Internet Engineering Task Force (IETF) L. Ginsberg
Request for Comments: 7356 S. Previdi
Category: Standards Track Y. Yang
ISSN: 2070-1721 Cisco Systems
September 2014
Internet Engineering Task Force (IETF) L. Ginsberg
Request for Comments: 7356 S. Previdi
Category: Standards Track Y. Yang
ISSN: 2070-1721 Cisco Systems
September 2014
IS-IS Flooding Scope Link State PDUs (LSPs)
IS-IS泛洪作用域链路状态PDU（LSP）
Abstract
摘要
Intermediate System to Intermediate System (IS-IS) provides efficient and reliable flooding of information to its peers; however, the current flooding scopes are limited to either area scope or domain scope. There are existing use cases where support of other flooding scopes is desirable. This document defines new Protocol Data Units (PDUs) that provide support for new flooding scopes as well as additional space for advertising information targeted for the currently supported flooding scopes. This document also defines extended Type-Length-Values (TLVs) and sub-TLVs that are encoded using 16-bit fields for Type and Length.
中间系统到中间系统（IS-IS）向其对等方提供高效可靠的信息洪流；但是，当前的泛洪范围仅限于区域范围或域范围。在现有的用例中，需要支持其他泛洪范围。本文档定义了新的协议数据单元（PDU），为新的泛洪作用域提供支持，并为针对当前支持的泛洪作用域的广告信息提供额外空间。本文档还定义了使用16位类型和长度字段编码的扩展类型长度值（TLV）和子TLV。
The protocol extensions defined in this document are not backwards compatible with existing implementations and so must be deployed with care.
本文档中定义的协议扩展与现有实现不向后兼容，因此必须小心部署。
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/rfc7356.
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/rfc7356.
Copyright Notice
版权公告
Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2014 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。
This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English.
本文件可能包含2008年11月10日之前发布或公开的IETF文件或IETF贡献中的材料。控制某些材料版权的人员可能未授予IETF信托允许在IETF标准流程之外修改此类材料的权利。在未从控制此类材料版权的人员处获得充分许可的情况下，不得在IETF标准流程之外修改本文件，也不得在IETF标准流程之外创建其衍生作品，除了将其格式化以RFC形式发布或将其翻译成英语以外的其他语言。
Table of Contents
目录
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. Extended TLVs . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Use of Extended TLVs and Extended Sub-TLVs . . . . . . . 5
2.2. Use of Standard Code Points in Extended TLVs and Extended
Sub-TLVs . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Definition of New PDUs . . . . . . . . . . . . . . . . . . . 6
3.1. Flooding Scoped LSP Format . . . . . . . . . . . . . . . 7
3.2. Flooding Scoped CSNP Format . . . . . . . . . . . . . . . 10
3.3. Flooding Scope PSNP Format . . . . . . . . . . . . . . . 12
4. Flooding Scope Update Process Operation . . . . . . . . . . . 13
4.1. Scope Types . . . . . . . . . . . . . . . . . . . . . . . 14
4.2. Operation on Point-to-Point Circuits . . . . . . . . . . 14
4.3. Operation on Broadcast Circuits . . . . . . . . . . . . . 14
4.4. Use of Authentication . . . . . . . . . . . . . . . . . . 15
4.5. Priority Flooding . . . . . . . . . . . . . . . . . . . . 15
5. Deployment Considerations . . . . . . . . . . . . . . . . . . 15
6. Graceful Restart Interactions . . . . . . . . . . . . . . . . 16
7. Multi-instance Interactions . . . . . . . . . . . . . . . . . 16
8. Circuit Scope Flooding . . . . . . . . . . . . . . . . . . . 16
9. Extending LSP Set Capacity . . . . . . . . . . . . . . . . . 17
10. Domain Scope Flooding . . . . . . . . . . . . . . . . . . . . 18
11. Announcing Support for Flooding Scopes . . . . . . . . . . . 19
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
13. Security Considerations . . . . . . . . . . . . . . . . . . . 21
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
15.1. Normative References . . . . . . . . . . . . . . . . . . 21
15.2. Informative References . . . . . . . . . . . . . . . . . 22
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. Extended TLVs . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Use of Extended TLVs and Extended Sub-TLVs . . . . . . . 5
2.2. Use of Standard Code Points in Extended TLVs and Extended
Sub-TLVs . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Definition of New PDUs . . . . . . . . . . . . . . . . . . . 6
3.1. Flooding Scoped LSP Format . . . . . . . . . . . . . . . 7
3.2. Flooding Scoped CSNP Format . . . . . . . . . . . . . . . 10
3.3. Flooding Scope PSNP Format . . . . . . . . . . . . . . . 12
4. Flooding Scope Update Process Operation . . . . . . . . . . . 13
4.1. Scope Types . . . . . . . . . . . . . . . . . . . . . . . 14
4.2. Operation on Point-to-Point Circuits . . . . . . . . . . 14
4.3. Operation on Broadcast Circuits . . . . . . . . . . . . . 14
4.4. Use of Authentication . . . . . . . . . . . . . . . . . . 15
4.5. Priority Flooding . . . . . . . . . . . . . . . . . . . . 15
5. Deployment Considerations . . . . . . . . . . . . . . . . . . 15
6. Graceful Restart Interactions . . . . . . . . . . . . . . . . 16
7. Multi-instance Interactions . . . . . . . . . . . . . . . . . 16
8. Circuit Scope Flooding . . . . . . . . . . . . . . . . . . . 16
9. Extending LSP Set Capacity . . . . . . . . . . . . . . . . . 17
10. Domain Scope Flooding . . . . . . . . . . . . . . . . . . . . 18
11. Announcing Support for Flooding Scopes . . . . . . . . . . . 19
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
13. Security Considerations . . . . . . . . . . . . . . . . . . . 21
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
15.1. Normative References . . . . . . . . . . . . . . . . . . 21
15.2. Informative References . . . . . . . . . . . . . . . . . 22
The Update Process, as defined by [IS-IS], provides reliable and efficient flooding of information to all routers in a given flooding scope. Currently, the protocol supports two flooding scopes and associated PDUs. Level 1 (L1) Link State PDUs (LSPs) are flooded to all routers in an area. Level 2 (L2) LSPs are flooded to all routers in the Level 2 subdomain. The basic operation of the Update Process can be applied to any subset of the routers in a given topology so long as that topology is not partitioned. It is, therefore, possible to introduce new PDUs in support of other flooding scopes and utilize the same Update Process machinery to provide the same reliability and efficiency that the Update Process currently provides for L1 and L2 scopes. This document defines these new PDUs and the modified Update Process rules that are to be used in supporting new flooding scopes.
[IS-IS]定义的更新过程为给定泛洪范围内的所有路由器提供可靠、高效的信息泛洪。目前，该协议支持两个泛洪作用域和相关PDU。1级（L1）链路状态PDU（LSP）被淹没到一个区域中的所有路由器。2级（L2）LSP被淹没到2级子域中的所有路由器。更新过程的基本操作可以应用于给定拓扑中的任何路由器子集，只要该拓扑未分区。因此，有可能引入新的PDU来支持其他泛洪范围，并利用相同的更新过程机制来提供更新过程当前为L1和L2范围提供的相同可靠性和效率。本文档定义了这些新的PDU和修改后的更新过程规则，这些规则将用于支持新的泛洪范围。
New deployment cases have introduced the need for reliable and efficient circuit scope flooding. For example, Appointed Forwarder information, as defined in [RFC7176], needs to be flooded reliably and efficiently to all Routing Bridges (RBridges) on a broadcast circuit. Currently, only IS-IS Hellos (IIHs) have the matching scope -- but IIHs are unreliable, i.e., individual IIHs may be lost without affecting correct operation of the protocol. To provide reliability in cases where the set of information to be flooded exceeds the carrying capacity of a single PDU requires sending the information periodically even when no changes in the content have occurred. When the information content is large, this is inefficient and still does not provide a guarantee of reliability. This document defines circuit scope flooding in order to provide a solution for such cases.
