​MSTP OSN Series Product Service Opening Issue

Dear Loti_fa!

For a unidirectional trail, the source board is a tributary board that transmits services to the opposite end through the transport network, and the sink board is a tributary board that receives services from the opposite end through the transport network. 

For a bidirectional trail, the source and sink boards receive and transmit services at the same time. Therefore, it is meaningless to distinguish the source and sink boards in this scenario. 

Thank you！

Hello,
The source and reception boards are relative. For an A to B service, the board working in the forward direction is the source board, and the board working in the return direction is the reception board. If your service is bidirectional, the board is the source and the board it doesn't matter if the board is at place.
Thanks