normative References . . . . . . . . . . . . . . . . . . 31
9.2. Informative References . . . . . . . . . . . . . . . . . 32
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35
5. Other Considerations . . . . . . . . . . . . . . . . . . . . 27
5.1. Relationship to PCE Sequence . . . . . . . . . . . . . . 27
5.2. Relationship to RSVP-TE . . . . . . . . . . . . . . . . . 27
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
6.1. New Subobjects . . . . . . . . . . . . . . . . . . . . . 28
7. Security Considerations . . . . . . . . . . . . . . . . . . . 28
8. Manageability Considerations . . . . . . . . . . . . . . . . 29
8.1. Control of Function and Policy . . . . . . . . . . . . . 29
8.2. Information and Data Models . . . . . . . . . . . . . . . 29
8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 30
8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 30
8.5. Requirements on Other Protocols . . . . . . . . . . . . . 30
8.6. Impact on Network Operations . . . . . . . . . . . . . . 30
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 31
9.1. Normative References . . . . . . . . . . . . . . . . . . 31
9.2. Informative References . . . . . . . . . . . . . . . . . 32
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35
A Path Computation Element (PCE) may be used to compute end-to-end paths across multi-domain environments using a per-domain path computation technique [RFC5152]. The Backward-Recursive PCE-Based Computation (BRPC) mechanism [RFC5441] also defines a PCE-based path computation procedure to compute an inter-domain constrained path for (G)MPLS TE LSPs. However, both per-domain and BRPC techniques assume that the sequence of domains to be crossed from source to destination is known and is either fixed by the network operator or obtained by other means. Also, for inter-domain point-to-multipoint (P2MP) tree computation, it is assumed per [RFC7334] that the domain tree is known a priori.
路径计算元件（PCE）可用于使用每域路径计算技术计算跨多域环境的端到端路径[RFC5152]。基于PCE的反向递归计算（BRPC）机制[RFC5441]还定义了基于PCE的路径计算过程，以计算（G）MPLS TE LSP的域间约束路径。然而，每个域和BRPC技术都假定从源到目的地的域的交叉顺序是已知的，并且由网络运营商固定或通过其他方式获得。此外，对于域间点对多点（P2MP）树计算，根据[RFC7334]假设域树是先验的。
The list of domains (domain sequence) in point-to-point (P2P) or a domain tree in P2MP is usually a constraint in inter-domain path computation procedure.
点到点（P2P）中的域列表（域序列）或P2MP中的域树通常是域间路径计算过程中的一个约束。
The domain sequence (the set of domains traversed to reach the destination domain) is either administratively predetermined or discovered by some means like Hierarchical PCE (H-PCE).
域序列（为到达目的域而遍历的域的集合）或者是在管理上预先确定的，或者是通过诸如分层PCE（H-PCE）之类的方法来发现的。
[RFC5440] defines the Include Route Object (IRO) and the Explicit Route Object (ERO). [RFC5521] defines the Exclude Route Object (XRO) and the Explicit Exclusion Route subobject (EXRS). The use of an Autonomous System (albeit with a 2-byte AS number) as an abstract node representing a domain is defined in [RFC3209]. In the current document, we specify new subobjects to include or exclude domains including an IGP area or an AS (4 bytes as per [RFC6793]).
[RFC5440]定义包含路由对象（IRO）和显式路由对象（ERO）。[RFC5521]定义排除路由对象（XRO）和显式排除路由子对象（EXRS）。[RFC3209]中定义了使用自治系统（尽管以2字节作为数字）作为表示域的抽象节点。在当前文档中，我们指定了新的子对象，以包括或排除包含IGP区域或AS的域（根据[RFC6793]）。
Further, the domain identifier may simply act as a delimiter to specify where the domain boundary starts and ends in some cases.
此外，在某些情况下，域标识符可以简单地充当分隔符，以指定域边界的开始和结束位置。
This is a companion document to Resource Reservation Protocol - Traffic Engineering (RSVP-TE) extensions for the domain identifiers [RFC7898].
这是域标识符的资源预留协议-流量工程（RSVP-TE）扩展[RFC7898]的配套文档。
The procedures described in this document are experimental. The experiment is intended to enable research for the usage of the domain sequence at the PCEs for inter-domain paths. For this purpose, this document specifies new domain subobjects as well as how they incorporate with existing subobjects to represent a domain sequence.
本文件中描述的程序是实验性的。该实验旨在研究PCE中的域序列在域间路径中的使用。为此，本文档指定了新的域子对象以及它们如何与现有子对象合并以表示域序列。
The experiment will end two years after the RFC is published. At that point, the RFC authors will attempt to determine how widely this has been implemented and deployed.
实验将在RFC出版两年后结束。到那时，RFC作者将试图确定这项技术的实施和部署范围有多广。
This document does not change the procedures for handling existing subobjects in the PCE Communication Protocol (PCEP).
本文档不会更改处理PCE通信协议（PCEP）中现有子对象的过程。
The new subobjects introduced by this document will not be understood by legacy implementations. If a legacy implementation receives one of the subobjects that it does not understand in a PCEP object, the legacy implementation will behave according to the rules for a malformed object as per [RFC5440]. Therefore, it is assumed that this experiment will be conducted only when both the PCE and the Path Computation Client (PCC) form part of the experiment. It is possible that a PCC or PCE can operate with peers, some of which form part of the experiment and some that do not. In this case, since no capabilities exchange is used to identify which nodes can use these extensions, manual configuration should be used to determine which peerings form part of the experiment.
本文档引入的新子对象不会被遗留实现所理解。如果旧式实现接收到它在PCEP对象中不理解的子对象之一，则旧式实现将根据[RFC5440]中格式错误对象的规则进行操作。因此，假设仅当PCE和路径计算客户端（PCC）构成实验的一部分时，才会进行该实验。PCC或PCE可能与对等方一起运行，其中一些构成实验的一部分，而另一些则不构成实验的一部分。在这种情况下，由于没有使用功能交换来确定哪些节点可以使用这些扩展，因此应该使用手动配置来确定哪些对等构成实验的一部分。
When the results of implementation and deployment are available, this document will be updated and refined, and then it could be moved from Experimental to Standards Track.
当实现和部署的结果可用时，将更新和完善此文档，然后将其从实验性转移到标准轨道。
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 following terminology is used in this document.
本文件使用以下术语。
ABR: Area Border Router. Routers used to connect two IGP areas (Open Shortest Path First (OSPF) or Intermediate System to Intermediate System (IS-IS).
区域边界路由器。用于连接两个IGP区域（开放最短路径优先（OSPF）或中间系统到中间系统（IS-IS））的路由器。
AS: Autonomous System
AS：自治系统
ASBR: Autonomous System Border Router
自治系统边界路由器
BN: Boundary node; can be an ABR or ASBR.
BN：边界节点；可以是ABR或ASBR。
BRPC: Backward-Recursive PCE-Based Computation
BRPC：基于PCE的反向递归计算
Domain: As per [RFC4655], any collection of network elements within a common sphere of address management or path computational responsibility. Examples of domains include IGP area and AS.
域：根据[RFC4655]，在地址管理或路径计算责任的公共范围内的任何网络元素集合。域的示例包括IGP区域和AS。
Domain Sequence: An ordered sequence of domains traversed to reach the destination domain.
域序列：为到达目标域而遍历的域的有序序列。
ERO: Explicit Route Object
显式路由对象
H-PCE: Hierarchical PCE
H-PCE：分级PCE
IGP: Interior Gateway Protocol. Either of the two routing protocols: OSPF or IS-IS.
IGP：内部网关协议。两种路由协议之一：OSPF或IS-IS。
IRO: Include Route Object
IRO：包含路由对象
IS-IS: Intermediate System to Intermediate System
IS-IS：中间系统至中间系统
OSPF: Open Shortest Path First
开放最短路径优先
PCC: Path Computation Client. Any client application requesting a path computation to be performed by a Path Computation Element.
路径计算客户端。任何请求由路径计算元素执行的路径计算的客户端应用程序。
PCE: Path Computation Element. An entity (component, application, or network node) that is capable of computing a network path or route based on a network graph and applying computational constraints.
PCE：路径计算元素。能够基于网络图计算网络路径或路由并应用计算约束的实体（组件、应用程序或网络节点）。
P2MP: Point-to-Multipoint
P2MP：点对多点
P2P: Point-to-Point
P2P：点对点
RSVP: Resource Reservation Protocol
资源预留协议
TE LSP: Traffic Engineering Label Switched Path
TE LSP：流量工程标签交换路径
XRO: Exclude Route Object
XRO:排除路由对象
[RFC4726] and [RFC4655] define a domain as a separate administrative or geographic environment within the network. A domain could be further defined as a zone of routing or computational ability. Under these definitions, a domain might be categorized as an AS or an IGP area. Each AS can be made of several IGP areas. In order to encode a domain sequence, it is required to uniquely identify a domain in the domain sequence. A domain can be uniquely identified by an area-id, AS number, or both.
[RFC4726]和[RFC4655]将域定义为网络内单独的管理或地理环境。域可以进一步定义为路由或计算能力区域。根据这些定义，域可能被分类为as或IGP区域。每个AS可以由几个IGP区域组成。为了编码域序列，需要唯一地标识域序列中的域。域可以通过区域id、数字或两者来唯一标识。
A domain sequence is an ordered sequence of domains traversed to reach the destination domain.
域序列是为了到达目标域而遍历的域的有序序列。
A domain sequence can be applied as a constraint and carried in a path computation request to a PCE(s). A domain sequence can also be the result of a path computation. For example, in the case of H-PCE [RFC6805], a parent PCE could send the domain sequence as a result in a path computation reply.
域序列可以作为约束应用，并在路径计算请求中携带到PCE。域序列也可以是路径计算的结果。例如，在H-PCE[RFC6805]的情况下，父PCE可以发送域序列作为路径计算应答的结果。
In a P2P path, the domains listed appear in the order that they are crossed. In a P2MP path, the domain tree is represented as a list of domain sequences.
