Network Working Group C. Metz
Request for Comments: 5003 L. Martini
Category: Standards Track Cisco Systems Inc.
F. Balus
Alcatel-Lucent
J. Sugimoto
Nortel Networks
September 2007
Network Working Group C. Metz
Request for Comments: 5003 L. Martini
Category: Standards Track Cisco Systems Inc.
F. Balus
Alcatel-Lucent
J. Sugimoto
Nortel Networks
September 2007
Attachment Individual Identifier (AII) Types for Aggregation
用于聚合的附件单个标识符（AII）类型
Status of This Memo
关于下段备忘
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
本文件规定了互联网社区的互联网标准跟踪协议，并要求进行讨论和提出改进建议。有关本协议的标准化状态和状态，请参考当前版本的“互联网官方协议标准”（STD 1）。本备忘录的分发不受限制。
Abstract
摘要
The signaling protocols used to establish point-to-point pseudowires include type-length-value (TLV) fields that identify pseudowire endpoints called attachment individual identifiers (AIIs). This document defines AII structures in the form of new AII TLV fields that support AII aggregation for improved scalability and Virtual Private Network (VPN) auto-discovery. It is envisioned that this would be useful in large inter-domain virtual private wire service networks where pseudowires are established between selected local and remote provider edge (PE) nodes based on customer need.
用于建立点到点伪线的信令协议包括识别伪线端点的类型长度值（TLV）字段，称为附件单独标识符（AII）。本文档以新的AII TLV字段的形式定义了AII结构，这些字段支持AII聚合以提高可扩展性和虚拟专用网络（VPN）自动发现。可以预见，这将有助于大型域间虚拟专用有线服务网络，其中根据客户需求在选定的本地和远程提供商边缘（PE）节点之间建立伪线。
Table of Contents
目录
1. Introduction ....................................................2
2. Specification of Requirements ...................................3
3. Structure for the New AII Type ..................................3
3.1. AII Type 1 .................................................3
3.2. AII Type 2 .................................................3
4. IANA Considerations .............................................5
5. Security Considerations .........................................5
6. Acknowledgments .................................................5
7. Normative References ............................................5
8. Informative References ..........................................5
1. Introduction ....................................................2
2. Specification of Requirements ...................................3
3. Structure for the New AII Type ..................................3
3.1. AII Type 1 .................................................3
3.2. AII Type 2 .................................................3
4. IANA Considerations .............................................5
5. Security Considerations .........................................5
6. Acknowledgments .................................................5
7. Normative References ............................................5
8. Informative References ..........................................5
[RFC4447] defines the signaling mechanisms for establishing point-to-point pseudowires (PWs) between two provider edge (PE) nodes. When a PW is set up, the LDP signaling messages include a forwarding equivalence class (FEC) element containing information about the PW type and an endpoint identifier used in the selection of the PW forwarder that binds the PW to the attachment circuit at each end.
[RFC4447]定义了用于在两个提供商边缘（PE）节点之间建立点对点伪线（PW）的信令机制。当设置PW时，LDP信令消息包括包含关于PW类型的信息的转发等价类（FEC）元素和在选择将PW绑定到每端的连接电路的PW转发器中使用的端点标识符。
There are two types of FEC elements defined for this purpose: PWid FEC (type 128) and the Generalized ID (GID) FEC (type 129). The PWid FEC element includes a fixed-length 32-bit value called the PWid that serves as an endpoint identifier. The same PWid value must be configured on the local and remote PE prior to PW setup.
