Internet Engineering Task Force (IETF) H. Li
Request for Comments: 6423 China Mobile
Updates: 5586 L. Martini
Category: Standards Track Cisco System
ISSN: 2070-1721 J. He
Huawei
F. Huang
Alcatel-Lucent
November 2011
Internet Engineering Task Force (IETF) H. Li
Request for Comments: 6423 China Mobile
Updates: 5586 L. Martini
Category: Standards Track Cisco System
ISSN: 2070-1721 J. He
Huawei
F. Huang
Alcatel-Lucent
November 2011
Using the Generic Associated Channel Label for Pseudowire in the MPLS Transport Profile (MPLS-TP)
在MPLS传输配置文件（MPLS-TP）中使用伪线的通用关联信道标签
Abstract
摘要
This document describes the requirements for using the Generic Associated Channel Label (GAL) in pseudowires (PWs) in MPLS Transport Profile (MPLS-TP) networks, and provides an update to the description of GAL usage in RFC 5586 by removing the restriction that is imposed on using GAL for PWs, especially in MPLS-TP environments.
本文档描述了在MPLS传输配置文件（MPLS-TP）网络中的伪线（PWs）中使用通用关联信道标签（GAL）的要求，并通过取消对PWs使用GAL的限制，特别是在MPLS-TP环境中，对RFC 5586中GAL使用的描述进行了更新。
Status of This Memo
关于下段备忘
This is an Internet Standards Track document.
这是一份互联网标准跟踪文件。
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741.
本文件是互联网工程任务组（IETF）的产品。它代表了IETF社区的共识。它已经接受了公众审查，并已被互联网工程指导小组（IESG）批准出版。有关互联网标准的更多信息，请参见RFC 5741第2节。
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6423.
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/rfc6423.
Copyright Notice
版权公告
Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2011 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 ....................................................2
2. Conventions Used in This Document ...............................2
2.1. Terminology ................................................3
3. GAL Usage for MPLS-TP PW ........................................3
4. Security Considerations .........................................4
5. Acknowledgments .................................................4
6. References ......................................................5
6.1. Normative References .......................................5
6.2. Informative References .....................................5
1. Introduction ....................................................2
2. Conventions Used in This Document ...............................2
2.1. Terminology ................................................3
3. GAL Usage for MPLS-TP PW ........................................3
4. Security Considerations .........................................4
5. Acknowledgments .................................................4
6. References ......................................................5
6.1. Normative References .......................................5
6.2. Informative References .....................................5
[RFC5586] generalizes the Associated Channel mechanism of [RFC5085] to be used for Sections, Label Switched Paths (LSPs), and Pseudowires (PWs) in MPLS networks. [RFC5085] defines the Associated Channel Header (ACH), and [RFC5586] generalizes this for use as the Generic Associated Channel (G-ACh).
[RFC5586]概括了[RFC5085]的相关信道机制，用于MPLS网络中的区段、标签交换路径（LSP）和伪线（PW）。[RFC5085]定义了相关信道头（ACH），并且[RFC5586]将其概括为通用相关信道（G-ACH）。
[RFC5586] defines a generalized label-based exception mechanism using the Generic Associated Channel Label (GAL) to work together with the ACH for use with LSPs but prohibits GAL usage with PWs.
[RFC5586]定义了一种通用的基于标签的异常机制，使用通用关联通道标签（GAL）与ACH一起工作，用于LSP，但禁止将GAL用于PWs。
This document removes the restriction imposed by [RFC5586].
本文件取消了[RFC5586]施加的限制。
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。
ACH Associated Channel Header
ACH相关信道头
CW Control Word
连续波控制字
G-ACh Generic Associated Channel
G-ACh通用关联信道
GAL Generic Associated Channel Label
GAL通用关联通道标签
MPLS-TP MPLS Transport Profile
MPLS-TP MPLS传输配置文件
OAM Operation, Administration, and Maintenance
OAM操作、管理和维护
According to the MPLS-TP requirements document [RFC5654], it is necessary that MPLS-TP mechanisms and capabilities be able to interoperate with the existing IETF MPLS [RFC3031] and IETF PWE3 [RFC3985] architectures as appropriate. [RFC5586] differentiates between the usage of the GAL with PWs in MPLS and MPLS-TP environments in Section 4.2 as follows:
根据MPLS-TP需求文件[RFC5654]，MPLS-TP机制和能力必须能够与现有的IETF MPLS[RFC3031]和IETF PWE3[RFC3985]架构（视情况而定）互操作。[RFC5586]在第4.2节中，对MPLS和MPLS-TP环境中使用带PWs的GAL的区别如下：
In MPLS-TP, the GAL MUST be used with packets on a G-ACh on LSPs, Concatenated Segments of LSPs, and with Sections, and MUST NOT be used with PWs.
在MPLS-TP中，GAL必须与LSP上G-ACh上的数据包、LSP的连接段和段一起使用，并且不得与PWs一起使用。
This indicates that the GAL can be used for MPLS-TP LSPs and Sections, but not for PWs in an MPLS-TP network.
这表明GAL可用于MPLS-TP LSP和段，但不能用于MPLS-TP网络中的PWs。
However, there is no restriction imposed on the usage of the GAL in MPLS PWs, which is described immediately afterwards in the same section (Section 4.2) of [RFC5586]:
但是，对于MPLS PWs中GAL的使用没有任何限制，这将在[RFC5586]的同一节（第4.2节）中立即描述：
However, in other MPLS environments, this document places no restrictions on where the GAL may appear within the label stack or its use with PWs.
但是，在其他MPLS环境中，本文档对GAL可能出现在标签堆栈中的位置或与PWs一起使用没有任何限制。
The inconsistency between the usage of the GAL with MPLS PWs and MPLS-TP PWs may cause unnecessary implementation differences and is in disagreement with the MPLS-TP requirements.
