2017年802.1CB标准：局域网与城域网的可靠帧复制与消除技术

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802.1CB-2017 是 IEEE (Institute of Electrical and Electronics Engineers) 对于本地和城域网络（Local and Metropolitan Area Networks, LAN/MAN）提出的一项标准，专注于帧复制（Frame Replication）和消除（Frame Elimination）技术，目的是提升网络的可靠性和性能。该标准由 LAN/MAN 标准委员会（LAN/MAN Standards Committee）赞助，经 IEEE 计算机学会（IEEE Computer Society）批准，于 2017 年 9 月 28 日通过 IEEE-SA 标准董事会（IEEE-SA Standards Board）的认可。帧复制和消除是 Time-Sensitive Networking (TSN) 概念下的关键特性，TSN 是 IEEE 802.1 标准家族的一部分，旨在解决传统以太网在实时通信和工业自动化等对低延迟、高带宽和确定性传输需求方面的问题。通过这些技术，网络能够在数据传输过程中创建冗余副本，确保在主帧丢失或延迟的情况下，备用副本可以被快速提供，从而提高系统的可用性和可靠性。 802.1CB 标准定义了复制和消除操作的机制，包括如何选择哪些帧进行复制，以及如何管理和同步这些副本。它还规定了帧生命周期管理策略，包括何时启动复制、何时停止或更新复制帧，以及如何协调不同节点间的复制操作，以避免冲突和数据一致性问题。此外，该标准还考虑了安全性，确保在复制帧时保护敏感信息，并规定了授权使用限制，如 Harry Potter 下载示例中提到的，用户只能在特定条件下使用此标准。版权方面，所有权利归 IEEE 所有，禁止未经许可的复制和分发。 802.1CB-2017 是一项重要的技术规范，对于那些依赖实时通信的行业，如工业自动化、医疗设备、交通控制等领域，提供了强大的网络基础设施支持，通过增强网络的冗余能力和故障恢复能力，显著提升了系统运行的稳定性和响应速度。实施这一标准需要遵循严格的协议和安全措施，以确保网络的高效运作。

List of tables

Table 6-1—Stream identification functions .................................................................................................. 27

Table 7-1—R-TAG EtherType...................................................................................................................... 49

Table 8-1—Managed objects for FRER in an FRER C-component ............................................................. 59

Table 9-1—Stream identification types......................................................................................................... 62

Table 10-1—Enumerated values for frerSeqRcvyAlgorithm ........................................................................ 69

Table 10-2—Sequence Encode/Decode types............................................................................................... 72

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IEEE Std 802.1CB-2017

IEEE Standard for Local and metropolitan area networks—Frame Replication and Elimination for Reliability

IEEE Standard for

Local and metropolitan area networks—

Frame Replication and Elimination for Reliability

1. Overview

1.1 Scope

This standard specifies procedures, managed objects, and protocols for bridges and end systems that provide

identification and replication of packets for redundant transmission, identification of duplicate packets, and

elimination of duplicate packets. It is not concerned with the creation of the multiple paths over which the

duplicates are transmitted.

1.2 Rationale

The reason for Frame Replication and Elimination for Reliability (FRER) is to increase the probability that a

given packet will be delivered. It is expected that, in many applications, other means to increase the

probability of delivery are likely to be used as well. When FRER is used over paths that are fixed to a

specific topology, and that are protected against congestion loss (e.g., by using techniques described by

IEEE Std 802.1BA™ [B1]), FRER can substantially reduce the probability of packet loss due to equipment

failures.

1.3 State diagram conventions

This document uses the programming language C (ISO/IEC 9899:2011) to document the operation of

conformant systems.

C functions are distinguished with this special fixed-width font (e.g.,

7.4.3.3). Each C function is executed when a given event occurs, as described for that code segment or in the

accompanying text. Events are assumed to take place sequentially, not simultaneously, and code routines

execute instantaneously.

1.4 Specification model

The model of operation documented by this standard is simply a basis for describing the functionality of

compliant equipment. Implementations can adopt any internal model of operation compatible with the

externally visible behavior that this standard specifies. Conformance of equipment to this standard is purely

in respect of observable protocol.

The numbers in brackets correspond to those of the bibliography in Annex D.

Information on references can be found in Clause 2.

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IEEE Std 802.1CB-2017

IEEE Standard for Local and metropolitan area networks—Frame Replication and Elimination for Reliability

1.5 Specification precedence

If any conflict among parts of this standard become apparent, C functions (see 1.3) take precedence over

other parts of the standard, followed by information in normative tables, followed by that in normative text,

followed by that in normative figures. Non-normative tables, figures, and text are in annexes and are clearly

marked as such.

1.6 Introduction

This standard is one of a number of IEEE 802.1™ and other standards suitable for Time-Sensitive

Networking (TSN) that together have the overall goal of providing extremely low packet loss rates and

finite, low, and stable end-to-end latencies. TSN supports unicast and multicast Streams of packets that

implement a wide range of demanding real-time applications including audio/video studios, industrial

processes, and the control of machines and vehicles. The TSN goals are not achieved at the expense of

hampering the ability of the network to carry traffic for non-time-critical applications.

At the highest level, this standard posits the existence of one Talker end system and one or more Listener

end systems per Stream. A Stream is characterized by a maximum packet size and number of packets

transmitted per time interval. Because the Stream’s maximum throughput is known, the resources, including

link bandwidth, buffer space, and control parameters, required at every hop along the Stream’s path to

guarantee that Stream zero congestion loss and finite latency, can be provided (by other standards, e.g.,

Clause 35 of IEEE Std 802.1Q™-2014). This provisioned path carrying the Stream is called a Reservation.

