Internet Engineering Task Force (IETF) W. Kumari
Request for Comments: 6472 Google, Inc.
BCP: 172 K. Sriram
Category: Best Current Practice U.S. NIST
ISSN: 2070-1721 December 2011
Internet Engineering Task Force (IETF) W. Kumari
Request for Comments: 6472 Google, Inc.
BCP: 172 K. Sriram
Category: Best Current Practice U.S. NIST
ISSN: 2070-1721 December 2011
Recommendation for Not Using AS_SET and AS_CONFED_SET in BGP
不在BGP中使用AS_集和AS_配制_集的建议
Abstract
摘要
This document recommends against the use of the AS_SET and AS_CONFED_SET types of the AS_PATH in BGPv4. This is done to simplify the design and implementation of BGP and to make the semantics of the originator of a route more clear. This will also simplify the design, implementation, and deployment of ongoing work in the Secure Inter-Domain Routing Working Group.
本文档建议不要在BGPv4中使用AS_路径的AS_集和AS_连接集类型。这样做是为了简化BGP的设计和实现，并使路由发起人的语义更加清晰。这也将简化安全域间路由工作组正在进行的工作的设计、实施和部署。
Status of This Memo
关于下段备忘
This memo documents an Internet Best Current Practice.
本备忘录记录了互联网最佳实践。
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 BCPs 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BCP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/rfc6472.
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/rfc6472.
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. Requirements Notation ...........................................3
3. Recommendation to Network Operators .............................3
4. Security Considerations .........................................4
5. Acknowledgements ................................................4
6. References ......................................................4
6.1. Normative References .......................................4
6.2. Informative References .....................................4
1. Introduction ....................................................2
2. Requirements Notation ...........................................3
3. Recommendation to Network Operators .............................3
4. Security Considerations .........................................4
5. Acknowledgements ................................................4
6. References ......................................................4
6.1. Normative References .......................................4
6.2. Informative References .....................................4
The AS_SET path segment type of the AS_PATH attribute (Sections 4.3 and 5.1.2 of [RFC4271]) is created by a router that is performing route aggregation and contains an unordered set of Autonomous Systems (ASes) that the update has traversed. The AS_CONFED_SET path type ([RFC5065]) of the AS_PATH attribute is created by a router that is performing route aggregation and contains an unordered set of Member AS Numbers in the local confederation that the update has traversed. It is very similar to AS_SETs but is used within a confederation.
AS_路径属性（RFC4271）的AS_集路径段类型（第4.3节和第5.1.2节）由正在执行路由聚合的路由器创建，并包含更新所经过的自治系统（ASE）的无序集。AS_路径属性的AS_CONFED_SET路径类型（[RFC5065]）由正在执行路由聚合的路由器创建，并包含更新所经过的本地联盟中的无序成员AS编号集。它与AS_集合非常相似，但在联盟中使用。
By performing aggregation, a router is, in essence, combining multiple existing routes into a single new route. This type of aggregation blurs the semantics of what it means to originate a route. Said aggregation can therefore cause operational issues, such as not being able to authenticate a route origin for the aggregate prefix in new BGP security technologies (such as those that take advantage of the "X.509 Extensions for IP Addresses and AS Identifiers" [RFC3779]). This in turn would result in reachability problems for the aggregated prefix and its components (i.e., more specifics). Said aggregation also creates traffic engineering issues, because the precise path information for the component prefixes is not preserved.
通过执行聚合，路由器本质上是将多个现有路由组合成一个新路由。这种类型的聚合模糊了发起路由意味着什么的语义。因此，所述聚合可能导致操作问题，例如无法在新的BGP安全技术（例如利用“IP地址和作为标识符的X.509扩展”[RFC3779]）中验证聚合前缀的路由来源。这反过来会导致聚合前缀及其组件的可达性问题（即更多细节）。所述聚合还产生流量工程问题，因为组件前缀的精确路径信息没有保留。
From analysis of past Internet routing data, it is apparent that aggregation that involves AS_SETs is very seldom used in practice on the public network [Analysis] and, when it is used, it is usually used incorrectly -- reserved AS numbers ([RFC1930]) and/or only a single AS in the AS_SET are by far the most common case. Because the aggregation involving AS_SETs is very rarely used, the reduction in table size provided by said aggregation is extremely small, and any advantage thereof is outweighed by additional complexity in BGP. As noted above, said aggregation also poses impediments to implementation of said new BGP security technologies.
