Method and system for managing traffic in fibre channel systems

• US 7,430,175 B2
• Filed: 07/20/2004
• Issued: 09/30/2008
• 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: Dropps, Frank R., Papenfuss, Gary M., Verba, Craig M., Owen, Mark A., Kohlwey, Ernest G
• Primary Examiner(s): Yao; Kwang B.
• Assistant Examiner(s): Lai; Andrew
• Application Number:
  US10/894,579
• Publication Number:
  US 20050030978A1
• Time in Patent Office: 1,533 Days
• Field of Search: 370/238, 370/395.62, 370/498, 370/229, 370/230.1, 370/442, 370/503, 370/509
• US Class Current: 370/238
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/28 in relation to timing considerations
• CPC Class Codes: H04L 47/32 by discarding or delaying data units, e.g. packets or frames
• CPC Class Codes: H04L 49/25 Routing or path finding in a switch fabric
• CPC Class Codes: H04L 49/254 Centralised controller, i.e. arbitration or scheduling
• CPC Class Codes: H04L 49/3009 Header conversion, routing tables or routing tags
• CPC Class Codes: H04L 49/357 Fibre channel switches

Abstract

Method and system for routing fiber channel frames using a fiber channel switch element is provided. The method includes, inserting a time stamp value in a fiber channel frame that is received at a receive segment of the fiber channel switch element; determining if a timeout occurs after a frame arrives at a receive buffer; and processing the frame if the timeout occurred. The method also includes, determining if a delta time value, which provides an accumulated wait time for a frame, is present in frame data; subtracting the delta time stamp value from a global time stamp value and using the resulting time stamp value to determine frame timeout status in the fiber channel switch element. A timeout checker circuit declares a timeout after comparing a time stamp value that is inserted in a fiber channel frame with a programmed time out value and global counter value.

Claims

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

inserting a time stamp value in a fibre channel frame that is received at a received segment of the fibre channel switch element;

determining if a minor time out of the frame has occurred by comparing the time stamp value to a global counter value and a minor time out value; and

processing the frame if the time out has occurred;

wherein if a major time out occurs while the frame is being read, then the frame read is completed;

or

if a major time out occurs when there is at least one active read request, then the read request is completed.

2. The method of claim 1, wherein the step of determining if a minor time out of the frame has occurred is performed by a time out checker circuit that extracts the time stamp value from the frame.

3. The method of claim 2, wherein a fibre channel switch element processor programs the minor time out value.

4. The method of claim 1, wherein if a minor time out occurs, the receive segment sets a status flag for a transmit segment of the switch element.

5. The method of claim 1, wherein end to end frame timing is provided, without synchronizing plural switch elements of a fabric.

6. The method of claim 1, further comprising the step of determining if a major time out of the frame has occurred by comparing the time stamp value to a global counter value and a major time out value.

7. The method of claim 6, wherein the step of determining if a major time out of the frame has occurred is performed by a time out checker circuit that extracts the time stamp value from the frame.

8. The method of claim 7, wherein a fibre channel switch element processor programs the major time out value.

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

a receive and transmit segment configured to receive and transmit fibre channel frames, and

a time out checker circuit configured to declare a major time out after comparing a time stamp value in a fibre channel frame with a programmed major time out value and a global counter value;

wherein if a major time out occurs while the frame is being read, then the frame read is completed;

or

if a major time out occurs when there is at least one active read request, then the read request is completed.

10. The switch element of claim 9, wherein if a major time out occurs and the frame is not being read, then the switch element tosses the frame.

11. The switch element of claim 9, wherein end to end frame timing is provided, without synchronizing plural switch elements of a fabric.

12. The switch element of claim 9, wherein the time out checker circuit is further configured to declare a minor time out after comparing the time stamp value with a programmed minor time out value and the global counter value.

13. The switch element of claim 12, wherein the switch continues processing the frame if a minor time out occurs.

14. The switch element of claim 9, wherein if a major time out occurs and the there are no active read requests, then the switch element tosses the frame.

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

inserting a time stamp value in a fibre channel frame that is received at a receive segment of the fibre channel switch element;

determining if a delta time value, which provides an accumulated elapsed time for the frame, is present in the frame'"'"'s data;

if the delta time value is present in the frame'"'"'s data, subtracting the delta time value from a global time value to determine an adjusted relative time stamp value;

using the adjusted relative time stamp value to determine if the frame has timed out after the frame arrives at a receive buffer; and

processing the frame if the time out occurs;

wherein if a major time out occurs while the frame is being read, then the frame read is completed;

or

if a major time out occurs when there is at least one active read request, then the read request is completed.

16. The method of claim 15, wherein the adjusted relative time stamp value is inserted into the frame.

17. The method of claim 15, wherein a delta time value is computed by subtracting the frame'"'"'s time stamp value from a global counter value and the time stamp value is inserted into the frame before the frame is transmitted.

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

a receive and transmit segment configured to receive and transmit fibre channel frames; and

a time out checker circuit configured to declare a frame time out after comparing a relative time stamp value in a fibre channel frame with a programmed time out value and a global counter value;

wherein the relative time stamp value is calculated using a delta time value from the frame, which specifies an accumulated elapsed time for the frame;

wherein if a major time out occurs while the frame is being read, then the frame read is completed;

or

if a major time out occurs when there is at least one active read request, then the read request is completed.

19. The switch element of claim 18, wherein an adjusted relative time stamp value is calculated by subtracting the delta time value from a global counter value.