When the working PQ1 board is oversized, the device will perform and the TFS protection...

cross-connect board checks the PQ1 board fault through the board status bus. .

If the protection PQ1 board is normal, the cross-connection board sends a switching message to the D75S corresponding to the faulty PQ1 board through the switching control bus. .

The D75S board responds to the switch message by transmitting the service to the shared protection bus and stopping sending the service to the tyrant PQ1 board

The protection PQ1 board receives and processes the services transmitted from the D75S board to the protection bus to complete the protection switching