MULTI-SPEED CUT THROUGH OPERATION IN FIBRE CHANNEL SWITCHES

• US 20100040074A1
• Filed: 07/14/2009
• Published: 02/18/2010
• 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.
• Granted Patent: US 9,118,586 B2
• Time in Patent Office: Days
• US Class Current: 370/401
• CPC Class Codes: H04L 49/251 Cut-through or wormhole routing
• CPC Class Codes: H04L 49/357 Fibre channel switches

Abstract

A method and system for routing frames based on a port'"'"'s speed using a fibre channel switch element is provided. The method includes, receiving a portion of a frame in a receive buffer of a port; determining a frame length threshold; and setting up a status bit based on the port'"'"'s speed, the frame length threshold and an amount of frame received. The status bit is sent to a transmit segment of the fibre channel switch element and the frame length threshold value is inversely proportional to the port'"'"'s speed. Also, if the receive buffer is almost full when a frame arrives at the receive port, then a cut status is based on a frames end of frame (“EOF”) value.

Claims

1. A method for routing frames based on a port'"'"'s speed using a fibre channel switch element, comprising:

receiving a portion of a frame in a receive buffer of a port;

determining a frame length threshold; and

setting up a status bit based on the port'"'"'s speed, the frame length threshold and an amount of frame received.

2. The method of claim 1, wherein the status bit is sent to a transmit segment of the fibre channel switch element.

3. The method of claim 1, wherein the frame length threshold value is inversely proportional to the port'"'"'s speed.

4. A method for routing frames based on a port'"'"'s speed using a fibre channel switch element, comprising:

determining if a status bit is set based on the port speed; and

routing frames based on the status bit and the port'"'"'s speed.

5. The method of claim 4, wherein a read and write operation are set up based on port speed to optimize throughput.

6. The method of claim 5, wherein a read operation is delayed for a 2G/4G/8G/10G ports, if the status bit is not set.

7. The method of claim 4, wherein a read and write operation occur simultaneously if a receive port is equal to or faster than a transmit port.

8. The method of claim 4, wherein based on a port'"'"'s speed, a read operation is delayed by a certain duration for optimizing frame routing.

9. A fibre channel switch element for routing frames based on a port'"'"'s speed, comprising:

a receive and a transmit port segment having the means for receiving a portion of a frame in a receive buffer of a port;

determining a frame length threshold; and

setting up a status bit based on the port'"'"'s speed;

the frame length threshold and an amount of frame received.

10. The switch element of claim 9, wherein the status bit is sent to the transmit port segment of the fibre channel switch element.

11. The method of claim 9, wherein the frame length threshold value is inversely proportional to the port'"'"'s speed.

12. A fibre channel switch element for routing frames based on a port'"'"'s speed, comprising:

a receive and a transmit port segment having the means for determining if a status bit is set based on the port speed; and

routing frames based on the status bit and the port'"'"'s speed.

13. The switch element of claim 12, wherein a read and write operation are set up based on port speed to optimize throughput.

14. The switch element of claim 13, wherein a read operation is delayed for a 2G/4G/8G/10G ports, if the status bit is not set.

15. The switch element of claim 12, wherein a read and write operation occur simultaneously if a receive port is equal to or faster than a transmit port.

16. The switch element of claim 12, wherein based on a port'"'"'s speed, a read operation is delayed for a certain duration to optimize frame routing.

17. A method for routing fibre channel frames using a fibre channel switch element having a receive segment with a receive buffer and a transmit segment with a transmit buffer, comprising:

determining if the receive buffer is almost full when a frame arrives at the receive port; and

setting a cut status based on a frames end of frame (“

EOF”

) value or once a frame length threshold is reached if the receive buffer is less than almost full.

18. The method of claim 17, wherein the cut status based on the EOF is set when the receive buffer is full.

19. The method of claim 17, wherein fibre channel switch element firmware defines when a receive buffer is considered to be almost full.