Method and system for using extended fabric features with fibre channel switch elements

• US 20050018673A1
• 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: Dropps, Frank R., Papenfuss, Gary M., Kohlwey, Ernest G., Verba, Craig M., Ross, Edward C.
• Granted Patent: US 7,684,401 B2
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04L 49/10 characterised by the switching fabric construction
• CPC Class Codes: H04L 49/111 Switch interfaces, e.g. port details
• CPC Class Codes: H04L 49/25 Routing or path finding in a switch fabric
• CPC Class Codes: H04L 49/357 Fibre channel switches

Abstract

A fibre channel switch element and method for routing fibre channel frames is provided. The switch element includes a receive segment that can add a virtual storage area network (“VSAN”) tagging header to frames that are received by the receive segment; and strip the VSAN tagging header before frames are sent to ports that do not support virtual fabric capability. The receive segment includes a table used for matching fabric extension parameters. An incoming frame'"'"'s VSAN identity value is compared to a control word entry to generate a value used for routing the incoming frame. The table is used to determine if a frame is part of a virtual fabric. The routing table for each port is used to route frames and the routing table includes entries for supported virtual fabrics.

Claims

1. A fibre channel frame format used for routing fibre channel frames, comprising:

a tagging header with a virtual storage area network identifier (“

VSAN_ID”

) field that specifies a virtual storage area network (“

VSAN”

) and a R_CTL field that is set to a certain value to indicate that the tagging header includes a VSAN value.

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

a receive segment that can add a virtual storage area network (“

VSAN”

) tagging header to frames that are received by the receive segment; and

strip the VSAN tagging header before frames are sent to ports that do not support virtual fabric capability.

3. The switch element of claim 2, wherein the receive segment includes a table used for matching fabric extension parameters.

4. The switch element of claim 2, wherein a control bit is used to enable support for VSAN at a particular port.

5. The switch element of claim 2, wherein a bit is used enable encapsulation mode for a switch element port.

6. The switch element of claim 3, wherein an incoming frame'"'"'s VSAN identity value is compared to a control word entry to generate a value used for routing the incoming frame.

7. The switch element of claim 3, wherein the table is used to determine if a frame is part of a virtual fabric.

8. The switch element of claim 3, wherein a routing table for each port is used to route frames and the routing table includes entries for supported virtual fabrics.

23. The switch element of claim 3, wherein cut-through routing is supported for virtual fabrics.

24. The switch element of claim 3, wherein hard-zoning is supported for virtual fabrics.

9. A method for routing fibre channel frames at a receive segment of a fibre channel switch element, comprising:

determining if support for virtual storage area network (“

VSAN”

) capability is enabled;

comparing incoming frames VSAN identifier with plural entries stored in a cache table if encapsulation mode is not set; and

routing incoming frames based on the comparison.

10. The method of claim 9, wherein an error message is generated if the comparison produces a multiple match.

11. A method for routing fibre channel frames at a transmit segment of a fibre channel switch element, comprising:

determining if a virtual storage area network (“

VSAN”

) support and encapsulation mode is enabled; and

comparing frame VSAN identifier entry values with a cache table entry values and setting up a multiple hit status if more than one entry matches the frame VSAN identifier.

12. The method of claim 11, wherein if encapsulation mode is set then the process determines if hard zoning is enabled.

13. The method of claim 12, wherein a frame'"'"'s parameters are compared to a look up table entries and if there is no match, the frame is rejected.

14. The method of claim 12, wherein a frame'"'"'s S_ID is compared to the look table entries.

15. The method of claim 14, wherein a frames S_ID Area value is compared to look up table entries and if there is a match then a frames S_ID port value is compared to look up table port entry values, if a look table compare mask is enabled.

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

a common segment that includes a look up table that is indexed by port values of a frame'"'"'s D_ID and a bit map to compare a zone mask of a matching entry generated by a virtual storage area network (“

VSAN”

) cache.

17. The switch element of claim 16, wherein lower 8 bits of D_ID are used to index the look up table.

18. The switch element of claim 16, wherein if the VSAN cache entry is used to select a column from the look up table, a logical comparison is performed between a zone map and look up table entries.

19. The switch element of claim 18, wherein if there is no match after the comparison and encapsulation mode is enabled, then a tagging header is stripped from a frame before the frame is transmitted.

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

a domain table at each port for routing fibre channel frames, wherein a column is selected to route frames based on a virtual storage area network (“

VSAN”

) identifier that is generated from a VSAN cache.

21. The switch element of claim 20, wherein if a domain identifier is not assigned for a virtual fabric, then a frame for the virtual fabric is rejected.

22. The switch element of claim 21, wherein a control register is used to control domain table column selection for routing fibre channel frames.

25. The switch element of claim 20, wherein E_ports may be shared among plural VSANs if area routing can be used.

26. The switch element of claim 20, wherein the VSAN cache can map plural VSAN identifier (VSAN_ID) values to a reduced value.

27. The switch element of claim 20, wherein N VSAN_ID values are mapped to M switch element values where N is greater than M.

28. The switch element of claim 27, wherein N is around 4096 and M is around 4.

29. The switch element of claim 20, wherein the VSAN cache table may be programmed to use plural fabric extension features in an extended header frame.