Method and system for improving bandwidth and reducing idles in fibre channel switches

• US 20050018649A1
• Filed: 07/20/2004
• Published: 01/27/2005
• Est. Priority Date: 07/21/2003
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: QLogic Corporation (Marvell Technology Group Limited)
• Inventors: Papenfuss, Gary M., Dropps, Frank R., Verba, Craig M.
• Granted Patent: US 7,583,597 B2
• Time in Patent Office: Days
• US Class Current: 370/351
• CPC Class Codes: H04L 12/5602 Bandwidth control in ATM Networks, e.g. leaky bucket

Abstract

A method for routing fibre channel frames using a fibre channel switch element is provided. The switch element includes, a receiving segment in a fibre channel port for receiving the frames and a transmit segment that transmits the received frames. The method includes requesting an early frame transfer, wherein the transmit segment of a fibre channel port requests an early frame transfer from a receiving segment of the fibre channel port before a frame has arrived at the transmit segment; activating an early frame transfer; determining if there is a need for aborting the early frame transfer request; and selecting a different source port if there is a need for aborting an early frame transfer request.

Claims

1. A method for routing fibre channel frames using a fibre channel switch element, comprising:

requesting an early frame transfer, wherein a transmit segment of a fibre channel port requests an early frame transfer from a receiving segment of the fibre channel port before a frame has arrived at the transmit segment;

activating an early frame transfer;

determining if there is a need for aborting the early frame transfer request; and

selecting a different source port if there is a need for aborting an early frame transfer request.

2. The method of claim 1, further comprising:

transferring a frame if there is no need to abort the early frame transfer request.

3. The method of claim 1, further comprising:

generating a request abort command to abort the early frame transfer request, wherein the transmit segment sends the request abort command to the receiving segment.

4. The method of claim 3, wherein a request abort command is generated if a frames status field lacks a destination bit value.

5. The method of claim 3, wherein a request abort command is generated if a frame'"'"'s status indicates that not enough part of a frame has arrived properly.

6. The method of claim 3, wherein a request abort command is generated if a frame'"'"'s status indicates that credit is unavailable for the frame.

7. The method of claim 3, wherein a request abort command is generated if the transmit segment does not have sufficient space to hold the frame.

8. The method of claim 3, wherein a request abort command is generated if an early frame transfer request was generated before a preference tag is received.

9. The method of claim 3, wherein a request abort command is generated by firmware used by the fibre channel switch element.

19. The method of claim 3, wherein a request abort command is generated based on other information within the fibre channel switch element.

10. A fibre channel switch element for routing fibre channel frames, comprising:

a receiving segment in a fibre channel port for receiving the frames and a transmit segment that transmits the received frames, wherein the transmit segment of the fibre channel port requests an early frame transfer from the receiving segment of the fibre channel port before a frame has arrived at the transmit segment;

the receive segment activates an early frame transfer;

the transmit segment determines if there is a need for aborting the early frame transfer request; and

a different source port is selected if there is a need for aborting an early frame transfer request.

11. The fibre channel switch element of claim 10, wherein the transmit segment transfers a frame if there is no need to abort the early frame transfer request.

12. The fibre channel switch element of claim 10, wherein the transmit segment sends a request abort command to the receiving segment.

13. The fibre channel switch element of claim 12, wherein a request abort command is generated if a frames status field lacks a destination bit value.

14. The fibre channel switch element of claim 12, wherein a request abort command is generated if a frame'"'"'s status indicates that not enough part of a frame has arrived properly.

15. The fibre channel switch element of claim 12, wherein a request abort command is generated if a frame'"'"'s status indicates that credit is unavailable for the frame.

16. The fibre channel switch element of claim 12, wherein a request abort command is generated if the transmit segment does not have sufficient space to hold the frame.

17. The fibre channel switch element of claim 12, wherein a request abort command is generated if an early frame transfer request was generated before a preference tag is received.

18. The fibre channel switch element of claim 12, wherein a request abort command is generated by firmware used by the fibre channel switch element.

20. The fibre channel switch element of claim 12, wherein a request abort command is generated based on other information within the fibre channel switch element.