IEC 61588:2021

IEC 61588 ®
Edition 3.0 2021-06
™
IEEE Std 1588
INTERNATIONAL
STANDARD
Precision Clock Synchronization Protocol for Networked Measurement and
Control Systems
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IEC 61588 ®
Edition 3.0 2021-06
IEEE Std 1588™
INTERNATIONAL
STANDARD
Precision Clock Synchronization Protocol for Networked Measurement and

Control Systems
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 25.040.40; 35.110; 35.240.50 ISBN 978-2-8322-9811-4

IEEE Std 1588™-2019 – i –
Contents
1. Scope . 14
2. Normative references . 15
3. Definitions, acronyms, and abbreviations. 16
3.1 Definitions . 16
3.2 Acronyms and abbreviations . 24
4. Conventions . 26
4.1 Descriptive lexical form syntax . 26
4.2 Word usage . 27
4.3 Behavioral specification notation . 28
5. Data types and on-the-wire formats . 30
5.1 General . 30
5.2 Primitive data type specifications . 30
5.3 Derived data type specifications . 31
5.4 On-the-wire formats . 35
6. Clock synchronization model . 36
6.1 General requirements on implementations . 36
6.2 Principal assumptions about the network and implementation recommendations . 39
6.3 PTP Networks . 39
6.4 PTP message classes . 40
6.5 PTP device types . 41
6.6 Synchronization overview. 53
6.7 PTP communications overview . 65
7. Characterization of PTP entities . 69
7.1 Domains . 69
7.2 Timescales used in PTP . 72
7.3 PTP communications . 74
7.4 PTP communication media . 81
7.5 PTP Ports . 84
7.6 PTP Instance characterization . 89
7.7 PTP timing characterization . 103
8. PTP data sets. 105
8.1 General specifications for data set members . 105
8.2 Data sets for PTP Instances . 113
8.3 Data sets for Transparent Clocks . 141
8.4 commonMeanLinkDelayService data sets . 144
9. PTP for Ordinary Clocks and Boundary Clocks . 144
9.1 General protocol requirements for PTP Ordinary Clocks and Boundary Clocks . 144
9.2 State protocol . 145
9.3 Best master clock algorithms . 154
9.4 Grandmaster PTP Instance timePropertiesDS updates . 164
9.5 PTP message processing semantics . 166
9.6 Changes in the PTP Instance . 182
10. PTP for Transparent Clocks . 182
10.1 Requirements for both end-to-end and peer-to-peer Transparent Clocks . 182
10.2 End-to-end Transparent Clock requirements . 182
10.3 Peer-to-peer Transparent Clock requirements . 191
11. Clock offset, path delay, residence time, and asymmetry corrections . 195

Published by IEC under licence from IEEE. © 2019 IEEE. All rights reserved.

– ii – IEEE Std 1588™-2019
11.1 General specifications . 195
11.2 Computation of in Ordinary Clocks and Boundary Clocks . 196
11.3 Delay request-response mechanism for Ordinary Clocks and Boundary Clocks . 197
11.4 Peer-to-peer delay mechanism . 199
11.5 MDMI interface and Special Ports . 204
12. Synchronization and syntonization of clocks . 214
12.1 Clock adjustments . 214
12.2 Syntonization . 214
12.3 Synchronization . 215
13. PTP message formats . 216
13.1 General. 216
13.2 General PTP message format requirements. 216
13.3 Header. 216
13.4 Suffix . 222
13.5 Announce message . 222
13.6 Sync and Delay_Req messages . 224
13.7 Follow_Up message . 224
13.8 Delay_Resp message . 225
13.9 Pdelay_Req message . 225
13.10 Pdelay_Resp message . 226
13.11 Pdelay_Resp_Follow_Up message . 226
13.12 Signaling message . 227
13.13 PTP management message . 228
14. TLV entity specifications . 228
14.1 General requirements . 228
14.2 Propagation of TLVs through Boundary Clocks . 230
14.3 Vendor and standard organization extension TLVs . 231
14.4 PAD TLV (optional) . 233
15. PTP management messages (optional) . 234
15.1 General. 234
15.2 PTP management mechanism . 234
15.3 Processing of PTP management messages . 234
15.4 PTP management message format . 235
15.5 Management TLVs . 238
16. General optional features . 272
16.1 Unicast message negotiation (optional) . 272
16.2 Path trace (optional) . 280
16.3 Alternate timescale offsets (optional) . 282
16.4 Holdover upgrade (optional) . 289
16.5 Isolation of PTP Instances running under profiles specified by different standards organizations
(optional) . 290
16.6 Common Mean Link Delay Service (optional). 291
16.7 Configurable correction of timestamps (optional) . 298
16.8 Calculation of the for certain media (optional) . 299
16.9 Mixed multicast/unicast operation (optional) . 301
16.10 Cumulative frequency transfer method for synchronizing clocks (optional) . 304
16.11 Slave Event Monitoring (optional) . 308
16.12 Enhanced synchronization accuracy metrics (optional) . 317
16.13 Message Length Extension (optional) . 323
16.14 PTP integrated security mechanism (optional) . 324
17. State configuration options . 338
17.1 General. 338
17.2 Grandmaster clusters (optional). 338

