Internet Engineering Task Force (IETF) D. Fedyk, Ed.
Request for Comments: 6329 Alcatel-Lucent
Category: Standards Track P. Ashwood-Smith, Ed.
ISSN: 2070-1721 Huawei
D. Allan
Ericsson
N. Bragg
Ciena Limited
P. Unbehagen
Avaya
April 2012
Internet Engineering Task Force (IETF) D. Fedyk, Ed.
Request for Comments: 6329 Alcatel-Lucent
Category: Standards Track P. Ashwood-Smith, Ed.
ISSN: 2070-1721 Huawei
D. Allan
Ericsson
N. Bragg
Ciena Limited
P. Unbehagen
Avaya
April 2012
IS-IS Extensions Supporting IEEE 802.1aq Shortest Path Bridging
IS-IS扩展支持IEEE 802.1aq最短路径桥接
Abstract
摘要
802.1aq Shortest Path Bridging (SPB) has been standardized by the IEEE as the next step in the evolution of the various spanning tree and registration protocols. 802.1aq allows for true shortest path forwarding in a mesh Ethernet network context utilizing multiple equal cost paths. This permits it to support much larger Layer 2 topologies, with faster convergence, and vastly improved use of the mesh topology. Combined with this is single point provisioning for logical connectivity membership, which includes point-to-point, point-to-multipoint, and multipoint-to-multipoint variations. This memo documents the IS-IS changes required to support this IEEE protocol and provides some context and examples.
802.1aq最短路径桥接（SPB）已被IEEE标准化，作为各种生成树和注册协议发展的下一步。802.1aq允许在网状以太网环境中使用多条等成本路径进行真正的最短路径转发。这允许它支持更大的第2层拓扑，具有更快的收敛速度，并大大改进了网格拓扑的使用。与此相结合的是逻辑连接成员资格的单点供应，包括点对点、点对多点和多点对多点的变化。本备忘录记录了支持本IEEE协议所需的IS-IS变更，并提供了一些上下文和示例。
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/rfc6329.
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/rfc6329.
Copyright Notice
版权公告
Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2012 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 ....................................................4
2. Terminology .....................................................4
3. Conventions Used in This Document ...............................5
4. 802.1aq Overview ................................................6
4.1. Multi-Topology Support .....................................8
4.2. Data Path SPBM - Unicast ...................................8
4.3. Data Path SPBM - Multicast (Head-End Replication) ..........9
4.4. Data Path SPBM - Multicast (Tandem Replication) ............9
4.5. Data Path SPBV Broadcast ..................................11
4.6. Data Path SPBV Unicast ....................................11
4.7. Data Path SPBV Multicast ..................................12
5. SPBM Example ...................................................12
6. SPBV Example ...................................................14
7. SPB Supported Adjacency types ..................................16
8. SPB IS-IS Adjacency Addressing .................................16
9. IS-IS Area Address and SYSID ...................................17
10. Level 1/2 Adjacency ...........................................17
11. Shortest Path Default Tie-Breaking ............................17
12. Shortest Path ECT .............................................18
13. Hello (IIH) Protocol Extensions ...............................19
13.1. SPB-MCID Sub-TLV .........................................20
13.2. SPB-Digest Sub-TLV .......................................21
13.3. SPB Base VLAN Identifiers (SPB-B-VID) Sub-TLV ............23
14. Node Information Extensions ...................................24
14.1. SPB Instance (SPB-Inst) Sub-TLV ..........................24
14.1.1. SPB Instance Opaque ECT-ALGORITHM
(SPB-I-OALG) Sub-TLV ..............................28
15. Adjacency Information Extensions ..............................29
15.1. SPB Link Metric (SPB-Metric) Sub-TLV .....................29
15.1.1. SPB Adjacency Opaque ECT-ALGORITHM
(SPB-A-OALG) Sub-TLV ..............................30
16. Service Information Extensions ................................30
16.1. SPBM Service Identifier and Unicast Address
(SPBM-SI) Sub-TLV ........................................30
16.2. SPBV MAC Address (SPBV-ADDR) Sub-TLV .....................32
17. Security Considerations .......................................34
18. IANA Considerations ...........................................34
19. References ....................................................35
19.1. Normative References .....................................35
19.2. Informative References ...................................36
20. Acknowledgments ...............................................36
1. Introduction ....................................................4
2. Terminology .....................................................4
3. Conventions Used in This Document ...............................5
4. 802.1aq Overview ................................................6
4.1. Multi-Topology Support .....................................8
4.2. Data Path SPBM - Unicast ...................................8
4.3. Data Path SPBM - Multicast (Head-End Replication) ..........9
4.4. Data Path SPBM - Multicast (Tandem Replication) ............9
4.5. Data Path SPBV Broadcast ..................................11
4.6. Data Path SPBV Unicast ....................................11
4.7. Data Path SPBV Multicast ..................................12
5. SPBM Example ...................................................12
6. SPBV Example ...................................................14
7. SPB Supported Adjacency types ..................................16
8. SPB IS-IS Adjacency Addressing .................................16
9. IS-IS Area Address and SYSID ...................................17
10. Level 1/2 Adjacency ...........................................17
11. Shortest Path Default Tie-Breaking ............................17
12. Shortest Path ECT .............................................18
13. Hello (IIH) Protocol Extensions ...............................19
13.1. SPB-MCID Sub-TLV .........................................20
13.2. SPB-Digest Sub-TLV .......................................21
13.3. SPB Base VLAN Identifiers (SPB-B-VID) Sub-TLV ............23
14. Node Information Extensions ...................................24
14.1. SPB Instance (SPB-Inst) Sub-TLV ..........................24
14.1.1. SPB Instance Opaque ECT-ALGORITHM
(SPB-I-OALG) Sub-TLV ..............................28
15. Adjacency Information Extensions ..............................29
15.1. SPB Link Metric (SPB-Metric) Sub-TLV .....................29
15.1.1. SPB Adjacency Opaque ECT-ALGORITHM
(SPB-A-OALG) Sub-TLV ..............................30
16. Service Information Extensions ................................30
16.1. SPBM Service Identifier and Unicast Address
(SPBM-SI) Sub-TLV ........................................30
16.2. SPBV MAC Address (SPBV-ADDR) Sub-TLV .....................32
17. Security Considerations .......................................34
18. IANA Considerations ...........................................34
19. References ....................................................35
19.1. Normative References .....................................35
19.2. Informative References ...................................36
20. Acknowledgments ...............................................36
802.1aq Shortest Path Bridging (SPB) [802.1aq] has been standardized by the IEEE as the next step in the evolution of the various spanning tree and registration protocols. 802.1aq allows for true shortest path forwarding in an Ethernet mesh network context utilizing multiple equal cost paths. This permits SPB to support much larger Layer 2 topologies, with faster convergence, and vastly improved use of the mesh topology. Combined with this is single point provisioning for logical connectivity membership, which includes point-to-point (E-LINE), point-to-multipoint (E-TREE), and multipoint-to-multipoint (E-LAN) variations.
802.1aq最短路径桥接（SPB）[802.1aq]已被IEEE标准化，作为各种生成树和注册协议发展的下一步。802.1aq允许在以太网网状网络环境中使用多条等成本路径进行真正的最短路径转发。这允许SPB支持更大的第2层拓扑，具有更快的收敛速度，并大大改进了网格拓扑的使用。与此相结合的是逻辑连接成员资格的单点供应，包括点对点（E-LINE）、点对多点（E-TREE）和多点对多点（E-LAN）变体。
The control protocol for 802.1aq is IS-IS [IS-IS] augmented with a small number of TLVs and sub-TLVs. This supports two Ethernet encapsulating data paths, 802.1ad (Provider Bridges) [PB] and 802.1ah (Provider Backbone Bridges) [PBB]. This memo documents those TLVs while providing some overview.
802.1aq的控制协议是由少量TLV和子TLV扩充而成的。这支持两个以太网封装数据路径，802.1ad（提供商网桥）[PB]和802.1ah（提供商主干网桥）[PBB]。本备忘录记录了这些TLV，同时提供了一些概述。
Note that 802.1aq requires no state machine or other substantive changes to [IS-IS]. 802.1aq simply requires a new Network Layer Protocol Identifier (NLPID) and set of TLVs. In the event of confusion between this document and [IS-IS], [IS-IS] should be taken as authoritative.
请注意，802.1aq不需要对[IS-IS]进行状态机或其他实质性更改。802.1aq只需要一个新的网络层协议标识符（NLPID）和一组TLV。如果本文件与[IS-IS]之间存在混淆，则应将[IS-IS]视为权威文件。
In addition to well-understood IS-IS terms, this memo uses terminology from IEEE 802.1 and introduces a few terms:
除了易于理解的IS-IS术语外，本备忘录还使用了IEEE 802.1中的术语，并介绍了一些术语：
802.1ad Provider Bridges (PBs) - Q-in-Q encapsulation
802.1ah Provider Backbone Bridges (PBBs), MAC-IN-MAC
encapsulation
802.1aq Shortest Path Bridging (SPB)
Base VID VID used to identify a VLAN in management operations
B-DA Backbone Destination Address 802.1ah PBB
B-MAC Backbone MAC Address
B-SA Backbone Source Address in 802.1ah PBB header
B-VID Backbone VLAN ID in 802.1ah PBB header
B-VLAN Backbone Virtual LAN
BPDU Bridge PDU
BridgeID 64-bit quantity = (Bridge Priority:16)<<48 | SYSID:48
BridgePriority 16-bit relative priority of a node for tie-breaking
C-MAC Customer MAC. Inner MAC in 802.1ah PBB header
C-VID Customer VLAN ID
ECT-ALGORITHM 32-bit unique ID of an SPF tie-breaking set of rules
ECT-MASK 64-bit mask XORed with BridgeID during tie-breaking
E-LAN Bidirectional Logical Connectivity between >2 UNIs
802.1ad Provider Bridges (PBs) - Q-in-Q encapsulation
802.1ah Provider Backbone Bridges (PBBs), MAC-IN-MAC
encapsulation
802.1aq Shortest Path Bridging (SPB)
Base VID VID used to identify a VLAN in management operations
B-DA Backbone Destination Address 802.1ah PBB
B-MAC Backbone MAC Address
B-SA Backbone Source Address in 802.1ah PBB header
B-VID Backbone VLAN ID in 802.1ah PBB header
B-VLAN Backbone Virtual LAN
BPDU Bridge PDU
BridgeID 64-bit quantity = (Bridge Priority:16)<<48 | SYSID:48
BridgePriority 16-bit relative priority of a node for tie-breaking
C-MAC Customer MAC. Inner MAC in 802.1ah PBB header
C-VID Customer VLAN ID
ECT-ALGORITHM 32-bit unique ID of an SPF tie-breaking set of rules
ECT-MASK 64-bit mask XORed with BridgeID during tie-breaking
E-LAN Bidirectional Logical Connectivity between >2 UNIs
E-LINE Bidirectional Logical Connectivity between two UNIs
E-TREE Asymmetric Logical Connectivity between UNIs
FDB Filtering Database: {DA/VID}->{next hops}
I-SID Ethernet Services Instance Identifier used for
Logical Grouping for E-LAN/LINE/TREE UNIs
LAN Local Area Network
LSDB Link State Database
LSP Link State PDU
MAC Media Access Control
MAC-IN-MAC Ethernet in Ethernet framing as per 802.1ah [PBB]
MDT Multicast Distribution Tree
MMRP Multiple MAC Registration Protocol 802.1ak [MMRP]
MT Multi-Topology. As used in [MT]
MT ID Multi-Topology Identifier (12 bits). As used in [MT]
NLPID Network Layer Protocol Identifier: IEEE 802.1aq= 0xC1
NNI Network-Network Interface
Q-in-Q Additional S-VID after a C-VID (802.1ad) [PB]
PBB Provider Backbone Bridge - forwards using PBB
Ingress Check Source Forwarding Check - drops misdirected frames
(S,G) Source & Group - identity of a source-specific tree
(*,G) Any Source & Group - identity of a shared tree
S-VID Service VLAN ID
SA Source Address
SPB Shortest Path Bridging - generally all of 802.1aq
SPB Shortest Path Bridge - device implementing 802.1aq
SPB-instance Logical SPB instance correlated by MT ID
SPBM Device implementing SPB MAC mode
SPBV Device implementing SPB VID mode
SPSourceID 20-bit identifier of the source of multicast frames
SPT Shortest Path Tree computed by one ECT-ALGORITHM
SPT Region A set of SPBs with identical VID usage on their NNIs
SPVID Shortest Path VLAN ID: a C-VID or S-VID that
identifies the source
STP Spanning Tree Protocol
UNI User-Network Interface: customer-to-SPB attach point
VID VLAN ID: 12-bit logical identifier after MAC header
VLAN Virtual LAN: a logical network in the control plane
E-LINE Bidirectional Logical Connectivity between two UNIs
E-TREE Asymmetric Logical Connectivity between UNIs
FDB Filtering Database: {DA/VID}->{next hops}
I-SID Ethernet Services Instance Identifier used for
Logical Grouping for E-LAN/LINE/TREE UNIs
LAN Local Area Network
LSDB Link State Database
LSP Link State PDU
MAC Media Access Control
MAC-IN-MAC Ethernet in Ethernet framing as per 802.1ah [PBB]
MDT Multicast Distribution Tree
MMRP Multiple MAC Registration Protocol 802.1ak [MMRP]
MT Multi-Topology. As used in [MT]
MT ID Multi-Topology Identifier (12 bits). As used in [MT]
NLPID Network Layer Protocol Identifier: IEEE 802.1aq= 0xC1
NNI Network-Network Interface
Q-in-Q Additional S-VID after a C-VID (802.1ad) [PB]
PBB Provider Backbone Bridge - forwards using PBB
Ingress Check Source Forwarding Check - drops misdirected frames
(S,G) Source & Group - identity of a source-specific tree
(*,G) Any Source & Group - identity of a shared tree
S-VID Service VLAN ID
SA Source Address
SPB Shortest Path Bridging - generally all of 802.1aq
SPB Shortest Path Bridge - device implementing 802.1aq
SPB-instance Logical SPB instance correlated by MT ID
SPBM Device implementing SPB MAC mode
SPBV Device implementing SPB VID mode
SPSourceID 20-bit identifier of the source of multicast frames
SPT Shortest Path Tree computed by one ECT-ALGORITHM
SPT Region A set of SPBs with identical VID usage on their NNIs
SPVID Shortest Path VLAN ID: a C-VID or S-VID that
identifies the source
STP Spanning Tree Protocol
UNI User-Network Interface: customer-to-SPB attach point
VID VLAN ID: 12-bit logical identifier after MAC header
VLAN Virtual LAN: a logical network in the control plane
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。
The lowercase forms with an initial capital "Must", "Must Not", "Shall", "Shall Not", "Should", "Should Not", "May", and "Optional" in this document are to be interpreted in the sense defined in
本文件中首字母大写为“必须”、“不得”、“应”、“不应”、“应”、“不应”、“可”和“可选”的小写形式应按照
[RFC2119], but are used where the normative behavior is defined in documents published by SDOs other than the IETF.
