title={{IEEE} {Standard} for {Local} and {Metropolitan} {Area} {Networks--Bridges} and {Bridged} {Networks}},
title = {{IEEE Standard for LAN}},
year={2014},
month={Dec},
keywords={IEEE standards;access protocols;local area networks;metropolitan area networks;IEEE standard;MAC service;VLAN bridges;bridged networks;local area networks;media access control service;metropolitan area networks;Bridged circuits;IEEE standards;Local area networks;Media Access Protocol;Metropolitan area networks;Protofcols;Virtual environments;Bridged Network;IEEE 802.1Q(TM);LAN;MAC Bridge;MSTP;Multiple Spanning Tree Protocol;PBN;Provider Bridged Network;RSTP;Rapid Spanning Tree Protocol;SPB Protocol;Shortest Path Bridging Protocol;VLAN Bridge;Virtual Bridged Network;local area network;metropolitan area networks;virtual LAN},
author = "T.Levens and A.Boccardi and A.Butterworth and L.R.Carver and G.Daniluk and M.Gasior and W.Hofle and O.R.Jones and G.Kotzian and T.Lefevre and J.C.Molendijk and M.Ojeda Sandonis and J.Serrano and D.Valuch and T.Wlostowski and F.Vanga",
author={E. F. Dierikx and A. E. Wallin and T. Fordell and J. Myyry and P. Koponen and M. Merimaa and T. J. Pinkert and J. C. J. Koelemeij and H. Z. Peek and R. Smets},
author={E. F. Dierikx and et al.},
journal={IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control},
title={White Rabbit Precision Time Protocol on Long-Distance Fiber Links},
year={2016},
...
...
@@ -344,15 +284,15 @@ ISSN={0885-3010},
month={July},}
@inproceedings{biblio:MIKES-50km,
author = "Anders Wallin and Mattia Rizzi and Guifré Molera Calvés and Thomas Fordell and Jyri Näränen",
author = "Anders Wallin and et al.",
title = "{Improved Systematic and Random Errors for Long-Distance Time-Transfer Using PTP White Rabbit }",
booktitle = "{32nd European Frequency and Time Forum 2018}",
\multicolumn{7}{|l|}{TF= time and frequency transfer, TC= time-triggered control, TS= timestamping,}\\
\multicolumn{7}{|l|}{TD= trigger distribution, FL= Fixed-latency data transfer, RF= Radio-Freq. transfer}\\
\multicolumn{7}{|l|}{N= number of WR nodes, S= number of WR switches, L= number of layers}\\\hline
% \multicolumn{7}{|l|}{A: accuracy, P: precision, Link len. - it is the lenght of link between devices in the network, Tot. distance = the total distance that the networks spans } \\
% \multicolumn{7}{|l|}{} \\ \hline
\end{tabular}
\label{tab:applications}
\end{table}
\section{WR Network Elements}
\label{sec:wrElements}
WR network elements are openly available on the Open Hardware Repository
(OHWR) \cite{biblio:OHWR} and available off-the-shelf from companies. %, see Figure~\ref{fig:WRN}.
WR network elements, nodes and switches, are openly available on the Open Hardware Repository (OHWR)
\cite{biblio:OHWR} and can be purchased from companies. %, see Figure~\ref{fig:WRN}.
While all of the WR networks use the same design of
WR switch \cite{biblio:wr-switch},
the WR switch \cite{biblio:wr-switch},
the design of WR nodes depends on application. Thus, WR node design is available
as open-source IP core \cite{biblio:wr-node} that can be easily used in one of
the supported boards or integrated into a custom design. WR-compatible boards
are available on OHWR in various form factors, including:
\caption{Radio-frequency transmission over White Rabbit.}
\label{fig:RFoverWR}
\end{figure}
In this schema, A didigatal direct synthesis (DDS) based on the WR frequency (125MHz)
is used to generate an RF signal that is compared with a phase detector to the
input RF signal. The error measured by the phase detector is an input to an
Integral-Proportional (PI) controller that steers the DDS to produce signal identical
to the RF input. The tuning words of the DDS are the digital form of the RF input
that is sent over WR network. Each of the receiving WR Nodes uses the tuning
words to recreate the RF input by controlling their local DDS with a fixed delay.
In such way, all the WR nodes produce RF outputs that are phase-aligned with sub-ns
accuracy and picoseconds precision and that are delayed with respect to the RF
input. This schema is used currently tested in ESRF (Sectoin~\ref{sec:ESFR-GMT})
and at CERN (Section~\ref{sec:CERN-RF})
a digital direct synthesis (DDS) based on the WR reference clock
signal (125MHz) is used to generate an RF signal. The generated RF signal is then compared by a phase detector to the
input RF signal. The error measured by the phase detector is an input to a
loop filter (e.g. Integral-Proportional controller) that steers the DDS to produce signal identical
to the RF input - effectively the DDS is locked to the input signal.
