Precision Time Protocol

About: Precision Time Protocol is a research topic. Over the lifetime, 604 publications have been published within this topic receiving 6006 citations. The topic is also known as: PTP & IEEE 1588.

Precision time protocol over LR-WPAN and 6LoWPAN

Abstract: Precision time synchronization is critical for distributed sensing, and coordinated actuation in various low-range wireless applications in Internet of Things and Robotics. The state-of-the-art time synchronization protocol however, known as Precision Time Protocol (PTP) is designed for wired networks. In this work, we make an effort to enable PTP for Low Range Wireless Personal Area Networks (LR-WPAN). IPv6 over Low power Personal Area Network (6LoWPAN) represents the upper layers for LR-WPAN MAC and PHY layers in the protocol stack. Since 6LoWPAN offers additional advantages of software portability and interoperability with IPv6 based networks, we enable PTP over 6LoWPAN interface. We leverage PTP software abstractions and the networking stack to implement hardware timestamping feature for LR-WPAN and 6LoWPAN interfaces. To achieve precise timing, we expose 6LoWPAN interface as a Precise Hardware Clock (PHC) that enables accurate times-tamping of external events, precise hardware interrupts and pulse-per-second signals generation. We transform 6LoWPAN enabled ultra-wideband radios to wireless PHCs and achieve sub-nanosecond synchronization accuracy.

Precision time protocol attack strategies and their resistance to existing security extensions

Abstract: The IEEE 1588 precision time protocol (PTP) is very important for many industrial sectors and applications that require time synchronization accuracy between computers down to microsecond and even nanosecond levels. Nevertheless, PTP and its underlying network infrastructure are vulnerable to cyber-attacks, which can stealthily reduce the time synchronization accuracy to unacceptable and even damage-causing levels for individual clocks or an entire network, leading to financial loss or even physical destruction. Existing security protocol extensions only partially address this problem. This paper provides a comprehensive analysis of strategies for advanced persistent threats to PTP infrastructure, possible attacker locations, and the impact on clock and network synchronization in the presence of security protocol extensions, infrastructure redundancy, and protocol redundancy. It distinguishes between attack strategies and attacker types as described in RFC7384, but further distinguishes between the spoofing and time source attack, the simple internal attack, and the advanced internal attack. Some experiments were conducted to demonstrate the impact of PTP attacks. Our analysis shows that a sophisticated attacker has a range of methodologies to compromise a PTP network. Moreover, all PTP infrastructure components can host an attacker, making the comprehensive protection of a PTP network against a malware infiltration, as for example exercised by Stuxnet, a very tedious task.

Smart IEEE–1588 GPS Clock Emulator for Cabled Ocean Sensors

Abstract: Today, cabled seafloor observatories are installed at many sites around the globe, gathering different types of sensors in the marine environment where a Global Positioning System (GPS) signal is not accessible. Accurate time marking of ocean sensor data is highly important in many marine applications. This paper presents a smart GPS emulator based on the IEEE-1588 Precision Time Protocol (PTP). The device was designed and implemented to be able to provide accurate timing data (trigger + time code) to any ocean sensor as a broadband seismometer. In this case, accurate location and magnitude of a detected earthquake are dependent on the accuracy of the data time marks. The performance of time synchronization is tested, using a commercial broadband seismometer, and the results are presented. These tests are based on a comparison of the synchronization trigger between master and slave clocks as well as the analysis of the data acquired by the seismometer. The work presented here leads to an improved performance of the ocean-bottom seismometers as well as tsunami warning systems.

Synchronization performance of the Precision Time Protocol: Effect of clock frequency drift on the line delay computation

Abstract: The Precision Time Protocol (PTP) of the IEEE 1588 standard relies on two processes: the timing propagation process and the line delay estimation process It is important to study the factors that affect the quality of these synchronization sub-processes, in order to expand the limit on the number of slaves synchronizable within a given synchronization precision This short work-in-progress paper analytically studies the sensitivity of the line delay computation to linear clock frequency drift

Synchronization precision monitoring system of time synchronization device of power equipment

Abstract: The invention discloses a synchronization precision monitoring system of a time synchronization device of power equipment. The synchronization precision monitoring system comprises a center monitoring system, a network management system and a measurement device. The measurement device is arranged in a transformer substation and is connected with master clock equipment, expanded clock equipment and equipment with time service which are in the transformer substation. The measurement device acquires a time signal of the master clock equipment in the transformer substation, converts the time signal into a precision time protocol (PTP) message packaged by E1, and then transmits to the center monitoring system through an E1 channel of an interstation synchronous digital hierarchy (SDH); the center monitoring system restores according to the PTP message so as to acquire the time signal of a master clock of the transformer substation, compares the time of the master clock of the transformer substation with current time so as to acquire a first time difference, and transmits the first time difference to the network management system; and the measurement device confirms a second time difference between the time of the master clock equipment and the time of the expanded clock equipment and the equipment with time service in the transformer substation, and transmits the second time difference to the network management system. The synchronization precision monitoring system can acquire the output accuracy of the time synchronization device in time.