新的部署案例引入了可靠和高效电路范围泛洪的需求。例如，[RFC7176]中定义的指定转发器信息需要可靠且有效地淹没到广播电路上的所有路由桥（RBridge）。目前，只有IS-IS Hellos（IIHs）具有匹配作用域，但IIHs不可靠，即单个IIH可能丢失，而不会影响协议的正确操作。要在待淹没的信息集超过单个PDU的承载能力的情况下提供可靠性，即使内容没有发生变化，也需要定期发送信息。当信息内容较大时，这是低效的，并且仍然不能保证可靠性。本文件定义了电路范围泛洪，以便为此类情况提供解决方案。
Another existing limitation of [IS-IS] is the carrying capacity of an LSP set. It has been noted in [RFC5311] that the set of LSPs that may be originated by a system at each level is limited to 256 LSPs, and the maximum size of each LSP is limited by the minimum Maximum Transmission Unit (MTU) of any link used to flood LSPs. [RFC5311] has defined a backwards-compatible protocol extension that can be used to overcome this limitation if needed. While the [RFC5311] solution is viable, in order to be interoperable with routers that do not support the extension, it imposes some restrictions on what can/ cannot be advertised in the Extended LSPs and requires allocation of multiple unique system IDs to a given router. A more flexible and less constraining solution is possible if interoperability with legacy routers is not a requirement. By definition, the introduction of new PDUs required to support new flooding scopes is not interoperable with legacy routers. It is, therefore, possible to simultaneously introduce an alternative solution to the limited LSP set carrying capacity of Level 1 and Level 2 LSPs as part of the extensions defined in this document. This capability is also defined in this document.
[IS-IS]的另一个现有限制是LSP集的承载能力。在[RFC5311]中已经注意到，系统在每一级发起的LSP集被限制为256个LSP，并且每个LSP的最大大小被用于泛洪LSP的任何链路的最小-最大传输单元（MTU）限制。[RFC5311]定义了向后兼容的协议扩展，如果需要，可用于克服此限制。虽然[RFC5311]解决方案是可行的，但为了与不支持扩展的路由器互操作，它对扩展LSP中可以/不能公布的内容施加了一些限制，并要求为给定路由器分配多个唯一的系统ID。如果不需要与传统路由器的互操作性，则可以使用更灵活、约束更少的解决方案。根据定义，引入支持新泛洪作用域所需的新PDU不能与传统路由器互操作。因此，作为本文件中定义的扩展的一部分，可以同时为1级和2级LSP的有限LSP集承载能力引入替代解决方案。此功能也在本文档中定义。
Standard IS-IS TLVs are encoded using an 8-bit type and an 8-bit length. In cases where the set of information about a single object exceeds 255 octets, multiple TLVs are required to encode all of the relevant information. This document introduces extended TLVs and extended sub-TLVs that use a 16-bit Type field and a 16-bit Length field.
标准IS-IS TLV使用8位类型和8位长度进行编码。如果单个对象的信息集超过255个八位字节，则需要多个TLV对所有相关信息进行编码。本文档介绍使用16位类型字段和16位长度字段的扩展TLV和扩展子TLV。
The PDU Type field in the common header for all IS-IS PDUs is a 5-bit field. Therefore, possible PDU types supported by the protocol are limited to a maximum of 32. In order to minimize the need to introduce additional PDU types in the future, the new PDUs introduced in this document are defined so as to allow multiple flooding scopes to be associated with the same PDU type. This means if new flooding scopes are required in the future, the same PDU type can be used.
所有IS-IS PDU的公共标头中的PDU类型字段为5位字段。因此，协议支持的可能PDU类型最多限制为32种。为了尽量减少将来引入其他PDU类型的需要，本文档中引入的新PDU被定义为允许多个泛洪作用域与同一PDU类型相关联。这意味着如果将来需要新的泛洪作用域，可以使用相同的PDU类型。
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。
Standard TLVs as defined in [IS-IS] as well as standard sub-TLVs (first introduced in [RFC5305]) have an 8-bit Type field and an eight-bit Length field. This constrains the information included in a single TLV or sub-TLV to 255 octets. With the increasing use of sub-TLVs, it becomes more likely that the amount of information about a single object that needs to be advertised may exceed 255 octets. In such cases, the information is encoded in multiple TLVs. This leads to less efficient encoding since the information that uniquely identifies the object must be repeated in each TLV and requires additional implementation complexity when receiving the information to ensure that all information about the object is correctly collected from the multiple TLVs.
[IS-IS]中定义的标准TLV以及标准子TLV（首次引入[RFC5305]）具有8位类型字段和8位长度字段。这将单个TLV或子TLV中包含的信息限制为255个八位字节。随着子TLV使用的增加，需要公布的单个对象的信息量可能超过255个八位字节。在这种情况下，信息被编码在多个TLV中。这导致编码效率较低，因为唯一标识对象的信息必须在每个TLV中重复，并且在接收信息时需要额外的实现复杂性，以确保正确地从多个TLV收集有关对象的所有信息。
This document introduces extended TLVs and extended sub-TLVs. These are encoded using a 16-bit Type field and a 16-bit Length field.
本文档介绍了扩展TLV和扩展子TLV。它们使用16位类型字段和16位长度字段进行编码。
The following restrictions apply to the use of extended TLVs and extended sub-TLVs:
以下限制适用于扩展TLV和扩展子TLV的使用：
o Extended TLVs and extended sub-TLVs are permitted only in Flooding Scope PDUs that have a flooding scope designated for their use (defined later in this document)
o 扩展TLV和扩展子TLV仅允许在泛洪范围PDU中使用，该PDU具有指定的泛洪范围（本文件稍后定义）
o A given flooding scope supports either the use of standard TLVs and standard sub-TLVs or the use of extended TLVs and extended sub-TLVs, but not both
o 给定的泛洪范围既支持使用标准TLV和标准子TLV，也支持使用扩展TLV和扩展子TLV，但不能同时支持两者
o Extended TLVs and extended sub-TLVs MUST be used together, i.e., using Standard sub-TLVs within an Extended TLV or using Extended sub-TLVs within a Standard TLV is invalid
o 扩展TLV和扩展子TLV必须一起使用，即在扩展TLV内使用标准子TLV或在标准TLV内使用扩展子TLV无效
o If additional levels of TLVs (e.g., sub-sub-TLVs) are introduced in the future, then the size of the Type and Length fields in these new sub-types MUST match the size used in the parent
o 如果将来引入其他级别的TLV（例如子TLV），则这些新子类型中的类型和长度字段的大小必须与父类型中使用的大小匹配
o The 16-bit Type and Length fields are encoded in network byte order
o 16位类型和长度字段按网络字节顺序编码
o Use of extended TLVs and extended sub-TLVs does not alter in any way the maximum size of PDUs that may sent or received
o 使用扩展TLV和扩展子TLV不会以任何方式改变可能发送或接收的PDU的最大大小
Standard TLV and standard sub-TLV code points as defined in the IANA "IS-IS TLV Codepoints" registry MAY be used in extended TLVs and extended sub-TLVs. Encoding is as specified for each of the standard TLVs and standard sub-TLVs with the following differences:
IANA“IS-IS TLV代码点”注册表中定义的标准TLV和标准子TLV代码点可用于扩展TLV和扩展子TLV。编码是为每个标准TLV和标准子TLV指定的，具有以下差异：
o The 8-bit Type field is encoded as an unsigned 16-bit integer where the 8 most significant bits (MSBs) are all 0
o 8位类型字段编码为无符号16位整数，其中8个最高有效位（MSB）均为0
o The 8-bit Length field is replaced by the 16-bit Length field
o 8位长度字段替换为16位长度字段
o The length MAY take on values greater than 255
o 长度值可能大于255
In support of new flooding scopes, the following new PDUs are required:
为支持新的泛洪范围，需要以下新PDU：
o Flooding Scope LSPs (FS-LSPs)
o 泛洪范围LSP（FS LSP）
o Flooding Scope Complete Sequence Number PDUs (FS-CSNPs)
o 泛洪范围完整序列号PDU（FS CSNPs）
o Flooding Scope Partial Sequence Number PDUs (FS-PSNPs)
o 泛洪范围部分序列号PDU（FS PSNPs）
Each of these PDUs is intentionally defined with a header as similar in format as possible to the corresponding PDU types currently defined in [IS-IS]. Although it might have been possible to eliminate or redefine PDU header fields in a new way, the existing formats are retained in order to allow maximum reuse of existing PDU processing logic in an implementation.