为此定义了两种类型的FEC元素：PWid FEC（类型128）和通用ID（GID）FEC（类型129）。PWid FEC元素包括一个名为PWid的固定长度32位值，该值用作端点标识符。在PW设置之前，必须在本地和远程PE上配置相同的PWid值。
The GID FEC element includes TLV fields for attachment individual identifiers (AIIs) that, in conjunction with an attachment group identifier (AGI), serve as PW endpoint identifiers. The endpoint identifier on the local PE (denoted as <AGI, source AII, or SAII>) is called the source attachment identifier (SAI) and the endpoint identifier on the remote PE (denoted as <AGI, target AII, or TAII>) is called the target attachment identifier (TAI). The SAI and TAI can be distinct values. This is useful for applications and provisioning models where the local PE (with a particular SAI) does not know and must somehow learn (e.g., via Multiprotocol BGP (MP-BGP) auto-discovery) of remote TAI values prior to launching PW setup messages towards the remote PE.
GID FEC元素包括用于附件单个标识符（AII）的TLV字段，该标识符与附件组标识符（AGI）一起用作PW端点标识符。本地PE上的端点标识符（表示为<AGI、源AII或SAII>）称为源附件标识符（SAI），远程PE上的端点标识符（表示为<AGI、目标AII或TAII>）称为目标附件标识符（TAI）。SAI和TAI可以是不同的值。这对于本地PE（具有特定SAI）在向远程PE发送PW设置消息之前不知道并且必须以某种方式了解（例如，通过多协议BGP（MP-BGP）自动发现）远程TAI值的应用程序和供应模型非常有用。
The use of the GID FEC TLV provides the flexibility to structure (source or target) AII values to best fit the needs of a particular application or provisioning model [L2VPN-SIG]. For example, an AII structure that enables many individual AII values to be identified as a single value could significantly reduce the burden on AII distribution mechanisms (e.g., MP-BGP) and on PE memory needed to store this AII information. It should be noted that Pseudowire Emulation Edge-to-Edge (PWE3) signaling messages will always include a fully qualified AII value.
GID FEC TLV的使用提供了构造（源或目标）AII值的灵活性，以最适合特定应用程序或供应模型的需要[L2VPN-SIG]。例如，能够将许多单个AII值标识为单个值的AII结构可以显著降低AII分布机制（例如MP-BGP）和存储此AII信息所需的PE内存的负担。应注意，伪线仿真边到边（PWE3）信令消息将始终包括完全限定的AII值。
An AII that is globally unique would facilitate PW management and security in large inter-AS (autonomous system) and inter-provider environments. Providers would not have to worry about AII value overlap during provisioning or the need for AII network address translation (NAT) boxes during signaling. Globally unique AII values could aid in troubleshooting and could be subjected to source-validity checks during AII distribution and signaling. An AII automatically derived from a provider's existing IP address space can simplify the provisioning process.
全球唯一的AII将促进大型AS（自治系统）和供应商间环境中的PW管理和安全。提供商不必担心供应期间的AII值重叠，也不必担心信令期间需要AII网络地址转换（NAT）框。全局唯一的AII值可以帮助进行故障排除，并且在AII分发和发送信号期间可以接受源有效性检查。从提供商的现有IP地址空间自动派生的AII可以简化资源调配过程。
This document defines an AII structure based on [RFC4447] that:
本文件基于[RFC4447]定义了一个AII结构，该结构：
o Enables many discrete attachment individual identifiers to be summarized into a single AII summary value. This will enhance scalability by reducing the burden on AII distribution mechanisms and on PE memory.
o 允许将多个离散附件单个标识符汇总为单个AII汇总值。这将通过减少AII分发机制和PE内存的负担来增强可伸缩性。
o Ensures global uniqueness if desired by the provider. This will facilitate Internet-wide PW connectivity and provide a means for providers to perform source validation on the AII distribution (e.g., MP-BGP) and signaling (e.g., LDP) channels.
o 如果提供程序需要，确保全局唯一性。这将促进互联网范围的PW连接，并为供应商提供一种手段，以对AII分发（如MP-BGP）和信令（如LDP）信道执行源验证。
This is accomplished by defining new AII types and the associated formats of the value field.
这是通过定义新的AII类型和值字段的关联格式来实现的。
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。
[RFC4447] defines the format of the GID FEC TLV and the use and semantics of the attachment group identifier (AGI).
