Internet Engineering Task Force (IETF) C. Pignataro
Request for Comments: 7884 Cisco
Category: Standards Track M. Bhatia
ISSN: 2070-1721 Ionos Networks
S. Aldrin
Huawei Technologies
T. Ranganath
Nokia
July 2016
Internet Engineering Task Force (IETF) C. Pignataro
Request for Comments: 7884 Cisco
Category: Standards Track M. Bhatia
ISSN: 2070-1721 Ionos Networks
S. Aldrin
Huawei Technologies
T. Ranganath
Nokia
July 2016
OSPF Extensions to Advertise Seamless Bidirectional Forwarding Detection (S-BFD) Target Discriminators
用于宣传无缝双向转发检测（S-BFD）目标鉴别器的OSPF扩展
Abstract
摘要
This document defines a new OSPF Router Information (RI) TLV that allows OSPF routers to flood the Seamless Bidirectional Forwarding Detection (S-BFD) Discriminator values associated with a target network identifier. This mechanism is applicable to both OSPFv2 and OSPFv3.
本文档定义了一个新的OSPF路由器信息（RI）TLV，该TLV允许OSPF路由器将无缝双向转发检测（S-BFD）鉴别器值与目标网络标识符关联。该机制适用于OSPFv2和OSPFv3。
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 7841.
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 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/rfc7884.
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/rfc7884.
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. Relationship between OSPF and S-BFD ........................3
2. Implementation ..................................................3
2.1. S-BFD Discriminator TLV ....................................4
2.2. Flooding Scope .............................................4
3. Backward Compatibility ..........................................5
4. Security Considerations .........................................5
5. IANA Considerations .............................................6
6. References ......................................................6
6.1. Normative References .......................................6
6.2. Informative References .....................................6
Acknowledgements ...................................................7
Authors' Addresses .................................................7
1. Introduction ....................................................3
1.1. Relationship between OSPF and S-BFD ........................3
2. Implementation ..................................................3
2.1. S-BFD Discriminator TLV ....................................4
2.2. Flooding Scope .............................................4
3. Backward Compatibility ..........................................5
4. Security Considerations .........................................5
5. IANA Considerations .............................................6
6. References ......................................................6
6.1. Normative References .......................................6
6.2. Informative References .....................................6
Acknowledgements ...................................................7
Authors' Addresses .................................................7
Seamless Bidirectional Forwarding Detection (S-BFD), specified in [RFC7880], is a simplified mechanism for using BFD with many negotiations eliminated. This is achieved by using 4-octet discriminators, unique within an administrative domain, to identify the network targets. These S-BFD Discriminators can be advertised by the IGPs, and this document concerns itself with OSPF. Specifically, this document defines a new TLV (named the S-BFD Discriminator TLV) to be carried within the OSPF Router Information (RI) Link State Advertisement (LSA) [RFC7770].
[RFC7880]中规定的无缝双向转发检测（S-BFD）是一种简化的机制，用于在消除许多协商的情况下使用BFD。这是通过使用管理域中唯一的4个八位组鉴别器来识别网络目标来实现的。这些S-BFD鉴别器可由IGPs发布，本文件涉及OSPF。具体而言，本文件定义了OSPF路由器信息（RI）链路状态公告（LSA）[RFC7770]中携带的新TLV（命名为S-BFD鉴别器TLV）。
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 RFC 2119 [RFC2119].
本文件中的关键词“必须”、“不得”、“要求”、“应”、“不应”、“应”、“不应”、“建议”、“可”和“可选”应按照RFC 2119[RFC2119]中所述进行解释。
This document implicitly defines a relationship between OSPF and S-BFD. S-BFD assigns one or more discriminators to each S-BFD reflector node. OSPF, in turn, learns about these from S-BFD and floods them in the newly defined TLV. After this information is flooded, it is stored in all the OSPF nodes such that S-BFD initiators can map out target nodes to target discriminators and can therefore construct the S-BFD probe.
