How to Effectively Enhance PTP Redundancy Using Dual Ports

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Publisher: SMPTE — White Plains, NY, USA
Doc Type: Conference Paper
Content Type: Original Research
Volume: 2023, No. 10, pp. 20–22
Abstract: In the recent past, media transport over IP networks has become a viable option for the broadcasting industry. The SMPTE ST-2110 family of standards has proven to be a key factor in guaranteeing the required level of performance as well as full interoperability between different vendors. A small but nevertheless crucial part of the All-IP-Studio is an accurate and reliable common notion of time throughout the whole network. The broadcasting industry chose the IEEE 1588 Precision Time Protocol (PTP) for time transfer because it is a well-established method and is used in many application domains. PTP offers a certain level of fault tolerance, coping with the loss of the reference (PTP Grandmaster) autonomously by electing an auxiliary device to assume this role. Mission-critical applications may require a higher level of resilience to detect and/or counteract more complex error conditions such as intermittent or permanent loss of time transfer as well as deterioration of its quality - both will remain undetected by PTP. Rather than keeping all auxiliary PTP Grandmasters in hot-standby mode, we propose to deploy more than one active time reference. This allows all PTP end devices (Followers) to select the best time source using extended selection criteria and thus cope with almost every error condition without transient or permanent deterioration of the synchronization accuracy. — We will describe in detail how to implement this extension without violating or extending the original PTP protocol, which is a mandatory requirement for any improvement of PTP time transfer. Within a multi-vendor testbed, we will demonstrate the performance and advantages of this approach by inducing the most common transient and permanent error conditions within a typical PTP network. The accuracy of the proposed solution will be evaluated by measuring the offset of the PTP hardware clocks of all Followers with respect to the PTP Grandmaster. The results will be compared with the performance of a commercial PTP implementation being subjected to the same error conditions. The paper will conclude by briefly describing how to implement this technology and commenting on the implementation overhead as well as the expected increase in resource usage.
Publication Date: 2023-10-16
DOI: 10.5594/M002029
ISBN: Print: 978-1-61482-964-5
Link: https://doi.org/10.5594/M002029
Author(s): Nikolaus KeroOregano Systems
Thomas KernenNvidia
Keyword(s): ST 2110, ST 2059-2, Redundant Clock Synchronization, PTP, IEEE-1588
Copyright: © 2023 Society of Motion Picture and Television Engineers, Inc.

Bibliographic Reference(s)

Efficient Monitoring of ST2059-2 Based Time Transfer Performance [Active]
Enhanced Redundancy of ST 2059-2 Time Transfer Over ST 2022-7 Redundant Networks [Active]
Strategies to Protect Time Transfer in ST 2059-2 PTP Networks [Active]
Monitoring and Analysis of SMPTE ST 2059-2 PTP Networks and Media Devices [Active]
A Multipronged Approach to Effectively Secure SMPTE ST 2059 Time Transfer [Active]
Can ST 2059-2 Benefit From PTP Version 2.1? [Active]
"IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems," in IEEE Std 1588-2019 (Revision of IEEE Std 1588-2008) , vol., no., pp.1-499, 16 June 2020, doi: 10.1109/IEEESTD.2020.9120376. EXTERNAL
T. Kovácsházy, “Holdover Improvements to the linuxptp Servo for Network Adapters with High-Precision Oscillators”, Proceedings of the ISPCS 2023, Sept 18-22 2023. EXTERNAL
G. Gaderer, S. Rinaldi, N. Kerö, Master Failures in the Precision Time Protocol, Proceedings of the ISPCS 2008, Sept. 22-26 2008, pp. 59-64. EXTERNAL
"IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems," in IEEE Std 1588-2008 (Revision of IEEE Std 1588-2002) , vol., no., pp.1-269, 24 July 2008, doi: 10.1109/IEEESTD.2008.4579760. EXTERNAL
K. O'Donoghue, D. Sibold and S. Fries, "New security mechanisms for network time synchronization protocols," 2017 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control, and Communication (ISPCS), Monterey, CA, USA, 2017, pp. 1-6, doi: 10.1109/ISPCS.2017.8056747. EXTERNAL
SMPTE ST 2022-7:2018 [Active]
SMPTE ST 2059-2:2020 [Active]
SMPTE ST 2110-20:2017 [Superseded]
SMPTE ST 2110-30:2017 [Superseded]
SMPTE ST 2110-40:2023-12 [Active]

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Nikolaus Kero and Thomas Kernen; How to Effectively Enhance PTP Redundancy Using Dual Ports, SMPTE Meetings and Conferences ( October 2023); SMPTE, 2023, ISBN: 978-1-61482-964-5. Available at https://doi.org/10.5594/M002029

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Nikolaus Kero and Thomas Kernen; How to Effectively Enhance PTP Redundancy Using Dual Ports, SMPTE Meetings and Conferences ( October 2023); SMPTE, 2023, ISBN: 978-1-61482-964-5. Available at https://doi.org/10.5594/M002029

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<span class="citation">Nikolaus Kero and Thomas Kernen; <cite>How to Effectively Enhance PTP Redundancy Using Dual Ports</cite>, SMPTE Meetings and Conferences ( October 2023); SMPTE, 2023, ISBN: 978-1-61482-964-5. Available at <a href="https://doi.org/10.5594/M002029" target="_blank" rel="noopener">https://doi.org/10.5594/M002029</a></span>

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Nikolaus Kero and Thomas Kernen; <cite id="bib-10-5594-m002029">How to Effectively Enhance PTP Redundancy Using Dual Ports</cite>, SMPTE Meetings and Conferences ( October 2023); SMPTE, 2023, ISBN: 978-1-61482-964-5
<span class="doi">10.5594/M002029</span>
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