[RFC4447]定义GID FEC TLV的格式以及附件组标识符（AGI）的使用和语义。
AII Type 1 has been allocated by IANA for use with provisioning models requiring a fixed-length 32-bit value [L2VPN-SIG]. This value is unique on the local PE.
IANA已将AII类型1分配给需要固定长度32位值[L2VPN-SIG]的供应模型。此值在本地PE上是唯一的。
The AII Type 2 structure permits varying levels of AII summarization to take place, thus reducing the scaling burden on the aforementioned AII distribution mechanisms and PE memory. In other words, it no longer becomes necessary to distribute or configure all individual AII values (which could number in the tens of thousands or more) on local PEs prior to establishing PWs to remote PEs. The details of how and where the aggregation of AII values is performed and then distributed as AII reachability information are not discussed in this document.
AII类型2结构允许进行不同级别的AII摘要，从而减少上述AII分布机制和PE内存的扩展负担。换句话说，在将PWs建立到远程PE之前，不再需要在本地PE上分发或配置所有单个AII值（可能数万或更多）。本文档不讨论如何以及在何处执行AII值的聚合，然后将其作为AII可达性信息分发。
AII Type 2 uses a combination of a provider's globally unique identifier (Global ID), a 32-bit prefix field, and a 4-octet attachment circuit identifier (AC ID) field to create globally unique AII values.
AII类型2使用提供者的全局唯一标识符（全局ID）、32位前缀字段和4位八位组连接电路标识符（AC ID）字段的组合来创建全局唯一的AII值。
The encoding of AII Type 2 is shown in Figure 1.
AII类型2的编码如图1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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII Type=02 | Length | Global ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Global ID (contd.) | Prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix (contd.) | AC ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AC 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII Type=02 | Length | Global ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Global ID (contd.) | Prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix (contd.) | AC ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AC ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1. AII Type 2 TLV Structure
图1。AII 2型TLV结构
o AII Type = 0x02
o 所有类型=0x02
o Length = length of value field in octets. The length is set to 12.
o 长度=值字段的长度（以八位字节为单位）。长度设置为12。
o Global ID = This is a 4-octet field containing a value that is unique to the provider. The global ID can contain the 2-octet or 4-octet value of the provider's Autonomous System Number (ASN). It is expected that the global ID will be derived from the globally unique ASN of the autonomous system hosting the PEs containing the actual AIIs. The presence of a global ID based on the provider's ASN ensures that the AII will be globally unique.
o Global ID=这是一个4个八位字节的字段，其中包含一个对提供程序唯一的值。全局ID可以包含提供商的自治系统号（ASN）的2-octet或4-octet值。预计全局ID将从承载包含实际AII的PEs的自治系统的全局唯一ASN派生。基于提供商的ASN的全局ID的存在确保了AII将是全局唯一的。
If the global ID is derived from a 2-octet AS number, then the two high-order octets of this 4-octet field MUST be set to zero.
如果全局ID是从2个八位字节作为数字派生的，则此4个八位字节字段的两个高阶八位字节必须设置为零。
Please note that the use of the provider's ASN as a global ID DOES NOT have anything at all to do with the use of the ASN in protocols such as BGP.
请注意，使用提供商的ASN作为全局ID与在协议（如BGP）中使用ASN没有任何关系。
o Prefix = The 32-bit prefix is a value assigned by the provider or it can be automatically derived from the PE's /32 IPv4 loopback address. Note that, for IP reachability, it is not required that the 32-bit prefix have any association with the IPv4 address space used in the provider's IGP or BGP.
o Prefix=32位前缀是由提供商分配的值，也可以从PE的/32 IPv4环回地址自动派生。请注意，对于IP可达性，不要求32位前缀与提供商的IGP或BGP中使用的IPv4地址空间有任何关联。
o Attachment Circuit (AC) ID = This is a fixed-length 4-octet field used to further refine identification of an attachment circuit on the PE. The inclusion of the AC ID is used to identify individual attachment circuits that share a common prefix.
o 附件电路（AC）ID=这是一个固定长度的4八位字节字段，用于进一步完善PE上附件电路的标识。包含AC ID用于标识共享公共前缀的各个连接电路。
IANA has allocated a value from the "Attachment Individual Identifier (AII) Type" registry defined in [RFC4446].
