Let’s consider a practical example using Huawei OSN equipment within a WDM network topology, involving the following boards:
- STG board
- SCC board
- ST2 board
- SFIU board
Board Functions and Synchronization Flow
- SFIU (Service Fiber Interface Unit):
This is the multiplexing and demultiplexing board responsible for combining and separating C-band traffic signals along with the Optical Supervisory Channel (OSC) and clock signals. - OSC (Optical Supervisory Channel):
The OSC is a dedicated management channel originating from the ST2 board, used for system supervision and management. - ST2 (Supervisory Transponder):
A specialized OSC board that collaborates with the SFIU to forward the clock signal to the STG board and the management signal to the SCC. - STG (Synchronization Timing Generator):
The STG is the central clock board responsible for distributing synchronization signals across all boards and nodes. When it “locks” to the clock, it means the STG adjusts its oscillator to align with the reference clock and synchronizes all other boards accordingly. - SCC (System Control and Communication):
The SCC is the primary control board managing and controlling the overall WDM system operations. - OA (Optical Amplifier):
The OA amplifies and transmits C-band traffic, interfacing between Reconfigurable Optical Add-Drop Multiplexers (ROADMs), the SFIU, and then to the line side.
Key Point:
This synchronization process is a frequent interview topic, particularly in discussions about the WDM optical transmission domain. Understanding how these boards work together to ensure synchronized and reliable traffic flow is essential for roles involving optical transport networks.
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