在P2P路径中，列出的域按交叉顺序显示。在P2MP路径中，域树表示为域序列列表。
A domain sequence enables a PCE to select the next domain and the PCE serving that domain to forward the path computation request based on the domain information.
域序列使得PCE能够选择下一个域，并且服务于该域的PCE能够基于域信息转发路径计算请求。
A domain sequence can include boundary nodes (ABR or ASBR) or border links (inter-AS links) to be traversed as an additional constraint.
域序列可以包括边界节点（ABR或ASBR）或边界链路（AS间链路），以作为附加约束进行遍历。
Thus, a domain sequence can be made up of one or more of the following:
因此，域序列可以由以下一个或多个组成：
o AS Number
o 作为号码
o Area ID
o 区域ID
o Boundary Node ID
o 边界节点ID
o Inter-AS Link Address
o 内部AS链接地址
These are encoded in the new subobjects defined in this document as well as in the existing subobjects that represent a domain sequence.
它们编码在本文档中定义的新子对象以及表示域序列的现有子对象中。
Consequently, a domain sequence can be used by:
因此，域序列可用于：
1. a PCE in order to discover or select the next PCE in a collaborative path computation, such as in BRPC [RFC5441];
1. 用于在协作路径计算中发现或选择下一个PCE的PCE，例如在BRPC[RFC5441]中；
2. the parent PCE to return the domain sequence when unknown; this can then be an input to the BRPC procedure [RFC6805];
2. 未知时返回域序列的父PCE；这可以作为BRPC程序[RFC6805]的输入；
3. a PCC or a PCE to constrain the domains used in inter-domain path computation, explicitly specifying which domains to be expanded or excluded; and
3. PCC或PCE，用于约束域间路径计算中使用的域，明确指定要扩展或排除的域；和
4. a PCE in the per-domain path computation model [RFC5152] to identify the next domain.
4. 每个域路径计算模型[RFC5152]中的PCE，用于识别下一个域。
A domain sequence appears in PCEP messages, notably in:
域序列出现在PCEP消息中，尤其是在：
o Include Route Object (IRO): As per [RFC5440], IRO can be used to specify a set of network elements to be traversed to reach the destination, which includes subobjects used to specify the domain sequence.
o 包含路由对象（IRO）：根据[RFC5440]，IRO可用于指定一组要通过以到达目的地的网元，其中包括用于指定域序列的子对象。
o Exclude Route Object (XRO): As per [RFC5521], XRO can be used to specify certain abstract nodes, to be excluded from the whole path, which include subobjects used to specify the domain sequence.
o 排除路由对象（XRO）：根据[RFC5521]，XRO可用于指定要从整个路径中排除的某些抽象节点，其中包括用于指定域序列的子对象。
o Explicit Exclusion Route Subobject (EXRS): As per [RFC5521], EXRS can be used to specify exclusion of certain abstract nodes (including domains) between a specific pair of nodes. EXRS is a subobject inside the IRO.
o 显式排除路由子对象（EXRS）：根据[RFC5521]，EXRS可用于指定特定节点对之间某些抽象节点（包括域）的排除。EXRS是IRO中的一个子对象。
o Explicit Route Object (ERO): As per [RFC5440], ERO can be used to specify a computed path in the network. For example, in the case of H-PCE [RFC6805], a parent PCE can send the domain sequence as a result in a path computation reply using ERO.
o 显式路由对象（ERO）：根据[RFC5440]，ERO可用于指定网络中的计算路径。例如，在H-PCE[RFC6805]的情况下，父PCE可以使用ERO在路径计算应答中发送域序列作为结果。
As per [RFC5440], IRO can be used to specify that the computed path needs to traverse a set of specified network elements or abstract nodes.
根据[RFC5440]，IRO可用于指定计算路径需要遍历一组指定的网络元素或抽象节点。
Some subobjects are defined in [RFC3209], [RFC3473], [RFC3477], and [RFC4874], but new subobjects related to domain sequence are needed.
[RFC3209]、[RFC3473]、[RFC3477]和[RFC4874]中定义了一些子对象，但需要与域序列相关的新子对象。
This document extends the support for 4-byte AS numbers and IGP areas.
本文档扩展了对4字节AS数字和IGP区域的支持。
Value Description
----- ----------------
5 4-byte AS number
6 OSPF Area ID
7 IS-IS Area ID
Value Description
----- ----------------
5 4-byte AS number
6 OSPF Area ID
7 IS-IS Area ID
Note: Identical subobjects are carried in RSVP-TE messages as defined in [RFC7898].
注：按照[RFC7898]中的定义，RSVP-TE消息中包含相同的子对象。
[RFC3209] already defines 2-byte AS numbers.
[RFC3209]已将2字节定义为数字。
To support 4-byte AS numbers as per [RFC6793], the following subobject is defined:
根据[RFC6793]，为支持4字节AS编号，定义了以下子对象：
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS Number (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS Number (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L: The L bit is an attribute of the subobject as defined in [RFC3209], and its usage in the IRO subobject is defined in [RFC7896].
L:L位是[RFC3209]中定义的子对象的属性，其在IRO子对象中的用法在[RFC7896]中定义。
Type: 5 (indicating a 4-byte AS number).
类型：5（表示4字节作为数字）。
Length: 8 (total length of the subobject in bytes).
长度：8（子对象的总长度（字节）。
Reserved: Zero at transmission; ignored at receipt.
保留：传输时为零；收到时忽略。
AS Number: The 4-byte AS number. Note that if 2-byte AS numbers are in use, the low-order bits (16 through 31) MUST be used, and the high-order bits (0 through 15) MUST be set to zero.
AS编号：4字节AS编号。请注意，如果使用2字节AS数字，则必须使用低位（16到31），高位（0到15）必须设置为零。
Since the length and format of Area ID is different for OSPF and IS-IS, the following two subobjects are defined below:
由于OSPF和is-is的区域ID的长度和格式不同，下面定义了以下两个子对象：
For OSPF, the Area ID is a 32-bit number. The subobject is encoded as follows:
对于OSPF，区域ID是32位数字。子对象的编码如下所示：
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OSPF Area ID (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OSPF Area ID (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L: The L bit is an attribute of the subobject as defined in [RFC3209], and its usage in the IRO subobject is defined in [RFC7896].
L:L位是[RFC3209]中定义的子对象的属性，其在IRO子对象中的用法在[RFC7896]中定义。
Type: 6 (indicating a 4-byte OSPF Area ID).
类型：6（表示一个4字节的OSPF区域ID）。
Length: 8 (total length of the subobject in bytes).
长度：8（子对象的总长度（字节）。
Reserved: Zero at transmission; ignored at receipt.
保留：传输时为零；收到时忽略。
OSPF Area ID: The 4-byte OSPF Area ID.
OSPF区域ID：4字节的OSPF区域ID。
For IS-IS, the Area ID is of variable length; thus, the length of the subobject is variable. The Area ID is as described in IS-IS by the ISO standard [ISO10589]. The subobject is encoded as follows:
对于IS-IS，区域ID具有可变长度；因此，子对象的长度是可变的。区域ID如ISO标准[ISO10589]is-is中所述。子对象的编码如下所示：
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Area-Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// IS-IS Area ID //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Area-Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// IS-IS Area ID //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L: The L bit is an attribute of the subobject as defined in [RFC3209], and its usage in the IRO subobject is defined in [RFC7896].
L:L位是[RFC3209]中定义的子对象的属性，其在IRO子对象中的用法在[RFC7896]中定义。
Type: 7 (indicating the IS-IS Area ID).
类型：7（表示IS-IS区域ID）。
Length: Variable. The length MUST be at least 8 and MUST be a multiple of 4.
长度：可变。长度必须至少为8，并且必须是4的倍数。
Area-Len: Variable (length of the actual (non-padded) IS-IS area identifier in octets; valid values are from 1 to 13, inclusive).
Area Len：变量（实际（非填充）IS-IS区域标识符的长度，以八位字节为单位；有效值为1到13，包括在内）。
Reserved: Zero at transmission; ignored at receipt.
保留：传输时为零；收到时忽略。
IS-IS Area ID: The variable-length IS-IS area identifier. Padded with trailing zeroes to a 4-byte boundary.
IS-IS区域ID：可变长度IS-IS区域标识符。用尾随零填充到4字节边界。
[RFC5440] describes IRO as an optional object used to specify network elements to be traversed by the computed path. It further states that the L bit of such subobject has no meaning within an IRO. It also does not mention if IRO is an ordered or unordered list of subobjects.
[RFC5440]将IRO描述为一个可选对象，用于指定计算路径要遍历的网络元素。它进一步声明，该子对象的L位在IRO中没有意义。它也没有提到IRO是有序的还是无序的子对象列表。
An update to the IRO specification [RFC7896] makes IRO as an ordered list and includes support for the L bit.
对IRO规范[RFC7896]的更新使IRO成为一个有序列表，并包括对L位的支持。
The use of IRO for the domain sequence assumes the updated specification is being used for IRO, as per [RFC7896].
根据[RFC7896]，在域序列中使用IRO时，假定已更新的规范用于IRO。
The subobject type for IPv4, IPv6, and unnumbered Interface IDs can be used to specify boundary nodes (ABR/ASBR) and inter-AS links. The subobject type for the AS Number (2 or 4 bytes) and the IGP area are used to specify the domain identifiers in the domain sequence.
IPv4、IPv6和未编号接口ID的子对象类型可用于指定边界节点（ABR/ASBR）和AS间链路。AS编号（2或4字节）的子对象类型和IGP区域用于指定域序列中的域标识符。
The IRO can incorporate the new domain subobjects with the existing subobjects in a sequence of traversal.
IRO可以在遍历序列中将新域子对象与现有子对象合并。
Thus, an IRO, comprising subobjects, that represents a domain sequence defines the domains involved in an inter-domain path computation, typically involving two or more collaborative PCEs.
因此，包含表示域序列的子对象的IRO定义域间路径计算中涉及的域，通常涉及两个或多个协作pce。
A domain sequence can have varying degrees of granularity. It is possible to have a domain sequence composed of, uniquely, AS identifiers. It is also possible to list the involved IGP areas for a given AS.
