EN 62439-2:2010

SLOVENSKI STANDARD
01-maj-2010
Industrijska komunikacijska omrežja za avtomatizacijo z visoko razpoložljivostjo -
2. del: Protokol z redundanco medijev (MRP) (IEC 62439-2:2010)
Industrial communication networks high availability automation networks - Part 2: Media
Redundancy Protocol (MRP) (IEC 62439-2:2010)
Industrielle Kommunikationsnetze - Hochverfügbare Automatisierungsnetze - Teil 2:
Medienredundanz-Protokoll (MRP) (IEC 62439-2:2010)
Réseaux de communication industrielle – Réseaux d’automatisme à haute disponibilité –
Partie 2 : Protocol de redondance de média (MRP) (IEC 62439-2:2010)
Ta slovenski standard je istoveten z: EN 62439-2:2010
ICS:
25.040.01 Sistemi za avtomatizacijo v Industrial automation
industriji na splošno systems in general
35.110 Omreževanje Networking
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 62439-2
NORME EUROPÉENNE
March 2010
EUROPÄISCHE NORM
ICS 25.040; 35.040 Supersedes EN 62439:2008 (partially)

English version
Industrial communication networks -
High availability automation networks -
Part 2: Media Redundancy Protocol (MRP)
(IEC 62439-2:2010)
Réseaux de communication industrielle – Industrielle Kommunikationsnetze -
Réseaux d’automatisme à haute Hochverfügbare Automatisierungsnetze -
disponibilité – Teil 2: Medienredundanz-Protokoll (MRP)
Partie 2 : Protocol de redondance (IEC 62439-2:2010)
de média (MRP)
(CEI 62439-2:2010)
This European Standard was approved by CENELEC on 2010-03-01. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: Avenue Marnix 17, B - 1000 Brussels

© 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62439-2:2010 E
Foreword
The text of document 65C/583/FDIS, future edition 1 of IEC 62439-2, prepared by SC 65C, Industrial
networks, of IEC TC 65, Industrial-process measurement, control and automation, was submitted to the
IEC-CENELEC parallel vote and was approved by CENELEC as EN 62439-2 on 2010-03-01.
This EN 62439-2 together with EN 62439-1, EN 62439-3, EN 62439-4, EN 62439-5 and EN 62439-6
supersedes EN 62439:2008.
– adding a calculation method for RSTP (rapid spanning tree protocol, IEEE 802.1Q),
– adding two new redundancy protocols: HSR (High-availability Seamless Redundancy) and DRP
(Distributed Redundancy Protocol),
– moving former Clauses 1 to 4 (introduction, definitions, general aspects) and the Annexes (taxonomy,
availability calculation) to EN 62439-1, which serves now as a base for the other documents,
– moving Clause 5 (MRP) to EN 62439-2 with minor editorial changes,
– moving Clause 6 (PRP) was to EN 62439-3 with minor editorial changes,
– moving Clause 7 (CRP) was to EN 62439-4 with minor editorial changes, and
– moving Clause 8 (BRP) was to EN 62439-5 with minor editorial changes,
– adding a method to calculate the maximum recovery time of RSTP in a restricted configuration (ring)
to EN 62439-1 as Clause 8,
– adding specifications of the HSR (High-availability Seamless Redundancy) protocol, which shares the
principles of PRP to EN 62439-3 as Clause 5, and
– introducing the DRP protocol as EN 62439-6.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent
rights.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2010-12-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2013-03-01
Annex ZA has been added by CENELEC.
__________
- 3 - EN 62439-2:2010
Endorsement notice
The text of the International Standard IEC 62439-2:2010 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 61158-2:2007 NOTE  Harmonized as EN 61158-2:2008 (not modified).
IEC 61158-5-10 NOTE  Harmonized as EN 61158-5-10.
IEC 61784-1:2007 NOTE  Harmonized as EN 61784-1:2008 (not modified).
IEC 61784-2:2007 NOTE  Harmonized as EN 61784-2:2008 (not modified).
IEC 62439-3 NOTE  Harmonized as EN 62439-3.
IEC 62439-4 NOTE  Harmonized as EN 62439-4.
IEC 62439-5 NOTE  Harmonized as EN 62439-5.
IEC 62439-6 NOTE  Harmonized as EN 62439-6.
__________
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

