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M120 External Clock Interface Ports on the Craft Interface


Two external clock ports EXT CLOCK to the right of the craft interface alarm LEDs enable you to connect the router’s internal Stratum 3 clock to an external reference clock source with an RJ-45 cable. Using the router’s software, you can configure the internal Stratum 3 clock to synchronize with an external Building Integrated Timing System (BITS) or SDH Equipment Timing Source (SETS) timing source by including a clock synchronization statement at the [edit chassis] hierarchy level.


Refer to the, Junos OS Administration Library for configuration information.

The EXT CLOCK ports are labeled A and B. They accept two RJ-45 connectors for external clock inputs with T1 or E1 reference clocks.

Two bi-color LEDs in the lower left and right corners of each port indicate port status. The LED on the lower left as you face the craft interface indicates whether an external clock source is present. The LED on the lower right as you face the craft interface indicates if there is a fault. External Clock LEDs on the M120 Craft Interface describes the external clock port LEDs,