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Version 2 of IEEE 1588 contains an extension to secure the given service of clock synchronization. This article describes a practical implementation of this extension for a clock synchronization network. Pitfalls also relevant to other implementations and important properties are discussed and performance results that cover normal operation and stress tests such as denial of service attacks are presented...
We explore the robustness of synchronization performed in the presence of variable latencies using two software clocks: the TSCclock, designed to replace ntpd for Internet synchronisation, and ptpd, a software implementation of IEEE-1588. Using a precise comparison methodology the TSCclock is shown to be more accurate and far more robust. We discuss the reasons why and the implications for IEEE-1588...
The IEEE 1588 precision time protocol seems to be a promising way to handle synchronization requirements of tomorrow substation automation. However, one of the remaining issues is its lack of reliability in case of the loss of the GPS signal (e.g. due to atmospheric disturbances or failure of the GPS antenna) which would lead to the desynchronization of the devices inside a substation or between different...
This paper presents a telecom circuit-emulation system that uses the precision time protocol (PTP) aka IEEE1588 v2 for frequency distribution. In particular, a differential clock recovery mechanism is described that uses PTP as its reference clock based at one time on OCXO and at the other time on TCXO. A performance comparison is demonstrated for various test scenarios and compared against the stability...
This paper discusses a device, the spider transparent clock, which can be used to retrofit existing bridges and routers to allow them to deliver highly accurate time using the IEEE 1588 protocol. The spider transparent clock corrects for the internal queuing jitter and asymmetry introduced by these bridges and routers.
Secure localization protocols enable a group of cooperating verifier nodes in a wireless LAN to determine the physical location of a stranger (called the prover), using precision timing measurements during a carefully scripted packet exchange. After identifying a number of common features between the localization and precision clock synchronization problems, we describe a small set of additional physical-layer...
A growing number of applications today are based on the transfer of time and/or frequency over packet networks. This has created a requirement for new methods to support the modeling, testing and implementation of packet based time services. This paper describes a new metric called minTDEV. An overview of the Allan variance family and how this metric fits in is provided. A conceptual and formal definition...
A precise time synchronization is essential in many wireless sensor networking applications, e.g. in order to correlate observations of the same event from different sites or to efficiently share the wireless channel. Generally, wireless sensors are designed having in mind low cost and low power. In the past, several protocols have been suggested, each one with its pros and cons, aiming at the maximization...
This paper quantifies the ldquo1 mus-conformrdquo line-length of the Transparent Clock Mechanism of peer-to-peer Precision Time Protocol (PTP Version 2), i.e. the number of elements that stay within the plusmn1 mus sync error tolerance, for crystal oscillator output frequencies of 100 MHz, 250 MHz, 500 MHz and 1 GHz, i.e. for time quantization errors of 10 ns, 4 ns, 2 ns and 1 ns.
This paper describes an application of the IEEE 1588 standard to industrial automation. Key application use cases are identified that can benefit from time-based control techniques to improve performance results over traditional control methods. A brief discussion of how the 1588 standard may be adopted suitable to these applications. Application problems specific to industrial automation are enumerated...
Next generation Navy platform designs are evolving towards generalized multipurpose infrastructures based on open standards and commercial products. These platforms will support a wide range of new and expanding applications in a more flexible and dynamic manner than in previous designs. These applications are increasingly being more finely partitioned and distributed over this generalized infrastructure...
The ability to acquire quality equipment and process data is important for future real-time process control systems to maximize opportunities for semiconductor manufacturing yield enhancement and equipment efficiency. Clock synchronization for accurate time-stamping and maintaining a consistent frequency in trace data collection are essential for accurate merging of data from heterogeneous sources...
This paper describes clock synchronization requirements for a modern military and crisis management sensor network. This paper also presents a network architecture utilizing IEEE 1588 implemented for sensor network use and some solutions selected to complete the special requirements. The requirements for the sensor network presented in the paper relate to clock synchronization accuracy, availability...
IEEE 802.1AS is being developed in the 802.1 working group as part of a set of standards for audio/video bridging (AVB). AVB networks will carry time-sensitive, high-quality, audio/video traffic, and IEEE 802.1AS will provide synchronization for these networks and ensure that the jitter, wander, and synchronization requirements for the time-sensitive traffic can be met. IEEE 802.1AS includes an IEEE...
The following topics were dealt with: clock synchronization; time synchronization; Internet QoS; IEEE 1588; real-time performance; precision time protocol; network synchronization; military applications and wireless sensor networks.
This paper investigates Real-Time Ethernet (RTE) protocols for industrial applications and their clock synchronization performance. In fact, if different RTE protocols coexist on the same network sharing the same infrastructure, clock synchronization capabilities can be affected. This paper introduces a simulation environment to evaluate coexistence of RTE protocols. The proposed tool is described...
The Precision Time Protocol (PTP) is an application layer protocol and therefore destined to be implemented in software. Hardware functions, if present, include a high resolution clock that helps to generate precise timestamps for PTP messages. The presented paper describes an IEEE 1588 clock that realizes syntonization and synchronization functions completely in hardware. It combines a three-port...
Keeping slave clocks with sub-microsecond accuracy is believed to require hardware-assistance at physical layer and network. This paper presents software-only implementations of a slave for such accuracy. Time-stamps are read in the interrupt handler and a system resource conflicts detector filters out system-inside noise. We adopted Packet Inter-Arrival based clock servo technique that has fast convergence...
Fred Baker is one of the architects behind Internet quality of service technology, authoring or editing many of the defining documents in the IETF. In this talk, he comment on Internet traffic behavior in LANs, congested WANs, and in ISP networks. Looking at the requirements of timing services including NTP and IEEE 1588, he comment on ways to reduce the noise in the timing signal and on the utility...
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