通过对过去互联网路由数据的分析，很明显，涉及AS_集的聚合在公共网络上的实践中很少使用[analysis]，而且在使用时，它通常被错误地使用——保留为数字（[RFC1930]）和/或AS_集中只有一个AS是最常见的情况。由于涉及AS_集的聚合很少使用，因此所述聚合提供的表大小的减少非常小，并且其任何优点都被BGP中的额外复杂性所抵消。如上所述，所述聚合还对所述新BGP安全技术的实施构成障碍。
In the past, AS_SET had been used in a few rare cases to allow route aggregation where two or more providers could form the same prefix, using the exact match of the other's prefix in some advertisement and configuring the aggregation differently elsewhere. The key to configuring this correctly was to form the aggregate at the border in the outbound BGP policy and omit prefixes from the AS that the aggregate was being advertised to. The AS_SET therefore allowed this practice without the loss of BGP's AS_PATH loop protection. This use of AS_SET served a purpose that fell in line with the original intended use. Without the use of AS_SET, aggregates must always contain only less specific prefixes (not less than or equal to), and must never aggregate an exact match.
过去，AS_集曾在少数情况下被用于允许路由聚合，其中两个或多个提供商可以形成相同的前缀，在某些广告中使用另一方前缀的精确匹配，并在其他地方以不同方式配置聚合。正确配置此策略的关键是在出站BGP策略的边界处形成聚合，并从AS中省略将向其播发聚合的前缀。因此，AS_集合允许这种做法，而不会丢失BGP的AS_路径环路保护。使用AS_装置的目的与最初的预期用途一致。如果不使用AS_SET，聚合必须始终只包含不太特定的前缀（不小于或等于），并且决不能聚合完全匹配的前缀。
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。
It is RECOMMENDED that operators not generate any new announcements containing AS_SETs or AS_CONFED_SETs. If they have already announced routes with AS_SETs or AS_CONFED_SETs in them, then they SHOULD withdraw those routes and re-announce routes for the component prefixes (i.e., the additional specifics of the previously aggregated prefix) without AS_SETs in the updates. This involves undoing the aggregation that was previously performed (with AS_SETs), and announcing more specifics (without AS_SETs). Route aggregation that was previously performed by proxy aggregation (i.e., without the use of AS_SETs) is still possible under some conditions. As with any change, the operator should understand the full implications of the change.
建议运营商不要生成任何包含AS_集或AS_CONFED_集的新公告。如果他们已经宣布了包含AS_集或AS_CONFED_集的路由，那么他们应该撤回这些路由，并重新宣布更新中不包含AS_集的组件前缀（即先前聚合前缀的附加细节）的路由。这涉及撤消以前执行的聚合（使用AS_集），并宣布更多细节（不使用AS_集）。在某些条件下，以前由代理聚合执行的路由聚合（即，不使用AS_集）仍然是可能的。与任何变更一样，运营商应了解变更的全部含义。
It is worth noting that new technologies (such as those that take advantage of the "X.509 Extensions for IP Addresses and AS Identifiers" [RFC3779]) might not support routes with AS_SETs/ AS_CONFED_SETs in them, and may treat as infeasible routes containing them. Future BGP implementations may also do the same. It is expected that, even before the deployment of these new or future technologies, operators may filter routes with AS_SETs/AS_CONFED_SETs in them. Other than making that observation, this document is not intended to make any recommendation for how an operator should behave when receiving a route with AS_SET or AS_CONFED_SET in it. This document's focus is entirely on the sender side, as discussed in the preceding paragraph.
值得注意的是，新技术（例如利用“IP地址和as标识符的X.509扩展”[RFC3779]）可能不支持包含as_集/as_CONFED_集的路由，并且可能会将其视为不可行的路由。未来的BGP实施也可以这样做。预计，即使在部署这些新的或未来的技术之前，运营商可能会过滤其中包含AS_集/AS_CONFED_集的路由。除了进行观察外，本文件不打算对操作员在接收带有AS_集或AS_CONFED_集的路线时的行为提出任何建议。如前一段所述，本文件的重点完全在发送方。
This document discourages the use of aggregation techniques that create AS_SETs. Future work may update the protocol to remove support for the AS_SET path segment type of the AS_PATH attribute. This future work will remove complexity and code that are not exercised very often, thereby decreasing the attack surface. This future work will also simplify the design and implementation of the Resource Public Key Infrastructure (RPKI) and systems that will rely on it.