[RFC2119]，但用于SDO（而非IETF）发布的文件中定义规范行为的情况。
This section provides an overview of the behavior of [802.1aq] and is not intended to be interpreted as normative text. For the definitive behavior, the reader should consult [802.1aq]. Nonetheless, lowercase forms with initial capitalization of the conventions in RFC 2119 are used in this section to give the reader an indication of the intended normative behaviors as above.
本节概述了[802.1aq]的行为，并不打算将其解释为规范性文本。对于最终行为，读者应参考[802.1aq]。尽管如此，RFC 2119中约定的首字母大写的小写形式在本节中用于向读者说明上述预期规范行为。
802.1aq utilizes 802.1Q-based Ethernet bridging. The filtering database (FDB) is populated as a consequence of the topology computed from the IS-IS database. For the reader unfamiliar with IEEE terminology, the definition of Ethernet behavior is almost entirely in terms of "filtering" (of broadcast traffic) rather than "forwarding" (the explicit direction of unicast traffic). This document uses the generic term "forwarding", and it has to be understood that these two terms simply represent different ways of expressing the same behaviors.
802.1aq利用基于802.1Q的以太网桥接。根据从is-is数据库计算的拓扑结构填充筛选数据库（FDB）。对于不熟悉IEEE术语的读者来说，以太网行为的定义几乎完全是“过滤”（广播流量）而不是“转发”（单播流量的明确方向）。本文档使用通用术语“转发”，必须理解，这两个术语只是表示表达相同行为的不同方式。
802.1aq supports multiple modes of operation depending on the type of data plane and the desired behavior. For the initial two modes of 802.1aq (SPBV and SPBM), routes are shortest path, are forward- and reverse-path symmetric with respect to any source/destination pair within the SPB domain, and are congruent with respect to unicast and multicast. Hence, the shortest path tree (SPT) to a given node is congruent with the multicast distribution tree (MDT) from a given node. The MDT for a given VLAN is a pruned subset of the complete MDT for a given node that is identical to its SPT. Symmetry and congruency preserve packet ordering and proper fate sharing of Operations, Administration, and Maintenance (OAM) flows by the forwarding path. Such modes are fully supported by existing [802.1ag] and [Y.1731] OAM mechanisms.
802.1aq支持多种操作模式，具体取决于数据平面的类型和所需的行为。对于802.1aq的最初两种模式（SPBV和SPBM），路由是最短路径，对于SPB域内的任何源/目的地对是前向和反向路径对称的，对于单播和多播是一致的。因此，到给定节点的最短路径树（SPT）与来自给定节点的多播分发树（MDT）是一致的。给定VLAN的MDT是与其SPT相同的给定节点的完整MDT的修剪子集。对称性和一致性通过转发路径保持分组顺序和操作、管理和维护（OAM）流的适当命运共享。现有[802.1ag]和[Y.1731]OAM机制完全支持此类模式。
VLANs provide a natural delineation of service instances. 802.1aq supports two modes, SPB VID (SPBV) and SPB MAC (SPBM). In SPBV, multiple VLANS can be used to distribute load on different shortest path trees (each computed by a different tie-breaking rule) on a service basis. In SPBM, service instances are delineated by I-SIDs but VLANs again can be used to distribute load on different shortest path trees.
VLAN提供了服务实例的自然描述。802.1aq支持两种模式，即SPB VID（SPBV）和SPB MAC（SPBM）。在SPBV中，可以使用多个VLAN以服务为基础在不同的最短路径树（每个树由不同的断开连接规则计算）上分配负载。在SPBM中，服务实例由I-SID描述，但VLAN可再次用于在不同的最短路径树上分配负载。
There are two encapsulation methods supported. SPBM can be used in a PBB network implementing PBB (802.1ah [PBB]) encapsulation. SPBV can be used in PB networks implementing VLANs, PB (802.1aq [PB]), or PBB
支持两种封装方法。SPBM可用于实现PBB（802.1ah[PBB]）封装的PBB网络中。SPBV可用于实现VLAN、PB（802.1aq[PB]）或PBB的PB网络
encapsulation. The two modes can co-exist simultaneously in an SPB network.
封装。这两种模式可以在SPB网络中同时共存。
The practical design goals for SPBV and SPBM in the current 802.1aq specification are networks of size 100 nodes and 1000 nodes respectively. However, since SPBV can be sparsely used in an SPB region it can simply span a large SPB region with a small number of SPVIDs.
当前802.1aq规范中SPBV和SPBM的实际设计目标分别是大小为100个节点和1000个节点的网络。然而，由于SPBV可以在SPB区域中稀疏使用，因此它可以用少量SPVID简单地跨越大SPB区域。
In SPBM and SPBV each bridge has at least one unique "known" MAC address which is advertised by IS-IS in the SYSID.
在SPBM和SPBV中，每个网桥至少有一个唯一的“已知”MAC地址，该地址由SYSID中的is-is公布。
In the forwarding plane, SPBM uses the combination of one or more B-VIDs and "known" Backbone-MAC (B-MAC) addresses that have been advertised in IS-IS. The term Backbone simply implies an encapsulation that is often used in the backbone networks, but the encapsulation is useful in other types of networks where hiding C-MACs is useful.
在转发平面中，SPBM使用一个或多个B-vid和在IS-IS中通告的“已知”骨干MAC（B-MAC）地址的组合。术语主干仅表示主干网络中经常使用的封装，但该封装在隐藏C-mac有用的其他类型的网络中很有用。
The SPBM filtering database (FDB) is computed and installed for unicast and multicast MAC addresses, while the SPBV filtering database is computed and installed for unidirectional VIDs (referred to as SPVIDs), after which MAC reachability is learned (exactly as in bridged Ethernet) for unicast MACs.
针对单播和多播MAC地址计算并安装SPBM过滤数据库（FDB），而针对单向VID（称为SPVID）计算并安装SPBV过滤数据库，然后学习单播MAC的MAC可达性（与桥接以太网完全相同）。
Both SPBV and SPBM use source-specific multicast trees. If they share the same ECT-ALGORITHM (32-bit worldwide unique definition of the computation), the tree is the same SPT. For SPBV, (S,G) is encoded by a source-specific VID (the SPVID) and a standard Group MAC address. For SPBM, (S,G) is encoded in the destination B-MAC address as the concatenation of a 20-bit SPB wide unique nodal nickname (referred to as the SPSourceID) and the 24-bit I-SID together with the B-VID that corresponds to the ECT-ALGORITHM network wide.
SPBV和SPBM都使用源特定的多播树。如果它们共享相同的ECT算法（32位全球唯一的计算定义），则树就是相同的SPT。对于SPBV，（S，G）由源特定的VID（SPVID）和标准组MAC地址编码。对于SPBM，（S，G）在目标B-MAC地址中编码为20位SPB范围的唯一节点昵称（称为SPSourceID）和24位I-SID以及对应于ECT-MAC网络范围算法的B-VID的级联。
802.1aq supports membership attributes that are advertised with the I-SID (SPBM) or Group Address (SPBV) that defines the group. Individual members can be transmitters (T) and/or receivers (R) within the group, and the multicast state is appropriately sized to these requests. Multicast group membership is possible even without transmit membership by performing head-end replication to the receivers thereby eliminating transit multicast state entirely.
802.1aq支持使用定义组的I-SID（SPBM）或组地址（SPBV）播发的成员身份属性。单个成员可以是组内的发射机（T）和/或接收机（R），并且多播状态的大小适合于这些请求。通过执行到接收器的头端复制，即使没有传输成员资格，也可以成为多播组成员，从而完全消除传输多播状态。
Some highly connected mesh networks provide for path diversity by offering multiple equal cost alternatives between nodes. Since congruency and symmetry Must be honored, a single tree may leave some links under-utilized. By using different deterministic tie-breakers, up to 16 shortest paths of arbitrary diversity are possible between any pair of nodes. This distributes the traffic on a VLAN basis.
一些高度连接的网状网络通过在节点之间提供多个等成本备选方案来提供路径多样性。由于一致性和对称性必须得到尊重，一棵树可能会留下一些未充分利用的链接。通过使用不同的确定性连接断路器，任何一对节点之间最多可以有16条任意分集的最短路径。这将在VLAN的基础上分配流量。
SPBV and SPBM May share a single SPT with a single ECT-ALGORITHM or use any combination of the 16 ECT-ALGORITHMs. An extensible framework permits additional or alternative algorithms with other properties and parameters (e.g., ECMP, (*,G)) to also be supported without any changes in this or the IEEE documents.
SPBV和SPBM可使用单个ECT-1算法共享单个SPT，或使用16个ECT算法的任意组合。可扩展框架允许在不改变本文件或IEEE文件的情况下，也支持具有其他属性和参数（例如ECMP，（*，g））的附加或替代算法。
SPB incorporates the multi topology features of [MT] thereby allowing multiple logical SPB instances within a single IS-IS instance.
SPB结合了[MT]的多拓扑特性，从而允许在单个IS-IS实例中使用多个逻辑SPB实例。
To accomplish this, all SPB-related information is either explicitly or implicitly associated with a Multi-Topology Identifier (MT ID). SPB information related to a given MT ID thus forms a single logical SPB instance.
为此，所有SPB相关信息都显式或隐式地与多拓扑标识符（MT ID）关联。因此，与给定MT ID相关的SPB信息形成单个逻辑SPB实例。
Since SPB has its own adjacency metrics and those metrics are also associated with an MT ID, it is possible to have different adjacency metrics (or infinite metrics) for SPB adjacencies that are not only distinct from IP or other NLPIDs riding in this IS-IS instance, but also distinct from those used by other SPB instances in the same IS-IS instance.
由于SPB有自己的邻接度量，并且这些度量也与MT ID关联，因此SPB邻接可能有不同的邻接度量（或无限度量），这些度量不仅不同于此is-is实例中的IP或其他NLPID，但也不同于同一IS-IS实例中其他SPB实例所使用的。
Data plane traffic for a given MT ID is intrinsically isolated by the VLANs assigned to the SPB instance in question. Therefore, VLANs (represented by VIDs in TLVs and in the data plane) Must Not overlap between SPB instances (regardless of how the control planes are isolated).
给定MT ID的数据平面流量本质上由分配给相关SPB实例的VLAN隔离。因此，VLAN（由TLV和数据平面中的VID表示）不得在SPB实例之间重叠（无论控制平面如何隔离）。
The [MT] mechanism when applied to SPB allows different routing metrics and topology subsets for different classes of services.
[MT]机制应用于SPB时，允许不同类别的服务使用不同的路由度量和拓扑子集。
The use of [MT] other than the default MT ID #0 is completely OPTIONAL.
除了默认的MT ID#0之外，使用[MT]是完全可选的。
The use of [MT] to separate SPB from other NLPIDs is also OPTIONAL.
使用[MT]将SPB与其他NLPID分开也是可选的。
Unicast frames in SPBM are encapsulated as per 802.1ah [PBB]. A Backbone Source Address (B-SA), Backbone Destination Address (B-DA), Backbone VLAN ID (B-VID), and an I-Component Service Instance ID (I-TAG) are used to encapsulate the Ethernet frame. The B-SA is a B-MAC associated with the ingress 802.1aq bridge, usually the "known" B-MAC of that entire bridge. The B-DA is one of the "known" B-MACs associated with the egress 802.1aq bridge. The B-VID and I-TAG are mapped based on the physical or logical UNI port (untagged, or tagged either by S-TAG or C-TAG) being bridged. Normal learning and
SPBM中的单播帧按照802.1ah[PBB]进行封装。主干源地址（B-SA）、主干目标地址（B-DA）、主干VLAN ID（B-VID）和I组件服务实例ID（I-TAG）用于封装以太网帧。B-SA是与入口802.1aq网桥相关联的B-MAC，通常是整个网桥的“已知”B-MAC。B-DA是与出口802.1aq网桥相关联的“已知”B-mac之一。B-VID和I-TAG根据桥接的物理或逻辑UNI端口（未标记，或通过S-TAG或C-TAG标记）进行映射。正常学习和
broadcast to unknown C-MACs is applied as per [PBB] at the ingress/egress SPBs only.
仅在入口/出口SPB处按照[PBB]应用对未知C-MAC的广播。
Unlike [PBB] on a (*,G) tree, the B-DA forwarding on tandem nodes (NNI to NNI) is performed without learning. Instead, the output of 802.1aq computations, based on the TLVs specified in this document, is used to populate the filtering databases (FDBs). The FDB entries map {B-DA, B-VID} to an outgoing interface and are only populated from the IS-IS database and computations.
与（*，G）树上的[PBB]不同，串联节点（NNI到NNI）上的B-DA转发是在没有学习的情况下执行的。相反，基于本文档中指定的TLV的802.1aq计算输出用于填充过滤数据库（FDB）。FDB条目将{B-DA，B-VID}映射到传出接口，并且仅从IS-IS数据库和计算填充。
The B-SA/B-VID is checked on tandem nodes against the ingress port. If the B-SA/B-VID (as a destination) entry in the FDB does not point to the port on which the packet arrived, the packet is discarded. This is referred to as an ingress check and serves as a very powerful loop mitigation mechanism.
在串联节点上对照入口端口检查B-SA/B-VID。如果FDB中的B-SA/B-VID（作为目的地）条目未指向数据包到达的端口，则丢弃该数据包。这称为入口检查，是一种非常强大的环路缓解机制。
Head-end replication is supported for instances where there is a sparse community of interest or a low likelihood of multicast traffic. Head-end replication requires no multicast state in the core. A UNI port wishing to use head-end replication Must Not advertise its I-SID membership with the Transmit (T) bit set but instead Must locally and dynamically construct the appropriate unicast serial replication to all the other receivers (Receive (R) bit set) of the same I-SID.
对于兴趣社区稀疏或多播流量可能性较低的情况，支持前端复制。头端复制不需要核心中的多播状态。希望使用头端复制的UNI端口不得使用传输（T）位集公布其I-SID成员资格，而是必须在本地和动态地构造到相同I-SID的所有其他接收器（接收（R）位集）的适当单播串行复制。
When an unknown customer unicast or a multicast frame arrives at an SPBM User-Network Interface (UNI) port that has been configured to replicate only at the head end, the packet is replicated once for each receiver, encapsulated, and sent as a unicast frame. The set of receivers is determined by inspecting the IS-IS database for other SPBs that have registered interest in the same I-SID with the R bit set. This R bit / I-SID pair is found in the SPBM Service Identifier and Unicast Address (SPBM-SI) sub-TLV. The packets are encapsulated as per the SPBM unicast forwarding above.
当未知客户单播或多播帧到达已配置为仅在前端复制的SPBM用户网络接口（UNI）端口时，将为每个接收器复制一次数据包，并将其封装并作为单播帧发送。接收器集是通过检查is-is数据库中是否有其他SPB在与R位集相同的I-SID中注册了兴趣来确定的。该R位/I-SID对位于SPBM服务标识符和单播地址（SPBM-SI）子TLV中。数据包按照上述SPBM单播转发进行封装。
Tandem replication uses the shortest path tree to replicate frames only where the tree forks and there is at least one receiver on each branch. Tandem replication is bandwidth efficient but uses multicast FDB entries (state) in core bridges, which might be unnecessary if there is little multicast traffic demand. The head-end replication mode is best suited for the case where there is little or no true multicast traffic for an I-SID. Tandem replication is triggered on transit nodes when the I-SID is advertised with the T bit set.
