The 7705 SAR supports frequency synchronization via a Layer 1 interface such as synchronous Ethernet, and ToD synchronization via a protocol such as NTP or PTP. In cases where these methods are not possible, or where accuracy cannot be ensured for the service, you can deploy a GNSS receiver as a synchronous timing source. GNSS data is used to provide network-independent frequency and ToD synchronization.
GNSS receivers on the following platforms support GPS reference only, or combined GPS and GLONASS reference:
7705 SAR-Ax
7705 SAR-H with a GPS Receiver module
7705 SAR-Wx variants with a GPS RF port
7705 SAR-8 Shelf V2 with a GNSS Receiver card
7705 SAR-18 with a GNSS Receiver card
A 7705 SAR chassis equipped with a GNSS receiver and an attached GNSS antenna can be configured to receive frequency traceable to Stratum-1 (PRC/PRS). The GNSS receiver provides a synchronization clock to the SSU in the router with the corresponding QL for SSM. This frequency can then be distributed to the rest of the router from the SSU as configured with the ref-order and ql-selection commands. The GNSS reference is qualified only if the GNSS receiver is operational, has five or more satellites locked, and has a frequency successfully recovered. A PTP master/boundary clock can also use this frequency reference with PTP peers.
In the event of GNSS signal loss or jamming resulting in the unavailability of timing information, the GNSS receiver automatically prevents output of clock or synchronization data to the system, and the system can revert to alternate timing sources.