这些PDU中的每一个都有意定义一个标题，其格式尽可能与[is-is]中当前定义的相应PDU类型相似。虽然可以以新的方式消除或重新定义PDU头字段，但保留现有格式是为了在实现中最大限度地重用现有PDU处理逻辑。
Note that in the case of all FS PDUs, the Maximum Area Addresses field in the header of the corresponding standard PDU has been replaced with a Scope field. Therefore, maximum area addresses checks specified in [IS-IS] are not performed on FS PDUs.
请注意，对于所有FS PDU，相应标准PDU标头中的最大区域地址字段已替换为范围字段。因此，[IS-IS]中指定的最大区域地址检查不会在FS PDU上执行。
An FS-LSP has the following format:
FS-LSP具有以下格式：
No. of octets
+-------------------------+
| Intradomain Routeing | 1
| Protocol Discriminator |
+-------------------------+
| Length Indicator | 1
+-------------------------+
| Version/Protocol ID | 1
| Extension |
+-------------------------+
| ID Length | 1
+-------------------------+
|R|R|R| PDU Type | 1
+-------------------------+
| Version | 1
+-------------------------+
| Reserved | 1
+-------------------------+
|P| Scope | 1
+-------------------------+
| PDU Length | 2
+-------------------------+
| Remaining Lifetime | 2
+-------------------------+
| FS LSP ID | ID Length + 2
+-------------------------+
| Sequence Number | 4
+-------------------------+
| Checksum | 2
+-------------------------+
|Reserved|LSPDBOL|IS Type | 1
+-------------------------+
: Variable-Length Fields : Variable
+-------------------------+
No. of octets
+-------------------------+
| Intradomain Routeing | 1
| Protocol Discriminator |
+-------------------------+
| Length Indicator | 1
+-------------------------+
| Version/Protocol ID | 1
| Extension |
+-------------------------+
| ID Length | 1
+-------------------------+
|R|R|R| PDU Type | 1
+-------------------------+
| Version | 1
+-------------------------+
| Reserved | 1
+-------------------------+
|P| Scope | 1
+-------------------------+
| PDU Length | 2
+-------------------------+
| Remaining Lifetime | 2
+-------------------------+
| FS LSP ID | ID Length + 2
+-------------------------+
| Sequence Number | 4
+-------------------------+
| Checksum | 2
+-------------------------+
|Reserved|LSPDBOL|IS Type | 1
+-------------------------+
: Variable-Length Fields : Variable
+-------------------------+
Intradomain Routeing Protocol Discriminator: 0x83 (as defined in [IS-IS]).
域内路由协议鉴别器：0x83（定义见[IS-IS]）。
Length Indicator: Length of the fixed header in octets.
长度指示器：以八位字节为单位的固定标头的长度。
Version/Protocol ID Extension: 1
版本/协议ID扩展：1
ID Length: As defined in [IS-IS].
ID长度：如[IS-IS]中所定义。
PDU Type: 10 - Format as defined in [IS-IS].
PDU类型：10-格式如[IS-IS]中所定义。
Version: 1
版本:1
Reserved: Transmitted as zero, ignored on receipt.
保留：传输为零，接收时忽略。
Scope: Bits 1-7 define the flooding scope.
范围：位1-7定义泛洪范围。
The value 0 is reserved and MUST NOT be used. Received FS-LSPs with a scope of 0 MUST be ignored and MUST NOT be flooded.
值0是保留的，不能使用。必须忽略接收到的作用域为0的FS LSP，并且不能将其淹没。
P: Bit 8 - Priority Bit. If set to 1, this LSP SHOULD be flooded at high priority.
P：位8-优先级位。如果设置为1，此LSP应以高优先级被淹没。
Scopes (1 - 63) are reserved for use with standard TLVs and standard sub-TLVs.
范围（1-63）保留用于标准TLV和标准子TLV。
Scopes (64 - 127) are reserved for use with extended TLVs and extended sub-TLVs.
作用域（64-127）保留用于扩展TLV和扩展子TLV。
PDU Length: Entire length of this PDU, in octets, including the header.
PDU长度：此PDU的整个长度，以八位字节为单位，包括标头。
Remaining Lifetime: Number of seconds before this FS-LSP is considered expired.
剩余寿命：此FS-LSP被视为过期之前的秒数。
FS LSP ID: The system ID of the source of the FS-LSP. One of the following two formats is used:
FS LSP ID：FS-LSP源的系统ID。使用以下两种格式之一：
FS LSP ID Standard Format
FS LSP ID标准格式
+-------------------------+
| Source ID | ID Length
+-------------------------+
| Pseudonode ID | 1
+-------------------------+
| FS LSP Number | 1
+-------------------------+
+-------------------------+
| Source ID | ID Length
+-------------------------+
| Pseudonode ID | 1
+-------------------------+
| FS LSP Number | 1
+-------------------------+
FS LSP ID Extended Format
FS LSP ID扩展格式
+-------------------------+
| Source ID | ID Length
+-------------------------+
| Extended FS LSP Number | 2
+-------------------------+
+-------------------------+
| Source ID | ID Length
+-------------------------+
| Extended FS LSP Number | 2
+-------------------------+
Which format is used is specific to the scope and MUST be defined when the specific flooding scope is defined.
使用哪种格式是特定于范围的，并且必须在定义特定泛洪范围时定义。
Sequence Number: Sequence number of this FS-LSP.
序号：此FS-LSP的序号。
Checksum: Checksum of contents of FS-LSP from the Source ID to the end. Checksum is computed as defined in [IS-IS].
校验和：FS-LSP内容从源ID到结尾的校验和。校验和按照[is-is]中的定义计算。
Reserved/LSPDBOL/IS Type
保留/LSPDBOL/IS类型
Bits 4-8 are reserved, which means they are transmitted as 0 and ignored on receipt.
位4-8是保留的，这意味着它们作为0传输，在接收时被忽略。
LSPDBOL: Bit 3 - A value of 0 indicates no FS-LSP Database Overload and a value of 1 indicates that the FS-LSP Database is overloaded. The overload condition is specific to FS-LSPs with the scope specified in the Scope field.
LSPDBOL:位3-值0表示没有FS-LSP数据库过载，值1表示FS-LSP数据库过载。重载条件特定于在范围字段中指定范围的FS LSP。
IS Type: Bits 1 and 2. The type of Intermediate System as defined in [IS-IS].
IS类型：第1位和第2位。[IS-IS]中定义的中间系统类型。
Variable-length fields that are allowed in an FS-LSP are specific to the defined scope.