串联复制使用最短路径树仅在树分叉且每个分支上至少有一个接收器的情况下复制帧。串联复制具有带宽效率，但在核心网桥中使用多播FDB条目（状态），如果多播流量需求很少，则可能不需要这样做。头端复制模式最适合于I-SID几乎没有或根本没有真正的多播通信量的情况。当使用T位集播发I-SID时，在传输节点上触发串联复制。
Broadcast, unknown unicast, or multicast frames arriving at an SPBM UNI port are encapsulated with a B-DA multicast address that uniquely identifies the encapsulating node (the root of the Multicast Distribution Tree) and the I-SID scoping this multicast.
到达SPBM UNI端口的广播、未知单播或多播帧使用B-DA多播地址进行封装，该地址唯一标识封装节点（多播分发树的根）和该多播的I-SID范围。
This B-DA address is a well-formed multicast group address (as per 802.1Q and 802.1ah) that concatenates the SPSourceID A' with the I-SID M (written as DA=<A',M> and uniquely identifying the (S,G) tree). This exact format is given in Figure 1 below:
此B-DA地址是一个格式良好的多播组地址（根据802.1Q和802.1ah），它将SPSourceID a'与I-SID M（写为DA=<a'，M>，并唯一标识（S，G）树）。下面的图1给出了确切的格式：
M L TYP
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|1|0|0|SPSrcMS| SPSrc [8:15] | SPSrc [0:7] | I-SID [16:23] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| I-SID [8:15] | I-SID [0:7] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
M L TYP
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|1|0|0|SPSrcMS| SPSrc [8:15] | SPSrc [0:7] | I-SID [16:23] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| I-SID [8:15] | I-SID [0:7] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: SPBM Multicast Address Format (SPSrcMS represents SPSrc [16:19])
图1:SPBM多播地址格式（SPSrcMS表示SPSrc[16:19]）
Note: In Figure 1, the index numbering from less significant bit to more significant bit within a byte or field within a byte gives the wire order of the bits in the address consistent with the IETF format in the rest of this document. (The IEEE convention for number representation reverses the bits within an octet compared with IETF practice.)
注：在图1中，一个字节或一个字节内的字段中从低有效位到高有效位的索引编号给出了地址中位的连线顺序，与本文档其余部分中的IETF格式一致。（与IETF实践相比，IEEE数字表示公约将八位字节内的位反转。）
o M is the multicast bit, always set to 1 for a multicast DA. (It is the lowest bit in the most significant byte.)
o M是多播位，对于多播DA始终设置为1。（它是最高有效字节中的最低位。）
o L is the local bit, always set to 1 for an SPBM-constructed multicast DA.
o L是本地位，对于SPBM构造的多播DA，始终设置为1。
o TYP is the SPSourceID type. 00 is the only type supported at this time.
o TYP是SPSourceID类型。00是目前唯一受支持的类型。
o SPSrc (SPSourceID) is a 20-bit quantity that uniquely identifies a SPBM node for all B-VIDs allocated to SPBM operation. This is just the SPSourceID advertised in the SPB Instance (SPB-Inst) sub-TLV. The value SPSourceID = 0 has special significance; it is advertised by an SPBM node that has been configured to assign its SPSourceID dynamically, which requires LSDB synchronization, but where the SPSourceID assignment has not yet completed.
o SPSrc（SPSourceID）是一个20位的数量，它唯一地标识分配给SPBM操作的所有B-VID的SPBM节点。这只是SPB实例（SPB Inst）子TLV中公布的SPSourceID。SPSourceID=0的值具有特殊意义；它由SPBM节点播发，该节点已配置为动态分配其SPSourceID，这需要LSDB同步，但SPSourceID分配尚未完成。
o I-SID is the 24-bit I-Component Service ID advertised in the SPBM Service Identifier TLV. It occupies the lower 24 bits of the SPBM multicast DA. The I-SID value 0xfff is reserved for SPBM control traffic (refer to the default I-SID in [802.1aq]).
o I-SID是在SPBM服务标识符TLV中公布的24位I组件服务ID。它占用SPBM多播DA的较低24位。I-SID值0xfff是为SPBM控制流量保留的（请参阅[802.1aq]中的默认I-SID）。
This multicast address format is used as the DA on frames when they are first encapsulated at ingress to the SPBM network. The DA is also installed into the FDBs on all SPBM nodes that are on the corresponding SPT between the source and other nodes that have registered receiver interest in the same I-SID.
此多播地址格式在帧首次封装到SPBM网络入口时用作帧上的DA。DA还安装在源和在同一I-SID中注册了接收器兴趣的其他节点之间的对应SPT上的所有SPBM节点上的FDB中。
Just as with unicast forwarding, the B-SA/B-VID May be used to perform an ingress check, but the SPSourceID encoded in the DA and the "drop-on-unknown" functionality of the FDB in [PBB] achieve the same effect.
与单播转发一样，B-SA/B-VID可用于执行入口检查，但DA中编码的SPSourceID和[PBB]中FDB的“未知下降”功能实现相同的效果。
The I-Component at the egress SPBM device has completely standard [PBB] behavior and therefore will:
出口SPBM设备处的I组件具有完全标准的[PBB]行为，因此将：
1) learn the remote C-SA to B-SA relationship and
1) 了解远程C-SA到B-SA的关系，以及
2) bridge the original customer frame to the set of local UNI ports that are associated with the I-SID.
2) 将原始客户帧桥接到与I-SID关联的本地UNI端口集。
When a packet for an unknown DA arrives at an SPBV UNI port, VID translation (or VID encapsulation for untagged Frames) with the corresponding SPVID for this VLAN and ingress SPB is performed.
当未知DA的数据包到达SPBV UNI端口时，使用该VLAN和入口SPB的相应SPVID执行VID转换（或未标记帧的VID封装）。
SPVID forwarding is simply an SPT that follows normal VLAN forwarding behavior, with the exception that the SPVID is unidirectional. As a result, shared VLAN learning (SVL) is used between the forward- and reverse-path SPVIDs associated with the same Base VID to allow SPBV unicast forwarding to operate in the normal reverse learning fashion.
SPVID转发只是遵循正常VLAN转发行为的SPT，但SPVID是单向的除外。因此，共享VLAN学习（SVL）在与同一基本VID相关联的正向和反向路径SPVID之间使用，以允许SPBV单播转发以正常反向学习方式运行。
Ingress check is done by simply verifying that the bridge to which the SPVID has been assigned is indeed "shortest path" reachable over the link over which the packet tagged with that SPVID arrived. This is computed from the IS-IS database and is implied when the SPVID is associated with a specific incoming port.
入口检查是通过简单地验证分配了SPVID的网桥是否确实可以通过带有该SPVID标签的数据包到达的链路到达“最短路径”来完成的。这是从is-is数据库计算出来的，并且在SPVID与特定的传入端口关联时暗示。
When a packet for a known DA arrives at an SPBV UNI port, VID translation (or VID encapsulation for untagged Frames) with the corresponding SPVID for this VLAN and ingress bridge is performed.
当已知DA的数据包到达SPBV UNI端口时，使用该VLAN和入口网桥的相应SPVID执行VID转换（或未标记帧的VID封装）。
Since the SPVID will have been configured to follow a source-specific SPT and the DA is known, the packet will follow the source-specific path towards the destination C-MAC.
由于SPVID将被配置为跟随源特定的SPT并且DA是已知的，因此分组将跟随源特定的路径到达目的地C-MAC。
Ingress check is as per the previous SPBV section.
入口检查按照前面的SPBV章节进行。
C-DA multicast addresses May be advertised from SPBV UNI ports. These may be configured or learned through the Multiple MAC Registration Protocol (MMRP). MMRP is terminated at the edge of the SPBV network and IS-IS carries the multicast addresses. Tandem SPBV devices will check to see if they are on the SPF tree between SPBV UNI ports advertising the same C-DA multicast address, and if so will install multicast state to follow the SPBV SPF trees.
可以从SPBV UNI端口播发C-DA多播地址。这些可以通过多MAC注册协议（MMRP）进行配置或学习。MMRP在SPBV网络边缘终止，is-is承载多播地址。串联SPBV设备将检查它们是否位于SPBV UNI端口之间的SPF树上，这些端口宣传相同的C-DA多播地址，如果是，则将安装多播状态以遵循SPBV SPF树。
Ingress check is as per the previous two SPBV sections.
入口检查按照前两个SPBV章节进行。
Consider the small example network shown in Figure 2. Nodes are drawn in boxes with the last nibble of their B-MAC address :1..:7. The rest of the B-MAC address nibbles are 4455-6677-00xx. Links are drawn as "--" and "/", while the interface indexes are drawn as numbers next to the links. UNI ports are shown as "<==>" with the desired I-SID shown at the end of the UNI ports as "i1".
考虑图2所示的小示例网络。节点在框中绘制，其B-MAC地址的最后一个半字节为：1..:7。其余的B-MAC地址半字节是4455-6677-00xx。链接被绘制为“-”和“/”，而接口索引被绘制为链接旁边的数字。UNI端口显示为“<=>”，所需的I-SID显示在UNI端口的末尾为“i1”。
+----+ +----+
| :4 | 2 ------1 | :5 | <==> i1
+----+ +----+
1 3 3 2
/ \ / \
1 4 3 2
+----+ +----+ +----+
i1 <==> | :1 | 2----1 | :2 | 2------1 | :3 | <==> i1
+----+ +----+ +----+
3 6 5 3
\ / \ /
3 2 1 2
+----+ +----+
| :6 | 1-------3 | :7 | <==> i1
+----+ +----+
+----+ +----+
| :4 | 2 ------1 | :5 | <==> i1
+----+ +----+
1 3 3 2
/ \ / \
1 4 3 2
+----+ +----+ +----+
i1 <==> | :1 | 2----1 | :2 | 2------1 | :3 | <==> i1
+----+ +----+ +----+
3 6 5 3
\ / \ /
3 2 1 2
+----+ +----+
| :6 | 1-------3 | :7 | <==> i1
+----+ +----+
Figure 2: SPBM Example 7-Node Network
图2:SPBM示例7节点网络
Using the default ECT-ALGORITHM (00-80-C2-01), which picks the equal cost path with the lowest BridgeID, this ECT-ALGORITHM is assigned to B-VID 100. When all links have the same cost, then the 1-hop shortest paths are all direct and the 2-hop shortest paths (which are of course symmetric) are as follows:
使用默认的ECT算法（00-80-C2-01），选择具有最低BridgeID的等成本路径，将此ECT算法分配给B-VID 100。当所有链路的成本相同时，则1跳最短路径都是直接的，2跳最短路径（当然是对称的）如下所示：
{ 1-2-3, 1-2-5, 1-2-7, 6-2-5, 4-2-7, 4-1-6, 5-2-7, 6-2-3, 4-2-3 }
{ 1-2-3, 1-2-5, 1-2-7, 6-2-5, 4-2-7, 4-1-6, 5-2-7, 6-2-3, 4-2-3 }
Node :1's unicast forwarding table therefore routes toward B-MACs :7, :3, and :5 via interface/2, while its single-hop paths are all direct as can be seen from its FDB given in Figure 3.
因此，Node:1的单播转发表通过接口/2路由到B-MAC:7、:3和：5，而其单跳路径都是直接的，如图3中给出的FDB所示。
Node :1 originates multicast since it is at the head of the MDT to nodes :3, :5, and :7 and is a transmitter of I-SID 1, which nodes :3, :5, and :7 all wish to receive. Node :1 therefore produces a multicast forwarding entry whose DA contains its SPSourceID (which is the last 20 bits of the B-MAC in the example) and the I-SID 1. Node :1 thereafter sends packets matching this entry to interface if/2 with B-VID=100. Node :1's full unicast (U) and multicast (M) table is shown in Figure 3. Note that the IN/IF (incoming interface) field is not specified for unicast traffic, and for multicast traffic has to point back to the root of the tree, unless it is the head of the tree -- in which case, we use the convention if/00. Since node :1 is not transit for any multicast, it only has a single entry for the root of its tree for I-SID=1.
节点：1发起多播，因为它位于节点：3、：5和：7的MDT的头部，并且是节点：3、：5和：7都希望接收的I-SID 1的发送器。因此，Node:1生成一个多播转发条目，其DA包含其SPSourceID（在本例中是B-MAC的最后20位）和I-SID 1。节点：1随后将匹配此条目的数据包发送到接口if/2，B-VID=100。Node:1的完整单播（U）和多播（M）表如图3所示。请注意，IN/IF（传入接口）字段不是为单播通信量指定的，对于多播通信量，必须指向树的根，除非它是树的头——在这种情况下，我们使用约定IF/00。由于node:1不是任何多播的传输，因此对于I-SID=1，它的树根只有一个条目。
+-------+-------------------+------+-----------------+
| IN/IF | DESTINATION ADDR | BVID | OUT/IF(s) |
+-------+-------------------+------+-----------------+
U| if/** | 4455-6677-0002 | 0100 | {if/2 }
U| if/** | 4455-6677-0003 | 0100 | {if/2 }
U| if/** | 4455-6677-0004 | 0100 | {if/1 }
U| if/** | 4455-6677-0005 | 0100 | {if/2 }
U| if/** | 4455-6677-0006 | 0100 | {if/3 }
U| if/** | 4455-6677-0007 | 0100 | {if/2 }
M| if/00 | 7300-0100-0001 | 0100 | {if/2 }
+-------+-------------------+------+-----------------+
| IN/IF | DESTINATION ADDR | BVID | OUT/IF(s) |
+-------+-------------------+------+-----------------+
U| if/** | 4455-6677-0002 | 0100 | {if/2 }
U| if/** | 4455-6677-0003 | 0100 | {if/2 }
U| if/** | 4455-6677-0004 | 0100 | {if/1 }
U| if/** | 4455-6677-0005 | 0100 | {if/2 }
U| if/** | 4455-6677-0006 | 0100 | {if/3 }
U| if/** | 4455-6677-0007 | 0100 | {if/2 }
M| if/00 | 7300-0100-0001 | 0100 | {if/2 }
Figure 3: SPBM Node :1 FDB - Unicast (U) and Multicast (M)
Figure 3: SPBM Node :1 FDB - Unicast (U) and Multicast (M)
Node :2, being at the center of the network, has direct 1-hop paths to all other nodes; therefore, its unicast FDB simply sends packets with the given B-MAC/B-VID=100 to the interface directly to the addressed node. This can be seen by looking at the unicast entries (the first 6) shown in Figure 4.