域序列可以具有不同程度的粒度。可以有一个由唯一标识符组成的域序列。也可以列出给定AS的相关IGP区域。
In any case, the mapping between domains and responsible PCEs is not defined in this document. It is assumed that a PCE that needs to obtain a "next PCE" from a domain sequence is able to do so (e.g., via administrative configuration or discovery).
在任何情况下，本文档中均未定义域和责任PCE之间的映射。假设需要从域序列获得“下一个PCE”的PCE能够这样做（例如，通过管理配置或发现）。
A PCC builds an IRO to encode the domain sequence, so that the cooperating PCEs could compute an inter-domain shortest constrained path across the specified sequence of domains.
PCC构建一个IRO来对域序列进行编码，以便协作PCE可以计算跨指定域序列的域间最短约束路径。
A PCC may intersperse area and AS subobjects with other subobjects without change to the previously specified processing of those subobjects in the IRO.
PCC可以将区域和作为子对象与其他子对象穿插在一起，而不改变IRO中先前指定的对这些子对象的处理。
If a PCE receives an IRO in a Path Computation Request (PCReq) message that contains the subobjects defined in this document that it does not recognize, it will respond according to the rules for a malformed object as per [RFC5440]. The PCE MAY also include the IRO in the PCEP Error (PCErr) message as per [RFC5440].
如果PCE在路径计算请求（PCReq）消息中接收到IRO，该消息包含其无法识别的本文档中定义的子对象，则PCE将根据[RFC5440]中的错误对象规则进行响应。根据[RFC5440]，PCE还可以在PCEP错误（PCErr）消息中包括IRO。
The interpretation of the L bit is as per Section 4.3.3.1 of [RFC3209] (as per [RFC7896]).
根据[RFC3209]第4.3.3.1节（根据[RFC7896]）解释L位。
In a Path Computation Reply (PCRep), PCE MAY also supply IRO (with domain sequence information) with the NO-PATH object indicating that the set of elements (domains) of the request's IRO prevented the PCEs from finding a path.
在路径计算应答（PCRep）中，PCE还可以向NO-Path对象提供IRO（具有域序列信息），该NO-Path对象指示请求的IRO的元素集（域）阻止PCE查找路径。
The following processing rules apply for a domain sequence in IRO:
以下处理规则适用于IRO中的域序列：
o When a PCE parses an IRO, it interprets each subobject according to the AS number associated with the preceding subobject. We call this the "current AS". Certain subobjects modify the current AS, as follows.
o 当PCE解析IRO时，它根据与前一个子对象关联的AS编号解释每个子对象。我们称之为“当前AS”。某些子对象修改当前对象，如下所示。
* The current AS is initialized to the AS number of the PCC.
* 当前AS被初始化为PCC的AS编号。
* If the PCE encounters an AS subobject, then it updates the current AS to this new AS number.
* 如果PCE遇到AS子对象，则会将当前AS更新为此新AS编号。
* If the PCE encounters an area subobject, then it assumes that the area belongs to the current AS.
* 如果PCE遇到面积子对象，则假定该面积属于当前AS。
* If the PCE encounters an IP address that is globally routable, then it updates the current AS to the AS that owns this IP address. This document does not define how the PCE learns which AS owns the IP address.
* 如果PCE遇到可全局路由的IP地址，则它会将当前AS更新为拥有该IP地址的AS。本文档未定义PCE如何了解哪个AS拥有IP地址。
* If the PCE encounters an IP address that is not globally routable, then it assumes that it belongs to the current AS.
* 如果PCE遇到不可全局路由的IP地址，则它假定它属于当前AS。
* If the PCE encounters an unnumbered link, then it assumes that it belongs to the current AS.
* 如果PCE遇到未编号的链接，则假定它属于当前AS。
o When a PCE parses an IRO, it interprets each subobject according to the Area ID associated with the preceding subobject. We call this the "current area". Certain subobjects modify the current area, as follows.
o 当PCE解析IRO时，它根据与前一个子对象关联的区域ID解释每个子对象。我们称之为“当前区域”。某些子对象修改当前区域，如下所示。
* The current area is initialized to the Area ID of the PCC.
* 当前区域初始化为PCC的区域ID。
* If the current AS is changed, the current area is reset and needs to be determined again by a current or subsequent subobject.
* 如果更改了当前AS，则会重置当前区域，并且需要由当前或后续子对象再次确定。
* If the PCE encounters an area subobject, then it updates the current area to this new Area ID.
* 如果PCE遇到区域子对象，则会将当前区域更新为此新区域ID。
* If the PCE encounters an IP address that belongs to a different area, then it updates the current area to the area that has this IP address. This document does not define how the PCE learns which area has the IP address.
* 如果PCE遇到属于不同区域的IP地址，则会将当前区域更新为具有此IP地址的区域。本文档未定义PCE如何了解哪个区域具有IP地址。
* If the PCE encounters an unnumbered link that belongs to a different area, then it updates the current Area to the area that has this link.
* 如果PCE遇到属于不同区域的未编号链接，则会将当前区域更新为具有此链接的区域。
* Otherwise, it assumes that the subobject belongs to the current area.
* 否则，它假定子对象属于当前区域。
o In case the current PCE is not responsible for the path computation in the current AS or area, then the PCE selects the "next PCE" in the domain sequence based on the current AS and area.
o 如果当前PCE不负责当前AS或区域中的路径计算，则PCE基于当前AS和区域选择域序列中的“下一PCE”。
Note that it is advised that PCC should use AS and area subobjects while building the domain sequence in IRO and avoid using other mechanisms to change the "current AS" and "current area" as described above.
请注意，建议PCC在IRO中构建域序列时使用AS和area子对象，并避免使用其他机制来更改上述“当前AS”和“当前区域”。
XRO [RFC5521] is an optional object used to specify exclusion of certain abstract nodes or resources from the whole path.
XRO[RFC5521]是一个可选对象，用于指定从整个路径中排除某些抽象节点或资源。
Some subobjects are to be used in XRO as defined in [RFC3209], [RFC3477], [RFC4874], and [RFC5520], but new subobjects related to domain sequence are needed.
根据[RFC3209]、[RFC3477]、[RFC4874]和[RFC5520]中的定义，XRO中将使用一些子对象，但需要与域序列相关的新子对象。
This document extends the support for 4-byte AS numbers and IGP areas.
本文档扩展了对4字节AS数字和IGP区域的支持。
Value Description
----- ----------------
5 4-byte AS number
6 OSPF Area ID
7 IS-IS Area ID
Value Description
----- ----------------
5 4-byte AS number
6 OSPF Area ID
7 IS-IS Area ID
Note: Identical subobjects are carried in RSVP-TE messages as defined in [RFC7898].
注：按照[RFC7898]中的定义，RSVP-TE消息中包含相同的子对象。
The new subobjects to support 4-byte AS numbers and the IGP (OSPF/IS-IS) area MAY also be used in the XRO to specify exclusion of certain domains in the path computation procedure.
支持4字节作为数字的新子对象和IGP（OSPF/IS-IS）区域也可在XRO中用于指定路径计算过程中排除某些域。
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS Number (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS Number (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The X-bit indicates whether the exclusion is mandatory or desired.
X位表示排除是强制的还是需要的。
0: indicates that the AS specified MUST be excluded from the path computed by the PCE(s).
0：表示指定的必须从PCE计算的路径中排除。
1: indicates that the AS specified SHOULD be avoided from the inter-domain path computed by the PCE(s), but it MAY be included subject to PCE policy and the absence of a viable path that meets the other constraints.
1：表示应该从PCE计算的域间路径中避免指定的路径，但根据PCE策略和缺少满足其他约束的可行路径，可以包括该路径。
All other fields are consistent with the definition in Section 3.4.
所有其他字段与第3.4节中的定义一致。
Since the length and format of the Area ID is different for OSPF and IS-IS, the following two subobjects are defined:
由于OSPF和is-is的区域ID的长度和格式不同，因此定义了以下两个子对象：
For OSPF, the Area ID is a 32-bit number. The subobject is encoded as follows:
对于OSPF，区域ID是32位数字。子对象的编码如下所示：
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OSPF Area ID (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OSPF Area ID (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The X-bit indicates whether the exclusion is mandatory or desired.
X位表示排除是强制的还是需要的。
0: indicates that the OSPF area specified MUST be excluded from the path computed by the PCE(s).
0：表示指定的OSPF区域必须从PCE计算的路径中排除。
1: indicates that the OSPF area specified SHOULD be avoided from the inter-domain path computed by the PCE(s), but it MAY be included subject to PCE policy and the absence of a viable path that meets the other constraints.
1：表示指定的OSPF区域应从PCE计算的域间路径中避免，但根据PCE策略和缺少满足其他约束的可行路径，可以将其包括在内。
All other fields are consistent with the definition in Section 3.4.
所有其他字段与第3.4节中的定义一致。
For IS-IS, the Area ID is of variable length; thus, the length of the subobject is variable. The Area ID is as described in IS-IS by the ISO standard [ISO10589]. The subobject is encoded as follows:
对于IS-IS，区域ID具有可变长度；因此，子对象的长度是可变的。区域ID如ISO标准[ISO10589]is-is中所述。子对象的编码如下所示：
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X| Type | Length | Area-Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// IS-IS Area ID //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X| Type | Length | Area-Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// IS-IS Area ID //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The X-bit indicates whether the exclusion is mandatory or desired.
X位表示排除是强制的还是需要的。
0: indicates that the IS-IS area specified MUST be excluded from the path computed by the PCE(s).
0：表示指定的IS-IS区域必须从PCE计算的路径中排除。
1: indicates that the IS-IS area specified SHOULD be avoided from the inter-domain path computed by the PCE(s), but it MAY be included subject to PCE policy and the absence of a viable path that meets the other constraints.
1：表示指定的IS-IS区域应从PCE计算的域间路径中避免，但根据PCE策略和缺少满足其他约束的可行路径，可以将其包括在内。
All other fields are consistent with the definition in Section 3.4.