IEC 60050-191 1990 International Electrotechnical Vocabulary - -
(IEV) - Chapter 191: Dependability and quality
of service
IEC 61158-6-10 - Industrial communication networks - Fieldbus EN 61158-6-10 -
specifications -
Part 6-10: Application layer protocol
specification - Type 10 elements

IEC 62439-1 2010 Industrial communication networks - High EN 62439-1 2010
availability automation networks -
Part 1: General concepts and calculation
methods
ISO/IEC 8802-3 2000 Information technology - Telecommunications - -
and information exchange between systems -
Local and metropolitan area networks -
Specific requirements -
Part 3: Carrier sense multiple access with
collision detection (CSMA/CD) access method
and physical layer specifications

IEEE 802.1D 2004 IEEE Standard for Local and Metropoitan - -
Area Networks - Media Access Control (MAC)
Bridges
IEEE 802.1Q - IEEE Standard for Local and Metropolitan - -
Area Networks - Virtual Bridged Local Area
Networks
IEC 62439-2 ®
Edition 1.0 2010-02
INTERNATIONAL
STANDARD
Industrial communication networks – High availability automation networks –
Part 2: Media Redundancy Protocol (MRP)

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XB
ICS 25.040, 35.040 ISBN 2-8318-1081-2
– 2 – 62439-2 © IEC:2010(E)
CONTENTS
FOREWORD.5
INTRODUCTION.7
1 Scope.8
2 Normative references .8
3 Terms, definitions, abbreviations, acronyms, and conventions.8
3.1 Terms and definitions .8
3.2 Abbreviations and acronyms.8
3.3 Conventions .9
4 MRP Overview.9
5 MRP Media redundancy behavior .10
5.1 Ring ports .10
5.2 Media Redundancy Manager (MRM).11
5.3 Media Redundancy Client (MRC).12
5.4 Redundancy domain.12
5.5 Usage with diagnosis and alarms .12
5.6 Ring diagnosis.13
5.7 Multiple MRM in a single ring .13
5.8 BLOCKED not supported (option) .13
6 MRP Class specification .14
6.1 General .14
6.2 Template .14
6.3 Attributes.14
7 MRP service specification.17
7.1 Start MRM.17
7.2 Stop MRM .18
7.3 State Change .19
7.4 Start MRC .20
7.5 Stop MRC.21
7.6 Read MRM .22
7.7 Read MRC .24
8 MRP protocol specification .25
8.1 PDU description .25
8.1.1 Basic data types .25
8.1.2 DLPDU abstract syntax reference.25
8.1.3 Coding of the DLPDU field SourceAddress .26
8.1.4 Coding of the DLPDU field DestinationAddress.26
8.1.5 Coding of the field TagControlInformation.27
8.1.6 Coding of the field LT .27
8.1.7 MRP APDU abstract syntax .27
8.1.8 Coding of the field MRP_TLVHeader .28
8.1.9 Coding of the field MRP_Version .29
8.1.10 Coding of the field MRP_SequenceID .29
8.1.11 Coding of the field MRP_SA .29
8.1.12 Coding of the field MRP_Prio.29
8.1.13 Coding of the field MRP_PortRole .29
8.1.14 Coding of the field MRP_RingState.29