节点：2位于网络的中心，具有到所有其他节点的直接1跳路径；因此，其单播FDB简单地将具有给定B-MAC/B-VID＝100的分组直接发送到接口到寻址节点。这可以通过查看图4中所示的单播条目（前6个）看到。
+-------+-------------------+------+-----------------+
| IN/IF | DESTINATION ADDR | BVID | OUT/IF(s) |
+-------+-------------------+------+-----------------+
U| if/** | 4455-6677-0001 | 0100 | {if/1 }
U| if/** | 4455-6677-0003 | 0100 | {if/2 }
U| if/** | 4455-6677-0004 | 0100 | {if/4 }
U| if/** | 4455-6677-0005 | 0100 | {if/3 }
U| if/** | 4455-6677-0006 | 0100 | {if/6 }
U| if/** | 4455-6677-0007 | 0100 | {if/5 }
M| if/01 | 7300-0100-0001 | 0100 | {if/2,if/3,if/5 }
M| if/02 | 7300-0300-0001 | 0100 | {if/1 }
M| if/03 | 7300-0500-0001 | 0100 | {if/1,if/5 }
M| if/05 | 7300-0700-0001 | 0100 | {if/1,if/3 }
+-------+-------------------+------+-----------------+
| IN/IF | DESTINATION ADDR | BVID | OUT/IF(s) |
+-------+-------------------+------+-----------------+
U| if/** | 4455-6677-0001 | 0100 | {if/1 }
U| if/** | 4455-6677-0003 | 0100 | {if/2 }
U| if/** | 4455-6677-0004 | 0100 | {if/4 }
U| if/** | 4455-6677-0005 | 0100 | {if/3 }
U| if/** | 4455-6677-0006 | 0100 | {if/6 }
U| if/** | 4455-6677-0007 | 0100 | {if/5 }
M| if/01 | 7300-0100-0001 | 0100 | {if/2,if/3,if/5 }
M| if/02 | 7300-0300-0001 | 0100 | {if/1 }
M| if/03 | 7300-0500-0001 | 0100 | {if/1,if/5 }
M| if/05 | 7300-0700-0001 | 0100 | {if/1,if/3 }
Figure 4: SPBM Node :2 FDB Unicast (U) and Multicast (M)
图4:SPBM节点：2 FDB单播（U）和多播（M）
Node :2's multicast is more complicated since it is a transit node for the 4 members of I-SID=1; therefore, it requires 4 multicast FDB entries depending on which member it is forwarding/replicating on behalf of. For example, node :2 is on the shortest path between each of nodes {:3, :5, :7} and :1. So it must replicate from node :1 I-SID 1 out on interfaces { if/2, if/3 and if/5 } (to reach nodes :3, :5, and :7). It therefore creates a multicast DA with the SPSourceID of node :1 together with I-SID=1, which it expects to receive over interface/1 and will replicate out interfaces { if/2, if/3 and if/5 }. This can be seen in the first multicast entry in Figure 4.
节点：2的多播更复杂，因为它是I-SID=1的4个成员的传输节点；因此，它需要4个多播FDB条目，这取决于它代表哪个成员进行转发/复制。例如，节点：2位于节点{：3、：5、：7}和：1之间的最短路径上。因此，它必须在接口{if/2、if/3和if/5}上从节点1 I-sid1复制出来（以到达节点3、5和7）。因此，它创建了一个多播DA，SPSourceID为node:1，I-SID=1，它希望通过接口/1接收，并将复制出接口{if/2、if/3和if/5}。这可以在图4中的第一个多播条目中看到。
Note that node :2 is not on the shortest path between nodes :3 and :5 nor between nodes :3 and :7; however, it still has to forward packets to node :1 from node :3 for this I-SID, which results in the second multicast forwarding entry in Figure 4. Likewise, for packets originating at nodes :5 or :7, node :2 only has to replicate twice, which results in the last two multicast forwarding entries in Figure 4.
请注意，节点：2不在节点：3和：5之间的最短路径上，也不在节点：3和：7之间的最短路径上；但是，对于这个I-SID，它仍然必须将数据包从节点3转发到节点1，这将导致图4中的第二个多播转发条目。同样，对于源自节点5或节点7的数据包，节点2只需复制两次，这导致图4中的最后两个多播转发条目。
Using the same example network as Figure 2, we will look at the FDBs produced for SPBV mode forwarding. Nodes :1, :5, :3, and :7 wish to transmit and receive the same multicast MAC traffic using multicast address 0300-0000-000f and at the same time require congruent and symmetric unicast forwarding. In SPBV mode, the only encapsulation is the C-TAG or S-TAG, and the MAC addresses SA and DA are reverse-path learned, as in traditional bridging.
使用与图2相同的示例网络，我们将查看为SPBV模式转发生成的FDB。节点：1、：5、：3和：7希望使用多播地址0300-0000-000f发送和接收相同的多播MAC流量，同时要求一致和对称的单播转发。在SPBV模式下，唯一的封装是C-TAG或S-TAG，MAC地址SA和DA是反向路径学习的，就像在传统桥接中一样。
+----+ +----+
| :4 | 2 ------1 | :5 | <==> MMAC ..:f
+----+ +----+
1 3 3 2
/ \ / \
1 4 3 2
+----+ +----+ +----+
MMAC<==> | :1 | 2----1 | :2 | 2------1 | :3 | <==> MMAC ..:f
..:f +----+ +----+ +----+
3 6 5 3
\ / \ /
3 2 1 2
+----+ +----+
| :6 | 1-------3 | :7 | <==> MMAC ..:f
+----+ +----+
+----+ +----+
| :4 | 2 ------1 | :5 | <==> MMAC ..:f
+----+ +----+
1 3 3 2
/ \ / \
1 4 3 2
+----+ +----+ +----+
MMAC<==> | :1 | 2----1 | :2 | 2------1 | :3 | <==> MMAC ..:f
..:f +----+ +----+ +----+
3 6 5 3
\ / \ /
3 2 1 2
+----+ +----+
| :6 | 1-------3 | :7 | <==> MMAC ..:f
+----+ +----+
Figure 5: SPBV Example 7-Node Network
图5:SPBV示例7节点网络
Assuming the same ECT-ALGORITHM (00-80-C2-01), which picks the equal cost path with the lowest BridgeID, this ECT-ALGORITHM is assigned to Base VID 100, and for each node the SPVID = Base VID + Node ID (i.e., 101, 102..107). When all links have the same cost, then the 1-hop shortest paths are all direct, and the 2-hop shortest paths (which are of course symmetric) are as previously given for Figure 2.
假设相同的ECT算法（00-80-C2-01）选择具有最低桥接ID的等成本路径，则该ECT算法被分配给基本VID 100，并且对于每个节点，SPVID=基本VID+节点ID（即101、102..107）。当所有链路的成本相同时，1跳最短路径都是直接的，2跳最短路径（当然是对称的）如图2所示。
Node :1's SPT for this ECT-ALGORITHM is therefore (described as a sequence of unidirectional paths):
因此，该ECT-1算法的节点：1的SPT为（描述为一系列单向路径）：
{ 1->4, 1->6, 1->2->3, 1->2->5, 1->2->7 }
{ 1->4, 1->6, 1->2->3, 1->2->5, 1->2->7 }
The FDBs therefore must have entries for the SPVID reserved for packets originating from node :1, which in this case is VID=101.
因此，fdb必须具有为源自节点1的数据包保留的SPVID条目，在本例中，该节点为VID＝101。
Node :2 therefore has an FDB that looks like Figure 6. In particular, it takes packets from VID 101 on interface/01 and sends to nodes :3, :5, and :7 via if/2, if/3, and if/5. It does not replicate anywhere else because the other nodes (:4 and :6) are reached by the SPT directly from node :1. The rest of the FDB unicast entries follow a similar pattern; recall that the shortest path between :4 and :6 is via node :1, which explains replication onto only two interfaces from if/4 and if/6. Note that the destination addresses are wild cards, and SVL exists between these SPVIDs because they are all associated with Base VID = 100, which defines the VLAN being bridged.
因此，节点2有一个类似于图6的FDB。特别地，它从接口/01上的VID 101获取数据包，并通过if/2、if/3和if/5发送到节点：3、：5和：7。它不会复制到其他任何地方，因为SPT直接从节点1到达其他节点（：4和：6）。其余的FDB单播条目遵循类似的模式；回想一下：4和：6之间的最短路径是通过节点：1，这解释了从if/4和if/6复制到两个接口的原因。请注意，目标地址是通配符，这些SPVID之间存在SVL，因为它们都与基本VID=100关联，基本VID=100定义了要桥接的VLAN。
+-------+-------------------+------+-----------------+
| IN/IF | DESTINATION ADDR | VID | OUT/IF(s) |
+-------+-------------------+------+-----------------+
U| if/01 | ************** | 0101 | {if/2,if/3,if/5 }
U| if/02 | ************** | 0103 | {if/1,if/4,if/6 }
U| if/04 | ************** | 0104 | {if/2,if/5 }
U| if/03 | ************** | 0105 | {if/1,if/5,if/6 }
U| if/06 | ************** | 0106 | {if/2,if/3 }
U| if/05 | ************** | 0107 | {if/1,if/3,if/4 }
+-------+-------------------+------+-----------------+
| IN/IF | DESTINATION ADDR | VID | OUT/IF(s) |
+-------+-------------------+------+-----------------+
U| if/01 | ************** | 0101 | {if/2,if/3,if/5 }
U| if/02 | ************** | 0103 | {if/1,if/4,if/6 }
U| if/04 | ************** | 0104 | {if/2,if/5 }
U| if/03 | ************** | 0105 | {if/1,if/5,if/6 }
U| if/06 | ************** | 0106 | {if/2,if/3 }
U| if/05 | ************** | 0107 | {if/1,if/3,if/4 }
Figure 6: SPBV Node :2 FDB Unicast
图6:SPBV节点：2 FDB单播
Now, since nodes :5, :3, :7 and :1 are advertising membership in the same multicast group address :f, Node 2 requires additional entries to replicate just to these specific nodes for the given multicast group address. These additional multicast entries are given below in Figure 7.
现在，由于节点：5、：3、：7和：1是同一多播组地址：f中的播发成员身份，因此节点2需要额外的条目，以便针对给定多播组地址仅复制到这些特定节点。这些额外的多播条目如图7所示。
+-------+-------------------+------+-----------------+
| IN/IF | DESTINATION ADDR | VID | OUT/IF(s) |
+-------+-------------------+------+-----------------+
M| if/01 | 0300-0000-000f | 0101 | {if/2,if/3,if/5 }
M| if/02 | 0300-0000-000f | 0103 | {if/1 }
M| if/03 | 0300-0000-000f | 0105 | {if/1,if/5 }
M| if/05 | 0300-0000-000f | 0107 | {if/1,if/3 }
+-------+-------------------+------+-----------------+
| IN/IF | DESTINATION ADDR | VID | OUT/IF(s) |
+-------+-------------------+------+-----------------+
M| if/01 | 0300-0000-000f | 0101 | {if/2,if/3,if/5 }
M| if/02 | 0300-0000-000f | 0103 | {if/1 }
M| if/03 | 0300-0000-000f | 0105 | {if/1,if/5 }
M| if/05 | 0300-0000-000f | 0107 | {if/1,if/3 }
Figure 7: SPBV Node :2 FDB Multicast (M)
图7:SPBV节点：2 FDB多播（M）
IS-IS for SPB currently only supports peer-to-peer adjacencies. Other link types are for future study. As a result, pseudonodes and links to/from pseudonodes are not considered as part of the IS-IS SPF computations and will be avoided if present in the physical topology. Other NLPIDs MAY of course use them as per normal.
IS-IS for SPB目前仅支持对等邻接。其他链接类型供将来研究。因此，伪节点和到/来自伪节点的链接不被视为IS-IS SPF计算的一部分，如果存在于物理拓扑中，则将避免。其他NLPID当然可以按照正常方式使用它们。
IS-IS for SPB Must use the IS-IS three-way handshake for IS-IS point-to-point adjacencies described in RFC 5303.
对于RFC 5303中描述的IS-IS点到点邻接，SPB的IS-IS必须使用IS-IS三向握手。
The default behavior of 802.1aq is to use the normal IS-IS Ethernet multicast addresses for IS-IS.
802.1aq的默认行为是使用is-is的正常is-is以太网多播地址。
There are however additional Ethernet multicast addresses that have been assigned for 802.1aq for special use cases. These do not in any way change the state machinery or packet formats of IS-IS but simply
但是，在特殊情况下，为802.1aq分配了额外的以太网多播地址。这些不会以任何方式改变IS-IS的状态机制或数据包格式，只是
recommend and reserve different multicast addresses. Refer to [802.1aq] for additional details.
建议并保留不同的多播地址。有关更多详细信息，请参阅[802.1aq]。
A stand-alone implementation (supporting ONLY the single NLPID=0xC1) of SPB Must use an IS-IS area address value of 0, and the SYSID Must be the well-known MAC address of the SPB device.
SPB的独立实现（仅支持单个NLPID=0xC1）必须使用IS-IS区域地址值0，并且SYSID必须是SPB设备的已知MAC地址。
Non-stand-alone implementations (supporting other NLPIDs) MUST use the normal IS-IS rules for the establishment of a level 1 domain (i.e., multiple area addresses are allowed only where immediate adjacencies share a common area address). Level 2 operations of course place no such restriction on adjacent area addresses.
非独立实现（支持其他NLPID）必须使用正常IS-IS规则来建立1级域（即，仅当直接邻接共享公共区域地址时，才允许使用多个区域地址）。2级操作当然不会对相邻区域地址进行此类限制。
SPBV and SPBM will operate within either an IS-IS level 1 or level 2. As a result, the TLVs specified here MAY propagate in either level 1 or level 2 LSPs. IS-IS SPB implementations Must support level 1 and May support level 2 operations. Hierarchical SPB is for further study; therefore, these TLVs Should Not be leaked between level 1 and level 2.
SPBV和SPBM将在IS-IS 1级或2级内运行。因此，此处指定的TLV可能在1级或2级LSP中传播。IS-IS SPB实施必须支持级别1，并且可能支持级别2操作。层次SPB有待进一步研究；因此，这些TLV不应在1级和2级之间泄漏。
The default algorithm is ECT-Algorithm = 00-80-c2-01.
默认算法为ECT算法=00-80-c2-01。
Two mechanisms are used to ensure symmetry and determinism in the shortest path calculations.
两种机制用于确保最短路径计算中的对称性和确定性。
The first mechanism addresses the problem when different ends (nodes) of an adjacency advertise different values for the SPB-LINK-METRIC. To solve this, SPB shortest path calculations Must use the maximum value of the two nodes' advertised SPB-LINK-METRICs when accumulating and minimizing the (sub)path costs.
第一种机制解决了相邻关系的不同端点（节点）为SPB-LINK-METRIC公布不同值时的问题。为了解决这个问题，在累积和最小化（子）路径成本时，SPB最短路径计算必须使用两个节点公布的SPB链路度量的最大值。
The second mechanism addresses the problem when two equal sums of link metrics (sub)paths are found. To solve this, the (sub)path with the fewest hops between the fork/join points Must win the tie. However, if both (sub)paths have the same number of hops between the fork and join points, then the default tie-breaking Must pick the path traversing the intermediate node with the lower BridgeID. The BridgeID is an 8-byte quantity whose upper 2 bytes are the node's BridgePriority and lower 6 bytes are the node's SYSID.