Published by IEC under licence from IEEE. © 2019 IEEE. All rights reserved.

IEEE Std 1588™-2019 – iii –
17.3 Alternate master (optional). 340
17.4 Unicast discovery (optional) . 343
17.5 Acceptable master table (optional) . 345
17.6 Mechanism for external configuration of a PTP Instance’s PTP Port state (optional) . 347
17.7 Reduced state sets and use of the feature (optional) . 353
18. Interactions between PTP Instances in different PTP domains . 354
18.1 General specifications . 354
18.2 Interfaces enabling interdomain interactions . 355
19. Compatibility of this edition with earlier and future editions . 355
19.1 General. 355
19.2 Compatibility between version 2 and future versions . 356
19.3 Compatibility with IEEE Std 1588-2002 . 356
19.4 Compatibility between the PTP Instance conformant to this edition and the implementations
conformant to IEEE Std 1588-2008 . 356
20. Conformance . 361
20.1 Conformance objective . 361
20.2 PTP conformance requirements. 361
20.3 PTP Profiles . 362
Annex A (informative) Using the Precision Time Protocol (PTP). 365
A.1 Overview . 365
A.2 Physical layout . 366
A.3 Logical layout. 366
A.4 Component issues . 367
A.5 Local implementation issues . 368
A.6 System implementation issues . 370
A.7 Guidelines to achieve optimal performance . 371
A.8 Recommendations to aid in conformance testing . 371
A.9 Recommendation for implementations in unicast networks or networks with non-PTP bridges and routers
........................................................................................................................................................ 372
Annex B (informative) Timescales and epochs in PTP . 375
B.1 General considerations . 375
B.2 UTC, TAI and the PTP epoch and timescale updates . 375
B.3 Standard time sources . 378
B.4 Meaning and uses of the attributes of the timePropertiesDS data set . 379
Annex C (normative) Transport of PTP over User Datagram Protocol over Internet Protocol Version 4 . 382
C.1 General . 382
C.2 UDP port numbers . 382
C.3 IPv4 multicast addresses . 382
C.4 sdoId field values . 383
C.5 Optional values . 384
C.6 IPv4 Options . 384
C.7 Protocol addresses . 384
Annex D (normative)  Transport of PTP over User Datagram Protocol over Internet Protocol Version 6 385
D.1 General. 385
D.2 UDP port numbers . 385
D.3 IPv6 multicast addresses . 386
D.4 Optional values . 386
D.5 Protocol addresses . 386
Annex E (normative) Transport of PTP over IEEE 802.3 transports . 387
E.1 General . 387
E.2 Ethertype . 387
E.3 Multicast media access control (MAC) addresses . 387

Published by IEC under licence from IEEE. © 2019 IEEE. All rights reserved.