62439-2 © IEC:2010(E) – 3 –
8.1.15 Coding of the field MRP_Interval .30
8.1.16 Coding of the field MRP_Transition .30
8.1.17 Coding of the field MRP_TimeStamp .30
8.1.18 Coding of the field MRP_Blocked.30
8.1.19 Coding of the field MRP_ManufacturerOUI .31
8.1.20 Coding of the field MRP_ManufacturerData .31
8.1.21 Coding of the field MRP_DomainUUID.31
8.2 Protocol machines.31
8.2.1 MRM protocol machine .31
8.2.2 MRC protocol machine .41
8.2.3 MRM and MRC functions .48
8.2.4 FDB clear timer .51
8.2.5 Topology change timer .51
9 MRP installation, configuration and repair .51
9.1 Ring port parameters.51
9.2 Ring topology parameters.52
9.3 MRM parameters.52
9.4 MRC parameters and constraints .52
9.5 Calculation of MRP ring recovery time.53
9.5.1 Overview .53
9.5.2 Deduction of formula .53
9.5.3 Worst case calculation for recovery time of 10 ms .55
9.5.4 Worst case calculation for 50 devices .56
10 MRP Management Information Base (MIB) .56
10.1 General .56
10.2 MRP MIB with a monitoring view .56
10.3 MRP MIB with a management and monitoring view.64
Bibliography.73

Figure 1 – MRP stack .10
Figure 2 – MRP ring topology with one manager and clients .11
Figure 3 – MRP open ring with MRM.11
Figure 4 – MRP ring with more than one MRM .13
Figure 5 – MRP protocol machine for MRM.32
Figure 6 – MRP protocol machine for MRC .42

Table 1 – MRP Start MRM .17
Table 2 – MRP Stop MRM.18
Table 3 – MRP Change State.19
Table 4 – MRP Start MRC.20
Table 5 – MRP Stop MRC .21
Table 6 – MRP Read MRM .22
Table 7 – MRP Read MRC.24
Table 8 – MRP DLPDU syntax for ISO/IEC 8802-3 (IEEE 802.3).26
Table 9 – MRP OUI.26
Table 10 – MRP MulticastMACAddress.27

– 4 – 62439-2 © IEC:2010(E)
Table 11 – MRP TagControlInformation.Priority field.27
Table 12 – MRP LT field .27
Table 13 – MRP APDU syntax .28
Table 14 – MRP Substitutions.28
Table 15 – MRP_TLVHeader.Type.28
Table 16 – MRP_Version .29
Table 17 – MRP_Prio.29
Table 18 – MRP_PortRole .29
Table 19 – MRP_RingState.30
Table 20 – MRP_Interval .30
Table 21 – MRP_Transition.30
Table 22 – MRP_TimeStamp .30
Table 23 – MRP_Blocked.31
Table 24 – MRP_DomainUUID.31
Table 25 – MRP Local variables of MRM protocol machine .33
Table 26 – MRM State machine .34
Table 27 – MRP Local variables of MRC protocol machine .43
Table 28 – MRC state machine .43
Table 29 – MRP functions.49
Table 30 – MRP FDB clear timer.51
Table 31 – MRP topology change timer.51
Table 32 – MRP Network/Connection parameters .52
Table 33 – MRP MRM parameters .52
Table 34 – MRP MRC parameters.53

62439-2 © IEC:2010(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL COMMUNICATION NETWORKS –
HIGH AVAILABILITY AUTOMATION NETWORKS –

Part 2: Media Redundancy Protocol (MRP)

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
International Standard 62439-2 has been prepared by subcommittee 65C: Industrial Networks,
of IEC technical committee 65: Industrial-process measurement, control and automation.
This standard cancels and replaces IEC 62439 published in 2008. This first edition constitutes
a technical revision.
This edition includes the following significant technical changes with respect to IEC 62439
(2008):
– adding a calculation method for RSTP (rapid spanning tree protocol, IEEE 802.1Q),
– adding two new redundancy protocols: HSR (High-availability Seamless Redundancy)
and DRP (Distributed Redundancy Protocol),
– moving former Clauses 1 to 4 (introduction, definitions, general aspects) and the
Annexes (taxonomy, availability calculation) to IEC 62439-1, which serves now as a
base for the other documents,
– moving Clause 5 (MRP) to IEC 62439-2 with minor editorial changes,
– moving Clause 6 (PRP) was to IEC 62439-3 with minor editorial changes,
– moving Clause 7 (CRP) was to IEC 62439-4 with minor editorial changes, and

