Difference between STI and STG, and whether STI or STG can work independently

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An STI board is a clock interface board that inputs and outputs clock signals. An STG board is a clock processing board that provides clock signals and frame header signals for the system. STI is optional. It is required only when the 2M clock or IEEE 1588v2 function is required or when and the BITS clock needs to be connected to an OCS system.

Other related questions:
Function jointly provided by STG and STI
When the 2M clock or the IEEE 1588v2 function is required, a clock port is required to receive external clock signals. For the OSN 8800 T32/T64, TN52STG and TNK2STG boards do not provide a clock port, and the external clock port is provided by the STI board. For the OSN 6800, it does not support an STI board. An STG board provides an external clock port.

Whether the STG board is mandatory
The OSN 8800 of version V100R002 or later is a synchronous system, requiring that all service boards and cross-connect boards are synchronized (with the same frequencies and aligned frame headers). Therefore, a unique reference clock signal and a unique frame header are required. To meet this requirement, each service board outputs services based on the clock signal and frame header of the clock board. Therefore, the STG board is mandatory for the OSN 8800 of version V100R002 or later. Otherwise, centralized service grooming cannot be implemented. The OSN 6800 is asynchronous, having no requirement on a unique clock signal or frame header. Therefore, no clock board is required. The STG board is required only when IEEE 1588v2 needs to be enabled at the electrical layer.

Whether ST2 and STG must be installed in the same subrack
If the clock functions of the ST2 board need to be used, you must insert the board into the subrack equipped with clock boards.

Scenarios in which STG is required in the OSN 6800
The OSN 6800 is an asynchronous system and does not require a unique reference clock or unique frame header. Therefore, no STG board is required. The STG board is required only when IEEE 1588v2 needs to be enabled at the electrical layer.

Cause why the STG board is mandatory for the OSN 8800 but optional for the OSN 6800
The OSN 8800 of version V100R002 or later is a synchronous system, requiring that all service boards and cross-connect boards are synchronized (with the same frequencies and aligned frame headers). Therefore, a unique reference clock signal and a unique frame header are required. To meet this requirement, each service board outputs services according to the clock signal and frame header of a clock board. Therefore, the STG board is mandatory for the OSN 8800 of version V100R002 or later. If no STG board is configured, centralized service scheduling cannot be achieved. The OSN 6800 is an asynchronous system and does not require a unique reference clock or unique frame header. Therefore, no STG board needs to be configured for the OSN 6800.

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