– Receiver tells transmitter how many frame buffers it has (login credit)
– Transmitter keeps tally of available buffers (credits) at receiver (Credit_CNT)
• During frame transfer:
– Transmitter requires a credit before it can send a frame
– When receiver receives a frame, processes it and empties the buffer, it sends another credit to the transmitter
• When transmitter runs out of credits, it must stop sending frames
Each port stores information about every other port in a table held in the ULP driver memory. When each port logs into each other port, the following information can be collated and stored:
• Port_ID
• Frame size • Login BB credits available • Login EE credits available • Type of port • Node World Wide Name • Port World Wide Name