Acknowledged fabric frame flow is where there is an acknowledgment (at a Fibre Channel level) of the receipt of a frame (or frames): • Class 2 uses ACK_1 frames to inform the transmitting port of correct receipt of each frame by the receiving port.
• It is the responsibility of the transmitting port to correctly manage delivery of a sequence of frames. Only when it receives the last ACK_1 frame in response to the sequence of frames sent does it know that all frames have been delivered correctly, and only then will it empty its ULP data buffers.
• If the returning ACK indicated that an error has been detected by the destination port the transmitting port has access to the ULP data buffers and can resend all frames in the sequence.