Safran WR-Z16 User Manual page 76

5.2 General Timing Management
Figure 5-8: Reference topology with different presets.
External Reference Layer: It includes the devices that will be fed by several
external references (in grey), such as an Atomic Clock or a GNSS receiver,
and will receive ToD (Time of Day) from an NTP server (external or embed-
ded). These devices will act as Grand-Master (GM) in the timing network
and their timing information will be forwarded to all the timing nodes.
The Fan-Out Layer or Middle Layer: The devices in this layer are mainly ded-
icated to spread (fan-out) the timing synchronization to more devices on
the down layers. In order to ensure continuous operation, they can be con-
figured with redundant timing sources (e.g., BC FO wr0-wr1) or could incor-
porate the Holdover option (e.g., BC wr0 slave HO).
The interoperability Layer: The devices that belong to this layer are also
known as last-hop devices. Typically, one of these devices is placed per
rack cabinet and is in charge of distributing the ultra-accurate timing
provided by the White Rabbit network to other 3rd party devices in the cab-
inet via PTP, via 10MHz/PPS (legacy devices), etc.
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66 5 WR-Z16 User Manual Rev. v5.0