第二种机制解决了当找到两个相等的链路度量（子）路径和时的问题。要解决这个问题，分叉点/连接点之间跳数最少的（子）路径必须赢得平局。但是，如果两条（子）路径在分叉点和连接点之间具有相同的跳数，则默认的断开连接必须拾取穿过具有较低BridgeID的中间节点的路径。BridgeID是一个8字节的数量，其上2个字节是节点的BridgePriority，下6个字节是节点的SYSID。
For example, consider the network in Figure 2 when a shortest path computation is being done from node :1. Upon reaching node :7, two competing sub-paths fork at node :1 and join at node :7, the first via :2 and the second via :6. Assuming that all the nodes advertise a Bridge Priority of 0, the default tie-breaking rule causes the path traversing node :2 to be selected since it has a lower BridgeID {0...:2} than node :6 {0...:6}. Note that the operator may cause the tie-breaking logic to pick the alternate path by raising the Bridge Priority of node :2 above that of node :6.
例如，考虑图2中的网络，当从节点1进行最短路径计算时。当到达节点7时，两个相互竞争的子路径在节点1处分叉并在节点7处连接，第一个过孔2和第二个过孔6。假设所有节点都公布网桥优先级为0，默认的断开连接规则会导致选择路径遍历节点：2，因为它的BridgeID{0…：2}低于节点：6{0…：6}。请注意，操作员可能会通过将节点2的网桥优先级提高到节点6的网桥优先级之上，从而导致断开连接逻辑选择备用路径。
The above algorithm guarantees symmetric and deterministic results in addition to having the critical property of transitivity (shortest path is made up of sub-shortest paths).
上述算法除了具有传递性（最短路径由次最短路径组成）的关键特性外，还保证了结果的对称性和确定性。
Standard ECT Algorithms initially have been proposed ranging from 00-80-c2-01 to 00-80-c2-10.
最初提出的标准ECT算法范围从00-80-c2-01到00-80-c2-10。
To create diversity in routing, SPB defines 16 variations on the above default tie-breaking algorithm; these have worldwide unique designations 00-80-C2-01 through 00-80-C2-10. These designations consist of the IEEE 802.1 OUI (Organizationally Unique Identifier) value 00-80-C2 concatenated with indexes 0X01..0X10. These individual algorithms are implemented by selecting the (sub)path with the lowest value of:
为了在路由中创造多样性，SPB在上述默认的中断连接算法上定义了16种变体；它们具有全球唯一的名称00-80-C2-01至00-80-C2-10。这些名称由IEEE 802.1 OUI（组织唯一标识符）值00-80-C2和索引0X01..0X10组成。这些单独的算法通过选择（子）路径来实现，该路径的最小值为：
XOR BYTE BY BYTE(ECT-MASK{ECT-ALGORITHM.index},BridgeID)
XOR BYTE BY BYTE(ECT-MASK{ECT-ALGORITHM.index},BridgeID)
Where:
哪里：
ECT-MASK{17} = { 0x00, 0x00, 0xFF, 0x88,
0x77, 0x44, 0x33, 0xCC,
0xBB, 0x22, 0x11, 0x66,
0x55, 0xAA, 0x99, 0xDD,
0xEE };
ECT-MASK{17} = { 0x00, 0x00, 0xFF, 0x88,
0x77, 0x44, 0x33, 0xCC,
0xBB, 0x22, 0x11, 0x66,
0x55, 0xAA, 0x99, 0xDD,
0xEE };
XOR BYTE BY BYTE - XORs BridgeID bytes with ECT-MASK
逐字节异或-带ECT-MASK的异或BridgeID字节
ECT-MASK{1}, since it XORs with all zeros, yields the default algorithm described above (00-80-C2-01); while ECT-MASK{2}, since it XORs with a mask of all ones, will invert the BridgeID, essentially picking the path traversing the largest Bridge ID. The other ECT-MASKs produce diverse alternatives. In all cases, the BridgePriority, since it is the most significant part of the BridgeID, permits overriding the SYSID as the selection criteria and gives the operator a degree of control on the chosen ECT paths.
ECT-MASK{1}，因为它与所有零进行异或运算，所以产生上述默认算法（00-80-C2-01）；而ECT-MASK{2}，因为它与所有的掩码异或，将反转BridgeID，实质上选择穿过最大桥接ID的路径。其他ECT掩码产生不同的选择。在所有情况下，由于BridgePriority是BridgeID的最重要部分，因此它允许覆盖SYSID作为选择标准，并为操作员提供对所选ECT路径的一定程度的控制。
To support many other tie-breaking mechanisms in the future, two opaque ECT TLVs are defined, which may be used to provide parameters to ECT-ALGORITHMs outside of the currently defined space.
为了支持将来的许多其他打破联系的机制，定义了两个不透明的ECT TLV，可用于在当前定义的空间之外为ECT算法提供参数。
ECT-ALGORITHMs are mapped to VIDs, and then services can be assigned to those VIDs. This permits a degree of traffic engineering since service assignment to VID is consistent end to end through the network.
ECT算法映射到VID，然后可以将服务分配给这些VID。这允许一定程度的流量工程，因为VID的服务分配通过网络端到端是一致的。
IEEE 802.1aq can run in parallel with other network layer protocols such as IPv4 and IPv6; therefore, failure of two SPB nodes to establish an adjacency MUST NOT cause rejection of an adjacency for the purposes of other network layer protocols.
IEEE 802.1aq可以与其他网络层协议（如IPv4和IPv6）并行运行；因此，两个SPB节点未能建立邻接不得导致出于其他网络层协议的目的拒绝邻接。
IEEE 802.1aq has been assigned the NLPID value 0xC1 [RFC6328], which MUST be used by Shortest Path Bridges (SPBs) to indicate their ability to run 802.1aq. This is done by including this NLPID value in the IS-IS IIH PDU Protocols Supported TLV (type 129). 802.1aq frames MUST only flow on adjacencies that advertise this NLPID in both directions of the IIH PDUs. 802.1aq computations MUST consider an adjacency that has not advertised 0xC1 NLPID in both directions as non-existent (infinite link metric) and MUST ignore any IIH SPB TLVs they receive over such adjacencies.
IEEE 802.1aq已分配NLPID值0xC1[RFC6328]，最短路径网桥（SPB）必须使用该值来指示其运行802.1aq的能力。这是通过将此NLPID值包含在支持TLV（类型129）的is-is IIH PDU协议中来实现的。802.1aq帧必须仅在IIH PDU的两个方向上公布此NLPID的邻接上流动。802.1aq计算必须考虑没有在两个方向上广告0xC1nLPID的邻接（不存在链路度量），并且必须忽略它们在这样的邻接处接收的任何IIH SPB TLVs。
IEEE 802.1aq augments the normal IIH PDU with three new TLVs, which like all other SPB TLVs, travel within Multi-Topology [MT] TLVs, therefore allowing multiple logical instances of SPB within a single IS-IS protocol instance.
IEEE 802.1aq使用三个新的TLV（与所有其他SPB TLV一样，在多拓扑[MT]TLV中移动）来扩展普通IIH PDU，因此允许在单个IS-IS协议实例中使用SPB的多个逻辑实例。
Since SPB can use many VIDs and Must agree on which VIDs are used for which purposes, the IIH PDUs carry a digest of all the used VIDs (on the NNIs) referred to as the SPB-MCID TLV, which uses a common and compact encoding reused from 802.1Q.
由于SPB可以使用许多VID，并且必须就使用哪些VID的目的达成一致，IIH PDU携带了所有使用的VID（在NNI上）的摘要，称为SPB-MCID TLV，它使用了从802.1Q重新使用的通用压缩编码。
SPB neighbors May support a mechanism to verify that the contents of their topology databases are synchronized (for the purposes of loop prevention). This is done by exchanging a digest of SPB topology information (computed over all MT IDs) and taking specific actions on forwarding entries when the digests indicate a mismatch in topology. This digest is carried in the Optional SPB-Digest sub-TLV.
SPB邻居可能支持一种机制，以验证其拓扑数据库的内容是否同步（为了防止循环）。这是通过交换SPB拓扑信息摘要（在所有MT ID上计算）并在摘要指示拓扑不匹配时对转发条目采取特定操作来完成的。该摘要包含在可选的SPB摘要子TLV中。
Finally, SPB needs to know which SPT Sets (defined by ECT-ALGORITHMs) are being used by which VIDs, and this is carried in the Base VLAN Identifiers (SPB-B-VID) sub-TLV.
最后，SPB需要知道哪些VID正在使用哪些SPT集（由ECT算法定义），这在基本VLAN标识符（SPB-B-VID）子TLV中进行。
This sub-TLV is added to an IIH PDU to indicate the digest for the multiple spanning tree configuration a.k.a. MCID. This TLV is a digest of local configuration of which VIDs are running which protocols. (The information is not to the level of a specific algorithm in the case of SPB.) This information Must be the same on all bridges in the SPT Region controlled by an IS-IS instance. The data used to generate the MCID is populated by configuration and is a digest of the VIDs allocated to various protocols. Two MCIDs are carried to allow non-disruptive transitions between configurations when the changes are non-critical.
该子TLV被添加到IIH PDU中，以指示多生成树配置（又称MCID）的摘要。此TLV是哪些VID正在运行哪些协议的本地配置摘要。（在SPB的情况下，该信息不属于特定算法的级别。）在由is-is实例控制的SPT区域内的所有网桥上，该信息必须相同。用于生成MCID的数据由配置填充，是分配给各种协议的VID摘要。带有两个MCID，以便在更改非关键性时在配置之间进行无中断转换。
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=SPB-MCID | = 4
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MCID (51 Bytes) |
| ............... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Aux MCID (51 Bytes) |
| ............... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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=SPB-MCID | = 4
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MCID (51 Bytes) |
| ............... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Aux MCID (51 Bytes) |
| ............... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: sub-TLV type 4.
o 类型：子TLV类型4。
o Length: The size of the value defined below (102).
o 长度：下面定义的值的大小（102）。
o MCID (51 bytes): The complete MCID defined in IEEE 802.1Q, which identifies an SPT Region on the basis of matching assignments of VIDs to control regimes (xSTP, SPBV, SPBM, etc.). Briefly, the MCID consists of a 1-byte format selector, a 32-byte configuration name, a 2-byte revision level, and finally a 16-byte signature of type HMAC-MD5 over an array of 4096 elements that contain identifiers of the use of the corresponding VID. Refer to Section 13.8 of [802.1aq] for the exact format and procedure. Note that the use of the VID does not include specification of a specific SPB ECT-ALGORITHM; rather, it is coarser grain.
o MCID（51字节）：IEEE 802.1Q中定义的完整MCID，它根据VID与控制机制（xSTP、SPBV、SPBM等）的匹配分配来识别SPT区域。简单地说，MCID由一个1字节格式选择器、一个32字节配置名称、一个2字节版本级别，最后是一个HMAC-MD5类型的16字节签名组成，该签名覆盖4096个元素的数组，其中包含相应VID的使用标识符。有关确切的格式和程序，请参阅[802.1aq]第13.8节。注意，VID的使用不包括特定SPB-ECT算法的规范；相反，它是较粗的颗粒。
o Aux MCID (51 bytes): The complete MCID defined in IEEE 802.1Q, which identifies an SPT Region. The aux MCID allows SPT Regions to be migrated by the allocation of new VLAN to FDB Mappings without interruption to existing traffic.
o Aux MCID（51字节）：IEEE 802.1Q中定义的完整MCID，用于标识SPT区域。aux MCID允许通过分配新的VLAN到FDB映射来迁移SPT区域，而不会中断现有流量。
The SPB-MCID sub-TLV is carried within the MT-Port-Cap TLV [RFC6165] with the MT ID value of 0, which in turn is carried in an IIH PDU.
SPB-MCID子TLV在MT端口帽TLV[RFC6165]内携带，MT ID值为0，然后在IIH PDU中携带。
This sub-TLV is Optionally added to an IIH PDU to indicate the current SPB topology digest value. It is always carried in an MT-Port-Cap TLV [RFC6165] with an MT ID value of 0. This information should settle to be the same on all bridges in an unchanging topology. Matching digests indicate (with extremely high probability) that the topology view between two SPBs is synchronized; this match (or lack of match) is used to control the updating of forwarding information. The SPB Agreement Digest is computed based on contributions derived from the current topologies of all SPB MT instances and is designed to change when significant topology changes occur within any SPB instance.
该子TLV可选择性地添加到IIH PDU，以指示当前SPB拓扑摘要值。它始终携带在MT端口帽TLV[RFC6165]中，MT ID值为0。在不变拓扑中的所有网桥上，此信息应该是相同的。匹配摘要表明（极有可能）两个SPB之间的拓扑视图是同步的；此匹配（或不匹配）用于控制转发信息的更新。SPB协议摘要基于从所有SPB MT实例的当前拓扑中得出的贡献进行计算，并设计为在任何SPB实例内发生重大拓扑更改时进行更改。
During the propagation of LSPs, the Agreement Digest may vary between neighbors until the key topology information in the LSPs is common. The digest is therefore a summarized means of determining agreement between nodes on database commonality, and hence of inferring agreement on the distance to all multicast roots. When present, it is used for loop prevention as follows: for each shortest path tree where it has been determined the distance to the root has changed, "unsafe" multicast forwarding is blocked until the exchanged Agreement Digests match, while "safe" multicast forwarding is allowed to continue despite the disagreement in digests and hence topology views. Section 28.2 of [802.1aq] defines in detail what constitutes "safe" vs. "unsafe".