– 6 – 62439-2 © IEC:2010(E)
– moving Clause 8 (BRP) was to IEC 62439-5 with minor editorial changes,
– adding a method to calculate the maximum recovery time of RSTP in a restricted
configuration (ring) to IEC 62439-1 as Clause 8,
– adding specifications of the HSR (High-availability Seamless Redundancy) protocol,
which shares the principles of PRP to IEC 62439-3 as Clause 5, and
– introducing the DRP protocol as IEC 62439-6.
The text of this standard is based on the following documents:
FDIS Report on voting
65C/583/FDIS 65C/589/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This International Standard is to be read in conjunction with IEC 62439-1:2010, Industrial
communication networks – High availability automation networks – Part 1: General concepts
and calculation methods.
A list of the IEC 62439 series can be found, under the general title Industrial communication
networks – High availability automation networks, on the IEC website.
This publication has been drafted in accordance with ISO/IEC Directives, Part 2.
The committee has decided that the contents of this amendment and the base publication will
remain unchanged until the stability date indicated on the IEC web site under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this standard may be issued at a later date.

62439-2 © IEC:2010(E) – 7 –
INTRODUCTION
The IEC 62439 series specifies relevant principles for high availability networks that meet the
requirements for industrial automation networks.
In the fault-free state of the network, the protocols of the IEC 62439 series provide
ISO/IEC 8802-3 (IEEE 802.3) compatible, reliable data communication, and preserve
determinism of real-time data communication. In cases of fault, removal, and insertion of a
component, they provide deterministic recovery times.
These protocols retain fully the typical Ethernet communication capabilities as used in the
office world, so that the software involved remains applicable.
The market is in need of several network solutions, each with different performance
characteristics and functional capabilities, matching diverse application requirements. These
solutions support different redundancy topologies and mechanisms which are introduced in
IEC 62439-1 and specified in the other Parts of the IEC 62439 series. IEC 62439-1 also
distinguishes between the different solutions, giving guidance to the user.
The IEC 62439 series follows the general structure and terms of IEC 61158 series.
The International Electrotechnical Commission (IEC) draws attention to the fact that it is
claimed that compliance with this document may involve the use of a patent concerning ring
protocol given in Clause 5.
IEC takes no position concerning the evidence, validity and scope of this patent right.
The holder of this patent right has assured the IEC that he/she is willing to negotiate licences
either free of charge or under reasonable and non-discriminatory terms and conditions with
applicants throughout the world. In this respect, the statement of the holder of this patent right
is registered with IEC. Information may be obtained from:
Siemens AG A&D
Gleiwitzerstr. 555
Nürnberg 90475
Germany
and
Hirschmann Automation and Control GmbH
Stuttgarter Strasse 45-51
Neckartenzlingen 72654
Germany
Attention is drawn to the possibility that some of the elements of this document may be the
subject of patent rights other than those identified above. IEC shall not be held responsible for
identifying any or all such patent rights.
ISO (www.iso.org/patents) and IEC (http://www.iec.ch/tctools/patent_decl.htm) maintain on-
line data bases of patents relevant to their standards. Users are encouraged to consult the
data bases for the most up to date information concerning patents.

– 8 – 62439-2 © IEC:2010(E)
INDUSTRIAL COMMUNICATION NETWORKS –
HIGH AVAILABILITY AUTOMATION NETWORKS –

Part 2: Media Redundancy Protocol (MRP)

