Method and apparatus for tracking buffer availability

Claim 1

A fibre channel switch apparatus for interconnecting a plurality of devices having node ports (N -- ports), comprising: a plurality of interconnected fabric ports (F -- ports), each further comprising: a plurality of receive buffers for storing frames received from an N -- port, a receive credit counter for counting the number of frames that the N -- port is currently allowed to transmit at one time, and a smart credit counter for counting the number of receive buffers available to receive frames from the N -- port, status/control logic on the F -- port for transmitting a receiver ready signal to the N -- port when the F -- port is ready to receive another frame, the status/control logic further comprising: a transmit credit counter located on each N -- port for counting the number of frames that the N -- port is currently allowed to transmit to the F -- port at one time, wherein the transmit credit counter is decremented by one after a frame is transmitted to an F -- port and incremented by one upon the receipt of the receiver ready signal.

Claim 11

A method for transmitting frames from a plurality of node ports (N -- ports) to their associated fabric ports (F -- ports) for forwarding to other interconnected F -- ports, comprising the steps of: transmitting a frame from an N -- port to its associated F -- port, storing the transmitted frame in a plurality of receive buffers at the associated F -- port prior to forwarding to an interconnected F -- port, counting a receive credit count at each F -- port that corresponds to the number of frames that an N -- port is currently allowed to transmit to its associated F -- port at one time, counting a smart credit count at each F -- port that corresponds to the number of receive buffers available on an F -- port to receive frames, transmitting a receiver ready signal from an F -- port to its associated N -- port when the F -- port has forwarded a frame to another F -- port, counting a transmit credit count at each N -- port corresponding to the number of frames that an N -- port is currently allowed to transmit to its associated F -- port at one time, decrementing an N -- port transmit credit count by one upon transmitting a frame from the N -- port, and incrementing the transmit credit count by one when the N -- port receives a receiver ready signal.

Claim 12

A method for transmitting frames from a plurality of node ports (N -- ports) to their associated fabric ports (F -- ports) for forwarding to other interconnected F -- ports, comprising the steps of: transmitting a frame from an N -- port to its associated F -- port, storing the transmitted frame in a plurality of receive buffers at the associated F -- port prior to forwarding to an interconnected F -- port, counting a receive credit count at each F -- port that corresponds to the number of frames that an N -- port is currently allowed to transmit to its associated F -- port at one time, counting a smart credit count at each F -- port that corresponds to the number of receive buffers available on an F -- port to receive frames, transmitting a receiver ready signal from an F -- port to its associated N -- port when the F -- port has forwarded a frame to another F -- port, counting a transmit credit count at each N -- port corresponding to the number of frames that an N -- port is currently allowed to transmit to its associated F -- port at one time, decrementing an N -- port transmit credit count by one upon transmitting a frame from the N -- port, and incrementing the transmit credit count by one when the N -- port receives a receiver ready signal.