Agilent Measurement Journal - Issue 4 - 2008 - (Page 7)

The current international standard, IEC 61588, is based on IEEE-1588 2002, which is generally called “version 1” or “V1” of the PTP. V1 was published in 2002 and version 2 (V2) is due to be completed by early 2008. Both versions were represented at the PlugFest by various types of PTP devices: • Ordinary clocks, which are end devices providing or using the “time” • Boundary and transparent clocks, which are specialized switches that allow higher performance than normal networking gear • A management node There were plans to run precise synchronization measurements; however, with the large number of participants, time ran short so activities focused on functional and interoperability testing. Highlighting the results The V1 network proceeded through most of the test plan fairly smoothly, although some of the tests were skipped because no one had implemented every feature of the speciﬁcation. The end-to-end V2 IP network also completed its tests, as did the Layer 2 direct-Ethernet-mapping network. The peer-to-peer V2 network successfully completed a portion of its suggested plan. The telecom proﬁle group had the hardest job. It was slower than the other groups, but this was due to greater complexity, variations in the implementations and the newness of the proﬁle’s deﬁnition. Ultimately, though, the special negotiation between master and slaves was made to work, and correct unicast operation and synchronization was achieved with the much higher message rates that this proﬁle requires. The V1 and V2 end-to-end IP networks also were connected together in a test that resulted in a hiccup from one V1 ordinary clock but it recovered and everything else kept running. This was signiﬁcant because there is no speciﬁed compatibility between V1 and V2; however, they can coexist if the implementations are designed with this in mind (as apparently occurred in this case). The test networks Because interest in 1588 has expanded beyond the aims of the initial version, V2 operation is much more varied. As a result, a total of ﬁve separate Ethernet networks were set up to support the expected amount of testing (Figure 1). Ethernet was the dominant LAN technology at the conference; however, V2 will describe ways to carry PTP on other network types. Testing as much as possible Compared with 2006, PlugFest participation doubled in terms of attendees and the number of organizations they represented. Nearly three times as many devices were brought to this year’s event, representing industries such as industrial automation, test and measurement, telecom components, networking systems and components, ASIC/FPGA cores and microprocessors. Participants received a draft test plan in advance, and the majority seemed willing to follow the plan. While there were similarities among the test plans for the ﬁve networks, some differences were necessary to account for the diverse requirements of applications that used the wider range of options allowed in V2 compared to V1. Tests included basic synchronization and resolution of the “Best Master Clock” algorithm, which determines which clock will act as the network’s time source — the “Grandmaster” in PTP jargon. For the PlugFest, Grandmaster properties were changed to force the algorithm to re-run, pick a new master and verify that the “slave” devices moved over to the new master. In some networks, message generation frequency was altered, enabling participants to observe changes in the resultant synchronization performance between the master and its slave devices. Conclusion From testing of system-wide clock synchronization or device and system interoperability to resolution of compatibility issues, the 2007 PTP PlugFest made signiﬁcant progress. It will be interesting to see how many people and devices participate in ISPCS 2008 in Ann Arbor, Michigan, and how much progress is made in the implementation of V2. References 1. For more information, please visit www.ispcs.org. 2. The academy’s web site is available at www.oeaw.ac.at/english/home.html. 3. Details are available at www.oeaw.ac.at/ﬁss/. Agilent Measurement Journal 7 http://www.ispcs.org http://www.oeaw.ac.at/english/home.html http://www.oeaw.ac.at/fiss/

Table of Contents Feed for the Digital Edition of Agilent Measurement Journal - Issue 4 - 2008

Agilent Measurement Journal - Issue 4 - 2008 Delivering Confidence through Compliance with Standards Contents Emerging Innovations Trying Early Device Implementations at the IEEE 1588 PlugFest Achieving Greater Confidence in Measurement Accuracy through Consistency in Calibration Services Overcoming the Challenges of RFID Component Testing 3GPP LTE: Introducing Single- Carrier FDMA Ensuring Reliable Operation and Performance in Converged IP Networks Testing Storage Area Networks and Devices at 8.5-Gb/s Fibre Channel Rates Choosing an Appropriate Calibration Method for Vector Network Analysis Making Traceable EVM Measurements with Digital Oscilloscopes Exploring Terahertz Measurement, Imaging and Spectroscopy: The Electromagnetic Spectrum’s Final Frontier Interpreting Quoted Specifications when Selecting Digitizers

Agilent Measurement Journal - Issue 4 - 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.