所有其他字段与第3.4节中的定义一致。
All the processing rules are as per [RFC5521].
所有处理规则均符合[RFC5521]。
Note that if a PCE receives an XRO in a PCReq message that contains subobjects defined in this document that it does not recognize, it will respond according to the rules for a malformed object as per [RFC5440].
请注意，如果PCE在PCReq消息中接收到XRO，该消息包含其无法识别的本文档中定义的子对象，则它将根据[RFC5440]中格式错误对象的规则进行响应。
IGP area subobjects in the XRO are local to the current AS. In case multi-AS path computation excludes an IGP area in a different AS, the IGP area subobject should be part of EXRS in the IRO to specify the AS in which the IGP area is to be excluded. Further, policy may be applied to prune/ignore area subobjects in XRO after a "current AS" change during path computation.
XRO中的IGP区域子对象是当前AS的局部对象。如果多AS路径计算排除了不同AS中的IGP区域，则IGP区域子对象应是IRO中EXR的一部分，以指定要排除IGP区域的AS。此外，在路径计算期间发生“当前状态”更改后，可以应用策略来修剪/忽略XRO中的面积子对象。
The EXRS [RFC5521] is used to specify exclusion of certain abstract nodes between a specific pair of nodes.
EXRS[RFC5521]用于指定特定节点对之间某些抽象节点的排除。
The EXRS can carry any of the subobjects defined for inclusion in the XRO; thus, the new subobjects to support 4-byte AS numbers and the IGP (OSPF / IS-IS) area can also be used in the EXRS. The meanings of the fields of the new XRO subobjects are unchanged when the subobjects are included in an EXRS, except that the scope of the exclusion is limited to the single hop between the previous and subsequent elements in the IRO.
EXR可以携带定义为包含在XRO中的任何子对象；因此，支持4字节AS数字和IGP（OSPF/IS-IS）区域的新子对象也可以在EXRS中使用。当子对象包含在EXRS中时，新XRO子对象字段的含义不变，但排除范围仅限于IRO中先前和后续元素之间的单跳。
The EXRS should be interpreted in the context of the current AS and current area of the preceding subobject in the IRO. The EXRS does not change the current AS or current area. All other processing rules are as per [RFC5521].
EXR应在IRO中前一子对象的当前AS和当前区域的上下文中进行解释。EXRS不会更改当前AS或当前区域。所有其他处理规则均符合[RFC5521]。
Note that if a PCE that supports the EXRS in an IRO parses an IRO, and encounters an EXRS that contains subobjects defined in this document that it does not recognize, it will act according to the setting of the X-bit in the subobject as per [RFC5521].
请注意，如果在IRO中支持EXRS的PCE解析IRO，并遇到包含本文档中定义的子对象且其无法识别的EXRS，则它将根据[RFC5521]中子对象中的X位设置进行操作。
ERO [RFC5440] is used to specify a computed path in the network. PCEP ERO subobject types correspond to RSVP-TE ERO subobject types as defined in [RFC3209], [RFC3473], [RFC3477], [RFC4873], [RFC4874], and [RFC5520]. The subobjects related to the domain sequence are further defined in [RFC7898].
ERO[RFC5440]用于指定网络中的计算路径。PCEP ERO子对象类型对应于[RFC3209]、[RFC3473]、[RFC3477]、[RFC4873]、[RFC4874]和[RFC5520]中定义的RSVP-TE ERO子对象类型。[RFC7898]中进一步定义了与域序列相关的子对象。
The new subobjects to support 4-byte AS numbers and the IGP (OSPF/IS-IS) area can also be used in the ERO to specify an abstract node (a group of nodes whose internal topology is opaque to the ingress node of the LSP). Using this concept of abstraction, an explicitly routed LSP can be specified as a sequence of domains.
支持4字节AS数字的新子对象和IGP（OSPF/IS-IS）区域也可在ERO中用于指定抽象节点（其内部拓扑对LSP入口节点不透明的一组节点）。使用这种抽象概念，可以将显式路由LSP指定为域序列。
In case of H-PCE [RFC6805], a parent PCE can be requested to find the domain sequence. Refer to the example in Section 4.6 of this document. The ERO in reply from the parent PCE can then be used in per-domain path computation or BRPC.
对于H-PCE[RFC6805]，可以请求父PCE查找域序列。参考本文件第4.6节中的示例。然后，来自父PCE的响应ERO可用于每域路径计算或BRPC。
If a PCC receives an ERO in a PCRep message that contains a subobject defined in this document that it does not recognize, it will respond according to the rules for a malformed object as per [RFC5440].
如果PCC在PCRep消息中接收到ERO，该消息包含其无法识别的本文档中定义的子对象，则PCC将根据[RFC5440]中格式错误对象的规则进行响应。
The examples in this section are for illustration purposes only to highlight how the new subobjects could be encoded. They are not meant to be an exhaustive list of all possible use cases and combinations.
本节中的示例仅用于说明如何对新子对象进行编码。它们并不意味着是所有可能用例和组合的详尽列表。
In an inter-area path computation where the ingress and the egress nodes belong to different IGP areas within the same AS, the domain sequence could be represented using an ordered list of area subobjects.
在区域间路径计算中，其中入口和出口节点属于同一区域内的不同IGP区域，可以使用区域子对象的有序列表来表示域序列。
----------------- -----------------
| | | |
| +--+ | | +--+ |
| +--+ | | | | | | |
| | | +--+ | | +--+ +--+ |
| +--+ | | | | |
| | | +--+ |
| +--+ | | |
| | | | | +--+ |
| +--+ | | | | |
| | -------------------------- | +--+ |
| +--+ +--+ |
| | | +--+ | | |
|Area 2 +--+ | | +--+ Area 4 |
----------------- | +--+ | -----------------
| |
| +--+ |
| +--+ | | |
| | | +--+ |
| +--+ |
| |
| |
| |
| |
| +--+ |
| | | |
| +--+ |
----------------- | | ------------------
| +--+ +--+ |
| | | | | |
| +--+ Area 0 +--+ |
| | -------------------------- | +--+ |
| +--+ | | | | |
| | | | | +--+ |
| +--+ +--+ | | |
| | | | | +--+ |
| +--+ | | | | |
| | | +--+ |
| +--+ | | |
| | | | | +--+ |
| +--+ | | | | |
| | | +--+ |
| | | |
| Area 1 | | Area 5 |
----------------- ------------------
----------------- -----------------
| | | |
| +--+ | | +--+ |
| +--+ | | | | | | |
| | | +--+ | | +--+ +--+ |
| +--+ | | | | |
| | | +--+ |
| +--+ | | |
| | | | | +--+ |
| +--+ | | | | |
| | -------------------------- | +--+ |
| +--+ +--+ |
| | | +--+ | | |
|Area 2 +--+ | | +--+ Area 4 |
----------------- | +--+ | -----------------
| |
| +--+ |
| +--+ | | |
| | | +--+ |
| +--+ |
| |
| |
| |
| |
| +--+ |
| | | |
| +--+ |
----------------- | | ------------------
| +--+ +--+ |
| | | | | |
| +--+ Area 0 +--+ |
| | -------------------------- | +--+ |
| +--+ | | | | |
| | | | | +--+ |
| +--+ +--+ | | |
| | | | | +--+ |
| +--+ | | | | |
| | | +--+ |
| +--+ | | |
| | | | | +--+ |
| +--+ | | | | |
| | | +--+ |
| | | |
| Area 1 | | Area 5 |
----------------- ------------------
Figure 1: Inter-Area Path Computation
图1：区域间路径计算
The AS Number is 100.
AS号码是100。
If the ingress is in area 2, the egress is in area 4, and transit is through area 0, here are some possible ways a PCC can encode the IRO:
如果入口在区域2，出口在区域4，运输通过区域0，以下是PCC对IRO进行编码的一些可能方式：
+---------+ +---------+ +---------+
|IRO | |Sub- | |Sub- |
|Object | |object | |object |
|Header | |Area 0 | |Area 4 |
| | | | | |
| | | | | |
+---------+ +---------+ +---------+
+---------+ +---------+ +---------+
|IRO | |Sub- | |Sub- |
|Object | |object | |object |
|Header | |Area 0 | |Area 4 |
| | | | | |
| | | | | |
+---------+ +---------+ +---------+
or
或
+---------+ +---------+ +---------+ +---------+
|IRO | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object |
|Header | |Area 2 | |Area 0 | |Area 4 |
| | | | | | | |
| | | | | | | |
+---------+ +---------+ +---------+ +---------+
+---------+ +---------+ +---------+ +---------+
|IRO | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object |
|Header | |Area 2 | |Area 0 | |Area 4 |
| | | | | | | |
| | | | | | | |
+---------+ +---------+ +---------+ +---------+
or
或
+---------+ +---------+ +---------+ +---------+ +---------+
|IRO | |Sub- | |Sub- | |Sub- | |Sub- |
|Object | |object AS| |object | |object | |object |
|Header | |100 | |Area 2 | |Area 0 | |Area 4 |
| | | | | | | | | |
| | | | | | | | | |
+---------+ +---------+ +---------+ +---------+ +---------+
+---------+ +---------+ +---------+ +---------+ +---------+
|IRO | |Sub- | |Sub- | |Sub- | |Sub- |
|Object | |object AS| |object | |object | |object |
|Header | |100 | |Area 2 | |Area 0 | |Area 4 |
| | | | | | | | | |
| | | | | | | | | |
+---------+ +---------+ +---------+ +---------+ +---------+
The domain sequence can further include encompassing AS information in the AS subobject.
域序列还可以包括在AS子对象中包含AS信息。
In inter-AS path computation, where the ingress and egress belong to different ASes, the domain sequence could be represented using an ordered list of AS subobjects. The domain sequence can further include decomposed area information in the area subobject.
在AS间路径计算中，当入口和出口属于不同的AS时，域序列可以使用AS子对象的有序列表来表示。域序列还可以包括区域子对象中的分解区域信息。
As shown in Figure 2, where AS has a single area, the AS subobject in the domain sequence can uniquely identify the next domain and PCE.