在lsp的传播期间，协议摘要可能在邻居之间变化，直到lsp中的密钥拓扑信息是公共的。因此，摘要是确定节点之间在数据库公共性上的一致性，从而推断到所有多播根的距离的一致性的一种概括方法。当存在时，它用于循环预防，如下所示：对于每个已确定到根的距离已更改的最短路径树，“不安全”多播转发被阻止，直到交换的协议摘要匹配，而“安全”尽管在摘要和拓扑视图中存在分歧，但允许多播转发继续。[802.1aq]第28.2节详细定义了“安全”与“不安全”的构成。
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=SPB-Digest| = 5
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-----+-+---+---+
| Res |V| A | D | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Agreement Digest (Length - 1) |
| ............... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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=SPB-Digest| = 5
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-----+-+---+---+
| Res |V| A | D | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Agreement Digest (Length - 1) |
| ............... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: sub-TLV type 5.
o 类型：子TLV类型5。
o Length: The size of the value.
o 长度：值的大小。
o V bit: Agreed digest valid bit. See Section 28.2 of [802.1aq].
o V位：有效位。参见[802.1aq]第28.2节。
o A (2 bits): The Agreement Number 0-3, which aligns with the BPDU's Agreement Number concept [802.1aq]. When the Agreement Digest for this node changes, this number is incremented. The node then checks for Agreement Digest match (as below). The new local Agreement Number and the updated local Discarded Agreement Number are then transmitted with the new Agreement Digest to the node's neighbors in the Hello PDU. Once an Agreement Number has been sent, it is considered outstanding until a matching or more recent Discarded Agreement Number is received from the neighbor.
o A（2位）：协议编号0-3，与BPDU的协议编号概念[802.1aq]一致。当此节点的协议摘要更改时，此数字将递增。然后，节点检查协议摘要匹配（如下所示）。然后，新的本地协议号和更新的本地丢弃协议号与新协议摘要一起传输到Hello PDU中节点的邻居。一旦发送了协议号，则在从邻居接收到匹配的或最近丢弃的协议号之前，该协议号被视为未完成。
o D (2 bits): The Discarded Agreement Number 0-3, which aligns with BPDU's Agreement Number concept. When an Agreement Digest is received from a neighbor, this number is set to the received Agreement Number to signify that this node has received this new agreement and discarded any previous ones. The node then checks whether the local and received Agreement Digests match. If they do, this node then sets:
o D（2位）：丢弃的协议号0-3，与BPDU的协议号概念一致。当从邻居处接收到协议摘要时，此编号被设置为接收到的协议编号，以表示此节点已接收到此新协议并丢弃了任何以前的协议。然后，节点检查本地和接收的协议摘要是否匹配。如果有，则此节点将设置：
the local Discarded Agreement Number = received Agreement Number + 1
本地丢弃的协议编号=收到的协议编号+1
If the Agreement Digests match, AND received Discarded Agreement Number == local Agreement Number + N (N = 0 || 1)
如果协议摘要匹配，并收到丢弃的协议号==本地协议号+N（N=0 | | 1）
then the node has a topology matched to its neighbor.
然后，节点具有与其邻居匹配的拓扑。
Whenever the local Discarded Agreement Number relating to a neighbor changes, the local Agreement Digest, Agreement Number, and Discarded Agreement Number are transmitted.
每当与邻居相关的本地丢弃的协议号发生变化时，就会传输本地协议摘要、协议号和丢弃的协议号。
o Agreement Digest. This digest is used to determine when SPB is synchronized between neighbors for all SPB instances. The Agreement Digest is a hash computed over the set of all SPB adjacencies in all SPB instances. In other words, the digest includes all VIDs and all adjacencies for all MT instances of SPB (but not other network layer protocols). This reflects the fact that all SPB nodes in a region Must have identical VID allocations (see Section 13.1), and so all SPB instances will contain the same set of nodes. The exact procedure for computing the Agreement Digest and its size are defined in Section 28.2 of [802.1aq].
o 协议摘要。此摘要用于确定何时在所有SPB实例的邻居之间同步SPB。协议摘要是在所有SPB实例中的所有SPB邻接集合上计算的哈希。换句话说，摘要包括SPB的所有MT实例的所有VID和所有邻接（但不包括其他网络层协议）。这反映了一个事实，即一个区域中的所有SPB节点必须具有相同的VID分配（参见第13.1节），因此所有SPB实例将包含相同的节点集。[802.1aq]第28.2节规定了计算协议摘要及其大小的确切程序。
The SPB-Digest sub-TLV is carried within the MT-Port-Cap TLV [RFC6165] (with the MT ID value 0), which in turn is carried in an IIH PDU.
SPB摘要子TLV在MT端口Cap TLV[RFC6165]（MT ID值为0）内携带，然后在IIH PDU中携带。
When supported, this sub-TLV MUST be carried on every IIH between SPB neighbors, not just when a Digest changes.
支持时，必须在SPB邻居之间的每个IIH上执行此子TLV，而不仅仅是在摘要更改时。
When one peer supports this TLV and the other does not, loop prevention by Agreement Digest Must Not be done by either side.
当一个对等方支持此TLV而另一个不支持时，任何一方都不能通过协议摘要进行环路预防。
This sub-TLV is added to an IIH PDU to indicate the mappings between ECT algorithms and Base VIDs (and by implication the VID(s) used on the forwarding path for each SPT Set for a VLAN identified by a Base VID) that are in use. Under stable operational conditions, this information should be the same on all bridges in the topology identified by the MT-Port-Cap TLV [RFC6165] it is being carried within.
该子TLV被添加到IIH PDU，以指示ECT算法和正在使用的基本VID之间的映射（以及暗示在转发路径上为基本VID标识的VLAN的每个SPT集使用的VID）。在稳定运行条件下，该信息在MT Port Cap TLV[RFC6165]识别的拓扑中的所有网桥上都应相同。
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= SPB-B-VID| = 68
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-----------------------------------------------+
| ECT-VID Tuple (1) (6 bytes) |
+---------------------------------+-----------------------------+
| ... | ECT-VID Tuple(2) (6 bytes) |
+---------------------------------+-----------------------------+
| ..... |
+---------------------------------------------------------------+
| ..... |
| ..... |
+---------------------------------------------------------------+
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= SPB-B-VID| = 68
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-----------------------------------------------+
| ECT-VID Tuple (1) (6 bytes) |
+---------------------------------+-----------------------------+
| ... | ECT-VID Tuple(2) (6 bytes) |
+---------------------------------+-----------------------------+
| ..... |
+---------------------------------------------------------------+
| ..... |
| ..... |
+---------------------------------------------------------------+
o Type: sub-TLV type 6.
o 类型：子TLV类型6。
o Length: The size of the value is ECT-VID Tuples*6 bytes. Each 6-byte part of the ECT-VID tuple is formatted as follows:
o 长度：值的大小为ECT-VID元组*6字节。ECT-VID元组的每个6字节部分的格式如下：
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECT-ALGORITHM (32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Base VID (12 bits) |U|M|RES|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECT-ALGORITHM (32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Base VID (12 bits) |U|M|RES|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o ECT-ALGORITHM (4 bytes): The ECT-ALGORITHM is advertised when the bridge supports a given ECT-ALGORITHM (by OUI/Index) on a given Base VID. There are 17 predefined IEEE algorithms for SPB with index values 0X00..0X10 occupying the low 8 bits and the IEEE OUI=00-80-C2 occupying the top 24 bits of the ECT-ALGORITHM.
o ECT-ALGORITHM（4字节）：当网桥在给定的基本VID上支持给定的ECT-ALGORITHM（通过OUI/索引）时，会公布ECT-ALGORITHM。SPB有17种预定义的IEEE算法，索引值0X00..0X10占用低8位，IEEE OUI=00-80-C2占用ECT-C算法的前24位。
o Base VID (12 bits): The Base VID that is associated with the SPT Set.
o 基本视频（12位）：与SPT集关联的基本视频。
o Use-Flag (1 bit): The Use-Flag is set if this bridge, or any bridge in the LSDB, is currently using this ECT-ALGORITHM and Base VID. Remote usage is discovered by inspection of the U bit in the SPB-Inst sub-TLV of other SPB bridges (see Section 14.1)
o 使用标志（1位）：如果此网桥或LSDB中的任何网桥当前正在使用此ECT算法和基本VID，则设置使用标志。通过检查其他SPB桥的SPB Inst子TLV中的U位发现远程使用（见第14.1节）
o M bit (1 bit): The M bit indicates if this Base VID operates in SPBM (M = 1) or SPBV (M = 0) mode.
o M位（1位）：M位指示此基本VID是否在SPBM（M=1）或SPBV（M=0）模式下工作。
The SPB-B-VID sub-TLV is carried within the MT-Port-Cap TLV [RFC6165], which in turn is carried in an IIH PDU.
SPB-B-VID子TLV在MT端口帽TLV[RFC6165]内承载，而MT端口帽TLV又在IIH PDU中承载。
All SPB nodal information extensions travel within a new multi-topology capability TLV MT-Capability (type 144).
所有SPB节点信息扩展在新的多拓扑能力TLV MT能力（144型）内运行。
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 = MT-CAP | = 144
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|O R R R| MT ID | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(sub-TLVs ... )
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 = MT-CAP | = 144
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|O R R R| MT ID | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(sub-TLVs ... )
The format of this TLV is identical in its first 2 bytes to all current MT TLVs and carries the MT ID as defined in [MT].
此TLV的格式在其前2个字节中与所有当前MT TLV相同，并携带[MT]中定义的MT ID。
The O (overload) bit carried in bit 16 has the same semantics as specified in [MT], but in the context of SPB adjacencies only.
位16中携带的O（重载）位具有与[MT]中指定的相同语义，但仅在SPB邻接上下文中。
There can be multiple MT-Capability TLVs present, depending on the amount of information that needs to be carried.
根据需要携带的信息量，可能存在多个MT能力TLV。
The SPB-Inst sub-TLV gives the SPSourceID for this node/topology instance. This is the 20-bit value that is used in the formation of multicast DAs for frames originating from this node/instance. The SPSourceID occupies the upper 20 bits of the multicast DA together with 4 other bits (see the SPBM 802.1ah multicast DA address format section). This sub-TLV MUST be carried within the MT-Capability TLV in the fragment ZERO LSP. If there is an additional SPB instance, it
SPB Inst子TLV提供此节点/拓扑实例的SPSourceID。这是20位的值，用于形成多播DAs，用于来自此节点/实例的帧。SPSourceID与其他4位一起占用多播DA的上20位（请参阅SPBM 802.1ah多播DA地址格式部分）。该子TLV必须在零碎片LSP中的MT能力TLV内携带。如果存在其他SPB实例，则
MUST be declared under a separate MT-Capability TLV and also carried in the fragment ZERO LSP.
必须在单独的MT能力TLV下声明，并在零LSP片段中携带。
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 = SPB-Inst| = 1
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CIST Root Identifier (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CIST Root Identifier (cont) (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CIST External Root Path Cost (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bridge Priority | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R R R R R R R R R R R|V| SPSourceID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Num of Trees | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VLAN-ID (1) Tuples (8 bytes) |
| ........................... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...........................
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VLAN-ID (N) Tuples (8 bytes) |
| ........................... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 = SPB-Inst| = 1
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CIST Root Identifier (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CIST Root Identifier (cont) (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CIST External Root Path Cost (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bridge Priority | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R R R R R R R R R R R|V| SPSourceID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Num of Trees | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VLAN-ID (1) Tuples (8 bytes) |
| ........................... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...........................
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VLAN-ID (N) Tuples (8 bytes) |
| ........................... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where VLAN-ID tuples have the format as:
其中VLAN-ID元组的格式为：
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
+-+-+-+-+-+-+-+-+
|U|M|A| Res |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECT-ALGORITHM (32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Base VID (12 bits) | SPVID (12 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+
|U|M|A| Res |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECT-ALGORITHM (32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Base VID (12 bits) | SPVID (12 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: sub-TLV type 1.
o 类型：子TLV类型1。
o Length: Total number of bytes contained in the value field.
o 长度：值字段中包含的总字节数。
o CIST Root Identifier (64 bits): The CIST Root Identifier is for SPB interworking with Rapid STP (RSTP) and Multiple STP (MSTP) at SPT Region boundaries. This is an imported value from a spanning tree.
o CIST根标识符（64位）：CIST根标识符用于SPB在SPT区域边界与Rapid STP（RSTP）和多个STP（MSTP）互通。这是从生成树导入的值。
o CIST External Root Path Cost (32 bits): The CIST External Root Path Cost is the cost to root, derived from the spanning tree algorithm.
o CIST外部根路径成本（32位）：CIST外部根路径成本是根的成本，源自生成树算法。
o Bridge Priority (16 bits): Bridge priority is the 16 bits that together with the 6 bytes of the System ID form the Bridge Identifier. This allows SPB to build a compatible spanning tree using link state by combining the Bridge Priority and the System ID to form the 8-byte Bridge Identifier. The 8-byte Bridge Identifier is also the input to the 16 predefined ECT tie-breaker algorithms.
o 网桥优先级（16位）：网桥优先级是16位，与系统ID的6个字节一起构成网桥标识符。这允许SPB通过组合网桥优先级和系统ID来形成8字节网桥标识符，使用链路状态构建兼容的生成树。8字节的网桥标识符也是16个预定义ECT连接断路器算法的输入。
o V bit (1 bit): The V bit (SPBM) indicates this SPSourceID is auto-allocated (Section 27.11 of [802.1aq]). If the V bit is clear, the SPSourceID has been configured and Must be unique. Allocation of SPSourceID is defined in IEEE [802.1aq]. Bridges running SPBM will allocate an SPSourceID if they are not configured with an explicit SPSourceID. The V bit allows neighbor bridges to determine if the auto-allocation was enabled. In the rare chance of a collision of SPsourceID allocation, the bridge with the highest priority Bridge Identifier will win conflicts. The lower priority bridge will be re-allocated; or, if the lower priority bridge is configured, it will not be allowed to join the SPT Region.
o V位（1位）：V位（SPBM）表示该SPSourceID是自动分配的（见[802.1aq]第27.11节）。如果V位是清除的，则SPSourceID已配置且必须是唯一的。SPSourceID的分配在IEEE[802.1aq]中定义。如果未使用显式SPSourceID配置运行SPBM的网桥，则它们将分配SPSourceID。V位允许相邻网桥确定是否启用了自动分配。在SPsourceID分配发生冲突的罕见机会中，具有最高优先级网桥标识符的网桥将赢得冲突。较低优先级的网桥将被重新分配；或者，如果配置了低优先级网桥，则不允许其加入SPT区域。
o SPSourceID: a 20-bit value used to construct multicast DAs as described below for multicast frames originating from the origin (SPB node) of the Link State Packet (LSP) that contains this TLV. More details are in IEEE [802.1aq].
o SPSourceID：一个20位的值，用于为源自包含此TLV的链路状态数据包（LSP）的源（SPB节点）的多播帧构建多播DAs，如下所述。更多详细信息请参见IEEE[802.1aq]。
o Number of Trees (8 bits): The Number of Trees is set to the number of {ECT-ALGORITHM, Base VID plus flags} tuples that follow. Each ECT-ALGORITHM has a Base VID, an SPVID, and flags described below. This Must contain at least the one ECT-ALGORITHM (00-80-C2-01).
o 树数（8位）：树数设置为后面的{ECT-ALGORITHM，Base VID plus flags}元组数。每个ECT算法都有一个基本VID、一个SPVID和下面描述的标志。这必须至少包含一个ECT算法（00-80-C2-01）。
Each VID Tuple consists of:
每个视频元组包括：
o U bit (1 bit): The U bit is set if this bridge is currently using this ECT-ALGORITHM for I-SIDs it sources or sinks. This is a strictly local indication; the semantics differ from the Use-Flag found in the Hello, which will set the Use-Flag if it sees other nodal U bits are set OR it sources or sinks itself.
o U位（1位）：如果此网桥当前正在为I-SIDs it源或汇使用此ECT算法，则设置U位。这是一个严格的本地指示；语义不同于Hello中的Use标志，如果它看到其他节点U位被设置，或者它自身是源还是汇，那么Hello将设置Use标志。
o M bit (1 bit): The M bit indicates if this is SPBM or SPBV mode. When cleared, the mode is SPBV; when set, the mode is SPBM.
