White-Rabbit -> Master
White Rabbit network provides two services:
- network-wide high-accuracy time distribution (synchronization) - in most cases a reference time provided by atomic clock or/and GPS receiver is distributed over White Rabbit Network. A device which connects White Rabbit Network with time reference (atomic clock/GPS receiver) is called Timing Master.
- deterministic and reliable data distribution (delivery) - in most cases a controller-node sends control messages to controlled-nodes. A device which implements a controller function and sends critical data onto White Rabbit network is called a Data Master.
Timing Master
- a WR Switch or a WR Node connected (and synchronized) to a time reference (atomic clock or/and GPS receiver)
- acts as a PTP Grandmaster
- multiple Timing Masters in a single White Rabbit Network are allowed, note that seamless switchover between them is not yet supported
Note: the official White Rabbit PTP Core documentation contains instructions how to setup a Timing Master on a WR Node (SPEC PCIe board).
Data Master
- a WR Node (maybe WR Switch) that implements a functionality of a controller to the WR Nodes connected by the White Rabbit Network
- multiple Timing Masters in a single White Rabbit Network are allowed
- implementations:
- a proposed future General Machine Network at CERN with several Data Masters - a brief description is provided on pages 11-16 of Discussion On A White Rabbit based CERN Control and Timing Network
- an existing WR-BTrain system at CERN where there is a single
Data Master that transmits the value of magnetic field (Bvalue)
- Real-Time Distribution of Magnetic Field Measurements Over White-Rabbit (page 24 for network layout) (presentation)
- White Rabbit based revolution frequency program for the longitudinal beam control of the CERN PS (paper)
Maciej Lipinski / 03 July 2017