FS-LSP中允许的可变长度字段特定于定义的范围。
An FS-CSNP has the following format:
FS-CSNP具有以下格式：
No. of octets
+-------------------------+
| Intradomain Routeing | 1
| Protocol Discriminator |
+-------------------------+
| Length Indicator | 1
+-------------------------+
| Version/Protocol ID | 1
| Extension |
+-------------------------+
| ID Length | 1
+-------------------------+
|R|R|R| PDU Type | 1
+-------------------------+
| Version | 1
+-------------------------+
| Reserved | 1
+-------------------------+
|R| Scope | 1
+-------------------------+
| PDU Length | 2
+-------------------------+
| Source ID | ID Length + 1
+-------------------------+
| Start FS-LSP ID | ID Length + 2
+-------------------------+
| End FS-LSP ID | ID Length + 2
+-------------------------+
: Variable-Length Fields : Variable
+-------------------------+
No. of octets
+-------------------------+
| Intradomain Routeing | 1
| Protocol Discriminator |
+-------------------------+
| Length Indicator | 1
+-------------------------+
| Version/Protocol ID | 1
| Extension |
+-------------------------+
| ID Length | 1
+-------------------------+
|R|R|R| PDU Type | 1
+-------------------------+
| Version | 1
+-------------------------+
| Reserved | 1
+-------------------------+
|R| Scope | 1
+-------------------------+
| PDU Length | 2
+-------------------------+
| Source ID | ID Length + 1
+-------------------------+
| Start FS-LSP ID | ID Length + 2
+-------------------------+
| End FS-LSP ID | ID Length + 2
+-------------------------+
: Variable-Length Fields : Variable
+-------------------------+
Intradomain Routeing Protocol Discriminator: 0x83 (as defined in [IS-IS]).
域内路由协议鉴别器：0x83（定义见[IS-IS]）。
Length Indicator: Length of the fixed header in octets.
长度指示器：以八位字节为单位的固定标头的长度。
Version/Protocol ID Extension: 1
版本/协议ID扩展：1
ID Length: As defined in [IS-IS].
ID长度：如[IS-IS]中所定义。
PDU Type: 11 - Format as defined in [IS-IS].
PDU类型：11-格式如[IS-IS]中所定义。
Version: 1
版本:1
Reserved: Transmitted as zero, ignored on receipt.
保留：传输为零，接收时忽略。
Scope: Bits 1-7 define the flooding scope.
范围：位1-7定义泛洪范围。
The value 0 is reserved and MUST NOT be used. Received FS-CSNPs with a scope of 0 MUST be ignored.
值0是保留的，不能使用。必须忽略收到的作用域为0的FS CSNPs。
Bit 8 is Reserved, which means it is transmitted as 0 and ignored on receipt.
位8是保留的，这意味着它作为0传输，并在接收时被忽略。
Scopes (1 - 63) are reserved for use with standard TLVs and standard sub-TLVs.
范围（1-63）保留用于标准TLV和标准子TLV。
Scopes (64 - 127) are reserved for use with extended TLV and extended sub-TLVs.
作用域（64-127）保留用于扩展TLV和扩展子TLV。
PDU Length: Entire length of this PDU, in octets, including the header.
PDU长度：此PDU的整个长度，以八位字节为单位，包括标头。
Source ID: The system ID of the Intermediate System (with zero Circuit ID) generating this Sequence Number's PDU.
源ID：生成此序列号的PDU的中间系统的系统ID（电路ID为零）。
Start FS-LSP ID: The FS-LSP ID of the first FS-LSP with the specified scope in the range covered by this FS-CSNP.
Start FS-LSP ID：此FS-CSNP覆盖范围内具有指定范围的第一个FS-LSP的FS-LSP ID。
End FS-LSP ID: The FS-LSP ID of the last FS-LSP with the specified scope in the range covered by this FS-CSNP.
End FS-LSP ID：此FS-CSNP覆盖范围内指定范围的最后一个FS-LSP的FS-LSP ID。
Variable-length fields that are allowed in an FS-CSNP are limited to those TLVs that are supported by standard CSNP.
FS-CSNP中允许的可变长度字段仅限于标准CSNP支持的TLV。
An FS-PSNP has the following format:
FS-PSNP具有以下格式：
No. of octets
+-------------------------+
| Intradomain Routeing | 1
| Protocol Discriminator |
+-------------------------+
| Length Indicator | 1
+-------------------------+
| Version/Protocol ID | 1
| Extension |
+-------------------------+
| ID Length | 1
+-------------------------+
|R|R|R| PDU Type | 1
+-------------------------+
| Version | 1
+-------------------------+
| Reserved | 1
+-------------------------+
|U| Scope | 1
+-------------------------+
| PDU Length | 2
+-------------------------+
| Source ID | ID Length + 1
+-------------------------+
: Variable-Length Fields : Variable
+-------------------------+
No. of octets
+-------------------------+
| Intradomain Routeing | 1
| Protocol Discriminator |
+-------------------------+
| Length Indicator | 1
+-------------------------+
| Version/Protocol ID | 1
| Extension |
+-------------------------+
| ID Length | 1
+-------------------------+
|R|R|R| PDU Type | 1
+-------------------------+
| Version | 1
+-------------------------+
| Reserved | 1
+-------------------------+
|U| Scope | 1
+-------------------------+
| PDU Length | 2
+-------------------------+
| Source ID | ID Length + 1
+-------------------------+
: Variable-Length Fields : Variable
+-------------------------+
Intradomain Routeing Protocol Discriminator: 0x83 (as defined in [IS-IS]).
域内路由协议鉴别器：0x83（定义见[IS-IS]）。
Length Indicator: Length of the fixed header in octets.
长度指示器：以八位字节为单位的固定标头的长度。
Version/Protocol ID Extension: 1
版本/协议ID扩展：1
ID Length: As defined in [IS-IS].
ID长度：如[IS-IS]中所定义。
PDU Type: 12 - Format as defined in [IS-IS].
PDU类型：12-格式如[IS-IS]中所定义。
Version: 1
版本:1
Reserved: Transmitted as zero, ignored on receipt.
保留：传输为零，接收时忽略。
Scope: Bits 1-7 define the flooding scope.
范围：位1-7定义泛洪范围。
The value 0 is reserved and MUST NOT be used. Received FS-PSNPs with a scope of 0 MUST be ignored.
值0是保留的，不能使用。必须忽略收到的作用域为0的FS PSNPs。
U: Bit 8 - A value of 0 indicates that the specified flooding scope is supported. A value of 1 indicates that the specified flooding scope is unsupported. When U = 1, variable-length fields other than authentication MUST NOT be included in the PDU.
U:位8-值为0表示支持指定的泛洪范围。值1表示不支持指定的泛洪作用域。当U=1时，PDU中不得包含除身份验证以外的可变长度字段。
Scopes (1 - 63) are reserved for use with standard TLVs and standard sub-TLVs.
范围（1-63）保留用于标准TLV和标准子TLV。
Scopes (64 - 127) are reserved for use with extended TLVs and extended sub-TLVs.
作用域（64-127）保留用于扩展TLV和扩展子TLV。
PDU Length: Entire length of this PDU, in octets, including the header.
PDU长度：此PDU的整个长度，以八位字节为单位，包括标头。
Source ID: The system ID of the Intermediate System (with zero Circuit ID) generating this Sequence Number's PDU.
源ID：生成此序列号的PDU的中间系统的系统ID（电路ID为零）。
Variable-length fields that are allowed in an FS-PSNP are limited to those TLVs that are supported by standard PSNPs.
