Autonomous mapping of protected data streams to Fibre channel frames

• US 20080307122A1
• Filed: 06/11/2007
• Published: 12/11/2008
• Est. Priority Date: 06/11/2007
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Emulex Design & Manufacturing Corp. (Broadcom, Inc.)
• Inventors: Tien, Joe Chung-Ping, Butler, Jim Donald, Jin, Daming
• Granted Patent: US 7,765,336 B2
• Time in Patent Office: Days
• US Class Current: 710/23
• CPC Class Codes: H04L 49/90 Buffering arrangements
• CPC Class Codes: H04L 49/9042 Separate storage for different parts of the packet, e.g. header and payload

Abstract

A hardware-based offload engine is disclosed for mapping protected data into frames. For a write operation, the HBA determines host addresses and the size of data to be read from those addresses. The HBA also determines the frame size and protection scheme for data to be written. A frame transmit engine reads each host descriptor in the host data descriptor list to determine the location and byte count of the data to be read. A DMA engine reads the protection information/scratch area to determine the exact data size used to fill each frame and the protection scheme, and retrieves one or more free frame buffers. Check bytes are inserted alongside the data and stored in free frame buffers. After each frame is filled, the frame transmit engine also generates and stores header information for that frame, and then combines header, data and check bytes for transmission over the network.

Claims

1. An apparatus for transmitting host data to a target over a frame-based communications network, comprising:

one or more frame transmit engines, each frame transmit engine configured for

determining one or more addresses, byte counts and a protection scheme of the host data to be transmitted in a particular sequence of frames, a frame size of the frames to be transmitted, and one or more free frame buffers for storing the frames prior to transmission,

generating and storing headers for the frames to be transmitted, and

combining the header information, data and check bytes into frames for transmission over the network; and

a direct memory access (DMA) engine coupled to the one or more frame transmit engines and configured for reading the host data to be transmitted from host memory in accordance with the addresses and byte counts determined by a particular frame transmit engine, calculating check bytes for the host data in accordance with the protection scheme, and storing the data and check bytes into the one or more free frame buffers.

2. The apparatus of claim 1, further comprising one or more host data descriptor lists, each host data descriptor list accessible to a particular frame transmit engine for storing the addresses and byte counts of the host data to be transmitted for a particular sequence.

3. The apparatus of claim 2, further comprising a protection information/scratch area accessible to the one or more frame transmit engines for storing the frame size and protection scheme of the host data to be transmitted for one or more sequences.

4. The apparatus of claim 3, further comprising a free buffer pool accessible to the one or more frame transmit engines for identifying free frame buffers.

5. The apparatus of claim 1, further comprising a local processor configured for receiving a request from a host to transmit the host data to the target, determining the host addresses for the host data to be transmitted from the host and the byte count at those addresses, and storing this information as host descriptor information into a host data descriptor list.

6. The apparatus of claim 1, further comprising a local processor configured for receiving a request from a host to transmit the host data to the target, determining the frame size and the protection scheme for the host data to be transmitted from the host, and storing this information in a protection information/scratch area.

7. The apparatus of claim 3, each frame transmit engine comprising a DMA state machine configured for reading an appropriate host data descriptor list to determine the addresses and byte count of the host data to be transmitted, and reading the protection information/scratch area to determine the protection scheme and frame size of the host data or single host descriptor to be transmitted.

8. The apparatus of claim 4, each frame transmit engine comprising a DMA completion frame builder configured for receiving a frame completion message from the DMA engine and generating a header for a frame to be transmitted.

9. The apparatus of claim 8, each frame transmit engine comprising link logic configured for receiving a header from the DMA completion frame builder, storing the header in at a location specified by a free frame buffer, using the free frame buffer to locate the host data, check bytes and header, assembling a completed frame, and sending the completed frame out over the network.

10. The apparatus of claim 9, each frame transmit engine comprising a frame completion state machine configured for receiving a frame completion message from the link logic and sending a message to a local processor completion memory when the sequence of frames being handled by the frame transmit engine is to be terminated.

11. A host bus adapter (HBA) comprising the apparatus of claim 1.

12. A host computer comprising the HBA of claim 11.

13. A storage area network (SAN) comprising the host computer of claim 12.

14. An apparatus for transmitting host data to a target over a frame-based communications network, comprising:

a first memory area for storing addresses of host data and a byte count of the host data to be transmitted at those addresses;

a second memory area for storing a protection scheme and a frame size for the host data to be transmitted; and

a frame transmit engine and a direct memory access (DMA) engine coupled to and configured for reading the first and second memory area, generating check bytes in accordance with the protection scheme, generating one or more headers, and combining the headers, host data and check bytes into one or more frames for transmission over the network without involvement by a local processor.

15. The apparatus of claim 14, further comprising a third memory area for storing the host data and check bytes, and a fourth memory area for storing the one or more headers.

16. An apparatus for transmitting host data to a target over a frame-based communications network, comprising:

means for determining one or more addresses and byte counts of the host data to be transmitted in a particular sequence of frames, determining a protection scheme and a frame size of the host data to be transmitted in the particular sequence of frames, and determining one or more free frame buffers for storing the frames prior to transmission;

means for reading the host data to be transmitted from host memory in accordance with the determined addresses and byte counts, calculating check bytes for the host data in accordance with the protection scheme, and storing the data and check bytes into the one or more free frame buffers;

means for generating and storing headers for the frames to be transmitted; and

means for combining the header information, data and check bytes into frames for transmission over the network.

17. A method for transmitting host data to a target over a frame-based communications network, comprising:

determining one or more addresses and byte counts of the host data to be transmitted in a particular sequence of frames, determining a protection scheme and a frame size of the host data to be transmitted in the particular sequence of frames, and determining one or more free frame buffers for storing the frames prior to transmission;

reading the host data to be transmitted from host memory in accordance with the determined addresses and byte counts, calculating check bytes for the host data in accordance with the protection scheme, and storing the data and check bytes into the one or more free frame buffers;

generating and storing headers for the frames to be transmitted; and

combining the header information, data and check bytes into frames for transmission over the network;

wherein the method is performed without involvement by a local processor.

18. The method of claim 17, further comprising determining the addresses and byte counts of the host data to be transmitted in the particular sequence of frames from a host data descriptor list.

19. The method of claim 18, further comprising determining the protection scheme and the frame size of the host data to be transmitted in the particular sequence of frames from a protection information/scratch area.

20. The method of claim 19, further comprising determining the one or more free frame buffers for storing the frames prior to transmission from a free buffer pool.

21. The method of claim 18, further comprising receiving a request from a host to transmit the host data to the target, determining from the host the addresses for the host data and the byte count at those addresses, and storing this information into the host data descriptor list.

22. The method of claim 19, further comprising receiving a request from a host to transmit the host data to the target, determining the frame size and the protection scheme for the host data to be transmitted, and storing this information in the protection information/scratch area.

23. The method of claim 17, further comprising sending a sequence termination message to a local processor completion memory when the transmission of the sequence of frames is to be terminated.

24. A method for transmitting host data to a target over a frame-based communications network, comprising:

storing addresses of host data and a byte count of the host data to be transmitted at those addresses into a first memory area;

storing a protection scheme and a frame size for the host data to be transmitted into a second memory area; and

reading the first and second memory area, generating check bytes in accordance with the protection scheme, generating one or more headers, and combining the headers, host data and check bytes into one or more frames for transmission over the network without involvement by a local processor.