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Configuring Junos OS to Support an External Clock Synchronization Interface for M Series, MX Series, and T Series Routers

The M40e, M120, M320, T640, and T1600 routers support an external synchronization interface that can be configured to synchronize the internal Stratum 3 clock to an external source, and then synchronize the chassis interface clock to that source.

This feature can be configured for external primary and secondary interfaces that use building-integrated timing system (BITS), SDH Equipment Timing Source (SETS) timing sources, or an equivalent quality timing source. When internal timing is set for SONET/SDH, Plesiochronous Digital Hierarchy (PDH), or digital hierarchy (DS-1) interfaces on the Physical Interface Cards (PICs), the transmit clock of the interface is synchronized to BITS/SETS timing and is traceable to timing within the network.

Routers and switches that support an external clock synchronization interface include:

  • M40e, M120, and M320 routers

  • T640 and T1600 routers

To configure external synchronization on the router, include the synchronization statement at the [edit chassis] hierarchy level:

Use the synchronization statement options to specify a primary and secondary timing source. To do this, configure the following options:

  • For the M120 and M320 routers, specify a signal type mode for interfaces, either t1 or e1. For the M40e, T640, and T1600 routers, only the t1 signal type mode is supported. The default setting is t1.

  • For the T640 and T1600 routers, external clock interfaces are supported on the SONET Clock Generators (SCG-T-EC). The external clock interfaces on the SONET Clock Generators (SCG-T) are not supported.

  • Specify the switching mode as revertive if a lower-priority synchronization can be switched to a valid, higher-priority synchronization.

  • For the M320 router, specify that a single signal should be wired to both Control Boards (CBs) using a Y-cable. For the M40e router, the signal is wired to the CIP and Y-cable functionality is embedded in this system.

    The y-cable-line-termination option is not available on the M40e, M120, T640, and T1600 routers.

  • Control whether the diagnostic timing signal is transmitted.

    The transmitter-enable option is not available on the M120, T640, and T1600 routers.

  • Set a validation interval. The validation-interval option validates the synchronized deviation of the synchronization source. If revertive switching is enabled and a higher-priority clock is validated, the clock module is directed to the higher-priority clock, and all configured and active synchronizations are validated. The validation timer resumes after the current validation interval expires. The validation interval can be a value from 90 through 86,400 seconds. The default value is 90 seconds. For the M120 router, the range for the validation-interval option is 30 through 86,400 and the default value is 30.

  • Specify the primary external timing source by using the primary (external-a | external-b) statement.

  • Specify the secondary external timing source by using the secondary (external-a | external-b) statement.