IANA已从[RFC4446]中定义的“附件个人标识符（AII）类型”注册表中分配了一个值。
The value for this AII type is 0x02.
此AII类型的值为0x02。
AII values appear in AII distribution protocols [L2VPN-SIG] and PW signaling protocols [RFC4447] and are subject to various authentication schemes (i.e., MD5) if so desired.
AII值出现在AII分发协议[L2VPN-SIG]和PW信令协议[RFC4447]中，如果需要，受各种身份验证方案（即MD5）的约束。
The use of global ID values (e.g., ASN) in the inter-provider case could enable a form of source-validation checking to ensure that the AII value (aggregated or explicit) originated from a legitimate source.
在提供者之间的情况下使用全局ID值（例如ASN）可以启用某种形式的源验证检查，以确保AII值（聚合或显式）源自合法源。
Thanks to Carlos Pignataro, Scott Brim, Skip Booth, George Swallow, and Bruce Davie for their input into this document.
感谢Carlos Pignataro、Scott Brim、Skip Booth、George Swallow和Bruce Davie对本文档的贡献。
[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。
[RFC4447] Martini, L., Ed., Rosen, E., El-Aawar, N., Smith, T., and G. Heron, "Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)", RFC 4447, April 2006.
[RFC4447]Martini，L.，Ed.，Rosen，E.，El Aawar，N.，Smith，T.，和G.Heron，“使用标签分发协议（LDP）的伪线设置和维护”，RFC 4447，2006年4月。
[RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge Emulation (PWE3)", BCP 116, RFC 4446, April 2006.
[RFC4446]Martini，L.，“伪线边到边仿真（PWE3）的IANA分配”，BCP 116，RFC 4446，2006年4月。
[L2VPN-SIG] Rosen, E., Luo, W., Davie, B., and V. Radoaca, "Provisioning, Autodiscovery, and Signaling in L2VPNs", Work in Progress, May 2006.
[L2VPN-SIG]Rosen，E.，Luo，W.，Davie，B.，和V.Radoaca，“L2VPN中的资源调配、自动发现和信令”，正在进行的工作，2006年5月。
Authors' Addresses
作者地址
Luca Martini Cisco Systems, Inc. 9155 East Nichols Avenue, Suite 400 Englewood, CO, 80112 EMail: lmartini@cisco.com
Luca Martini Cisco Systems，Inc.地址：科罗拉多州恩格尔伍德东尼科尔斯大道9155号400室，邮编：80112电子邮件：lmartini@cisco.com
Chris Metz Cisco Systems, Inc. 3700 Cisco Way San Jose, Ca. 95134 EMail: chmetz@cisco.com
Chris Metz Cisco Systems，Inc.位于加利福尼亚州圣何塞市思科大道3700号，邮编95134电子邮件：chmetz@cisco.com
Florin Balus Alcatel-Lucent 701 East Middlefield Rd. Mountain View, CA 94043 EMail: florin.balus@alcatel-lucent.com
Florin Balus Alcatel-Lucent加利福尼亚州山景城东米德菲尔德路701号94043电子邮件：Florin。balus@alcatel-朗讯网
Jeff Sugimoto Nortel Networks 3500 Carling Ave. Ottawa, Ontario, CANADA EMail: sugimoto@nortel.com
Jeff Sugimoto Nortel Networks加拿大安大略省渥太华卡林大道3500号电子邮件：sugimoto@nortel.com
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