本文档隐式定义了OSPF和S-BFD之间的关系。S-BFD为每个S-BFD反射器节点分配一个或多个鉴别器。反过来，OSPF从S-BFD处了解这些信息，并将其淹没在新定义的TLV中。在该信息被淹没后，它被存储在所有OSPF节点中，以便S-BFD启动器可以将目标节点映射到目标鉴别器，从而可以构造S-BFD探测器。
When multiple S-BFD Discriminators are advertised, how a given discriminator is mapped to a specific use case is out of scope for this document.
当发布多个S-BFD鉴别器时，给定鉴别器如何映射到特定用例超出了本文档的范围。
This extension makes use of the Router Information (RI) Opaque LSA, defined in [RFC7770], for both OSPFv2 [RFC2328] and OSPFv3 [RFC5340] by defining a new OSPF Router Information (RI) TLV: the S-BFD Discriminator TLV.
此扩展通过定义新的OSPF路由器信息（RI）TLV（S-BFD鉴别器TLV），为OSPFv2[RFC2328]和OSPFv3[RFC5340]使用[RFC7770]中定义的路由器信息（RI）不透明LSA。
The S-BFD Discriminator TLV is OPTIONAL. Upon receipt of the TLV, a router may decide to install the S-BFD Discriminator in the BFD target identifier table.
S-BFD鉴别器TLV是可选的。收到TLV后，路由器可决定在BFD目标标识符表中安装S-BFD鉴别器。
In the presence of multiple instances of the OSPFv2/OSPFv3 Router Information LSA, the S-BFD Discriminators for an OSPF router are the union of all discriminators advertised in all instances of the S-BFD Discriminator TLV (see Section 2.1) in all advertised non-MaxAge OSPF Router Information LSAs.
在存在OSPFv2/OSPFv3路由器信息LSA的多个实例的情况下，OSPF路由器的S-BFD鉴别器是在所有公布的非MaxAge OSPF路由器信息LSA中的S-BFD鉴别器TLV（见第2.1节）的所有实例中公布的所有鉴别器的联合。
The format of the S-BFD Discriminator TLV is as follows:
S-BFD鉴别器TLV的格式如下：
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator 2 (Optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator n (Optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator 2 (Optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator n (Optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type - S-BFD Discriminator TLV Type (11)
类型-S-BFD鉴别器TLV类型（11）
Length - This field represents the total length of the discriminator(s) that appears in the Value field, in octets. Each discriminator is 4 octets, so the Length is four times the number of discriminators included in the TLV. There is no optional padding for this field.
长度-此字段表示值字段中出现的鉴别器的总长度（以八位字节为单位）。每个鉴别器是4个八位字节，因此长度是TLV中包括的鉴别器数量的四倍。此字段没有可选的填充。
Discriminator(s) - The Value field of the TLV includes the S-BFD network target Discriminator value or values.
鉴别器-TLV的值字段包括s-BFD网络目标鉴别器值。
Routers that do not recognize the S-BFD Discriminator TLV Type will ignore the TLV [RFC7770] and therefore will not learn S-BFD Discriminators via OSPF.
不识别S-BFD鉴别器TLV类型的路由器将忽略TLV[RFC7770]，因此不会通过OSPF学习S-BFD鉴别器。
The S-BFD Discriminator TLV is advertised within OSPFv2 Router Information LSAs (Opaque type of 4 and Opaque ID of 0) or OSPFv3 Router Information LSAs (function code of 12), which are defined in [RFC7770]. As such, elements of this procedure are inherited from those defined in [RFC7770].