The tuning words of the DDS are the digital form of the RF input
that is sent over WR network. Each of the receiving WR nodes recreate the RF input signal
by using the received tuning words to control the local DDS with a fixed delay.
In such way, the WR slave nodes produce RF outputs that are syntonized with
the RF input, phase-aligned among each other with sub-ns accuracy and picoseconds precision, and precisely delayed with respect to the RF input.
\subsection{Example Applications}
European Synchrotron Radiation Facility (ESRF)
The WR-based radio-frequency transfer is being implemented in the European Synchrotron Radiation
Facility (ESRF) \cite{biblio:ESRF}. The operation of the ESRF accelerator facility
is controlled by a "Bunch Clock" system that delivers to accelerator subsystems
$\approx$352 MHz RF signal and triggers initiating sequential actions synchronous
to the RF signal, such as "gun trigger", "injection trigger", "extraction trigger".
The jitter of the output RF signal is required to be below 50~ps. The RF signal is continuously
trimmed around the 352~MHz value as the tuning parameter in the "fast orbit feedback"
process. Apart from 352~MHz signal, other frquencies are distributed, such as
355~kH Storage Ring revolution frequency or 10~Hz Injection sequence.
The current ESRF "Bunch Clock" system is being refurbished to use WR \cite{biblio:ESRF-WR}.
The solution has passed 6-months validation tests in 2015. In 2016, a prototype system
consisting of a WR switch, a WR master node and a WR slave node successfully injected
bunches in the storage ring providing $<$10ps jitter. A system consisting
of 1 master and 7 slaves is expected to be operational in July 2018. It
will be expanded to 40 WR slaves nodes and 4-5 WR switches by 2020.
The ESRF "Bunch Clock" system not only distributs a number of RF frequencies,
it also provides timestamps and triggers that can be synchronous with these RF
frequencies.
The radio-frequency transfer in CERN's Super Proton Synchrotron (SPS)
accelerator is also being upgraded to use WR. The SPS requires distribution
of a ???~MHz RF signal with 0.25ps RMS jitter (100Hz to 100kHz) and accuracy of $\pm$10ps.
These requirements necessitate enhancements of WR performance.
% \section{WR Applications outside CERN}
% \label{sec:GSI-GMT}
...
...
@@ -737,83 +843,154 @@ European Synchrotron Radiation Facility (ESRF)
% \label{sec:power}
% The Distributed Electrical Systems Laboratory (DESL) [1] at the Swiss Federal Institute of Technology Lausanne (EPFL), one of world’s best technical universities, operates its own experimental Smart Grid [2][5]. Within the framework of technology improvements for the Smart Grid, one of the research studies [3] evaluated White Rabbit for distributed measurement of synchrophasors via Phasor Measurement Units (PMUs). This study investigated application of WR as a way to improve the steady state PMU accuracy and mitigate the well-known disadvantages of the currently-used GPS-base synchronization of PMUs: accessibility of clear-sky view and vulnerability of GPS signals. The results of the research show that WR-PMU can provide slightly better performance than the GPS-PMU, and is an appropriate alternative for GPS-based PMUs. The performance of the WR-PMU was limited by PMU’s hardware and not WR performance[4]. In terms of security, neither GPS nor WR are secure. In the case of WR, an attack can be counteracted by using redundant and disjoint communication paths or using the GPS as a redundant time sources.
\begin{table*}[!t]
\caption{White Rabbit Applications}
\centering
\tiny
\begin{tabular}
{| p{0.9cm} | p{1cm} | p{0.4cm} | p{1.7cm} | p{1.8cm} | p{1.1cm} | c | c | p{1.5cm} |}\hline
\multicolumn{9}{|l|}{TF = time and frequency transfer, TC = time-triggered control, TS = timestamping, TD = trigger distribution, FL = Fixed-latency data transfer, RF = Radio=-frequency transfer}\\
\multicolumn{9}{|l|}{A: accuracy, P: precision, Link len. - it is the lenght of link between devices in the network, Tot. distance = the total distance that the networks spans }\\
\multicolumn{9}{|l|}{}\\\hline
\end{tabular}
\label{tab:applications}
\end{table*}
% \begin{table}[!t]
% \caption{Non-exhaustive list of White Rabbit applications}
% % \multicolumn{7}{|l|}{A: accuracy, P: precision, Link len. - it is the lenght of link between devices in the network, Tot. distance = the total distance that the networks spans } \\
% \multicolumn{9}{|l|}{TF = time and frequency transfer, TC = time-triggered control, TS = timestamping, TD = trigger distribution, FL = Fixed-latency data transfer, RF = Radio=-frequency transfer} \\
% \multicolumn{9}{|l|}{A: accuracy, P: precision, Link len. - it is the lenght of link between devices in the network, Tot. distance = the total distance that the networks spans } \\