– iv – IEEE Std 1588™-2019
E.4 majorSdoId field values . 388
E.5 Optional values . 388
E.6 Protocol addresses . 388
Annex F (normative) Transport of PTP over DeviceNET . 389
F.1 Protocol . 389
F.2 message timestamp point . 389
F.3 clockIdentity . 389
F.4 PTP message formats . 389
F.5 DeviceNet addressing for PTP . 390
Annex G (normative) Transport of PTP over ControlNET . 391
G.1 Protocol . 391
G.2 clockIdentity. 391
G.3 PTP message formats . 391
G.4 ControlNet addressing for PTP. 391
Annex H (normative) Transport of PTP over IEC 61158 Type 10 . 392
H.1 Background . 392
H.2 Message specification . 393
H.3 DLPDU of the IEC 61158 TYPE10 . 394
H.4 Encoding specifications . 395
Annex I (normative) Default PTP Profiles . 398
I.1 General . 398
I.2 General requirements . 398
I.3 Delay Request-Response Default PTP Profile . 398
I.4 Peer-to-Peer Default PTP Profile . 400
I.5 High-Accuracy Delay Request-Response Default PTP Profile . 401
Annex J (normative) Performance monitoring options (optional) . 407
J.1 General . 407
J.2 Timestamp monitoring . 407
J.3 Additional parameters . 410
J.4 Record data types . 412
J.5 Data sets for performance monitoring . 414
Annex K (informative) Suppression of rogue Announce messages . 419
K.1 Example—Star topology . 420
K.2 Example—PTP Network with a single loop with an odd number of PTP Instances in the loop . 422
K.3 Example—More complex single loop PTP Network . 423
K.4 Example—Linear chain . 423
Annex L (normative) Layer-1 based synchronization performance enhancement (optional) . 425
L.1 General . 425
L.2 Basic terms . 426
L.3 Link Reference Model . 427
L.4 L1Sync port characteristics. 429
L.5 L1Sync data sets . 431
L.6 L1Sync message exchange . 434
L.7 L1Sync port operation specification . 437
L.8 Optional parameters (option within this option) . 439
L.9 Link verification using Signaling messages (informative) . 444
Annex M (informative)  Sub-nanosecond synchronization using the High Accuracy Default PTP
Profile . 445
M.1 General . 445
M.2 Frequency loopback . 445
M.3 Timestamping precision . 447
M.4 Timestamping accuracy . 448

Published by IEC under licence from IEEE. © 2019 IEEE. All rights reserved.

IEEE Std 1588™-2019 – v –
M.5 Medium and its asymmetry . 449
M.6 Timing characteristics . 450
Annex N (informative) Calibration procedures . 452
N.1 General. 452
N.2 Theoretical background. 455
N.3 Assumptions and requirements . 457
N.4 Calibration procedures . 459
Annex O (informative) Example inter-domain interactions . 466
O.1 General. 466
O.2 Sourcing timing to multiple domains . 466
O.3 Providing timing to users (sinks) from multiple independent domains . 467
O.4 Transferring time from PTP domain A to PTP domain B . 468
O.5 Example use for external configuration of port state . 473
Annex P (informative) Security . 474
P.1 Overview, assumptions, and approach . 474
P.2 Multipronged approach—detailed definition . 474
Annex Q (informative) Bibliography . 495
Annex R (informative) IEEE List of participants . 498

Published by IEC under licence from IEEE. © 2019 IEEE. All rights reserved.

– vi – IEEE Std 1588™-2019
PRECISION CLOCK SYNCHRONIZATION PROTOCOL
FOR NETWORKED MEASUREMENT AND CONTROL SYSTEMS

FOREWORD
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IEEE Std 1588™-2019 – vii –
IEC 61588/IEEE Std 1588 was processed through IEC technical committee 65C: Industrial
networks, under the IEC/IEEE Dual Logo Agreement. It is an International Standard.
The text of this International Standard is based on the following documents:
IEEE Std FDIS Report on voting
1588 (2019) 65C/1084/FDIS 65C/1091/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
The IEC Technical Committee and IEEE Technical Committee have decided that the contents
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will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
Published by IEC under licence from IEEE. © 2019 IEEE. All rights reserved.

Abstract: In this standard, a protocol is defined that provides precise synchronization of clocks in
packet-based networked systems. Synchronization of clocks can be achieved in heterogeneous
systems that include clocks of different inherent precision, resolution, and stability. The protocol
supports synchronization accuracy and precision in the sub-microsecond range with minimal
network and local computing resources. Customization is supported by means of profiles. The
protocol includes default profiles that permit simple systems to be installed and operated without
the need for user management. Sub-nanosecond time transfer accuracy can be achieved in a
properly designed network.
TM
Keywords: Boundary Clock, clock, Grandmaster Clock, IEEE 1588 , management, Ordinary
Clock, security, synchronization, Transparent Clock
•
Published by IEC under licence from IEEE. © 2019 IEEE. All rights reserved.

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