FS-PSNP中允许的可变长度字段仅限于标准PSNP支持的TLV。
The Update Process, as defined in [IS-IS], maintains a Link State Database (LSDB) for each level supported. Each level-specific LSDB contains the full set of LSPs generated by all routers operating in that level-specific scope. The introduction of FS-LSPs creates additional LSDBs (FS-LSDBs) for each additional scope supported. The set of FS-LSPs in each FS-LSDB consists of all FS-LSPs generated by all routers operating in that scope. Therefore, there is an additional instance of the Update Process for each supported flooding scope.
[IS-IS]中定义的更新过程为支持的每个级别维护一个链路状态数据库（LSDB）。每个特定于级别的LSDB包含由在该特定于级别的范围内运行的所有路由器生成的完整LSP集。FS LSP的引入为每个支持的附加作用域创建了附加的LSDB（FS LSDB）。每个FS-LSDB中的FS LSP集由在该范围内运行的所有路由器生成的所有FS LSP组成。因此，每个受支持的泛洪作用域都有一个更新过程的附加实例。
Operation of the scope-specific Update Process follows the Update Process specification in [IS-IS]. The circuit(s) on which FS-LSPs are flooded is limited to those circuits that are participating in the given scope. Similarly, the sending/receiving of FS-CSNPs and FS-PSNPs is limited to the circuits participating in the given scope.
范围特定更新过程的操作遵循[IS-IS]中的更新过程规范。FS LSP被淹没的电路仅限于参与给定范围的电路。类似地，FS-csnp和FS-psnp的发送/接收仅限于参与给定范围的电路。
Consistent support of a given flooding scope on a circuit by all routers operating on that circuit is required.
需要在一条电路上运行的所有路由器对该电路上给定泛洪范围的一致支持。
A flooding scope may be limited to a single circuit (circuit scope). Circuit scopes may be further limited by level (L1 Circuit Scope / L2 Circuit Scope).
泛洪范围可能仅限于单个回路（回路范围）。电路范围可能进一步受到级别（L1电路范围/L2电路范围）的限制。
A flooding scope may be limited to all circuits enabled for L1 routing (area scope).
泛洪范围可能限制为L1路由启用的所有电路（区域范围）。
A flooding scope may be limited to all circuits enabled for L2 routing (L2 subdomain scope).
泛洪作用域可能限于为L2路由启用的所有电路（L2子域作用域）。
Additional scopes may be defined that include all circuits enabled for either L1 or L2 routing (domain scope).
可以定义其他范围，包括为L1或L2路由启用的所有电路（域范围）。
When a new adjacency is formed, synchronization of all FS-LSDBs supported on that circuit is required; therefore, FS-CSNPs for all supported scopes MUST be sent when a new adjacency reaches the UP state. The Send Receive Message (SRM) bit MUST be set for all FS-LSPs associated with the scopes supported on that circuit. Receipt of an FS-PSNP with the U bit equal to 1 indicates that the neighbor does not support that scope (although it does support FS PDUs). This MUST cause the SRM bit to be cleared for all FS-LSPs with the matching scope, which are currently marked for flooding on that circuit.
当形成新的邻接时，需要同步该电路上支持的所有FS lsdb；因此，当新邻接达到UP状态时，必须发送所有受支持作用域的FS CSNPs。必须为与该电路上支持的作用域关联的所有FS LSP设置发送接收消息（SRM）位。接收到U位等于1的FS-PSNP表示邻居不支持该作用域（尽管它确实支持FS PDU）。这必须导致具有匹配作用域的所有FS LSP的SRM位被清除，当前在该电路上标记为泛洪。
FS PDUs are sent to the same destination address(es) as standard PDUs for the given protocol instance. For specification of the defined destination addresses, consult [IS-IS], [IEEEaq], [RFC6822], and [RFC6325].
FS PDU被发送到与给定协议实例的标准PDU相同的目标地址。有关定义的目标地址的规范，请参阅[IS-IS]、[IEEEaq]、[RFC6822]和[RFC6325]。
The Designated Intermediate System (DIS) for a broadcast circuit has the responsibility to generate periodic scope-specific FS-CSNPs for all supported scopes. A scope-specific DIS is NOT elected as all routers on a circuit MUST support a consistent set of flooding scopes.
广播电路的指定中间系统（DIS）负责为所有受支持的作用域生成周期性的特定于作用域的FS CSNP。由于电路上的所有路由器都必须支持一组一致的泛洪作用域，因此不能选择特定于作用域的DI。
It is possible that a scope may be defined that is not level specific. In such a case, the DIS for each level enabled on a broadcast circuit MUST independently send FS PDUs for that scope to the appropriate level-specific destination address. This may result in redundant flooding of FS-LSPs for that scope.
可能定义的范围不是特定于级别的。在这种情况下，广播电路上启用的每个级别的DIS必须独立地将该作用域的FS PDU发送到适当的特定级别目标地址。这可能会导致该范围内FS LSP的冗余泛洪。
Authentication TLVs MAY be included in FS PDUs. When authentication is in use, the scope is first used to select the authentication configuration that is applicable. The authentication check is then performed as normal. Although scope-specific authentication MAY be used, sharing of authentication among multiple scopes and/or with the standard LSPs/CSNPs/PSNPs is considered sufficient.
验证TLV可能包含在FS PDU中。使用身份验证时，首先使用作用域选择适用的身份验证配置。然后，将正常执行身份验证检查。尽管可以使用范围特定的身份验证，但在多个范围之间和/或与标准LSP/CSNPs/PSNPs共享身份验证被认为是足够的。
When the FS LSP ID Extended format is used, the set of LSPs generated by an IS may be quite large. It may be useful to identify those LSPs in the set that contain information of higher priority. Such LSPs will have the P bit set to 1 in the Scope field in the LSP header. Such LSPs SHOULD be flooded at a higher priority than LSPs with the P bit set to 0. This is a suggested behavior on the part of the originator of the LSP. When an LSP is purged, the original state of the P bit MUST be preserved.
使用FS LSP ID扩展格式时，is生成的LSP集可能相当大。识别集合中包含更高优先级信息的那些lsp可能是有用的。此类LSP将在LSP标头的范围字段中将P位设置为1。此类LSP应以比P位设置为0的LSP更高的优先级被淹没。这是LSP发起人的建议行为。清除LSP时，必须保留P位的原始状态。
Introduction of new PDU types is incompatible with legacy implementations. Legacy implementations do not support the FS-specific Update process(es) and, therefore, flooding of the FS-LSPs throughout the defined scope is unreliable when not all routers in the defined scope support FS PDUs. Further, legacy implementations will likely treat the reception of an FS PDU as an error. Even when all routers in a given scope support FS PDUs, if not all routers in the flooding domain for a given scope support that scope, then flooding of the FS-LSPs may be compromised. When deploying a new flooding scope, correct operation therefore requires that both FS PDUs and the new scope be supported by all routers in the flooding domain of the new scope.
新PDU类型的引入与旧式实现不兼容。遗留实现不支持特定于FS的更新过程，因此，当定义范围内的所有路由器都不支持FS PDU时，在整个定义范围内泛洪FS LSP是不可靠的。此外，传统实现可能会将接收FS PDU视为错误。即使给定作用域中的所有路由器都支持FS PDU，如果给定作用域的泛洪域中的所有路由器都不支持该作用域，则FS LSP的泛洪可能会受到影响。因此，在部署新的泛洪作用域时，正确的操作要求新作用域的泛洪域中的所有路由器都支持FS PDU和新作用域。
The U bit in FS-PSNPs provides a means to suppress retransmissions of unsupported scopes. Routers that support FS PDUs SHOULD support the sending of PSNPs with the U bit equal to 1 when an FS-LSP is received with a scope that is unsupported. Routers that support FS PDUs SHOULD trigger management notifications when FS PDUs are received for unsupported scopes and when PSNPs with the U bit equal to 1 are received.
