Method and apparatus for tracking buffer availability
AssigneeHewlett-Packard Company
InventorDwayne Bennett
Life of this patent
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Abstract
The invention is a method and apparatus for transmitting frames from a plurality of node ports (N.sub.-- ports) to their associated fabric ports (F.sub.-- ports) for forwarding to other interconnected F.sub.-- ports on a Fibre Channel switch in which the transmitted frames are stored in a plurality of receive buffers at the associated F.sub.-- port prior to forwarding to an interconnected F.sub.-- port, and a receive credit counter, a smart credit counter and a transmit credit counter are employed for tracking the availability of the receive buffers.
Claims16
A fibre channel switch apparatus for interconnecting a plurality of devices having node ports (N.sub.-- ports), comprising:
- a plurality of interconnected fabric ports (F.sub.-- ports), each further comprising:
- a plurality of receive buffers for storing frames received from an N.sub.-- port,
- a receive credit counter for counting the number of frames that the N.sub.-- 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.sub.-- port,
- status/control logic on the F.sub.-- port for transmitting a receiver ready signal to the N.sub.-- port when the F.sub.-- port is ready to receive another frame, the status/control logic further comprising:
- a transmit credit counter located on each N.sub.-- port for counting the number of frames that the N.sub.-- port is currently allowed to transmit to the F.sub.-- port at one time, wherein the transmit credit counter is decremented by one after a frame is transmitted to an F.sub.-- port and incremented by one upon the receipt of the receiver ready signal.
A method for transmitting frames from a plurality of node ports (N.sub.-- ports) to their associated fabric ports (F.sub.-- ports) for forwarding to other interconnected F.sub.-- ports, comprising the steps of:
- transmitting a frame from an N.sub.-- port to its associated F.sub.-- port,
- storing the transmitted frame in a plurality of receive buffers at the associated F.sub.-- port prior to forwarding to an interconnected F.sub.-- port,
- counting a receive credit count at each F.sub.-- port that corresponds to the number of frames that an N.sub.-- port is currently allowed to transmit to its associated F.sub.-- port at one time,
- counting a smart credit count at each F.sub.-- port that corresponds to the number of receive buffers available on an F.sub.-- port to receive frames,
- transmitting a receiver ready signal from an F.sub.-- port to its associated N.sub.-- port when the F.sub.-- port has forwarded a frame to another F.sub.-- port,
- counting a transmit credit count at each N.sub.-- port corresponding to the number of frames that an N.sub.-- port is currently allowed to transmit to its associated F.sub.-- port at one time,
- decrementing an N.sub.-- port transmit credit count by one upon transmitting a frame from the N.sub.-- port, and
- incrementing the transmit credit count by one when the N.sub.-- port receives a receiver ready signal.
Dependencies are inferred from the claim text.