A packet filtering mechanism with a packet delay distribution estimation function for IEEE 1588 time synchronization in a congested network

Murakami, Takahide; Homma, Yukio; Nishimura, Kosuke

doi:10.1109/ispcs.2011.6070159

Cited by 16 publications

(9 citation statements)

References 5 publications

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“…P ACKET-BASED time synchronization techniques based on the IEEE 1588 Precision Time Protocol (PTP) are being increasingly considered as a means of providing microsecondlevel synchronization between cell towers in 4G LTE (Long Term Evolution) mobile networks [2]- [6]. Such a high degree of synchronization accuracy is a necessity in 4G networks since it helps ensure seamless handovers between cell towers, helps reduce inter-cell interference, and also enables the use of MIMO techniques to improve capacity [7].…”

Section: Introductionmentioning

confidence: 99%

“…The IEEE 1588 PTP standard [10] and related literature prescribe the use of simple POE schemes such as the sample mean, minimum and maximum filtering schemes. Several recent papers [2], [6], [7] have studied methods to improve the performance of these schemes. However, it is not well understood as to how close these POE schemes come to achieving the best possible performance.…”

Section: Introductionmentioning

confidence: 99%

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Performance Lower Bounds for Phase Offset Estimation in IEEE 1588 Synchronization

Guruswamy

Blum

Kishore

et al. 2015

IEEE Trans. Commun.

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In this paper, we describe new lower bounds on error variance of phase offset estimation schemes used in IEEE 1588 based synchronization. The motivation for this study is to determine the feasibility of providing microsecond-level time synchronization over mobile backhaul networks for the backend in 4G cellular systems. Many packet filtering/selection techniques for phase offset estimation have been proposed in synchronization literature, however, lower limits on the performance of such estimators have not yet been described. In this paper, we re-derive two Bayesian estimation bounds, namely the Ziv-Zakai and Weiss-Weinstien bounds, for use under a non-Bayesian formulation. This enables us to apply these bounds to the problem of phase offset estimation. Simulation results compare the performance of existing estimation schemes against these lower bounds under a variety of different network scenarios.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Performance Lower Bounds for Phase Offset Estimation in IEEE 1588 Synchronization

Guruswamy

Blum

Kishore

et al. 2015

IEEE Trans. Commun.

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“…With regard to the distribution of packet sizes in background traffic, we consider Traffic Models 1 (TM1) and 2 (TM2) from the ITU-T recommendation G.8261 [2] for cross traffic flows, as specified in Table I. For inline traffic flows, we consider a third traffic model where packet sizes are uniformly distributed between 64 and 1500 bytes [7]. We assume that the interarrival times between packets in all background traffic flows follow exponential distributions.…”

Section: Simulation Resultsmentioning

confidence: 99%

Minimax Optimum Estimators for Phase Synchronization in IEEE 1588

Guruswamy

Blum

Kishore

et al. 2015

IEEE Trans. Commun.

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The IEEE 1588 protocol has received recent interest as a means of delivering sub-microsecond level clock phase synchronization over packet-switched mobile backhaul networks. Due to the randomness of the end-to-end delays in packet networks, the recovery of clock phase from packet timestamps in IEEE 1588 must be treated as a statistical estimation problem. A number of estimators for this problem have been suggested in the literature, but little is known about the best achievable performance. In this paper, we describe new minimax estimators for this problem, that are optimum in terms of minimizing the maximum mean squared error over all possible values of the unknown parameters. Minimax estimators that utilize information from past timestamps to improve accuracy are also introduced.Simulation results indicate that significant performance gains over conventional estimators can be obtained via such optimum processing techniques. These minimax estimators also provide fundamental limits on the performance of phase offset estimation schemes.

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“…Mitigation The most basic mitigation for this attack is to add thresholds on the legal message delay ratio, as suggested in [20]: As can be seen in Figure 2, these techniques are already implemented in PTPd, resulting in extended attack efforts to create even a small time change at the target. With these countermeasures the adversary's ability to control the target's time is limited and demands a large effort, both in time and in message count.…”

Section: Delay Spoofing Attack Scenariomentioning

confidence: 99%

A Security Analysis and Revised Security Extension for the Precision Time Protocol

Itkin

Wool

2020

IEEE Trans. Dependable and Secure Comput.

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The Precision Time Protocol (PTP) aims to provide highly accurate and synchronized clocks. Its defining standard, IEEE 1588, has a security section ("Annex K") which relies on symmetrickey secrecy. In this paper we present a detailed threat analysis of the PTP standard, in which we highlight the security properties that should be addressed by any security extension. During this analysis we identify a sequence of new attacks and non-cryptographic network-based defenses that mitigate them. We then suggest to replace Annex K's symmetric cryptography by an efficient elliptic-curve Public-Key signatures. We implemented all our attacks to demonstrate their effectiveness, and also implemented and evaluated both the network and cryptographic defenses. Our results show that the proposed schemes are extremely practical, and much more secure than previous suggestions.

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A packet filtering mechanism with a packet delay distribution estimation function for IEEE 1588 time synchronization in a congested network

Cited by 16 publications

References 5 publications

Performance Lower Bounds for Phase Offset Estimation in IEEE 1588 Synchronization

Performance Lower Bounds for Phase Offset Estimation in IEEE 1588 Synchronization

Minimax Optimum Estimators for Phase Synchronization in IEEE 1588

A Security Analysis and Revised Security Extension for the Precision Time Protocol

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