o M位（1位）：M位表示这是SPBM模式还是SPBV模式。清除时，模式为SPBV；设置时，模式为SPBM。
o A bit (1 bit): The A bit (SPB), when set, declares this is an SPVID with auto-allocation. The VID allocation logic details are in IEEE [802.1aq]. Since SPVIDs are allocated from a small pool of 12-bit resources, the chances of collision are high. To minimize collisions during auto-allocation, LSPs are initially advertised with the originating bridge setting the SPVID to 0. Only after learning the other bridges' SPVID allocations does this bridge re-advertise this sub-TLV with a non-zero SPVID. This will minimize but not eliminate the chance of a clash. In the event of a clash, the highest Bridge Identifier is used to select the winner, while the loser(s) with lower Bridge Identifier(s) Must withdraw their SPVID allocation(s) and select an alternative candidate for another trial. SPVID May also be configured. When the A bit is set to not specify auto-allocation and the SPVID is set to 0, this SPBV bridge is used for transit only within the SPB region. If a port is configured with the Base VID as a neighbor using RSTP or MSTP, the bridge will act as an ingress filter for that VID.
o A位（1位）：A位（SPB）在设置时声明这是一个自动分配的SPVID。视频分配逻辑详细信息见IEEE[802.1aq]。由于SPVID是从12位资源的小池中分配的，因此冲突的可能性很高。为了使自动分配期间的冲突最小化，LSP最初会通过原始网桥将SPVID设置为0进行播发。只有在了解其他网桥的SPVID分配后，该网桥才使用非零SPVID重新公布该子TLV。这将最小化但不会消除冲突的可能性。在发生冲突的情况下，最高网桥标识符用于选择胜利者，而网桥标识符较低的失败者必须撤回其SPVID分配，并为另一次试验选择替代候选人。还可以配置SPVID。当A位设置为不指定自动分配且SPVID设置为0时，此SPBV桥接器仅用于SPB区域内的传输。如果使用RSTP或MSTP将端口配置为基本VID作为邻居，则网桥将充当该VID的入口过滤器。
o ECT-ALGORITHM (4 bytes): ECT-ALGORITHM is advertised when the bridge supports a given ECT-ALGORITHM (by OUI/Index) on a given VID. This declaration Must match the declaration in the Hello PDU originating from the same bridge. The ECT-ALGORITHM and Base VID Must match what is generated in the IIHs of the same node. The ECT-ALGORITHM, Base VID tuples can come in any order, however. There are currently 17 worldwide unique 802.1aq defined ECT-ALGORITHMs given by values 00-80-C2-00 through 00-80-C2-10.
o ECT-ALGORITHM（4字节）：当网桥在给定的VID上支持给定的ECT-ALGORITHM（通过OUI/索引）时，会公布ECT-ALGORITHM。此声明必须与源自同一网桥的Hello PDU中的声明相匹配。ECT算法和基本VID必须匹配在同一节点的IIH中生成的内容。然而，在ECT算法中，基本VID元组可以以任何顺序出现。目前有17种全球唯一的802.1aq定义的ECT算法，由值00-80-C2-00到00-80-C2-10给出。
o Base VID (12 bits): The Base VID that associated the SPT Set via the ECT-ALGORITHM.
o 基本视频（12位）：通过ECT-1算法关联SPT集的基本视频。
o SPVID (12 bits): The SPVID is the Shortest Path VID assigned for the Base VID to this node when using SPBV mode. It is not defined for SPBM mode and Must be 0 for SPBM mode B-VIDs.
o SPVID（12位）：SPVID是使用SPBV模式时为基本VID分配到此节点的最短路径VID。未为SPBM模式定义，对于SPBM模式B-VIDs，它必须为0。
There are multiple ECT algorithms defined for SPB; however, for the future, additional algorithms may be defined including but not limited to ECMP- or hash-based behaviors and (*,G) multicast trees. These algorithms will use this Optional TLV to define new algorithm parametric data. For tie-breaking parameters, there are two broad classes of algorithm, one that uses nodal data to break ties and one that uses link data to break ties. This sub-TLV is used to associate opaque tie-breaking data with a node. This sub-TLV, when present, MUST be carried within the MT-Capability TLV (along with a valid SPB-Inst sub-TLV). Multiple copies of this sub-TLV MAY be carried for different ECT-ALGORITHMs relating to this node.
为SPB定义了多个ECT算法；然而，对于未来，可以定义其他算法，包括但不限于基于ECMP或哈希的行为和（*，G）多播树。这些算法将使用此可选TLV定义新的算法参数数据。对于连接断开参数，有两大类算法，一类使用节点数据断开连接，另一类使用链路数据断开连接。此子TLV用于将不透明的领带断裂数据与节点关联。该子TLV（如果存在）必须在MT能力TLV内携带（连同有效的SPB Inst子TLV）。可针对与该节点相关的不同ECT算法携带该子TLV的多个副本。
There are of course many other uses of this opaque data that have yet to be defined.
当然，这种不透明数据还有许多其他用途尚未定义。
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=SPB-I-OALG| = 2
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opaque ECT-ALGORITHM (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opaque ECT Information (variable) |
| ....................... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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=SPB-I-OALG| = 2
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opaque ECT-ALGORITHM (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opaque ECT Information (variable) |
| ....................... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: sub-TLV type 2.
o 类型：子TLV类型2。
o Length: Total number of bytes contained in the value field.
o 长度：值字段中包含的总字节数。
o ECT-ALGORITHM: ECT-ALGORITHM is advertised when the bridge supports a given ECT-ALGORITHM (by OUI/Index) on a given VID.
o ECT-ALGORITHM：当网桥在给定的VID上支持给定的ECT-ALGORITHM（通过OUI/Index）时，ECT-ALGORITHM被公布。
o ECT Information: ECT-ALGORITHM Information of variable length which SHOULD be in sub-TLV format with an IANA numbering space where appropriate.
o ECT信息：可变长度的ECT算法信息，应采用sub-TLV格式，并在适当情况下使用IANA编号空间。
The SPB-Metric sub-TLV (type 29) occurs within the Multi-Topology Intermediate System Neighbor (MT-ISN) TLV (type 222) or within the Extended IS Reachability TLV (type 22). If this sub-TLV is not present for an IS-IS adjacency, then that adjacency Must not carry SPB traffic for the given topology instance.
SPB度量子TLV（类型29）出现在多拓扑中间系统邻居（MT-ISN）TLV（类型222）或扩展IS可达性TLV（类型22）内。如果is-is邻接不存在此子TLV，则该邻接不得承载给定拓扑实例的SPB流量。
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=SPB-Metric| = 29
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SPB-LINK-METRIC | (3 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Num of Ports | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port Identifier | ( 2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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=SPB-Metric| = 29
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SPB-LINK-METRIC | (3 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Num of Ports | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port Identifier | ( 2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: sub-TLV type 29.
o 类型：分TLV类型29。
o Length: Total number of bytes contained in the value field.
o 长度：值字段中包含的总字节数。
o SPB-LINK-METRIC: the administrative cost or weight of using this link as a 24-bit unsigned number. This metric applies to the use of this link for SPB traffic only. Smaller numbers indicate lower weights and are more likely to carry SPB traffic. Only one metric is allowed per SPB instance per link. If multiple metrics are required, multiple SPB instances Must be used, either within IS-IS or within several independent IS-IS instances. If this metric is different at each end of a link, the maximum of the two values Must be used in all SPB calculations for the weight of this link. The maximum SPB-LINK-METRIC value 2^24 - 1 has a special significance; this value indicates that although the IS-IS adjacency has formed, incompatible values have been detected in parameters configured within SPB itself (for example, different regions), and the link Must Not be used for carrying SPB traffic. Full details are found in [802.1aq].
o SPB-LINK-METRIC：将此链接用作24位无符号数的管理成本或权重。此指标仅适用于将此链路用于SPB流量。较小的数字表示较低的权重，更可能承载SPB流量。每个链接的每个SPB实例只允许一个度量。如果需要多个度量，则必须在IS-IS或多个独立的IS-IS实例中使用多个SPB实例。如果此度量在链路的每一端不同，则在所有SPB计算中必须使用这两个值中的最大值来计算此链路的重量。最大SPB-LINK-METRIC值2^24-1具有特殊意义；该值表示，尽管已形成IS-IS邻接，但在SPB自身（例如，不同区域）内配置的参数中已检测到不兼容的值，并且链路不得用于承载SPB流量。有关详细信息，请参见[802.1aq]。
o Num of Ports: the number of ports associated with this link.
o 端口数：与此链接关联的端口数。
o Port Identifier: the standard IEEE port identifier used to build a spanning tree associated with this link.
o 端口标识符：用于构建与此链接关联的生成树的标准IEEE端口标识符。
There are multiple ECT algorithms defined for SPB; however, for the future, additional algorithms may be defined. The SPB-A-OALG sub-TLV occurs within the Multi-Topology Intermediate System TLV (type 222) or the Extended IS Reachability TLV (type 22). Multiple copies of this sub-TLV MAY be carried for different ECT-ALGORITHMs related to this adjacency.
为SPB定义了多个ECT算法；然而，对于未来，可能会定义其他算法。SPB-A-OALG子TLV出现在多拓扑中间系统TLV（222型）或扩展IS可达性TLV（22型）内。该子TLV的多个副本可用于与该邻接相关的不同ECT算法。
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=SPB-A-OALG| = 30
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opaque ECT Algorithm (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opaque ECT Information (variable) |
| ......................... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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=SPB-A-OALG| = 30
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opaque ECT Algorithm (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opaque ECT Information (variable) |
| ......................... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: sub-TLV type 30.
o 类型：子TLV类型30。
o Length: Total number of bytes contained in the value field.
o 长度：值字段中包含的总字节数。
o ECT-ALGORITHM: ECT-ALGORITHM is advertised when the bridge supports a given ECT-ALGORITHM (by OUI/Index) on a given VID.
o ECT-ALGORITHM：当网桥在给定的VID上支持给定的ECT-ALGORITHM（通过OUI/Index）时，ECT-ALGORITHM被公布。
o ECT Information: ECT-ALGORITHM Information of variable length in sub-TLV format using new IANA type values as appropriate.
o ECT信息：ECT-sub TLV格式的可变长度算法信息，使用新的IANA类型值（视情况而定）。
The SPBM-SI sub-TLV (type 3) is used to introduce service group membership on the originating node and/or to advertise an additional B-MAC unicast address present on, or reachable by the node.
SPBM-SI子TLV（类型3）用于在发起节点上引入服务组成员资格和/或播发存在于该节点上或可由该节点访问的附加B-MAC单播地址。
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 = SPBM-SI | = 3
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| B-MAC ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| B-MAC ADDRESS (6 bytes) | Res. | Base VID (12 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|T|R| Reserved | I-SID #1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|T|R| Reserved | I-SID #2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
.................
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|T|R| Reserved | I-SID #n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 = SPBM-SI | = 3
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| B-MAC ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| B-MAC ADDRESS (6 bytes) | Res. | Base VID (12 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|T|R| Reserved | I-SID #1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|T|R| Reserved | I-SID #2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
.................
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|T|R| Reserved | I-SID #n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: sub-TLV type 3.
o 类型：子TLV类型3。
o Length: Total number of bytes contained in the value field.
o 长度：值字段中包含的总字节数。
o B-MAC ADDRESS: a unicast address of this node. It may be the single nodal address, or it may address a port or any other level of granularity relative to the node. In the case where the node only has one B-MAC address, this Should be the same as the SYSID of the node. To add multiple B-MACs this TLV MUST be repeated per additional B-MAC.
o B-MAC地址：此节点的单播地址。它可以是单个节点地址，也可以寻址端口或与节点相关的任何其他粒度级别。如果节点只有一个B-MAC地址，则该地址应与节点的SYSID相同。要添加多个B-MAC，必须对每个附加B-MAC重复此TLV。
o Base VID (12 bits): The Base VID associated with the B-BMAC allows the linkage to the ECT-ALGORITHM and SPT Set defined in the SPB-Inst sub-TLV.
o 基本VID（12位）：与B-BMAC相关的基本VID允许链接到SPB Inst sub TLV中定义的ECT算法和SPT集。
o I-SID #1 .. #n: 24-bit service group membership identifiers. If two nodes have an I-SID in common, intermediate nodes on the unique shortest path between them will create forwarding state for the related B-MAC addresses and will also construct multicast forwarding state using the I-SID and the node's SPSourceID to construct a multicast DA as described in IEEE 802.1aq LSB. Each I-SID has a Transmit (T) and Receive (R) bit that indicates if the membership is as a transmitter, a receiver, or both (with both bits set). In the case where the Transmit (T) and Receive (R) bits are both zero, the I-SID instance is ignored for the purposes of distributed multicast computation, but the unicast B-MAC address Must be processed and installed at nodes providing transit to that address. If more I-SIDs are associated with a particular
o I-SID#1#n:24位服务组成员身份标识符。如果两个节点共用一个I-SID，则它们之间唯一最短路径上的中间节点将为相关的B-MAC地址创建转发状态，并且还将使用I-SID和节点的SPSourceID来构造多播转发状态，以构造IEEE 802.1aq LSB中所述的多播DA。每个I-SID都有一个发送（T）和接收（R）位，用于指示成员身份是作为发送器、接收器还是同时作为两者（设置了两个位）。在发送（T）和接收（R）位都为零的情况下，为了分布式多播计算的目的，I-SID实例被忽略，但是单播B-MAC地址必须在提供到该地址的传输的节点上处理和安装。如果更多的I-SID与特定的
B-MAC than can fit in a single sub-TLV, this sub-TLV can be repeated with the same B-MAC but with different I-SID values.
B-MAC比单个子TLV更适合，该子TLV可以用相同的B-MAC但不同的I-SID值重复。
o Note: When the T bit is not set, an SPB May still multicast to all the other receiving members of this I-SID (those advertising with their R bits set), by configuring edge replication and serial unicast to each member locally.
o 注意：当未设置T位时，SPB仍可以通过在本地配置边缘复制和串行单播到每个成员，将多播发送到该I-SID的所有其他接收成员（使用其R位进行广告的成员）。
The SPBM-SI sub-TLV, when present, MUST be carried within the MT-Capability TLV and can occur multiple times in any LSP fragment.