FS PSNPs中的U位提供了一种抑制不受支持作用域的重传的方法。支持FS PDU的路由器应支持在不支持的范围内接收FS-LSP时发送U位等于1的PSNPs。当接收到不支持作用域的FS PDU时，以及当接收到U位等于1的PSNPs时，支持FS PDU的路由器应触发管理通知。
[RFC5306] defines protocol extensions in support of graceful restart of a routing instance. Synchronization of all supported FS-LSDBs is required in order for database synchronization to be complete. This involves the use of additional T2 timers. Receipt of a PSNP with the U bit equal to 1 will cause FS-LSDB synchronization with that neighbor to be considered complete for that scope. See [RFC5306] for further details.
[RFC5306]定义协议扩展以支持路由实例的正常重启。为了完成数据库同步，需要同步所有受支持的FS LSDB。这涉及到使用额外的T2定时器。接收U位等于1的PSNP将导致与该邻居的FS-LSDB同步在该范围内被视为完成。详见[RFC5306]。
In cases where FS-PDUs are associated with a non-zero instance, the use of Instance Identifier TLVs (IID-TLVs) in FS-PDUs follows the rules for use in LSPs, CSNPs, and PSNPs as defined in [RFC6822].
在FS PDU与非零实例关联的情况下，FS PDU中实例标识符TLV（IID TLV）的使用遵循[RFC6822]中定义的LSP、CSNPs和PSNPs中的使用规则。
This document defines four circuit scope flooding identifiers:
本文件定义了四个电路范围泛洪标识符：
o Level 1 Circuit Scope (L1CS) -- this uses standard TLVs and standard sub-TLVs
o 1级电路范围（L1CS）——使用标准TLV和标准子TLV
o Level 2 Circuit Scope (L2CS) -- this uses standard TLVs and standard sub-TLVs
o 2级电路范围（L2CS）——使用标准TLV和标准子TLV
o Extended Level 1 Circuit Scope (E-L1CS) -- this uses extended TLVs and extended sub-TLVs
o 扩展1级电路范围（E-L1CS）——这使用扩展TLV和扩展子TLV
o Extended Level 2 Circuit Scope (E-L2CS) -- this uses extended TLVs and extended sub-TLVs
o 扩展二级电路范围（E-L2CS）——这使用扩展TLV和扩展子TLV
FS-LSPs with the Scope field set to one of these values contain information specific to the circuit on which they are flooded. When received, such FS-LSPs MUST NOT be flooded on any other circuit. The FS LSP ID Extended format is used in these PDUs. The FS-LSDB associated with circuit scope FS-LSPs consists of the set of FS-LSPs that both have matching circuit scopes and are transmitted (locally generated) or received on a specific circuit.
“作用域”字段设置为这些值之一的FS LSP包含其被淹没的电路的特定信息。接收时，此类FS LSP不得淹没在任何其他电路上。这些PDU中使用FS LSP ID扩展格式。与电路作用域FS LSP相关联的FS-LSDB由具有匹配电路作用域且在特定电路上传输（本地生成）或接收的一组FS LSP组成。
The set of TLVs that may be included in such FS-LSPs is specific to the given use case and is outside the scope of this document.
可能包含在此类FS LSP中的TLV集特定于给定用例，不在本文档的范围内。
The need for additional space in the set of LSPs generated by a single IS has been articulated in [RFC5311]. When legacy interoperability is not a requirement, the use of FS-LSPs meets that need without requiring the assignment of alias system-ids to a single IS. Four flooding scopes are defined for this purpose:
[RFC5311]中阐述了单个IS生成的LSP集合中对额外空间的需求。当不需要遗留互操作性时，使用FS LSP可以满足这一需要，而无需将别名系统ID分配给单个is。为此，定义了四个泛洪范围：
o Level 1 Flooding Scope (L1FS) -- this uses standard TLVs and standard sub-TLVs
o 1级泛洪范围（L1FS）——使用标准TLV和标准子TLV
o Level 2 Flooding Scope (L2FS) -- this uses standard TLVs and standard sub-TLVs
o 二级泛洪范围（L2FS）——使用标准TLV和标准子TLV
o Extended Level 1 Flooding Scope (E-L1FS) -- this uses extended TLVs and extended sub-TLVs
o 扩展1级泛洪范围（E-L1FS）——这使用扩展TLV和扩展子TLV
o Extended Level 2 Flooding Scope (E-L2FS) -- this uses extended TLVs and extended sub-TLVs
o 扩展2级泛洪范围（E-L2FS）——这使用扩展TLV和扩展子TLV
L1FS and E-L1FS LSPs are flooded on all L1 circuits. L2FS and E-L2FS LSPs are flooded on all L2 circuits.
所有L1电路上的L1FS和E-L1FS LSP均被淹没。L2FS和E-L2FS LSP被淹没在所有L2电路上。
The FS LSP ID Extended format is used in these PDUs. This provides 64 K of additional LSPs that may be generated by a single system at each level.
这些PDU中使用FS LSP ID扩展格式。这提供了64 K的额外LSP，可由单个系统在每个级别生成。
LxFS and E-LxFS LSPs are used by the level-specific Decision Process (defined in [IS-IS]) in the same manner as standard LSPs (i.e., as additional information sourced by the same IS) subject to the following restrictions:
LxFS和E-LxFS LSP由特定级别决策流程（定义见[IS-IS]）以与标准LSP相同的方式使用（即，作为同一IS来源的附加信息），但受以下限制：
o A valid version of standard LSP #0 from the same IS at the corresponding level MUST be present in the LSDB in order for the LxFS/E-LxFS set to be usable.
o LSDB中必须存在相应级别的标准LSP#0的有效版本，以便LxFS/E-LxFS集可用。
o Information in an LxFS of E-LxFS LSP (e.g., IS-Neighbor information) that supports using the originating IS as a transit node MUST NOT be used when the Overload bit is set in the corresponding standard LSP #0.
o 当在相应的标准LSP#0中设置过载位时，不得使用支持将始发IS用作传输节点的E-LxFS LSP的LxFS中的信息（例如，是邻居信息）。
o TLVs that are restricted to standard LSP #0 MUST NOT appear in LxFS LSPs.
o 限制为标准LSP#0的TLV不得出现在LxFS LSP中。
There are no further restrictions as to what TLVs may be advertised in FS-LSPs.
对于在FS LSP中公布的TLV，没有进一步的限制。
Existing support for flooding information throughout a domain (i.e., to L1 routers in all areas as well as to routers in the Level 2 subdomain) requires the use of leaking procedures between levels. For further details, see [RFC4971]. This is sufficient when the data being flooded throughout the domain consists of individual TLVs. If it is desired to retain the identity of the originating IS for the complete contents of a PDU, then support for flooding the unchanged PDU is desirable. This document, therefore, defines two flooding scopes in support of domain flooding. FS-LSPs with this scope MUST be flooded on all circuits regardless of what level(s) is supported on that circuit.
对整个域（即所有区域中的L1路由器以及级别2子域中的路由器）的泛洪信息的现有支持要求在级别之间使用泄漏过程。有关更多详细信息，请参阅[RFC4971]。当整个域中的数据由单个TLV组成时，这就足够了。如果希望为PDU的完整内容保留始发is的标识，则需要支持泛洪未更改的PDU。因此，本文档定义了两个泛洪作用域以支持域泛洪。具有此作用域的FS LSP必须在所有电路上泛洪，无论该电路上支持什么级别。
o Domain Flooding Scope (DFS) -- this uses standard TLVs and standard sub-TLVs
o 域泛洪作用域（DFS）——它使用标准TLV和标准子TLV
o Extended Domain Flooding Scope (E-DFS) -- this uses extended TLVs and extended sub-TLVs
o 扩展域泛洪作用域（E-DFS）——它使用扩展TLV和扩展子TLV
The FS LSP ID Extended format is used in these PDUs.