如图2所示，其中As具有单个区域，域序列中的As子对象可以唯一标识下一个域和PCE。
AS A AS E AS C
<-------------> <----------> <------------->
AS A AS E AS C
<-------------> <----------> <------------->
A4----------E1---E2---E3---------C4
/ / \
/ / \
/ / AS B \
/ / <----------> \
Ingress------A1---A2------B1---B2---B3------C1---C2------Egress
\ / /
\ / /
\ / /
\ / /
A3----------D1---D2---D3---------C3
A4----------E1---E2---E3---------C4
/ / \
/ / \
/ / AS B \
/ / <----------> \
Ingress------A1---A2------B1---B2---B3------C1---C2------Egress
\ / /
\ / /
\ / /
\ / /
A3----------D1---D2---D3---------C3
<---------->
AS D
<---------->
AS D
* All ASes have one area (area 0)
* 所有ASE都有一个区域（区域0）
Figure 2: Inter-AS Path Computation
图2：内部AS路径计算
If the ingress is in AS A, the egress is in AS C, and transit is through AS B, here are some possible ways a PCC can encode the IRO:
如果入口为A，出口为C，运输为B，以下是PCC对IRO进行编码的一些可能方式：
+-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- |
|Object | |object | |object |
|Header | |AS B | |AS C |
| | | | | |
+-------+ +-------+ +-------+
+-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- |
|Object | |object | |object |
|Header | |AS B | |AS C |
| | | | | |
+-------+ +-------+ +-------+
or
或
+-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object |
|Header | |AS A | |AS B | |AS C |
| | | | | | | |
+-------+ +-------+ +-------+ +-------+
+-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object |
|Header | |AS A | |AS B | |AS C |
| | | | | | | |
+-------+ +-------+ +-------+ +-------+
or
或
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object | |object | |object | |object |
|Header | |AS A | |Area 0 | |AS B | |Area 0 | |AS C | |Area 0 |
| | | | | | | | | | | | | |
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+ +-------+
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object | |object | |object | |object |
|Header | |AS A | |Area 0 | |AS B | |Area 0 | |AS C | |Area 0 |
| | | | | | | | | | | | | |
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+ +-------+
Note that to get a domain disjoint path, the ingress could also request the backup path with:
请注意，要获得域不相交路径，入口还可以使用以下命令请求备份路径：
+-------+ +-------+
|XRO | |Sub |
|Object | |Object |
|Header | |AS B |
| | | |
+-------+ +-------+
+-------+ +-------+
|XRO | |Sub |
|Object | |Object |
|Header | |AS B |
| | | |
+-------+ +-------+
As described in Section 3.4.3, a domain subobject in IRO changes the domain information associated with the next set of subobjects till you encounter a subobject that changes the domain too. Consider the following IRO:
如第3.4.3节所述，IRO中的域子对象会更改与下一组子对象关联的域信息，直到遇到也更改域的子对象。考虑下面的IRO：
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object | |object | |object |
|Header | |AS B | |IP | |IP | |AS C | |IP |
| | | | |B1 | |B3 | | | |C1 |
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object | |object | |object |
|Header | |AS B | |IP | |IP | |AS C | |IP |
| | | | |B1 | |B3 | | | |C1 |
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
On processing subobject "AS B", it changes the AS of the subsequent subobjects till we encounter another subobject "AS C" that changes the AS for its subsequent subobjects.
在处理子对象“AS B”时，它会更改后续子对象的AS，直到遇到另一个子对象“AS C”，该子对象会更改其后续子对象的AS。
Consider another IRO:
考虑另一个I罗：
+-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object | |object |
|Header | |AS D | |IP | |IP | |IP |
| | | | |D1 | |D3 | |C3 |
+-------+ +-------+ +-------+ +-------+ +-------+
+-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object | |object |
|Header | |AS D | |IP | |IP | |IP |
| | | | |D1 | |D3 | |C3 |
+-------+ +-------+ +-------+ +-------+ +-------+
Here as well, on processing "AS D", it changes the AS of the subsequent subobjects till you encounter another subobject "C3" that belongs in another AS and changes the AS for its subsequent subobjects.
同样，在处理“as D”时，它会更改后续子对象的as，直到遇到属于另一个as的另一个子对象“C3”，并更改其后续子对象的as。
Further description for the boundary node and inter-AS link can be found in Section 4.3.
关于边界节点和AS间链路的进一步说明，请参见第4.3节。
In Figure 3, AS 200 is made up of multiple areas.
在图3中，AS 200由多个区域组成。
|
| +-------------+ +----------------+
| |Area 2 | |Area 4 |
| | +--+| | +--+ |
| | | || | | B| |
| | +--+ +--+| | +--+ +--+ |
| | | | | | | | |
| | +--+ | | +--+ |
| | +--+ | | +--+ |
| | | | | | | | |
| | +--+ | | +--+ +--+ |
| | +--+ |+--------------+| | | |
| | | | +--+ +--+ +--+ |
+-------------+| | +--+ | | | | |
| || | +--+ +--+ |
| +--+|| +-------------+| |+----------------+
| | ||| | +--+ |
| +--+|| | | | |
| +--+ || | +--+ |
| | | +---+ +--+ |
| +--+ | |----------------| | |
| +---+ Inter-AS +--+ +--+ |
|+--+ || Links | | | |
||A | +---+ +--+ +--+ |
|+--+ | |----------------| | |
| +---+ +--+ +--+ |
| +--+ || +------------+ | | | |+----------------+
| | | || |Area 3 +--+ +--+ +--+ Area 5 |
| +--+ || | | | | | |
| || | +--+ +--+ |
| +--+|| | +--+ | | Area 0 || +--+ |
| | ||| | | | | +--------------+| | | |
| +--+|| | +--+ | | +--+ |
| || | | | +--+ |
|Area 0 || | +--+ | | +--+ | | |
+-------------+| | | | | | | | +--+ |
| | +--+ +--+ | +--+ |
| | | | | |
| | +--+ | +--+ |
| | +--+ | | | C| |
| | | | | | +--+ |
| | +--+ | | |
| | | | |
| +------------+ +----------------+
|
AS 100 | AS 200
|
Figure 3: Inter-AS Path Computation
|
| +-------------+ +----------------+
| |Area 2 | |Area 4 |
| | +--+| | +--+ |
| | | || | | B| |
| | +--+ +--+| | +--+ +--+ |
| | | | | | | | |
| | +--+ | | +--+ |
| | +--+ | | +--+ |
| | | | | | | | |
| | +--+ | | +--+ +--+ |
| | +--+ |+--------------+| | | |
| | | | +--+ +--+ +--+ |
+-------------+| | +--+ | | | | |
| || | +--+ +--+ |
| +--+|| +-------------+| |+----------------+
| | ||| | +--+ |
| +--+|| | | | |
| +--+ || | +--+ |
| | | +---+ +--+ |
| +--+ | |----------------| | |
| +---+ Inter-AS +--+ +--+ |
|+--+ || Links | | | |
||A | +---+ +--+ +--+ |
|+--+ | |----------------| | |
| +---+ +--+ +--+ |
| +--+ || +------------+ | | | |+----------------+
| | | || |Area 3 +--+ +--+ +--+ Area 5 |
| +--+ || | | | | | |
| || | +--+ +--+ |
| +--+|| | +--+ | | Area 0 || +--+ |
| | ||| | | | | +--------------+| | | |
| +--+|| | +--+ | | +--+ |
| || | | | +--+ |
|Area 0 || | +--+ | | +--+ | | |
+-------------+| | | | | | | | +--+ |
| | +--+ +--+ | +--+ |
| | | | | |
| | +--+ | +--+ |
| | +--+ | | | C| |
| | | | | | +--+ |
| | +--+ | | |
| | | | |
| +------------+ +----------------+
|
AS 100 | AS 200
|
Figure 3: Inter-AS Path Computation
For LSP (A-B), where ingress A is in (AS 100, area 0), egress B is in (AS 200, area 4), and transit is through (AS 200, area 0), here are some possible ways a PCC can encode the IRO:
对于LSP（A-B），其中入口A在（AS 100，区域0），出口B在（AS 200，区域4），而运输通过（AS 200，区域0），以下是PCC对IRO进行编码的一些可能方式：
+-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object |
|Header | |AS 200 | |Area 0 | |Area 4 |
| | | | | | | |
+-------+ +-------+ +-------+ +-------+
+-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object |
|Header | |AS 200 | |Area 0 | |Area 4 |
| | | | | | | |
+-------+ +-------+ +-------+ +-------+
or
或
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object | |object | |object |
|Header | |AS 100 | |Area 0 | |AS 200 | |Area 0 | |Area 4 |
| | | | | | | | | | | |
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object | |object | |object |
|Header | |AS 100 | |Area 0 | |AS 200 | |Area 0 | |Area 4 |
| | | | | | | | | | | |
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
For LSP (A-C), where ingress A is in (AS 100, area 0), egress C is in (AS 200, area 5), and transit is through (AS 200, area 0), here are some possible ways a PCC can encode the IRO:
对于LSP（A-C），其中入口A在（AS 100，区域0），出口C在（AS 200，区域5），而运输通过（AS 200，区域0），以下是PCC对IRO进行编码的一些可能方式：
+-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object |
|Header | |AS 200 | |Area 0 | |Area 5 |
| | | | | | | |
+-------+ +-------+ +-------+ +-------+
+-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object |
|Header | |AS 200 | |Area 0 | |Area 5 |
| | | | | | | |
+-------+ +-------+ +-------+ +-------+
or
或
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object | |object | |object |
|Header | |AS 100 | |Area 0 | |AS 200 | |Area 0 | |Area 5 |
| | | | | | | | | | | |
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub- | |Sub- | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object | |object | |object |
|Header | |AS 100 | |Area 0 | |AS 200 | |Area 0 | |Area 5 |
| | | | | | | | | | | |
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
A PCC or PCE can include additional constraints covering which boundary nodes (ABR or ASBR) or border links (inter-AS link) to be traversed while defining a domain sequence. In which case, the boundary node or link can be encoded as a part of the domain sequence.