S-BFD鉴别器TLV在[RFC7770]中定义的OSPFv2路由器信息LSA（不透明类型为4，不透明ID为0）或OSPFv3路由器信息LSA（功能代码为12）中公布。因此，此过程的元素继承自[RFC7770]中定义的元素。
The flooding scope is controlled by the Opaque LSA type (as defined in [RFC5250]) in OSPFv2 and by the S1/S2 bits (as defined in [RFC5340]) in OSPFv3. If the flooding scope is area local, then the S-BFD Discriminator TLV MUST be carried within an OSPFv2 type 10 Router Information LSA or an OSPFV3 Router Information LSA with the S1 bit set and the S2 bit clear. If the flooding scope is the entire
泛洪范围由OSPFv2中的不透明LSA类型（定义见[RFC5250]）和OSPFv3中的S1/S2位（定义见[RFC5340]）控制。如果泛洪范围为区域本地，则S-BFD鉴别器TLV必须携带在设置了S1位且清除了S2位的OSPFv2类型10路由器信息LSA或OSPFV3路由器信息LSA内。如果泛洪范围是整个
IGP domain, then the S-BFD Discriminator TLV MUST be carried within an OSPFv2 type 11 Router Information LSA or OSPFv3 Router Information LSA with the S1 bit clear and the S2 bit set.
IGP域，则S-BFD鉴别器TLV必须携带在S1位清除且S2位设置的OSPFv2类型11路由器信息LSA或OSPFv3路由器信息LSA内。
When the S-BFD reflector is deactivated, the OSPF speaker advertising a particular S-BFD Discriminator MUST originate a new Router Information LSA that no longer includes the corresponding S-BFD Discriminator TLV, provided there are other TLVs in the LSA. If there are no other TLVs in the LSA, it MUST either send an empty Router Information LSA or purge it by prematurely aging it.
当S-BFD反射器被停用时，如果LSA中存在其他TLV，则播发特定S-BFD鉴别器的OSPF扬声器必须发起不再包括相应S-BFD鉴别器TLV的新路由器信息LSA。如果LSA中没有其他TLV，它必须向LSA发送一个空的路由器信息，或者通过提前老化将其清除。
For intra-area reachability, the S-BFD Discriminator TLV information regarding a specific target identifier is only considered current and usable when the router advertising that information is itself reachable via OSPF calculated paths in the same area of the LSA in which the S-BFD Discriminator TLV appears. In the case of domain-wide flooding, i.e., where the originator is sitting in a remote area, the mechanism described in Section 5 of [RFC5250] should be used.
对于区域内可达性，仅当路由器在出现S-BFD鉴别器TLV的LSA的同一区域中通过OSPF计算路径宣传该信息本身可到达时，才认为关于特定目标标识符的S-BFD鉴别器TLV信息是当前的和可用的。在域范围内泛洪的情况下，即发端人位于偏远地区，应使用[RFC5250]第5节中描述的机制。
Although the S-BFD Discriminators may change when enabling the S-BFD functionality or via an explicit configuration event, such changes are expected to occur very rarely. Such changes in information will require that the S-BFD Discriminator TLV in OSPF be advertised.
尽管在启用S-BFD功能或通过显式配置事件时，S-BFD鉴别器可能会发生变化，但此类变化预计很少发生。这种信息变化将要求公布OSPF中的S-BFD鉴别器TLV。
A change in information in the S-BFD Discriminator TLV MUST NOT trigger any SPF computations at a receiving router.
S-BFD鉴别器TLV中的信息变化不得触发接收路由器上的任何SPF计算。
The S-BFD Discriminator TLV defined in this document does not introduce any interoperability issues.
本文件中定义的S-BFD鉴别器TLV不会引入任何互操作性问题。
A router not supporting the S-BFD Discriminator TLV will just silently ignore the TLV, as specified in [RFC7770].
如[RFC7770]中所述，不支持S-BFD鉴别器TLV的路由器将自动忽略TLV。
This document defines OSPF extensions to distribute the S-BFD Discriminator within an administrative domain. Hence, the security of S-BFD Discriminator distribution relies on the security of OSPF.
本文档定义了OSPF扩展，以在管理域内分发S-BFD鉴别器。因此，S-BFD鉴别器分布的安全性依赖于OSPF的安全性。
OSPF provides no encryption mechanism for protecting the privacy of LSAs and, in particular, the privacy of the S-BFD Discriminator advertisement information. However, this is not a concern, as there isn't any need to hide the Discriminator value that can be used to reach the reflectors.