1 Scope
The IEC 62439 series is applicable to high-availability automation networks based on the
ISO/IEC 8802-3 (IEEE 802.3) (Ethernet) technology.
This part of the IEC 62439 series specifies a recovery protocol based on a ring topology,
designed to react deterministically on a single failure of an inter-switch link or switch in the
network, under the control of a dedicated media redundancy manager node.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60050-191:1990, International Electrotechnical Vocabulary – Chapter 191: Dependability
and quality of service
IEC 61158-6-10, Industrial communication networks – Fieldbus specifications – Part 6-10:
Application layer protocol specification – Type 10 elements
IEC 62439-1:2010, Industrial communication networks – High availability automation networks
– Part 1: General concepts and calculation methods
ISO/IEC 8802-3:2000, Information technology – Telecommunications and information
exchange between systems – Local and metropolitan area networks – Specific requirements –
Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and
physical layer specifications
IEEE 802.1Q, IEEE standards for local and metropolitan area network. Virtual bridged local
area networks
IEEE 802.1D:2004, IEEE standard for local Local and metropolitan area networks Media
Access Control (MAC) Bridges
3 Terms, definitions, abbreviations, acronyms, and conventions
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-191, as well
as in IEC 62439-1, apply.
3.2 Abbreviations and acronyms
For the purposes of this document, the abbreviations and acronyms given in IEC 62439-1
apply, in addition to the following.
MRC Media Redundancy Client
62439-2 © IEC:2010(E) – 9 –
MRM Media Redundancy Manager
MRP Media Redundancy Protocol
3.3 Conventions
This document follows the conventions defined in IEC 62439-1.
4 MRP Overview
The Media Redundancy Protocol (MRP) specifies a recovery protocol based on a ring
topology.
MRP is designed to react deterministically on a single failure of an inter-switch link or switch
in the network.
MRP is based on functions of ISO/IEC 8802-3 (IEEE 802.3) and IEEE 802.1D including the
Filtering Data Base (FDB) and is located between the Data Link Layer and Application Layer
(see Figure 1).
NOTE 1 Layering is assumed to be according to IEC 61158-1.
A compliant network shall have a ring topology with multiple nodes.
One of the nodes has the role of a media redundancy manager (MRM). The function of the
MRM is to observe and to control the ring topology in order to react on network faults. The
MRM does this by sending frames on one ring port over the ring and receiving them from the
ring over its other ring port, and vice-versa in the other direction.
The other nodes in the ring have the role of media redundancy clients (MRC). An MRC reacts
on received reconfiguration frames from the MRM and can detect and signal link changes on
its ring ports.
A compliant node shall have the ability to perform as one of the following:
• media redundancy manager (MRM),
• media redundancy client (MRC), or
• both MRM and MRC (but both roles shall not be active at the same time).
Each MRP compliant node requires a switch element with two ring ports connected to the ring.
NOTE 2 Additional ring ports may be used to connect to another ring.
Each node in the ring is able to detect the failure or recovery of an inter-switch link or the
failure or recovery of a neighboring node (see 5.1 ) .
The MRP consists of a service and a protocol entity, see stack model in Figure 1.
The service entity specifies, in an abstract way, the externally visible service provided by the
Data Link Layer in terms of:
• primitive actions and events of the service,
• parameters associated with each primitive action and event, and the form which they take,
and
• interrelationship between these actions and events, and their valid sequences.
MRP defines the services provided to

– 10 – 62439-2 © IEC:2010(E)
• the Application Layer at the boundary between the Application Layer and the Data Link
Layer, and
• the MRP Management at the boundary between the Data Link Layer and the MRP
Management.
Higher-Layer Entity
MRP MRP
Management
(Service)
(Protocol)
802.1
Data
Bridge
Link
Layer
802.3 802.3
Media Media
Access Access
Physical
802.3 802.3
Layer
PHY PHY
IEC  350/10
Figure 1 – MRP stack
5 MRP Media redundancy behavior
5.1 Ring ports
The MRM and the MRC shall have two ring ports.
The MRM and MRC shall be able to detect the failure or recovery of a link on a ring port with
mechanisms based on ISO/IEC 8802-3 (IEEE 802.3).
The MRM and MRC shall not forward MRP_Test frames, MRP_TopologyChange frames, and
MRP_LinkChange frames to non-ring ports.
A ring port shall take one of the following port states:
• DISABLED :
All frames shall be dropped.
• BLOCKED:
All frames shall be dropped except the following:
• MRP_TopologyChange frames and MRP_Test frames.
• MRP_LinkChange frames from an MRC.
• Frames specified in IEEE 802.1D (2004) Table 7-10 to pass ports in “Discarding” state
(e.g. LLDP, IEC 61588 (IEEE 1588) PTP).
• Frames only produced or consumed by the higher layer entities of this node and never
forwarded.
• FORWARDING:
All frames shall be passed through according to the forwarding behavior of IEEE 802.1D.
NOTE IEEE 802.1D refers to the port state corresponding to BLOCKED as “Discarding”.

