The OSN2500 SSN2EFT8A single board consists of an interface module, a service processing module, an encapsulation/mapping module, an interface conversion module, a communication and control module, and a power supply module.

1. Transmit Direction

The signals from the crossover unit are sent to the encapsulation/conversion module via the interface conversion module for demapping and de-encapsulation. The service processing module determines the routing according to the level at which the device is located. It completes the functions of frame delimitation, adding leading code, calculating CRC check code and Ethernet performance statistics. Finally, the interface processing module performs parallel/serial conversion and encoding to be sent out by the Ethernet interface.

2. Receiving direction

The interface processing module accesses the signals from external Ethernet devices (such as Ethernet switches, routers, etc.) and performs decoding and serial/parallel conversion. Then it enters the service processing module to perform functions such as frame delimitation, stripping leading code, terminating CRC ( Cyclic Redundancy Check ) check code and Ethernet performance statistics. The HDLC, LAPS or GFP-F encapsulation of Ethernet frames is completed in the encapsulation module, and then sent to the mapping module for mapping, and finally fed into the crossover unit via the interface conversion module.

3. Communication and Control Module

The communication and control module mainly realizes the communication, control and service configuration functions of the single board.

4. Power supply module

The power supply module provides the required DC voltage for all modules of the single board.