Granted Patent B2

US 7,430,175 · App. 10/894,579 · Granted Sep 30, 2008

Abstract

Claims (40)

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.

Assignments (6)