本文档不鼓励使用创建AS_集的聚合技术。未来的工作可能会更新协议，以删除对AS_路径属性的AS_集路径段类型的支持。这项未来的工作将消除不经常使用的复杂性和代码，从而减少攻击面。这项未来的工作还将简化资源公钥基础设施（RPKI）和依赖它的系统的设计和实现。
The authors would like to thank Tony Li, Randy Bush, John Scudder, Curtis Villamizar, Danny McPherson, Chris Morrow, Tom Petch, and Ilya Varlashkin, as well as Douglas Montgomery, Enke Chen, Florian Weimer, Jakob Heitz, John Leslie, Keyur Patel, Paul Jakma, Rob Austein, Russ Housley, Sandra Murphy, Steve Bellovin, Steve Kent, Steve Padgett, Alfred Hoenes, Alvaro Retana, everyone in the IDR working group, and everyone else who provided input.
作者要感谢Tony Li、Randy Bush、John Scudder、Curtis Villamizar、Danny McPherson、Chris Morrow、Tom Petch和Ilya Varlashkin，以及Douglas Montgomery、Enke Chen、Florian Weimer、Jakob Heitz、John Leslie、Keyur Patel、Paul Jakma、Rob Austein、Russ Housley、Sandra Murphy、Steve Bellovin、Steve Kent、Steve Padgett、，阿尔弗雷德·霍恩斯、阿尔瓦罗·雷塔纳、IDR工作组的每一位成员，以及提供意见的每一位其他人。
Apologies to those who we may have missed; it was not intentional.
向那些我们可能错过的人道歉；这不是故意的。
[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。
[Analysis] Sriram, K. and D. Montgomery, "Measurement Data on AS_SET and AGGREGATOR: Implications for {Prefix, Origin} Validation Algorithms", SIDR WG presentation, IETF 78, July 2010, <www.antd.nist.gov/~ksriram/ AS_SET_Aggregator_Stats.pdf>.
[分析]Sriram，K.和D.Montgomery，“AS_集和聚合器的测量数据：对{前缀，起源}验证算法的影响”，SIDR工作组报告，IETF 78，2010年7月，<www.antd.nist.gov/~ksriram/AS_集和聚合器统计数据.pdf>。
[RFC1930] Hawkinson, J. and T. Bates, "Guidelines for creation, selection, and registration of an Autonomous System (AS)", BCP 6, RFC 1930, March 1996.
[RFC1930]霍金森，J.和T.贝茨，“自主系统（AS）的创建、选择和注册指南”，BCP 6，RFC 1930，1996年3月。
[RFC3779] Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP Addresses and AS Identifiers", RFC 3779, June 2004.
[RFC3779]Lynn，C.，Kent，S.，和K.Seo，“IP地址和AS标识符的X.509扩展”，RFC 3779，2004年6月。
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4271]Rekhter，Y.，Ed.，Li，T.，Ed.，和S.Hares，Ed.，“边境网关协议4（BGP-4）”，RFC 42712006年1月。
[RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous System Confederations for BGP", RFC 5065, August 2007.
[RFC5065]Traina，P.，McPherson，D.，和J.Scudder，“BGP自治系统联合会”，RFC 5065，2007年8月。
Authors' Addresses
作者地址
Warren Kumari Google, Inc. 1600 Amphitheatre Parkway Mountain View, CA 94043 US
Warren Kumari Google，Inc.美国加利福尼亚州山景大道1600号圆形剧场，邮编94043
Phone: +1 571 748 4373
EMail: warren@kumari.net
Phone: +1 571 748 4373
EMail: warren@kumari.net
Kotikalapudi Sriram U.S. NIST 100 Bureau Drive Gaithersburg, MD 20899 US
Kotikalapudi Sriram美国国家标准与技术研究院美国马里兰州盖瑟斯堡100号局道20899
Phone: +1 301 975 3973
EMail: ksriram@nist.gov
Phone: +1 301 975 3973
EMail: ksriram@nist.gov