PCC或PCE可以包括附加约束，该约束覆盖在定义域序列时要遍历的边界节点（ABR或ASBR）或边界链路（AS间链路）。在这种情况下，可以将边界节点或链路编码为域序列的一部分。
Boundary nodes (ABR/ASBR) can be encoded using the IPv4 or IPv6 prefix subobjects, usually with a loopback address of 32 and a prefix length of 128, respectively. An inter-AS link can be encoded using the IPv4 or IPv6 prefix subobjects or unnumbered interface subobjects.
边界节点（ABR/ASBR）可以使用IPv4或IPv6前缀子对象进行编码，通常环回地址为32，前缀长度为128。可以使用IPv4或IPv6前缀子对象或未编号的接口子对象对AS间链路进行编码。
For Figure 1, an ABR (say, 203.0.113.1) to be traversed can be specified in IRO as:
对于图1，要遍历的ABR（例如203.0.113.1）可以在IRO中指定为：
+---------+ +---------+ +---------++---------+ +---------+
|IRO | |Sub- | |Sub- ||Sub- | |Sub- |
|Object | |object | |object ||object | |object |
|Header | |Area 2 | |IPv4 ||Area 0 | |Area 4 |
| | | | |203.0. || | | |
| | | | |112.1 || | | |
+---------+ +---------+ +---------++---------+ +---------+
+---------+ +---------+ +---------++---------+ +---------+
|IRO | |Sub- | |Sub- ||Sub- | |Sub- |
|Object | |object | |object ||object | |object |
|Header | |Area 2 | |IPv4 ||Area 0 | |Area 4 |
| | | | |203.0. || | | |
| | | | |112.1 || | | |
+---------+ +---------+ +---------++---------+ +---------+
For Figure 3, an inter-AS link (say, 198.51.100.1 - 198.51.100.2) to be traversed can be specified as:
对于图3，要遍历的AS间链路（例如198.51.100.1-198.51.100.2）可以指定为：
+---------+ +---------+ +---------+ +---------+
|IRO | |Sub- | |Sub- | |Sub- |
|Object | |object AS| |object | |object AS|
|Header | |100 | |IPv4 | |200 |
| | | | |198.51. | | |
| | | | |100.2 | | |
+---------+ +---------+ +---------+ +---------+
+---------+ +---------+ +---------+ +---------+
|IRO | |Sub- | |Sub- | |Sub- |
|Object | |object AS| |object | |object AS|
|Header | |100 | |IPv4 | |200 |
| | | | |198.51. | | |
| | | | |100.2 | | |
+---------+ +---------+ +---------+ +---------+
A single PCE can be responsible for multiple domains; for example, PCE function deployed on an ABR could be responsible for multiple areas. A PCE that can support adjacent domains can internally handle those domains in the domain sequence without any impact on the other domains in the domain sequence.
单个PCE可以负责多个域；例如，部署在ABR上的PCE功能可能负责多个领域。可以支持相邻域的PCE可以在内部处理域序列中的那些域，而不会对域序列中的其他域产生任何影响。
[RFC7334] describes an experimental inter-domain P2MP path computation mechanism where the path domain tree is described as a series of domain sequences; an example is shown in the figure below:
[RFC7334]描述了一种实验性域间P2MP路径计算机制，其中路径域树被描述为一系列域序列；下图显示了一个示例：
+----------------+
| |Domain D1
| R |
| |
| A |
| |
+-B------------C-+
/ \
/ \
/ \
Domain D2 / \ Domain D3
+-------------D--+ +-----E----------+
| | | |
| F | | |
| G | | H |
| | | |
| | | |
+-I--------------+ +-J------------K-+
/\ / \
/ \ / \
/ \ / \
/ \ / \
/ \ / \
/ \ / \
/ Domain D4 \ Domain D5 / Domain D6 \
+-L-------------W+ +------P---------+ +-----------T----+
| | | | | |
| | | Q | | U |
| M O | | S | | |
| | | | | V |
| N | | R | | |
+----------------+ +----------------+ +----------------+
+----------------+
| |Domain D1
| R |
| |
| A |
| |
+-B------------C-+
/ \
/ \
/ \
Domain D2 / \ Domain D3
+-------------D--+ +-----E----------+
| | | |
| F | | |
| G | | H |
| | | |
| | | |
+-I--------------+ +-J------------K-+
/\ / \
/ \ / \
/ \ / \
/ \ / \
/ \ / \
/ \ / \
/ Domain D4 \ Domain D5 / Domain D6 \
+-L-------------W+ +------P---------+ +-----------T----+
| | | | | |
| | | Q | | U |
| M O | | S | | |
| | | | | V |
| N | | R | | |
+----------------+ +----------------+ +----------------+
Figure 4: Domain Tree Example
图4：域树示例
The domain tree can be represented as a series of domain sequences:
域树可以表示为一系列域序列：
o Domain D1, Domain D3, Domain D6
o 域D1、域D3、域D6
o Domain D1, Domain D3, Domain D5
o 域D1、域D3、域D5
o Domain D1, Domain D2, Domain D4
o 域D1、域D2、域D4
The domain sequence handling described in this document could be applied to the P2MP path domain tree.
本文档中描述的域序列处理可应用于P2MP路径域树。
In case of H-PCE [RFC6805], the parent PCE can be requested to determine the domain sequence and return it in the path computation reply, using the ERO. For the example in Section 4.6 of [RFC6805], the domain sequence can possibly appear as:
在H-PCE[RFC6805]的情况下，可以使用ERO请求父PCE确定域序列并在路径计算回复中返回它。对于[RFC6805]第4.6节中的示例，域序列可能显示为：
+---------+ +---------+ +---------+ +---------+
|ERO | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object |
|Header | |Domain 1 | |Domain 2 | |Domain 3 |
| | | | | | | |
| | | | | | | |
+---------+ +---------+ +---------+ +---------+
+---------+ +---------+ +---------+ +---------+
|ERO | |Sub- | |Sub- | |Sub- |
|Object | |object | |object | |object |
|Header | |Domain 1 | |Domain 2 | |Domain 3 |
| | | | | | | |
| | | | | | | |
+---------+ +---------+ +---------+ +---------+
or
或
+---------+ +---------+ +---------+
|ERO | |Sub- | |Sub- |
|Object | |object | |object |
|Header | |BN 21 | |Domain 3 |
| | | | | |
| | | | | |
+---------+ +---------+ +---------+
+---------+ +---------+ +---------+
|ERO | |Sub- | |Sub- |
|Object | |object | |object |
|Header | |BN 21 | |Domain 3 |
| | | | | |
| | | | | |
+---------+ +---------+ +---------+
Instead of a domain sequence, a sequence of PCEs MAY be enforced by policy on the PCC, and this constraint can be carried in the PCReq message (as defined in [RFC5886]).
PCC上的策略可以强制PCE序列，而不是域序列，并且该约束可以在PCReq消息中进行（如[RFC5886]中所定义）。
Note that PCE Sequence can be used along with domain sequence, in which case PCE Sequence MUST have higher precedence in selecting the next PCE in the inter-domain path computation procedures.
请注意，PCE序列可以与域序列一起使用，在这种情况下，在域间路径计算过程中，PCE序列在选择下一个PCE时必须具有更高的优先级。
[RFC3209] already describes the notion of abstract nodes, where an abstract node is a group of nodes whose internal topology is opaque to the ingress node of the LSP. It further defines a subobject for AS but with a 2-byte AS number.
[RFC3209]已经描述了抽象节点的概念，其中抽象节点是一组内部拓扑对LSP的入口节点不透明的节点。它还为AS定义了一个子对象，但编号为2字节。
[RFC7898] extends the notion of abstract nodes by adding new subobjects for IGP areas and 4-byte AS numbers. These subobjects can be included in ERO, XRO, or EXRS in RSVP-TE.
[RFC7898]通过为IGP区域添加新的子对象和4字节作为数字，扩展了抽象节点的概念。这些子对象可以包含在RSVP-TE的ERO、XRO或EXR中。
In any case, subobject types defined in RSVP-TE are identical to the subobject types defined in the related documents in PCEP.
在任何情况下，RSVP-TE中定义的子对象类型都与PCEP中相关文档中定义的子对象类型相同。
IANA maintains the "Path Computation Element Protocol (PCEP) Numbers" registry at <http://www.iana.org/assignments/pcep>. Within this registry, IANA maintains two sub-registries:
IANA在以下位置维护“路径计算元素协议（PCEP）编号”注册表：<http://www.iana.org/assignments/pcep>. 在该注册中心内，IANA拥有两个子注册中心：
o IRO Subobjects
o IRO子对象
o XRO Subobjects
o XRO子对象
IANA has made identical additions to those registries as follows:
IANA对这些登记册进行了相同的补充，如下所示：
Value Description Reference
----- ---------------- -------------------
5 4-byte AS number RFC 7897, [RFC7898]
6 OSPF Area ID RFC 7897, [RFC7898]
7 IS-IS Area ID RFC 7897, [RFC7898]
Value Description Reference
----- ---------------- -------------------
5 4-byte AS number RFC 7897, [RFC7898]
6 OSPF Area ID RFC 7897, [RFC7898]
7 IS-IS Area ID RFC 7897, [RFC7898]
Further, IANA has added a reference to this document to the new RSVP numbers that are registered by [RFC7898], as shown on <http://www.iana.org/assignments/rsvp-parameters>.
此外，IANA在[RFC7898]注册的新RSVP编号中添加了对本文件的引用，如所示<http://www.iana.org/assignments/rsvp-parameters>.
The protocol extensions defined in this document do not substantially change the nature of PCEP. Therefore, the security considerations set out in [RFC5440] apply unchanged. Note that further security considerations for the use of PCEP over TCP are presented in [RFC6952].
