Showing papers on "Precision Time Protocol published in 2006"

NTP versus PTP in Com puter Networks Clock Synchronization

Abstract: Trusted and precise time sources are required in computer networks and Internet for various reasons: time stamps for electronic documents, online transactions, storage and document retrieval, electronic mail, multimedia applications and many others. Also, the demand for Ethernet as a real-time control network is increasing, as manufacturers realize the benefits of employing a single network technology across the plant. For control and measurement applications, the need of an accurate distribution-wide sense of time is even more stringent than regular applications. This paper is comparing two clock synchronization protocols, the Network Time Protocol and the IEEE-1588 Precision Time Protocol. It gives an overview of synchronization methods by the time stamping employed in IP-based real-time applications looking at the possible sources of errors as well as the achievable performance of the two standards.

Mechanism For Making Delay From Network Elements Transparent To IEEE 1588 Protocols

Abstract: Apparatus for making legacy network elements transparent to IEEE 1588 Precision Time Protocol operation. Network elements are wrapped by device(s) capable of providing either transparent clock or boundary clock operation. In one embodiment, smart interface converters are used to provide transparent clock or boundary clock operation. The smart interface converters work cooperatively.

Method and apparatus for establishing IEEE 1588 clock synchronization across a network element comprising first and second cooperating smart interface converters wrapping the network element

Abstract: Apparatus for making legacy network elements transparent to IEEE 1588 Precision Time Protocol operation. Network elements are wrapped by device(s) capable of providing either transparent clock or boundary clock operation. In one embodiment, smart interface converters are used to provide transparent clock or boundary clock operation. The smart interface converters work cooperatively.

Precise Time Synchronization Using IEEE 1588 for LXI Applications

Abstract: Next generation test systems are converging on Ethernet as the primary interconnect for data acquisition and instrument control. The emerging LXI standard relies on IEEE 1588 Precision Time Protocol (PTP) to synchronize distributed and large channel-count measurement systems over Ethernet. The authors of this paper present the results of synchronization tests using hardware time- stamping and the IEEE 1588 protocol. They discuss the limitations, advantages, and disadvantages of using PTP for time and frequency distribution; consider PTP performance under various network topologies and traffic scenarios; and share the test results of PTP performance over networks comprised of commercial off-the-shelf (COTS) network switches and hubs versus PTP-optimized devices.

Synchronizing operations of a plurality of devices via messages over a communication network

Abstract: A system and method synchronize operations of a plurality of devices via messages over a communication network. A plurality of devices are communicatively coupled via a communication network, and the devices have their local clocks synchronized to a high degree of precision using a technique, such as IEEE 1588 (Precision Time Protocol) or Network Time Protocol, for synchronizing their local clocks. Event messages can be sent that include an identification of an event, as well as a timestamp that is based on the local clock of the sender. The recipient of an event message determines if it is configured to act on the identified event, and if so it takes its action based on the timestamp included in the event message. In certain embodiments, the events that are to trigger an action and/or the specific responsive actions to be taken for a given event are dynamically programmable for each device.

Airborne network switch with ieee-1588 support

Abstract: Today’s data acquisition systems are typically comprised of data collectors connected to multiplexers via serial, point-to-point links. Data flows upstream from the sensors or avionics buses to the data acquisition units, to the multiplexer and finally to the recorder or telemetry transmitter. In a networked data acquisition system, data is transported through the network “cloud”. At the core of the network “cloud” is the network switch. The switch is responsible for distributing and directing data within the network. Network switches are commonplace in the commercial realm. Many businesses today could not function without them. A network-based data acquisition system, however, places additional burdens on the network switch. As in a commercial network, the switch in a data acquisition system must be able to distribute data packets within the network. In addition, it must be able to perform in a harsh environment, occupy a minimal amount of space, operate with limited or no external cooling, be configurable, and deal with the distribution of time information. This paper describes the required features of a ruggedized network switch and the implementation challenges facing its design. As a core component of a network-based data acquisition system, an ideal switch must be capable of operating in a large number of configurations, transporting and aggregating data between data sources and data sinks, with a mixture of devices operating at rates ranging from a few thousand bits per second to several gigabits per second, over twisted pair or fiber optic links. To ensure time coherency, the switch must also facilitate a time distribution mechanism, e.g., IEEE-1588 Precision Time Protocol (PTP). The gigabit switch described here uses the PTP to implement an end-to-end clock synchronization, for distributed acquisition nodes, to within 300 nanoseconds.

Study on automatic testing network based on LXI

Abstract: LXI (LAN eXtensions for Instrumentation), which is an extension of the widely used Ethernet technology in the automatic testing field, is the next generation instrumental platform. LXI standard is based on the industry standard Ethernet technolog, using the standard PC interface as the primary communication bus between devices. It implements the IEEE802.3 standard and supports TCP/IP protocol. LXI takes the advantage of the ease of use of GPIB-based instruments, the high performance and compact size of VXI/PXI instruments, and the flexibility and high throughput of Ethernet all at the same time. The paper firstly introduces the specification of LXI standard. Then, an automatic testing network architecture which is based on LXI platform is proposed. The automatic testing network is composed of several sets of LXI-based instruments, which are connected via an Ethernet switch or router. The network is computer-centric, and all the LXI-based instruments in the network are configured and initialized in computer. The computer controls the data acquisition, and displays the data on the screen. The instruments are using Ethernet connection as I/O interface, and can be triggered over a wired trigger interface, over LAN or over IEEE 1588 Precision Time Protocol running over the LAN interface. A hybrid automatic testing network comprised of LXI compliant devices and legacy instruments including LAN instruments as well as GPIB, VXI and PXI products connected via internal or external adaptors is also discussed at the end of the paper.