On the assumption that the time required for a dynamic network control protocol to recover from an

equipment failure is unacceptable in certain applications, this standard defines Frame Replication and

Elimination for Reliability (FRER), which divides a Stream into one or more linked Member Streams, thus

making the original Stream a Compound Stream. It replicates the packets of the Stream, splitting the copies

into the multiple Member Streams, and then rejoins those Member Streams at one or more other points,

eliminates the replicates, and delivers the reconstituted Stream from those points.

In order to accommodate existing applications and to promote interoperability with similar standards, this

standard defines a number of schemes for identifying packets belonging to Streams and distinguishing them

from other packets.

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IEEE Std 802.1CB-2017

IEEE Standard for Local and metropolitan area networks—Frame Replication and Elimination for Reliability

2. Normative references

The following referenced documents are indispensable for the application of this document (i.e., they must

be understood and used, so each referenced document is cited in text and its relationship to this document is

explained). For dated references, only the edition cited applies. For undated references, the latest edition of

the referenced document (including any amendments or corrigenda) applies. Non-normative references (i.e.,

that provide additional information not required for the application of this document) are given in Annex D.

IEC 62439-3:2016, Industrial communication networks—High availability automation networks—Part 3:

Parallel Redundancy Protocol (PRP) and High-availability Seamless Redundancy (HSR).

IEEE Std 802

, IEEE Standard for Local and metropolitan area networks: Overview and Architecture.

4, 5

IEEE Std 802.1AC™, IEEE Standard for Local and metropolitan area networks—Media Access Control

(MAC) Service Definition.

IEEE Std 802.1Q™, IEEE Standard for Local and metropolitan area networks—Bridges and Bridged

Networks.

IETF RFC 768, User Datagram Protocol, Postel, J., August 1980.

IETF RFC 791, Internet Protocol, Postel, J., Ed., September 1981.

IETF RFC 793, Transmission Control Protocol, Postel, J., Ed., September 1981.

IETF RFC 2460, Internet Protocol, Version 6 (IPv6) Specification, Deering, S. and R. Hinden, December

1998.

IETF RFC 2474, Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers,

Nichols, K., et al., December 1998.

IETF RFC 4960, Stream Control Transmission Protocol, Stewart, R., Ed., September 2007.

ISO/IEC 9899:2011, Information technology—Programming languages—C.

IEC publications are available from the International Electrotechnical Commission (http://www.iec.ch) and the American National

Standards Institute (http://www.ansi.org/).

The IEEE standards or products referred to in Clause 2 are trademarks owned by The Institute of Electrical and Electronics Engineers,

Incorporated.

IEEE publications are available from The Institute of Electrical and Electronics Engineers (http://standards.ieee.org).

IETF documents (i.e., RFCs) are available for download at http://www.rfc-archive.org/.

ISO/IEC publications are available from the International Organization for Standardization (http://www.iso.org/) and the American

National Standards Institute (http://www.ansi.org/).

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IEEE Std 802.1CB-2017

IEEE Standard for Local and metropolitan area networks—Frame Replication and Elimination for Reliability

3. Definitions

For the purposes of this document, the following terms and definitions apply. The IEEE Standards

Dictionary Online should be consulted for terms not defined in this clause.

This standard makes use of the following terms defined in IEEE Std 802

— End station

— Organizationally Unique Identifier (OUI)

— Company ID (CID)

bridge: A layer 2 interconnection device that conforms to IEEE Std 802.1Q.

Company ID (CID): CIDs allow a general means of assuring unique identifiers for a number of purposes.

See Clause 8 of IEEE Std 802-2014.

Compound Stream: A Compound Stream is a Stream composed of one or more Member Streams linked

together via Frame Replication and Elimination for Reliability (FRER).

down: The direction through the protocol stack from a sublayer using a service provided by another

sublayer to the sublayer whose services it uses; the direction of output packets.

end station: A device attached to a local area network (LAN) or metropolitan area network (MAN), which

acts as a source of and/or destination for data traffic carried on the LAN or MAN. (From IEEE Std 802)

end system: A system attached to a network that is an initial source or a final destination of packets

transmitted across that network.

NOTE—The term end system is often used in this document in places where the reader of IEEE 802 standards would

expect the term end station in order to avoid confusion caused by standards relating to routers. For example, a router, as

defined by IETF, is an IEEE 802 end station, but not an end system. Where this standard specifically refers to the use of

IEEE 802 services, the term end station is used. Where it refers to more generalized instances of connectionless services,

the term end system is used.

in-facing: In a system that includes a Stream Transfer Function, the “in-facing” protocol functions are those

functions that are below the Stream Transfer Function on the port that is not above the physical layer. On a

system that does not include a Stream Transfer Function, there are no in-facing protocol functions.

NOTE—See Figure 6-6.

input: Input packets are those moving up the protocol stack, regardless of the position of receiving function

relative to the physical media, for example, by the M_UNITDATA.indication primitive of the Internal

Sublayer Service (ISS).

Internal local area network (LAN): An instance of a connectionless packet service with two Service

Access Points (SAPs), both internal to a single system, that relays packets from one SAP to the other. It is

not observable externally to that system.

Internal Sublayer Service (ISS): An augmented version of the MAC Service, defined in 6.6 of

IEEE Std 802.1Q-2014.

IEEE Standards Dictionary Online is available at: http://dictionary.ieee.org.

Notes in text, tables, and figures of a standard are given for information only and do not contain requirements needed to implement this

standard.

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