本文件中定义的协议扩展并未实质性改变PCEP的性质。因此，[RFC5440]中规定的安全注意事项不作更改。请注意，[RFC6952]中介绍了通过TCP使用PCEP的进一步安全注意事项。
This document specifies a representation of the domain sequence and new subobjects, which could be used in inter-domain PCE scenarios as explained in [RFC5152], [RFC5441], [RFC6805], [RFC7334], etc. The security considerations set out in each of these mechanisms remain unchanged by the new subobjects and domain sequence representation in this document.
本文档规定了域序列和新子对象的表示，可用于域间PCE场景，如[RFC5152]、[RFC5441]、[RFC6805]、[RFC7334]中所述，等。由于本文档中的新子对象和域序列表示，这些机制中规定的安全注意事项保持不变。
But the new subobjects do allow finer and more specific control of the path computed by a cooperating PCE(s). Such control increases the risk if a PCEP message is intercepted, modified, or spoofed because it allows the attacker to exert control over the path that the PCE will compute or to make the path computation impossible. Consequently, it is important that implementations conform to the relevant security requirements of [RFC5440]. These mechanisms include:
但新的子对象确实允许对协作PCE计算的路径进行更精细和更具体的控制。如果PCEP消息被截获、修改或欺骗，这种控制会增加风险，因为它允许攻击者对PCE将要计算的路径施加控制或使路径计算不可能。因此，实现必须符合[RFC5440]的相关安全要求。这些机制包括：
o Securing the PCEP session messages using TCP security techniques (Section 10.2 of [RFC5440]). PCEP implementations SHOULD also consider the additional security provided by the TCP Authentication Option (TCP-AO) [RFC5925] or Transport Layer Security (TLS) [PCEPS].
o 使用TCP安全技术保护PCEP会话消息（RFC5440第10.2节）。PCEP实现还应该考虑TCP认证选项（TCP-AO）[RCF5925]或传输层安全（TLS）[PCEPS]所提供的附加安全性。
o Authenticating the PCEP messages to ensure the messages are intact and sent from an authorized node (Section 10.3 of [RFC5440]).
o 验证PCEP消息，以确保消息完好无损并从授权节点发送（RFC5440第10.3节）。
o PCEP operates over TCP, so it is also important to secure the PCE and PCC against TCP denial-of-service attacks. Section 10.7.1 of [RFC5440] outlines a number of mechanisms for minimizing the risk of TCP-based denial-of-service attacks against PCEs and PCCs.
o PCEP通过TCP运行，因此保护PCE和PCC免受TCP拒绝服务攻击也很重要。[RFC5440]的第10.7.1节概述了将针对PCE和PCC的基于TCP的拒绝服务攻击风险降至最低的一些机制。
o In inter-AS scenarios, attacks may be particularly significant with commercial- as well as service-level implications.
o 在AS间场景中，攻击可能特别重要，具有商业和服务级别影响。
Note, however, that the domain sequence mechanisms also provide the operator with the ability to route around vulnerable parts of the network and may be used to increase overall network security.
然而，请注意，域序列机制还为操作员提供了绕网络易受攻击部分路由的能力，并可用于提高整体网络安全性。
The exact behavior with regards to desired inclusion and exclusion of domains MUST be available for examination by an operator and MAY be configurable. Manual configurations are needed to identify which PCEP peers understand the new domain subobjects defined in this document.
关于域的期望包含和排除的确切行为必须可供操作员检查，并且可以配置。需要手动配置来确定哪些PCEP对等方了解本文档中定义的新域子对象。
A MIB module for management of the PCEP is being specified in a separate document [RFC7420]. This document does not imply any new extension to the current MIB module.
在单独的文件[RFC7420]中指定了用于管理PCEP的MIB模块。本文档并不意味着对当前MIB模块进行任何新的扩展。
Mechanisms defined in this document do not imply any new liveness detection and monitoring requirements aside from those already listed in [RFC5440].
除了[RFC5440]中已经列出的机制外，本文件中定义的机制并不意味着任何新的活性检测和监控要求。
Mechanisms defined in this document do not imply any new operation verification requirements aside from those already listed in [RFC5440].
除[RFC5440]中已列出的要求外，本文件中定义的机制并不意味着任何新的操作验证要求。
In case of per-domain path computation [RFC5152], where the full path of an inter-domain TE LSP cannot be determined (or is not determined) at the ingress node, a signaling message can use the domain identifiers. The subobjects defined in this document SHOULD be supported by RSVP-TE. [RFC7898] extends the notion of abstract nodes by adding new subobjects for IGP areas and 4-byte AS numbers.
在每域路径计算[RFC5152]的情况下，其中在入口节点处不能确定（或未确定）域间TE LSP的完整路径，信令消息可以使用域标识符。RSVP-TE应支持本文档中定义的子对象。[RFC7898]通过为IGP区域添加新的子对象和4字节作为数字，扩展了抽象节点的概念。
Apart from this, mechanisms defined in this document do not imply any requirements on other protocols aside from those already listed in [RFC5440].
除此之外，除[RFC5440]中已列出的协议外，本文件中定义的机制并不意味着对其他协议的任何要求。
The mechanisms described in this document can provide the operator with the ability to exert finer and more specific control of the path computation by inclusion or exclusion of domain subobjects. There may be some scaling benefit when a single domain subobject may substitute for many subobjects and can reduce the overall message size and processing.
本文档中描述的机制可以为操作员提供通过包含或排除域子对象来对路径计算施加更精细和更具体控制的能力。当单个域子对象可以替代多个子对象，并且可以减少总体消息大小和处理时，可能会有一些扩展优势。
Backward compatibility issues associated with the new subobjects arise when a PCE does not recognize them, in which case PCE responds according to the rules for a malformed object as per [RFC5440]. For successful operations, the PCEs in the network would need to be upgraded.
当PCE无法识别新子对象时，会出现与新子对象相关的向后兼容性问题，在这种情况下，PCE会根据[RFC5440]中的错误对象规则进行响应。为了成功运行，需要升级网络中的PCE。
[ISO10589] International Organization for Standardization, "Information technology -- Telecommunications and information exchange between systems -- Intermediate System to Intermediate System intra-domain routeing information exchange protocol for use in conjunction with the protocol for providing the connectionless-mode network service (ISO 8473)", ISO/IEC 10589:2002, Second Edition, 2002.
[ISO10589]国际标准化组织，“信息技术——系统间电信和信息交换——与提供无连接模式网络服务协议一起使用的中间系统到中间系统域内路由信息交换协议（ISO 8473）”，ISO/IEC 10589:2002，第二版，2002年。
[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>.
[RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, DOI 10.17487/RFC3473, January 2003, <http://www.rfc-editor.org/info/rfc3473>.
[RFC3473]Berger，L.，Ed.“通用多协议标签交换（GMPLS）信令资源预留协议流量工程（RSVP-TE）扩展”，RFC 3473，DOI 10.17487/RFC3473，2003年1月<http://www.rfc-editor.org/info/rfc3473>.
[RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links in Resource ReSerVation Protocol - Traffic Engineering (RSVP-TE)", RFC 3477, DOI 10.17487/RFC3477, January 2003, <http://www.rfc-editor.org/info/rfc3477>.
[RFC3477]Kompella，K.和Y.Rekhter，“资源预留协议中未编号链路的信令-流量工程（RSVP-TE）”，RFC 3477，DOI 10.17487/RFC3477，2003年1月<http://www.rfc-editor.org/info/rfc3477>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, DOI 10.17487/RFC5440, March 2009, <http://www.rfc-editor.org/info/rfc5440>.
[RFC5440]Vasseur，JP.，Ed.和JL。Le Roux主编，“路径计算元件（PCE）通信协议（PCEP）”，RFC 5440，DOI 10.17487/RFC5440，2009年3月<http://www.rfc-editor.org/info/rfc5440>.
[RFC5441] Vasseur, JP., Ed., Zhang, R., Bitar, N., and JL. Le Roux, "A Backward-Recursive PCE-Based Computation (BRPC) Procedure to Compute Shortest Constrained Inter-Domain Traffic Engineering Label Switched Paths", RFC 5441, DOI 10.17487/RFC5441, April 2009, <http://www.rfc-editor.org/info/rfc5441>.
[RFC5441]Vasseur，JP.，Ed.，Zhang，R.，Bitar，N.，和JL。Le Roux，“计算最短约束域间流量工程标签交换路径的基于PCE的反向递归计算（BRPC）程序”，RFC 5441，DOI 10.17487/RFC5441，2009年4月<http://www.rfc-editor.org/info/rfc5441>.
[RFC5521] Oki, E., Takeda, T., and A. Farrel, "Extensions to the Path Computation Element Communication Protocol (PCEP) for Route Exclusions", RFC 5521, DOI 10.17487/RFC5521, April 2009, <http://www.rfc-editor.org/info/rfc5521>.
[RFC5521]Oki，E.，Takeda，T.，和A.Farrel，“路由排除的路径计算元素通信协议（PCEP）扩展”，RFC 5521，DOI 10.17487/RFC5521，2009年4月<http://www.rfc-editor.org/info/rfc5521>.
[RFC6805] King, D., Ed. and A. Farrel, Ed., "The Application of the Path Computation Element Architecture to the Determination of a Sequence of Domains in MPLS and GMPLS", RFC 6805, DOI 10.17487/RFC6805, November 2012, <http://www.rfc-editor.org/info/rfc6805>.
[RFC6805]King，D.，Ed.和A.Farrel，Ed.，“路径计算元素架构在MPLS和GMPLS域序列确定中的应用”，RFC 6805，DOI 10.17487/RFC6805，2012年11月<http://www.rfc-editor.org/info/rfc6805>.
[RFC7896] Dhody, D., "Update to the Include Route Object (IRO) Specification in the Path Computation Element Communication Protocol (PCEP)", RFC 7896, DOI 10.17487/RFC7896, June 2016, <http://www.rfc-editor.org/info/rfc7896>.
[RFC7896]Dhody，D.，“路径计算元素通信协议（PCEP）中包含路由对象（IRO）规范的更新”，RFC 7896，DOI 10.17487/RFC7896，2016年6月<http://www.rfc-editor.org/info/rfc7896>.