这些PDU中使用FS LSP ID扩展格式。
Use of information in FS-LSPs for a given scope depends on determining the reachability to the IS originating the FS-LSP. This presents challenges for FS-LSPs with domain scopes because no single IS has the full view of the topology across all areas. It is, therefore, necessary for the originator of domain scope DSFS and E-DSFS LSPs to advertise an identifier that will allow an IS who receives such an FS-LSP to determine whether the source of the FS-LSP is currently reachable. The identifier required depends on what "address-families" are being advertised.
在给定范围内使用FS LSP中的信息取决于确定发起FS-LSP的用户的可达性。这对具有域作用域的FS LSP提出了挑战，因为没有一个IS可以全面查看所有区域的拓扑。因此，域范围DSF和E-DSF LSP的发起人有必要公布一个标识符，该标识符将允许接收此类FS-LSP的is确定FS-LSP的源当前是否可访问。所需的标识符取决于所公布的“地址族”。
When IS-IS is deployed in support of Layer 3 routing for IPv4 and/or IPv6, then FS-LSP #0 with domain scope MUST include at least one of the following TLVs:
当部署IS-IS以支持IPv4和/或IPv6的第3层路由时，具有域范围的FS-LSP#0必须至少包括以下TLV之一：
o IPv4 Traffic Engineering Router ID (TLV 134)
o IPv4流量工程路由器ID（TLV 134）
o IPv6 Traffic Engineering Router ID (TLV 140)
o IPv6流量工程路由器ID（TLV 140）
When IS-IS is deployed in support of Layer 2 routing, current standards (e.g., [RFC6325]) only support a single area. Therefore, domain scope is not yet applicable. When the Layer 2 standards are updated to include multi-area support, the identifiers that can be used to support inter-area reachability will be defined -- at which point the use of domain scope for Layer 2 can be fully defined.
当部署IS-IS以支持第2层路由时，当前标准（例如[RFC6325]）仅支持单个区域。因此，域范围还不适用。当第2层标准更新为包含多区域支持时，将定义可用于支持区域间可达性的标识符——此时可以完全定义第2层的域范围的使用。
Announcements of support for flooding scope may be useful in validating that full support has been deployed and/or in isolating the reasons for incomplete flooding of FS-LSPs for a given scope.
对泛洪范围的支持公告可能有助于验证是否已部署全面支持和/或隔离给定范围内FS LSP未完全泛洪的原因。
ISs supporting FS-PDUs MAY announce supported scopes in IIH PDUs. To do so, a new TLV is defined.
支持FS PDU的ISs可能会在IIH PDU中宣布支持的作用域。为此，定义了一个新的TLV。
Scope Flooding Support
Type: 243
Length: 1 - 127
Value
No. of octets
+----------------------+
|R| Supported Scope | 1
+----------------------+
: :
+----------------------+
|R| Supported Scope | 1
+----------------------+
Scope Flooding Support
Type: 243
Length: 1 - 127
Value
No. of octets
+----------------------+
|R| Supported Scope | 1
+----------------------+
: :
+----------------------+
|R| Supported Scope | 1
+----------------------+
A list of the circuit scopes supported on this circuit and other non-circuit-flooding scopes supported.
此回路支持的回路作用域和其他支持的非回路泛洪作用域的列表。
R bit MUST be 0 and is ignored on receipt.
R位必须为0，并且在接收时被忽略。
In a Point-to-Point IIH, L1, L2, domain, and all circuit scopes MAY be advertised.
在点对点IIH、L1、L2、域和所有电路范围中可以公布。
In Level 1 LAN IIHs, L1, domain, and L1 Circuit Scopes MAY be advertised. L2 Scopes and L2 Circuit Scopes MUST NOT be advertised.
在1级LAN IIH中，可以公布L1、域和L1电路范围。二级作用域和二级回路作用域不得公布。
In Level 2 LAN IIHs, L2, domain, and L2 Circuit Scopes MAY be advertised. L1 Scopes and L1 Circuit Scopes MUST NOT be advertised.
在2级LAN IIH中，可以公布L2、域和L2电路范围。不得公布L1作用域和L1回路作用域。
Information in this TLV MUST NOT be considered in adjacency formation.
邻接地层中不得考虑该TLV中的信息。
Whether information in this TLV is used to determine when FS-LSPs associated with a locally supported scope are flooded is an implementation choice.
是否使用此TLV中的信息确定与本地支持的作用域关联的FS LSP何时被淹没是一个实现选择。
This document includes the definition of three new PDU types that are reflected in the "IS-IS PDU Registry".
本文档包括“IS-IS PDU注册表”中反映的三种新PDU类型的定义。
Value Description
---- ---------------------
10 FS-LSP
11 FS-CSNP
12 FS-PSNP
Value Description
---- ---------------------
10 FS-LSP
11 FS-CSNP
12 FS-PSNP
A new IANA registry has been created to control the assignment of scope identifiers in FS-PDUs. The registration procedure is "Expert Review" as defined in [RFC5226]. The registry name is "LSP Flooding Scope Identifier Registry". A scope identifier is a number from 1-127, inclusive. Values 1 - 63 are reserved for PDUs that use standard TLVs and standard sub-TLVs. Values 64 - 127 are reserved for PDUs that use extended TLVs and extended sub-TLVs. The list of Hello PDUs in which support for a given scope MAY be announced (using Scope Flooding Support TLV) is specified for each defined scope.
已创建一个新的IANA注册表来控制FS PDU中范围标识符的分配。注册程序为[RFC5226]中定义的“专家评审”。注册表名为“LSP泛洪作用域标识符注册表”。范围标识符是1-127（含1-127）之间的数字。值1-63保留给使用标准TLV和标准子TLV的PDU。值64-127保留给使用扩展TLV和扩展子TLV的PDU。为每个定义的作用域指定了Hello PDU列表，其中可能会宣布对给定作用域的支持（使用作用域泛洪支持TLV）。
The following scope identifiers are defined by this document.
本文档定义了以下范围标识符。
FS LSP ID Format/ IIH Announce
Value Description TLV Format P2P L1LAN L2LAN
----- ------------------------------ ----------------- ---------------
1 Level 1 Circuit Flooding Scope Extended/Standard Y Y N
2 Level 2 Circuit Flooding Scope Extended/Standard Y N Y
3 Level 1 Flooding Scope Extended/Standard Y Y N
4 Level 2 Flooding Scope Extended/Standard Y N Y
5 Domain Flooding Scope Extended/Standard Y Y Y
(6-63)Unassigned
FS LSP ID Format/ IIH Announce
Value Description TLV Format P2P L1LAN L2LAN
----- ------------------------------ ----------------- ---------------
1 Level 1 Circuit Flooding Scope Extended/Standard Y Y N
2 Level 2 Circuit Flooding Scope Extended/Standard Y N Y
3 Level 1 Flooding Scope Extended/Standard Y Y N
4 Level 2 Flooding Scope Extended/Standard Y N Y
5 Domain Flooding Scope Extended/Standard Y Y Y
(6-63)Unassigned
64 Level 1 Circuit Flooding Scope Extended/Extended Y Y N 65 Level 2 Circuit Flooding Scope Extended/Extended Y N Y 66 Level 1 Flooding Scope Extended/Extended Y Y N 67 Level 2 Flooding Scope Extended/Extended Y N Y 68 Domain Flooding Scope Extended/Extended Y Y Y (69-127) Unassigned
64一级电路泛洪范围扩展/扩展Y Y N 65二级电路泛洪范围扩展/扩展Y N Y 66一级泛洪范围扩展/扩展Y Y N 67二级泛洪范围扩展/扩展Y N Y 68域泛洪范围扩展/扩展Y Y Y Y（69-127）未分配
The definition of a new IS-IS TLV is reflected in the "IS-IS TLV Codepoints" registry:
新IS-IS TLV的定义反映在“IS-IS TLV代码点”注册表中：
Value Name IIH LSP SNP Purge
---- ------------ --- --- --- -----
243 Scope Flooding Support Y N N N
Value Name IIH LSP SNP Purge
---- ------------ --- --- --- -----
243 Scope Flooding Support Y N N N
The IANA "IS-IS TLV Codepoints" registry has been extended to allow definition of codepoints less than or equal to 65535. Codepoints greater than 255 can only be used in PDUs designated to support extended TLVs. This registry has also been updated to point to this document as a reference (in addition to [RFC3563] and [RFC6233]).