62439-2 © IEC:2010(E) – 11 –
5.2 Media Redundancy Manager (MRM)
The first ring port of the MRM shall be connected to a ring port of an MRC. The other ring port
of that MRC shall be connected to a ring port of another MRC or to the second ring port of the
MRM, thereby forming a ring topology as shown in Figure 2.
enend d enend d eend nd
nonodede nnodeode nonodede
MRM blocked
LAN
MRC
MRC MRC MRC
enend d
nonodede
enend d enend d … enend d enend d enend d eend nd enend d enend d enend d
… switching
…
nonodede nonodede nonodede nnodeode nodnodee nonodede end node nonodede nonodede nonodede

IEC  351/10
Figure 2 – MRP ring topology with one manager and clients
The MRM shall control the ring state by:
• sending MRP_Test frames at a configured time period in both directions of the ring;
• setting one ring port in FORWARDING state and the other ring port in BLOCKED state if it
receives its own MRP_Test frames (this means that the ring is closed, see Figure 2);
• setting both ring ports in FORWARDING state if it does not receive its own MRP_Test
frames within a configured time according to MRP_TSTdefaultT, MRP_TSTshortT and
MRP_TSTNRmax in Table 33 (this means that the ring is open, see Figure 3).
enend d enend d enend d
nonodede nodnodee nonodede
MRM
LAN
MRC MRC MRC
MRC
endend
…
… nonodede
endend enend d endend enend d enend d enend d switching enend d enend d enend d
…
nonodede nodnodee nonodede nodnodee nonodede nonodede end node nonodede nodnodee nonodede

IEC  352/10
Figure 3 – MRP open ring with MRM
The following mechanism supports synchronization between MRM and MRC in ring topology
changes.
…
…
– 12 – 62439-2 © IEC:2010(E)
The MRM shall indicate changes in the ring state to the MRCs by means of
MRP_TopologyChange frames.
The MRM shall not forward MRP specific frames (MRP_Test frames, MRP_TopologyChange
frames, MRP_LinkChange frames) between its ring ports.
If the MRM receives an MRP_LinkUp or MRP_LinkDown frame, then the MRM shall reduce its
test monitoring time according to Table 33 to accelerate the detection of the open ring. When
the open ring is detected then the MRM shall send the MRP_TopologyChange frames through
both its ring ports.
Optionally the MRM shall send the MRP_TopologyChange frames through its ring ports. This
option is selected by setting the parameter REACT_ON_LINK_CHANGE, see Table 26.
The MRM shall send to the MRCs an MRP_TopologyChange frame with the delay, after which
the ring topology change will be performed. The parameter carrying this delay is called
MRP_Interval. When this time has expired, all MRCs shall clear their filtering database (FDB).
Each MRC shall send the configured delay in MRP_Interval to the MRM in the MRP_LinkUp
and MRP_LinkDown frames to tell the MRM after which time the MRC will change its port
state from BLOCKED to FORWARDING (MRP_LinkUp frame) or to DISABLED
(MRP_LinkDown frame).
Measures shall be included to prevent the MRM from remaining stuck in the closed state in
case of node failure.
5.3 Media Redundancy Client (MRC)
Each MRC shall forward MRP_Test frames received on one ring port to the other ring port and
vice versa.
If the MRC detects a failure or recovery of a ring port link, the MRC may optionally notify the
change by sending MRP_LinkChange frames through both of its ring ports. Each MRC shall
forward MRP_LinkChange frames received on one ring port to the other ring port and vice
versa.
Each MRC shall forward MRP_TopologyChange frames received on one ring port to the other
ring port and vice versa. Each MRC shall process these frames. It shall clear its FDB if
requested by an MRP_TopologyChange frame in a given time interval (see Table 33,
MRP_TOPchgT).
5.4 Redundancy domain
The redundancy domain represents a ring. By default, all MRM and MRCs belong to the
default domain. A unique domain ID can be allocated as a key attribute, especially if an MRM
or an MRC is member of multiple rings. A node shall assign exactly two unique ring ports per
redundancy domain.
NOTE 1 A device may have other ports than the two assigned to MRP. These other ports are not influenced by
MRP.
NOTE 2 MRP ports should behave as if RSTP is disabled.
5.5 Usage with diagnosis and alarms
If the attribute Check Media Redundancy has the value TRUE, media redundancy events shall
cause diagnosis events and alarm notifications.