GAL与MPLS PWs和MPLS-TP PWs之间的使用不一致可能导致不必要的实现差异，并且与MPLS-TP要求不一致。
Therefore, this document specifies that the GAL can be used with packets on a G-ACh on LSPs, Concatenated Segments of LSPs, Sections, and PWs in both MPLS and MPLS-TP environments without discrimination.
因此，本文件规定GAL可以在MPLS和MPLS-TP环境中与LSP上的G-ACh上的数据包、LSP的连接段、段和PW一起使用，而不受歧视。
[RFC5586] is updated by removing the restrictions on using GAL for PW as follows:
[RFC5586]通过删除对PW使用GAL的限制进行更新，如下所示：
- Section 1 (Introduction) in [RFC5586], the original text:
- [RFC5586]第1节（引言），原文：
The GAL mechanism is defined to work together with the ACH for LSPs and MPLS Sections.
GAL机制被定义为与LSP和MPLS部分的ACH一起工作。
is replaced by:
替换为：
The GAL mechanism is defined to work together with the ACH for LSPs and MPLS Sections, and for PWs.
GAL机制被定义为在LSP和MPLS段以及PWs中与ACH协同工作。
- Section 4.2. (GAL Applicability and Usage) in [RFC5586], the original text:
- 第4.2节。（GAL适用性和用法）在[RFC5586]中，原文：
In MPLS-TP, the GAL MUST be used with packets on a G-ACh on LSPs, Concatenated Segments of LSPs, and with Sections, and MUST NOT be used with PWs. It MUST always be at the bottom of the label stack (i.e., S bit set to 1). However, in other MPLS environments, this document places no restrictions on where the GAL may appear within the label stack or its use with PWs.
在MPLS-TP中，GAL必须与LSP上G-ACh上的数据包、LSP的连接段和段一起使用，并且不得与PWs一起使用。它必须始终位于标签堆栈的底部（即S位设置为1）。但是，在其他MPLS环境中，本文档对GAL可能出现在标签堆栈中的位置或与PWs一起使用没有任何限制。
is replaced by:
替换为：
In MPLS-TP, the GAL MUST be used with packets on a G-ACh on LSPs, Concatenated Segments of LSPs, and with Sections, and MAY be used with PWs. The presence of a GAL indicates that an ACH immediately follows the MPLS label stack.
在MPLS-TP中，GAL必须与LSP上G-ACh上的数据包、LSP的连接段和段一起使用，并且可以与PWs一起使用。GAL的存在表示ACH紧跟在MPLS标签堆栈之后。
There are no further security considerations than those in [RFC5586].
除了[RFC5586]中的安全注意事项外，没有其他安全注意事项。
The authors would like to thank Luyuan Fang, Adrian Farrel, Haiyan Zhang, Guanghui Sun, Italo Busi, and Matthew Bocci for their contributions to this work.
作者要感谢方卢元、阿德里安·法雷尔、张海燕、孙广辉、伊塔洛·布西和马修·博奇对这项工作的贡献。
The authors would also like to thank the authors of [RFC5586] and people who were involved in the development of [RFC5586].
作者还要感谢[RFC5586]的作者和参与[RFC5586]开发的人员。
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol Label Switching Architecture", RFC 3031, January 2001.
[RFC3031]Rosen，E.，Viswanathan，A.，和R.Callon，“多协议标签交换体系结构”，RFC 30312001年1月。
[RFC3985] Bryant, S., Ed., and P. Pate, Ed., "Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture", RFC 3985, March 2005.
[RFC3985]Bryant，S.，Ed.，和P.Pate，Ed.，“伪线仿真边到边（PWE3）架构”，RFC 39852005年3月。
[RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed., "MPLS Generic Associated Channel", RFC 5586, June 2009.
[RFC5586]Bocci，M.，Ed.，Vigoureux，M.，Ed.，和S.Bryant，Ed.，“MPLS通用关联信道”，RFC 55862009年6月。
[RFC5085] Nadeau, T., Ed., and C. Pignataro, Ed., "Pseudowire Virtual Circuit Connectivity Verification (VCCV): A Control Channel for Pseudowires", RFC 5085, December 2007.
[RFC5085]Nadeau，T.，Ed.，和C.Pignataro，Ed.，“伪线虚拟电路连接验证（VCCV）：伪线的控制通道”，RFC 5085，2007年12月。
[RFC5654] Niven-Jenkins, B., Ed., Brungard, D., Ed., Betts, M., Ed., Sprecher, N.,and S. Ueno, "Requirements of an MPLS Transport Profile", RFC 5654, September 2009.
[RFC5654]Niven Jenkins，B.，Ed.，Brungard，D.，Ed.，Betts，M.，Ed.，Sprecher，N.，和S.Ueno，“MPLS传输配置文件的要求”，RFC 56542009年9月。
Authors' Addresses
作者地址
Han Li China Mobile Communications Corporation EMail: lihan@chinamobile.com
韩丽中国移动通信股份有限公司电子邮件：lihan@chinamobile.com
Luca Martini Cisco Systems, Inc. EMail: lmartini@cisco.com
Luca Martini Cisco Systems，Inc.电子邮件：lmartini@cisco.com
Jia He Huawei Technologies Co., Ltd. EMail: hejia@huawei.com
嘉和华为技术有限公司邮箱：hejia@huawei.com
Feng Huang Alcatel-Lucent shanghai Bell EMail: feng.f.huang@alcatel-sbell.com.cn
凤凰阿尔卡特朗讯上海贝尔电子邮件：Feng.f。huang@alcatel-sbell.com.cn