OSPF不提供加密机制来保护LSA的隐私，特别是S-BFD鉴别器广告信息的隐私。但是，这不是一个问题，因为不需要隐藏可用于到达反射器的鉴别器值。
IANA has defined a registry for TLVs carried in the Router Information LSA defined in [RFC7770]. IANA has assigned a new TLV codepoint (11) for the S-BFD Discriminator TLV in the "OSPF Router Information (RI) TLVs" registry.
IANA已经为[RFC7770]中定义的路由器信息LSA中携带的TLV定义了一个注册表。IANA在“OSPF路由器信息（RI）TLV”注册表中为S-BFD鉴别器TLV分配了一个新的TLV码点（11）。
Value TLV Name Reference
----- -------- ----------
11 S-BFD RFC 7884
Discriminator
Value TLV Name Reference
----- -------- ----------
11 S-BFD RFC 7884
Discriminator
[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>.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, DOI 10.17487/RFC2328, April 1998, <http://www.rfc-editor.org/info/rfc2328>.
[RFC2328]Moy，J.，“OSPF版本2”，STD 54，RFC 2328，DOI 10.17487/RFC2328，1998年4月<http://www.rfc-editor.org/info/rfc2328>.
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, <http://www.rfc-editor.org/info/rfc5340>.
[RFC5340]Coltun，R.，Ferguson，D.，Moy，J.，和A.Lindem，“IPv6的OSPF”，RFC 5340，DOI 10.17487/RFC5340，2008年7月<http://www.rfc-editor.org/info/rfc5340>.
[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and S. Shaffer, "Extensions to OSPF for Advertising Optional Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, February 2016, <http://www.rfc-editor.org/info/rfc7770>.
[RFC7770]Lindem，A.，Ed.，Shen，N.，Vasseur，JP.，Aggarwal，R.，和S.Shaffer，“用于宣传可选路由器功能的OSPF扩展”，RFC 7770，DOI 10.17487/RFC7770，2016年2月<http://www.rfc-editor.org/info/rfc7770>.
[RFC7880] Pignataro, C., Ward, D., Akiya, N., Bhatia, M., and S. Pallagatti, "Seamless Bidirectional Forwarding Detection (S-BFD)", RFC 7880, DOI 10.17487/RFC7880, July 2016, <http://www.rfc-editor.org/info/rfc7880>.
[RFC7880]Pignataro，C.，Ward，D.，Akiya，N.，Bhatia，M.，和S.Pallagati，“无缝双向转发检测（S-BFD）”，RFC 7880，DOI 10.17487/RFC78802016年7月<http://www.rfc-editor.org/info/rfc7880>.
[RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The OSPF Opaque LSA Option", RFC 5250, DOI 10.17487/RFC5250, July 2008, <http://www.rfc-editor.org/info/rfc5250>.
[RFC5250]Berger，L.，Bryskin，I.，Zinin，A.，和R.Coltun，“OSPF不透明LSA选项”，RFC 5250，DOI 10.17487/RFC5250，2008年7月<http://www.rfc-editor.org/info/rfc5250>.
Acknowledgements
致谢
The authors would like to thank Nobo Akiya, Les Ginsberg, Mach Chen, and Peter Psenak for insightful comments and useful suggestions.
作者要感谢Nobo Akiya、Les Ginsberg、Mach Chen和Peter Psenak的深刻评论和有用的建议。
Authors' Addresses
作者地址
Carlos Pignataro Cisco Systems, Inc.
卡洛斯·皮格纳塔罗思科系统公司。
Email: cpignata@cisco.com
Email: cpignata@cisco.com
Manav Bhatia Ionos Networks
Manav Bhatia Ionios网络
Email: manav@ionosnetworks.com
Email: manav@ionosnetworks.com
Sam Aldrin Huawei Technologies
山姆·奥尔德林华为技术有限公司
Email: aldrin.ietf@gmail.com
Email: aldrin.ietf@gmail.com
Trilok Ranganath Nokia
Trilok Ranganath诺基亚
Email: trilok.ranganatha@nokia.com
Email: trilok.ranganatha@nokia.com