[RFC7898] Dhody, D., Palle, U., Kondreddy, V., and R. Casellas, "Domain Subobjects for Resource Reservation Protocol - Traffic Engineering (RSVP-TE)", RFC 7898, DOI 10.17487/RFC7898, June 2016, <http://www.rfc-editor.org/info/rfc7898>.
[RFC7898]Dhody，D.，Palle，U.，Kondreddy，V.，和R.Casellas，“资源预留协议的域子对象-流量工程（RSVP-TE）”，RFC 7898，DOI 10.17487/RFC78982016年6月<http://www.rfc-editor.org/info/rfc7898>.
[PCEPS] Lopez, D., Dios, O., Wu, W., and D. Dhody, "Secure Transport for PCEP", Work in Progress, draft-ietf-pce-pceps-09, November 2015.
[PCEP]Lopez，D.，Dios，O.，Wu，W.，和D.Dhody，“PCEP的安全运输”，正在进行的工作，草案-ietf-pce-PCEPS-092015年11月。
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, DOI 10.17487/RFC4655, August 2006, <http://www.rfc-editor.org/info/rfc4655>.
[RFC4655]Farrel，A.，Vasseur，J.，和J.Ash，“基于路径计算元素（PCE）的体系结构”，RFC 4655，DOI 10.17487/RFC4655，2006年8月<http://www.rfc-editor.org/info/rfc4655>.
[RFC4726] Farrel, A., Vasseur, J., and A. Ayyangar, "A Framework for Inter-Domain Multiprotocol Label Switching Traffic Engineering", RFC 4726, DOI 10.17487/RFC4726, November 2006, <http://www.rfc-editor.org/info/rfc4726>.
[RFC4726]Farrel，A.，Vasseur，J.，和A.Ayyangar，“域间多协议标签交换流量工程框架”，RFC 4726，DOI 10.17487/RFC4726，2006年11月<http://www.rfc-editor.org/info/rfc4726>.
[RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel, "GMPLS Segment Recovery", RFC 4873, DOI 10.17487/RFC4873, May 2007, <http://www.rfc-editor.org/info/rfc4873>.
[RFC4873]Berger，L.，Bryskin，I.，Papadimitriou，D.，和A.Farrel，“GMPLS段恢复”，RFC 4873，DOI 10.17487/RFC4873，2007年5月<http://www.rfc-editor.org/info/rfc4873>.
[RFC4874] Lee, CY., Farrel, A., and S. De Cnodder, "Exclude Routes - Extension to Resource ReserVation Protocol-Traffic Engineering (RSVP-TE)", RFC 4874, DOI 10.17487/RFC4874, April 2007, <http://www.rfc-editor.org/info/rfc4874>.
[RFC4874]Lee，CY.，Farrel，A.和S.De Cnodder，“排除路由-资源预留协议流量工程（RSVP-TE）的扩展”，RFC 4874，DOI 10.17487/RFC4874，2007年4月<http://www.rfc-editor.org/info/rfc4874>.
[RFC5152] Vasseur, JP., Ed., Ayyangar, A., Ed., and R. Zhang, "A Per-Domain Path Computation Method for Establishing Inter-Domain Traffic Engineering (TE) Label Switched Paths (LSPs)", RFC 5152, DOI 10.17487/RFC5152, February 2008, <http://www.rfc-editor.org/info/rfc5152>.
[RFC5152]Vasseur，JP.，Ed.，Ayyangar，A.，Ed.，和R.Zhang，“建立域间流量工程（TE）标签交换路径（LSP）的每域路径计算方法”，RFC 5152，DOI 10.17487/RFC5152，2008年2月<http://www.rfc-editor.org/info/rfc5152>.
[RFC5520] Bradford, R., Ed., Vasseur, JP., and A. Farrel, "Preserving Topology Confidentiality in Inter-Domain Path Computation Using a Path-Key-Based Mechanism", RFC 5520, DOI 10.17487/RFC5520, April 2009, <http://www.rfc-editor.org/info/rfc5520>.
[RFC5520]Bradford，R.，Ed.，Vasseur，JP.，和A.Farrel，“使用基于路径密钥的机制在域间路径计算中保持拓扑机密性”，RFC 5520，DOI 10.17487/RFC5520，2009年4月<http://www.rfc-editor.org/info/rfc5520>.
[RFC5886] Vasseur, JP., Ed., Le Roux, JL., and Y. Ikejiri, "A Set of Monitoring Tools for Path Computation Element (PCE)-Based Architecture", RFC 5886, DOI 10.17487/RFC5886, June 2010, <http://www.rfc-editor.org/info/rfc5886>.
[RFC5886]Vasseur，JP.，Ed.，Le Roux，JL.，和Y.Ikejiri，“基于路径计算元素（PCE）架构的一套监控工具”，RFC 5886，DOI 10.17487/RFC5886，2010年6月<http://www.rfc-editor.org/info/rfc5886>.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP Authentication Option", RFC 5925, DOI 10.17487/RFC5925, June 2010, <http://www.rfc-editor.org/info/rfc5925>.
[RFC5925]Touch，J.，Mankin，A.，和R.Bonica，“TCP认证选项”，RFC 5925，DOI 10.17487/RFC5925，2010年6月<http://www.rfc-editor.org/info/rfc5925>.
[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet Autonomous System (AS) Number Space", RFC 6793, DOI 10.17487/RFC6793, December 2012, <http://www.rfc-editor.org/info/rfc6793>.
[RFC6793]Vohra，Q.和E.Chen，“BGP对四个八位组自治系统（AS）数字空间的支持”，RFC 6793，DOI 10.17487/RFC6793，2012年12月<http://www.rfc-editor.org/info/rfc6793>.
[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of BGP, LDP, PCEP, and MSDP Issues According to the Keying and Authentication for Routing Protocols (KARP) Design Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013, <http://www.rfc-editor.org/info/rfc6952>.
[RFC6952]Jethanandani，M.，Patel，K.，和L.Zheng，“根据路由协议键控和认证（KARP）设计指南分析BGP，LDP，PCEP和MSDP问题”，RFC 6952，DOI 10.17487/RFC6952，2013年5月<http://www.rfc-editor.org/info/rfc6952>.
[RFC7334] Zhao, Q., Dhody, D., King, D., Ali, Z., and R. Casellas, "PCE-Based Computation Procedure to Compute Shortest Constrained Point-to-Multipoint (P2MP) Inter-Domain Traffic Engineering Label Switched Paths", RFC 7334, DOI 10.17487/RFC7334, August 2014, <http://www.rfc-editor.org/info/rfc7334>.
[RFC7334]Zhao，Q.，Dhody，D.，King，D.，Ali，Z.，和R.Casellas，“基于PCE计算最短约束点到多点（P2MP）域间流量工程标签交换路径的计算程序”，RFC 7334，DOI 10.17487/RFC7334，2014年8月<http://www.rfc-editor.org/info/rfc7334>.
[RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J. Hardwick, "Path Computation Element Communication Protocol (PCEP) Management Information Base (MIB) Module", RFC 7420, DOI 10.17487/RFC7420, December 2014, <http://www.rfc-editor.org/info/rfc7420>.
[RFC7420]Koushik，A.，Stephan，E.，Zhao，Q.，King，D.，和J.Hardwick，“路径计算元素通信协议（PCEP）管理信息库（MIB）模块”，RFC 7420，DOI 10.17487/RFC7420，2014年12月<http://www.rfc-editor.org/info/rfc7420>.
Acknowledgments
致谢
The authors would like to especially thank Adrian Farrel for his detailed reviews as well as providing text to be included in the document.
作者要特别感谢Adrian Farrel的详细评论，并提供了要包含在文档中的文本。
Further, we would like to thank Pradeep Shastry, Suresh Babu, Quintin Zhao, Fatai Zhang, Daniel King, Oscar Gonzalez, Chen Huaimo, Venugopal Reddy, Reeja Paul, Sandeep Boina, Avantika Sergio Belotti, and Jonathan Hardwick for their useful comments and suggestions.
此外，我们还要感谢Pradeep Shastry、Suresh Babu、Quintin Zhao、Fatai Zhang、Daniel King、Oscar Gonzalez、陈怀默、Venugopal Reddy、Reeja Paul、Sandeep Boina、Avantika Sergio Belotti和Jonathan Hardwick提出的有用意见和建议。
Thanks to Jonathan Hardwick for shepherding this document.
感谢Jonathan Hardwick指导这份文件。
Thanks to Deborah Brungard for being the responsible AD.
感谢Deborah Brungard作为负责任的广告。
Thanks to Amanda Baber for the IANA review.
感谢阿曼达·巴伯的IANA评论。
Thanks to Joel Halpern for the Gen-ART review.
感谢Joel Halpern的Gen艺术评论。
Thanks to Klaas Wierenga for the SecDir review.
感谢克拉斯·维伦加的SecDir评论。
Thanks to Spencer Dawkins and Barry Leiba for comments during the IESG review.
感谢Spencer Dawkins和Barry Leiba在IESG审查期间的评论。
Authors' Addresses
作者地址
Dhruv Dhody Huawei Technologies Divyashree Techno Park, Whitefield Bangalore, Karnataka 560066 India
印度卡纳塔克邦班加罗尔Whitefield Bangalore Dhruv Dhody华为技术分部，邮编560066
Email: dhruv.ietf@gmail.com
Email: dhruv.ietf@gmail.com
Udayasree Palle Huawei Technologies Divyashree Techno Park, Whitefield Bangalore, Karnataka 560066 India
Udayasree Palle华为技术分公司位于印度卡纳塔克邦Whitefield Bangalore的HREE技术园，邮编560066
Email: udayasree.palle@huawei.com
Email: udayasree.palle@huawei.com
Ramon Casellas CTTC Av. Carl Friedrich Gauss n7 Castelldefels, Barcelona 08860 Spain
拉蒙·卡塞拉斯CTTC Av。Carl Friedrich Gauss n7 Castelldefels，巴塞罗那08860西班牙
Email: ramon.casellas@cttc.es
Email: ramon.casellas@cttc.es