Methods and apparatus for fibre channel frame delivery

• US 7,406,034 B1
• Filed: 04/01/2002
• Issued: 07/29/2008
• Est. Priority Date: 04/01/2002
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Cometto, Maurilio, Lee, Scott S.
• Primary Examiner(s): NGUYEN, HANH N
• Application Number:
  US10/114,568
• Time in Patent Office: 2,311 Days
• Field of Search: 370/400, 370/394, 370/389, 370/392, 370/230, 370/235, 370/238, 370/395.1, 370/395.4, 370/468, 370/253, 370/412, 370/413, 370/252, 370/218, 370/216, 709/238, 709/400
• US Class Current: 370/218
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/32 by discarding or delaying data units, e.g. packets or frames
• CPC Class Codes: H04L 47/34 ensuring sequence integrity, e.g. using sequence numbers

Abstract

Methods and apparatus are provided for improving fibre channel frame delivery. Techniques are provided for the in order delivery of frames by intelligently delaying or dropping selected fibre channel frames. Other techniques are provided for in order delivery by using label switching and frame labels. The various techniques can be applied during circumstances such as a link state or channel change.

Claims

1. A method for selectively delivering frames in a fibre channel fabric, the method comprising:

detecting a fibre channel fabric link change at a fibre channel switch having a routing table;

generating an updated routing table associated with a topology version number, wherein generating the updated routing table comprises determining a next hop, an incoming label, and a destination corresponding to each entry in the updated routing table;

receiving a frame at the fibre channel switch, the frame having a first destination and a first label corresponding to a first entry in the updated routing table;

determining whether the fibre channel switch has received a first outgoing label having the same topology version number as the updated routing table, the first outgoing label corresponding to the first entry in the updated routing table; and

dropping the frame if it is determined that the fibre channel switch has not received the first outgoing label.

2. The method of claim 1, wherein the first label is equivalent to a first incoming label associated with the first entry.

3. The method of claim 2, further comprising:

receiving a first link state control message having the first outgoing label and a topology version number corresponding to the topology version number of the routing table.

4. The method of claim 3, further comprising:

advertising the first incoming label to other switches in the fibre channel fabric.

5. The method of claim 1, further comprising:

forwarding the frame to the next hop if it is determined that the fibre channel switch has received the first outgoing label.

6. The method of claim 5, wherein the routing table is associated with a particular virtual storage area network.

7. The method of claim 6, wherein the topology version number is derived using incarnation numbers with each switch in the virtual storage area network.

8. The method of claim 7, wherein the input and outgoing labels are MPLS labels.

9. The method of claim 1, wherein the first label in the frame is contained in the fibre channel frame header.

10. An apparatus, comprising:

a processor operable to detect a fibre channel fabric link change at a fibre channel switch having a routing table and generate an updated routing table associated with a topology version number, wherein generating the updated routing table comprises determining a next hop, an incoming label, and a destination corresponding to each entry in the updated routing table;

an interface connected to the processor, the interface operable to receive a frame at the fibre channel switch, the frame having a first destination and a first label corresponding to a first entry in the updated routing table;

wherein the processor is further operable to determine whether the fibre channel switch has received a first outgoing label having the same topology version number as the updated routing table, the first outgoing label corresponding to the first entry in the updated routing table and drop the frame if it is determined that the fibre channel switch has not received the first outgoing label.

11. The apparatus of claim 10, wherein the first label is equivalent to a first incoming label associated with the first entry.

12. The apparatus of claim 11, further comprising:

receiving a first link state control message having the first outgoing label and a topology version number corresponding to the topology version number of the routing table.

13. The apparatus of claim 12, further comprising:

advertising the first incoming label to other switches in the fibre channel fabric.

14. The apparatus of claim 10, further comprising:

forwarding the frame to the next hop if it is determined that the fibre channel switch has received the first outgoing label.

15. The apparatus of claim 14, wherein the routing table is associated with a particular virtual storage area network.

16. The apparatus of claim 15, wherein the topology version number is derived using incarnation numbers with each switch in the virtual storage area network.

17. The apparatus of claim 16, wherein the input and outgoing labels are MPLS labels.

18. The apparatus of claim 10, wherein the first label in the frame is contained in the fibre channel frame header.

19. An apparatus, comprising:

means for detecting a fibre channel fabric link change at a fibre channel switch having a routing table;

means for generating an updated routing table associated with a topology version number, wherein generating the updated routing table comprises determining a next hop, an incoming label, and a destination corresponding to each entry in the updated routing table;

means for receiving a frame at the fibre channel switch, the frame having a first destination and a first label corresponding to a first entry in the updated routing table;

means for determining whether the fibre channel switch has received a first outgoing label having the same topology version number as the updated routing table, the first outgoing label corresponding to the first entry in the updated routing table; and

means for dropping the frame if it is determined that the fibre channel switch has not received the first outgoing label.

20. The apparatus of claim 19, wherein the first label is equivalent to a first incoming label associated with the first entry.

21. The apparatus of claim 19, further comprising:

means for forwarding the frame to the next hop if it is determined that the fibre channel switch has received the first outgoing label.