GPS
The router can receive 1PPS, 10 MHz, and ToD signals from an external clocking and timing source. The three inputs are combined as a Sync-2 interface to form the external timing source or the GPS input.
The GPS front panel connector details are:
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ToD—RS422 format as input
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1PPS—RS422 or DIN connector as input
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10MHz—DIN connector as input
GPS input starts only when all the three signals – 1PPS, 10MHz, and ToD are UP.
 Note |
Unlike the Ethernet interface, the Sync-2 interface cannot receive or transmit QL. Ensure that you assign a QL value to the Sync-2 interface. |
By default, 1PPS and 10MHz are in output mode. ToD output mode is not configurable.
For these variants - N540-24Z8Q2C-SYS, N540X-ACC-SYS, N540-ACC-SYS, N540-28Z4C-SYS, 10MHZ and 1PPS can operate in output mode only when PTP Client or BC mode are configured.
Configuring GPS Settings for the Grandmaster Clock
RP/0/RP0/CPU0:router# configure
RP/0/RP0/CPU0:router(config)# clock-interface sync 2 location 0/RP0/CPU0
RP/0/RP0/CPU0:router(config-clock-if)# port-parameters
RP/0/RP0/CPU0:router(config-clk-parms)# gps-input tod-format cisco pps-input ttl
RP/0/RP0/CPU0:router(config-clk-parms)# exit
RP/0/RP0/CPU0:router(config-clock-if)# frequency synchronization
RP/0/RP0/CPU0:router(config-clk-freqsync)# selection input
RP/0/RP0/CPU0:router(config-clk-freqsync)# wait-to-restore 0
RP/0/RP0/CPU0:router(config-clk-freqsync)# quality receive exact itu-t option 1 PRC
RP/0/RP0/CPU0:router(config-clk-freqsync)# exit
RP/0/RP0/CPU0:router(config-clock-if)# frequency synchronization
RP/0/RP0/CPU0:router(config-clk-freqsync)# quality itu-t option 1
RP/0/RP0/CPU0:router(config-clk-freqsync)# clock-interface timing-mode system
RP/0/RP0/CPU0:router(config-clk-freqsync)# end
or
RP/0/RP0/CPU0:router(config-clk-freqsync)# commitVerifying the GPS Input
RP/0/RP0/CPU0:R1# show controllers timing controller clock
SYNCC Clock-Setting: -1 -1 6 -1
Port 0 Port 1 Port 2 Port 3
Config : No No Yes No
Mode : - - GPS -
Submode1 : - - CISCO -
Submode2 : - - UTC -
Submode3 : 0 0 0 0
Shutdown : 0 0 0 0
Direction : RX/TX RX/TX RX RX/TX
Baud-Rate : - - 9600 -
QL Option : O1 O1 - -
RX_ssm(raw): - - - -
TX_ssm : - - - -
If_state : DOWN DOWN UP DOWN << Port 2 is UP when GPS input is valid.
RP/0/RP0/CPU0:R1#
When the front panel timing LED is Green, it indicates that the GPS is configured and 1PPS, ToD, and 10M inputs are valid.
Timing LED Behavior:
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Timing LED is off: Indicates that no GPS is configured or the GPS port is down.
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Timing LED is green: Indicates that the GPS port is up.
SYNC LED Behavior:
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SYNC LED is applicable: Only when the timing configuration is applied.
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SYNC LED is green: Indicates that SyncE is locked.
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SYNC LED is amber: Indicates a holdover or free-running state.
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SYNC LED is off: Indicates that the configuration is removed.
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