IANA“IS-IS TLV码点”注册表已扩展，允许定义小于或等于65535的码点。大于255的代码点只能在指定用于支持扩展TLV的PDU中使用。此注册表也已更新，以指向此文档作为参考（除了[RFC3563]和[RFC6233]）。
Security concerns for IS-IS are addressed in [IS-IS], [RFC5304], and [RFC5310].
IS-IS的安全问题在[IS-IS]、[RFC5304]和[RFC5310]中有说明。
The new PDUs introduced are subject to the same security issues associated with their standard LSP/CSNP/PSNP counterparts. To the extent that additional PDUs represent additional load for routers in the network, this increases the opportunity for denial-of-service attacks.
引入的新PDU面临与其标准LSP/CSNP/PSNP对应产品相同的安全问题。如果额外的PDU代表网络中路由器的额外负载，则会增加拒绝服务攻击的机会。
The authors wish to thank Ayan Banerjee, Donald Eastlake, Hannes Gredler, and Mike Shand for their comments.
作者希望感谢阿扬·班纳吉、唐纳德·伊斯特莱克、汉内斯·格雷德勒和迈克·尚德的评论。
[IEEEaq] IEEE, "Standard for Local and metropolitan area networks -- Media Access Control (MAC) Bridges and Virtual Bridged Local Area Networks -- Amendment 20: Shortest Path Bridging", IEEE Std 802.1aq-2012, June 2012.
[IEEEaq]IEEE，“局域网和城域网标准——媒体访问控制（MAC）网桥和虚拟桥接局域网——修改件20：最短路径桥接”，IEEE标准802.1aq-2012，2012年6月。
[IS-IS] ISO/IEC 10589:2002, Second Edition, "Information technology -- Telecommunications and information exchange between systems -- Intermediate System to Intermediate System intradomain routeing information exchange protocol for use in conjunction with the protocol for providing the connectionless-mode network service (ISO 8473)", 2002.
[IS-IS]ISO/IEC 10589:2002，第二版，“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（ISO 8473）结合使用的中间系统到中间系统域内路由信息交换协议”，2002年。
[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。
[RFC4971] Vasseur, JP., Shen, N., and R. Aggarwal, "Intermediate System to Intermediate System (IS-IS) Extensions for Advertising Router Information", RFC 4971, July 2007.
[RFC4971]Vasseur，JP.，Shen，N.，和R.Aggarwal，“广告路由器信息的中间系统到中间系统（IS-IS）扩展”，RFC 49712007年7月。
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008.
[RFC5226]Narten，T.和H.Alvestrand，“在RFCs中编写IANA注意事项部分的指南”，BCP 26，RFC 5226，2008年5月。
[RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic Authentication", RFC 5304, October 2008.
[RFC5304]Li，T.和R.Atkinson，“IS-IS加密认证”，RFC 5304，2008年10月。
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic Engineering", RFC 5305, October 2008.
[RFC5305]Li，T.和H.Smit，“交通工程的IS-IS扩展”，RFC 5305，2008年10月。
[RFC5306] Shand, M. and L. Ginsberg, "Restart Signaling for IS-IS", RFC 5306, October 2008.
[RFC5306]Shand，M.和L.Ginsberg，“IS-IS的重启信号”，RFC 5306，2008年10月。
[RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., and M. Fanto, "IS-IS Generic Cryptographic Authentication", RFC 5310, February 2009.
[RFC5310]Bhatia，M.，Manral，V.，Li，T.，Atkinson，R.，White，R.，和M.Fanto，“IS-IS通用密码认证”，RFC 53102009年2月。
[RFC6822] Previdi, S., Ginsberg, L., Shand, M., Roy, A., and D. Ward, "IS-IS Multi-Instance", RFC 6822, December 2012.
[RFC6822]Previdi，S.，Ginsberg，L.，Shand，M.，Roy，A.，和D.Ward，“IS-IS多实例”，RFC 6822，2012年12月。
[RFC3563] Zinin, A., "Cooperative Agreement Between the ISOC/IETF and ISO/IEC Joint Technical Committee 1/Sub Committee 6 (JTC1/SC6) on IS-IS Routing Protocol Development", RFC 3563, July 2003.
[RFC3563]Zinin，A.“ISO/IETF和ISO/IEC联合技术委员会1/第6分委员会（JTC1/SC6）之间关于IS-IS路由协议开发的合作协议”，RFC 3563，2003年7月。
[RFC5311] McPherson, D., Ginsberg, L., Previdi, S., and M. Shand, "Simplified Extension of Link State PDU (LSP) Space for IS-IS", RFC 5311, February 2009.
[RFC5311]McPherson，D.，Ginsberg，L.，Previdi，S.，和M.Shand，“IS-IS链路状态PDU（LSP）空间的简化扩展”，RFC 5311，2009年2月。
[RFC6233] Li, T. and L. Ginsberg, "IS-IS Registry Extension for Purges", RFC 6233, May 2011.
[RFC6233]Li，T.和L.Ginsberg，“清洗的IS-IS注册扩展”，RFC 6233，2011年5月。
[RFC6325] Perlman, R., Eastlake, D., Dutt, D., Gai, S., and A. Ghanwani, "Routing Bridges (RBridges): Base Protocol Specification", RFC 6325, July 2011.
[RFC6325]Perlman，R.，Eastlake，D.，Dutt，D.，Gai，S.，和A.Ghanwani，“路由桥（RBridges）：基本协议规范”，RFC 63252011年7月。
[RFC7176] Eastlake, D., Senevirathne, T., Ghanwani, A., Dutt, D., and A. Banerjee, "Transparent Interconnection of Lots of Links (TRILL) Use of IS-IS", RFC 7176, May 2014.
[RFC7176]Eastlake，D.，Senevirathne，T.，Ghanwani，A.，Dutt，D.，和A.Banerjee，“IS-IS大量链路的透明互连（TRILL）使用”，RFC 7176，2014年5月。
Authors' Addresses
作者地址
Les Ginsberg Cisco Systems 510 McCarthy Blvd. Milpitas, CA 95035 USA
莱斯金斯伯格思科系统公司，麦卡锡大道510号。美国加利福尼亚州米尔皮塔斯95035
EMail: ginsberg@cisco.com
EMail: ginsberg@cisco.com
Stefano Previdi Cisco Systems Via Del Serafico 200 Rome 0144 Italy
Stefano Previdi Cisco Systems Via Del Serafico 200罗马0144意大利
EMail: sprevidi@cisco.com
EMail: sprevidi@cisco.com
Yi Yang Cisco Systems 7100-9 Kit Creek Road Research Triangle Park, NC 27709-4987 USA
益阳思科系统7100-9美国北卡罗来纳州Kit Creek路研究三角公园27709-4987
EMail: yiya@cisco.com
EMail: yiya@cisco.com