Synchronous Ethernet is supported on Ethernet satellite client ports. The satellite must be enabled for Synchronous Ethernet using the sync-e option. This enables the transmit timing of the client ports to be synchronous to the central frequency clock of the host. Synchronous Ethernet is delivered from the host into the satellite using uplink ports U1 and U2. Uplink ports U3 and U4, if available, are not used for this delivery. Both of the host ports connecting to the uplink ports must support Synchronous Ethernet. It is not possible to configure a satellite client port as a source-port of the ref1 or ref2 inputs to the central frequency clock.
When running PTP from a host out to external PTP clocks connected to satellite client ports, the ptp-tc option must be enabled for the satellite. When used with PTP over Ethernet from the host, the performance is optimized. This allows for the inclusion of the host and satellite system in a network chain targeting one microsecond accurate time in the end application (see ITU-T recommendation series G.827x). PTP over IP can be used with this solution, but the performance is much less than with PTP over Ethernet and one microsecond accurate time cannot be guaranteed.