62439-2 © IEC:2010(E) – 13 –
5.6 Ring diagnosis
In a redundancy domain the following diagnosis events handling shall be implemented by
each MRM.
• If a device is configured as MRM, but not operating in the manager role, it shall signal a
“MANAGER_ROLE_FAIL” diagnosis event and suspend reporting of all other media
redundancy diagnosis events while not in the manager role.
• If a device is operating in manager role and this device detects another active MRM, it
shall signal the “MULTIPLE_MANAGERS” event. This event can occur concurrently with
the ring state event “RING_OPEN”.
• If a device is operating in manager role and detects an open ring, it shall signal the
“RING_OPEN” event.
These events shall be signalled by using the State Change service see 7. 3.
NOTE The presence of MRP_Test frames enables the checking of the existence of an MRM.
5.7 Multiple MRM in a single ring
There shall be only one active MRM in the ring even if several nodes have this ability.
NOTE Multiple active MRMs cause the ring to divide itself into several segments.
As an option, in case of more than one node having the ability to become an MRM in the ring,
an enhanced protocol not specified in this International Standard may be used to decide
which of these nodes shall become the MRM, while the other nodes take over the MRC role
as shown in Figure 4. To this effect the nodes with the MRM ability have different priorities
that shall be conveyed in the MRP_Prio field of the MRP_Test frame.
If an optional protocol for multiple MRM in a single ring is used then all MRM in the ring shall
support the same protocol. The vendor shall specify the supported protocols.
enend d eend nd enend d
nodenode nodenode nodenode
MRM blocked
LAN
node with MRM capability
MRC MRC MRC
(in the MRC role)
eend nd
nodenode
endend enend d … enend d eend nd end end enend d switching eend nd eend nd endend
…
…
nonodede nnodeode nodenode nodnodee nodnodee nodenode end node nodnodee nodnodee nnodeode

IEC  353/10
Figure 4 – MRP ring with more than one MRM
5.8 BLOCKED not supported (option)
If an MRC is not able to support the BLOCKED port state at its ring ports, the MRC shall
report it in the corresponding parameter of the MRP_LinkChange frames.
…
– 14 – 62439-2 © IEC:2010(E)
If an MRC does not support the BLOCKED state in a ring, then a MRM shall support
additional functionalities (see Table 26, MRP_BLOCKED_SUPPORTED).
6 MRP Class specification
6.1 General
The MRP Application Service Element (ASE) defines one object type.
6.2 Template
An MRP object is described by the following template:
ASE: Media redundancy ASE
CLASS: Media redundancy
CLASS ID: not used
PARENT CLASS: IEEE 802.3, IEEE 802.1D
ATTRIBUTES:
1. (m) Key Attribute: Domain ID
2. (m) Attribute: Domain Name
3. (m) Attribute: Ring Port 1 ID
4. (m) Attribute: Ring Port 2 ID
5. (o) Attribute: VLAN ID
6. (m) Attribute: Expected Role (MANAGER, CLIENT)
7. (c) Constraint: Expected Role = MANAGER
7.1 (m) Attribute: Manager Priority
7.2 (m) Attribute: Topology Change Interval
7.3 (m) Attribute: Topology Change Repeat Count
7.4 (m) Attribute: Short Test Interval
7.5 (m) Attribute: Default Test Interval
7.6 (m) Attribute: Test Monitoring Count
7.7 (m) Attribute
...