SPBM-SI子TLV（如果存在）必须在MT能力TLV内携带，并且可以在任何LSP碎片中多次出现。
The SPBV-ADDR sub-TLV is IS-IS sub-TLV type 4. It Should be used for advertisement of Group MAC addresses in SPBV mode. Unicast MAC addresses will normally be distributed by reverse-path learning, but carrying them in this TLV is not precluded. It has the following format:
SPBV-ADDR子TLV为-is子TLV类型4。它应用于在SPBV模式下公布组MAC地址。单播MAC地址通常通过反向路径学习进行分配，但不排除在此TLV中携带它们。其格式如下：
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=SPBV-ADDR| = 4 (1 byte)
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|R| SR| SPVID | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+
|T|R| Reserved | MAC 1 Address | (1+6 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+
|T|R| Reserved | MAC N Address | (1+6 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+
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=SPBV-ADDR| = 4 (1 byte)
+-+-+-+-+-+-+-+-+
| Length | (1 byte)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|R| SR| SPVID | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+
|T|R| Reserved | MAC 1 Address | (1+6 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+
|T|R| Reserved | MAC N Address | (1+6 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+...+-+-+-+-+-+-+-+-+-+-+-+
o Type: sub-TLV type 4.
o 类型：子TLV类型4。
o Length: Total number of bytes contained in the value field. The number of MAC address associated with the SPVID is computed by (Length - 2)/7.
o 长度：值字段中包含的总字节数。与SPVID相关联的MAC地址的数量由（长度-2）/7计算。
o SR bits (2 bits): The SR bits are the service requirement parameter from MMRP. The service requirement parameters have the value 0 (Forward all Groups) and 1 (Forward All Unregistered Groups) defined. However, this attribute May also be missing. So the SR bits are defined as 0 not declared, 1 Forward all Groups, and 2 Forward All Unregistered Groups. The two 'R' reserved bits
o SR位（2位）：SR位是来自MMRP的服务需求参数。服务要求参数定义了值0（转发所有组）和1（转发所有未注册组）。但是，此属性也可能丢失。因此，SR位定义为0未声明，1转发所有组，2转发所有未注册组。两个“R”保留位
immediately preceding these SR bits Shall be set to zero when originating this sub-TLV and Shall be ignored on receipt.
当发起此子TLV时，这些SR位的前一位应设置为零，并在收到时忽略。
o SPVID (12 bits): The SPVID and by association Base VID and the ECT-ALGORITHM and SPT Set that the MAC addresses defined below will use. If the SPVID is not allocated the SPVID Value is 0. Note that if the ECT-ALGORITHM in use is spanning tree algorithm this value Must be populated with the Base VID and the MAC Must be populated.
o SPVID（12位）：下面定义的MAC地址将使用的SPVID和by关联基本VID以及ECT算法和SPT集。如果未分配SPVID，则SPVID值为0。请注意，如果使用的ECT算法是生成树算法，则必须使用基本VID填充该值，并且必须填充MAC。
o T bit (1 bit): This is the Transmit allowed bit for a following group MAC address. This is an indication that the Group MAC address in the context of the SPVID of the bridge advertising this Group MAC Must be installed in the FDB of transit bridges, when the bridge computing the trees is on the corresponding ECT-ALGORITHM shortest path between the bridge advertising this MAC with the T bit set and any receiver of this Group MAC address. A bridge that does not advertise this bit set for a MAC address Must Not cause multicast forwarding state to be installed on other transit bridges in the network for traffic originating from that bridge.
o T位（1位）：这是以下组MAC地址的传输允许位。这表示在传送桥的FDB中必须安装在传送桥的SPVID上下文中宣传该组MAC的组MAC地址，当计算树的网桥位于相应的ECT算法最短路径上时，该网桥使用T位集宣传该MAC和该组MAC地址的任何接收器之间。没有为MAC地址播发此位集的网桥不得导致在网络中的其他传输网桥上为来自该网桥的流量安装多播转发状态。
o R bit (1 bit): This is the Receive allowed bit for the following MAC address. This is an indication that MAC addresses as the receiver Must be populated and installed when the bridge computing the trees lies on the corresponding shortest path for this ECT-ALGORITHM between this receiver and any transmitter to this MAC address. An entry that does not have this bit set for a Group MAC address is prevented from receiving on this Group MAC address because transit bridges Must Not install multicast forwarding state towards it in their FDBs.
o R位（1位）：这是以下MAC地址允许接收的位。这表明，当计算树的网桥位于该接收机和该MAC地址的任何发射机之间的该ECT算法的相应最短路径上时，必须填充和安装作为接收机的MAC地址。禁止在此组MAC地址上接收未设置此位的组MAC地址项，因为传输桥不得在其FDB中向其安装多播转发状态。
o MAC Address (48 bits): The MAC address declares this bridge as part of the multicast interest for this destination MAC address. Multicast trees can be efficiently constructed for destination by populating FDB entries for the subset of the shortest path tree that connects the bridges supporting the MAC address. This replaces the function of MMRP for SPTs. The T and R bits above have meaning as specified above.
o MAC地址（48位）：MAC地址将此网桥声明为此目标MAC地址的多播兴趣的一部分。通过为连接支持MAC地址的网桥的最短路径树的子集填充FDB条目，可以有效地为目的地构建多播树。这取代了标准贯入试验的MMRP功能。上述T和R位的含义如上所述。
The SPBV-ADDR sub-TLV, when present, MUST be carried within the MT-Capability TLV and can occur multiple times in any LSP fragment.
SPBV-ADDR子TLV（如果存在）必须在MT能力TLV内携带，并且可以在任何LSP片段中多次出现。
This document adds no additional security risks to IS-IS, nor does it provide any additional security for IS-IS when used in a configured environment or a single-operator domain such as a data center.
本文档不会给IS-IS增加额外的安全风险，也不会为IS-IS在配置的环境或单个运营商域（如数据中心）中使用时提供任何额外的安全性。
However, this protocol may be used in a zero-configuration environment. Zero configuration may apply to the automatic detection and formation of an IS-IS adjacency (forming an NNI port). Likewise, zero configuration may apply to the automatic detection of VLAN-tagged traffic and the formation of a UNI port, with resultant I-SID advertisements.
但是，该协议可以在零配置环境中使用。零配置可应用于IS-IS邻接的自动检测和形成（形成NNI端口）。同样，零配置可应用于自动检测VLAN标记的通信量和形成UNI端口，并产生I-SID广告。
If zero configuration methods are used to autoconfigure NNIs or UNIs, there are intrinsic security concerns that should be mitigated with authentication procedures for the above cases. Such procedures are beyond the scope of this document and are yet to be defined.
如果使用零配置方法自动配置NNI或UNIs，则应通过针对上述情况的身份验证程序缓解固有的安全问题。此类程序超出了本文件的范围，尚待确定。
In addition, this protocol can create significant amounts of multicast state when an I-SID is advertised with the T bit set. Extra care should be taken to ensure that this cannot be used in a denial-of-service attack [RFC4732] in a zero-configuration environment.
此外，当I-SID使用T位集播发时，该协议可以创建大量多播状态。应格外小心，以确保在零配置环境中，此功能不能用于拒绝服务攻击[RFC4732]。
Note that the NLPID value 0xC1 [RFC6328] used in the IIH PDUs has already been assigned by IANA for the purpose of 802.1aq; therefore, no further action is required for this code point.
注意，IIH PDU中使用的NLPID值0xC1[RFC6328]已经由IANA分配用于802.1aq；因此，无需对此代码点采取进一步措施。
Since 802.1aq operates within the IS-IS Multi-Topology framework, every sub-TLV MUST occur in the context of the proper MT TLV (with the exception of the SPB-Metric sub-TLV, which MAY travel in TLV 22 where its MT ID is unspecified but implied to be 0). IANA has allocated sub-TLVs for three Multi-Topology TLVs per 802.1aq. These are the MT-Port-Cap TLV [RFC6165] used in the IIH, the MT-Capability TLV (new) used within the LSP, and finally the MT-ISN TLV [MT] used to contain adjacency information within the LSP.
由于802.1aq在IS-IS多拓扑框架内运行，因此每个子TLV必须在适当的MT TLV的上下文中出现（SPB度量子TLV除外，其可能在TLV 22中移动，其中其MT ID未指定，但暗示为0）。IANA已为每个802.1aq的三个多拓扑TLV分配了子TLV。这些是IIH中使用的MT端口Cap TLV[RFC6165]，LSP中使用的MT能力TLV（新），最后是用于包含LSP中邻接信息的MT-ISN TLV[MT]。
This document creates the following TLVs and sub-TLVs within the IIH and LSP PDUs MT TLVs as described below. The '*' indicates new IANA assignments (per this document). Other entries are shown to provide context only.
本文件在IIH和LSP PDU MT TLV内创建以下TLV和子TLV，如下所述。“*”表示新的IANA分配（根据本文件）。显示的其他条目仅提供上下文。
The MT-Capability TLV is the only TLV that required a new sub-registry. Type value 144 has been assigned, with a starting sub-TLV value of 1, and managed by Expert Review.
MT能力TLV是唯一需要新子注册表的TLV。已分配类型值144，起始子TLV值为1，并由专家评审管理。
+-----+----+-----------------+--------+------+-------------+
| PDU |TLV | SUB-TLV | TYPE | TYPE | #OCCURRENCE |
+-----+----+-----------------+--------+------+-------------+
IIH
MT-Port-Cap 143
* SPB-MCID 4 1
* SPB-Digest 5 >=0
* SPB-B-VID 6 1
+-----+----+-----------------+--------+------+-------------+
| PDU |TLV | SUB-TLV | TYPE | TYPE | #OCCURRENCE |
+-----+----+-----------------+--------+------+-------------+
IIH
MT-Port-Cap 143
* SPB-MCID 4 1
* SPB-Digest 5 >=0
* SPB-B-VID 6 1
LSP
* MT-Capability 144 >=1
* SPB-Inst 1 1
* SPB-I-OALG 2 >=0
* SPBM-SI 3 >=0
* SPBV-ADDR 4 >=0
LSP
* MT-Capability 144 >=1
* SPB-Inst 1 1
* SPB-I-OALG 2 >=0
* SPBM-SI 3 >=0
* SPBV-ADDR 4 >=0
MT-ISN 222 or Extended IS Reachability 22 * SPB-Metric 29 1 * SPB-A-OALG 30 >=0
MT-ISN 222或扩展IS可达性22*SPB度量29 1*SPB-A-OALG 30>=0
[802.1aq] "Standard for Local and Metropolitan Area Networks: Virtual Bridges and Virtual Bridged Local Area Networks - Amendment 9: Shortest Path Bridging", IEEE P802.1aq, Draft 4.6, 2012.
[802.1aq]“局域网和城域网标准：虚拟网桥和虚拟桥接局域网-修改件9：最短路径桥接”，IEEE P802.1aq，草案4.62012。
[IS-IS] ISO/IEC 10589:2002, Second Edition, "Intermediate System to Intermediate System Intra-Domain Routing 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，“与提供无连接模式网络服务的协议一起使用的中间系统到中间系统域内路由交换协议（ISO 8473）”，2002年。
[MT] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi Topology (MT) Routing in Intermediate System to Intermediate Systems (IS-ISs)", RFC 5120, February 2008.
[MT]Przygienda，T.，Shen，N.，和N.Sheth，“M-ISIS：中间系统到中间系统（IS-ISs）的多拓扑（MT）路由”，RFC 5120，2008年2月。
[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。
[RFC6165] Banerjee, A. and D. Ward, "Extensions to IS-IS for Layer-2 Systems", RFC 6165, April 2011.
[RFC6165]Banerjee，A.和D.Ward，“第2层系统的IS-IS扩展”，RFC 61652011年4月。
[RFC6328] Eastlake 3rd, D., "IANA Considerations for Network Layer Protocol Identifiers", BCP 164, RFC 6328, July 2011.
[RFC6328]Eastlake 3rd，D.，“网络层协议标识符的IANA考虑”，BCP 164，RFC 63282011年7月。
[802.1ag] "Standard for Local and Metropolitan Area Networks / Virtual Bridged Local Area Networks / Amendment 5: Connectivity Fault Management", IEEE STD 802.1ag, 2007.
[802.1ag]“局域网和城域网/虚拟桥接局域网标准/修改件5：连接故障管理”，IEEE标准802.1ag，2007年。
[MMRP] "Standard for Local and Metropolitan Area Networks Virtual Bridged Local Area Networks - Amendment 07: Multiple Registration Protocol", IEEE STD 802.1ak, 2007.
[MMRP]“局域网和城域网标准-虚拟桥接局域网-修订件07：多重注册协议”，IEEE标准802.1ak，2007年。
[PB] "Standard for Local and Metropolitan Area Networks / Virtual Bridged Local Area Networks / Amendment 4: Provider Bridges", IEEE STD 802.1ad, 2005.
[PB]“局域网和城域网/虚拟桥接局域网标准/修改件4：提供商网桥”，IEEE标准802.1ad，2005年。
[PBB] "Standard for Local and Metropolitan Area Networks / Virtual Bridged Local Area Networks / Amendment 7: Provider Backbone Bridges", IEEE STD 802.1ah, 2008.
[PBB]“局域网和城域网/虚拟桥接局域网标准/修改件7：提供商主干网桥”，IEEE标准802.1ah，2008年。
[RFC4732] Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet Denial-of-Service Considerations", RFC 4732, December 2006.
[RFC4732]Handley，M.，Ed.，Rescorla，E.，Ed.，和IAB，“互联网拒绝服务注意事项”，RFC 47322006年12月。
[Y.1731] ITU-T, "OAM Functions and Mechanisms for Ethernet based networks", ITU-T Y.1731, 2006.
[Y.1731]ITU-T，“基于以太网的网络的OAM功能和机制”，ITU-T Y.17312006。
The authors would like to thank Ayan Banerjee, Mick Seaman, Janos Farkas, Les Ginsberg, Stewart Bryant , Donald Eastlake, Matthew Bocci and Mike Shand for contributions and/or detailed review.
作者要感谢Ayan Banerjee、Mick Seaman、Janos Farkas、Les Ginsberg、Stewart Bryant、Donald Eastlake、Matthew Bocci和Mike Shand的贡献和/或详细评论。
Authors' Addresses
作者地址
Don Fedyk (editor) Alcatel-Lucent Groton, MA 01450 USA EMail: Donald.Fedyk@alcatel-lucent.com
唐·费迪克（编辑）阿尔卡特·朗讯·格罗顿，马萨诸塞州01450美国电子邮件：唐纳德。Fedyk@alcatel-朗讯网
Peter Ashwood-Smith (editor) Huawei Technologies Canada Ltd. 303 Terry Fox Drive, Suite 400 Kanata, Ontario, K2K 3J1 CANADA EMail: Peter.AshwoodSmith@huawei.com
Peter Ashwood Smith（编辑）华为技术加拿大有限公司加拿大安大略省卡纳塔市Terry Fox大道303号400室K2K 3J1电子邮件：Peter。AshwoodSmith@huawei.com
Dave Allan Ericsson 300 Holger Way San Jose, CA 95134 USA EMail: david.i.allan@ericsson.com
戴夫·艾伦·爱立信美国加利福尼亚州圣何塞霍尔格大道300号，邮编95134电子邮件：david.i。allan@ericsson.com
Nigel Bragg Ciena Limited Ciena House 43-51 Worship Street London EC2A 2DX UK EMail: nbragg@ciena.com
Nigel Bragg Ciena Limited Ciena House 43-51膜拜街伦敦EC2A 2DX英国电子邮件：nbragg@ciena.com
Paul Unbehagen Avaya 8742 Lucent Boulevard Highlands Ranch, CO 80129 USA EMail: unbehagen@avaya.com
Paul Unbehagen Avaya 8742美国科罗拉多州朗讯大道高地牧场80129电子邮件：unbehagen@avaya.com