Apparatus and method for stateless CRC calculation

• US 20070165672A1
• Filed: 02/17/2006
• Published: 07/19/2007
• Est. Priority Date: 01/19/2006
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: NetEffect, Inc. (Intel Corporation)
• Inventors: Makhervaks, Vadim, Keels, Kenneth, Hausauer, Brian, Schneider, Eric
• Granted Patent: US 7,782,905 B2
• Time in Patent Office: Days
• US Class Current: 370/474
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/0072 Error control for data other than payload data, e.g. control data
• CPC Class Codes: H04L 1/0083 Formatting with frames or packets; Protocol or part of protocol for error control
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/1607 Details of the supervisory signal
• CPC Class Codes: H04L 2001/0092 Error control systems characterised by the topology of the transmission link
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]

Abstract

A mechanism for performing remote direct memory access (RDMA) operations between a first server and a second server. The apparatus includes a packet parser and a protocol engine. The packet parser processes a TCP segment within an arriving network frame, where the packet parser performs one or more speculative CRC checks according to an upper layer protocol (ULP), and where the one or more speculative CRC checks are performed concurrent with arrival of the network frame. The protocol engine is coupled to the packet parser. The protocol engine receives results of the one or more speculative CRC checks, and selectively employs the results for validation of a framed protocol data unit (FPDU) according to the ULP.

Claims

1. An apparatus, for performing remote direct memory access (RDMA) operations between a first server and a second server over a network fabric, the apparatus comprising:

a packet parser, configured to process a TCP segment within an arriving network frame, wherein said packet parser performs one or more speculative CRC checks according to an upper layer protocol (ULP), wherein said one or more speculative CRC checks are performed concurrent with arrival of said network frame; and

a protocol engine, coupled to said packet parser, configured to receive results of said one or more speculative CRC checks, and configured to selectively employ said results for validation of a framed protocol data unit (FPDU) according to said ULP.

2. The apparatus as recited in claim 1, wherein said packet parser processes said TCP segment prior to when said protocol engine determines a corresponding connection context for said TCP segment.

3. The apparatus as recited in claim 1, wherein said one or more speculative CRC checks are performed simultaneously.

4. The apparatus as recited in claim 1, wherein said packet parser considers that said TCP segment comprises an aligned framed protocol data unit (FPDU), and wherein said aligned FPDU comprises a 2-byte FPDU length field at the beginning of said aligned FPDU.

5. The apparatus as recited in claim 1, wherein said ULP comprises the Marker PDU aligned protocol.

6. The apparatus as recited in claim 5, wherein said packet parser performs more than one speculative CRC check of the same type within said TCP segment.

7. The apparatus as recited in claim 5, wherein said packet parser comprises:

a no marker CRC engine, configured to perform a first CRC check to generate a first CRC corresponding to a first case where MPA protocol is employed with no markers enabled.

8. The apparatus as recited in claim 7, wherein said no marker CRC engine generates no marker results, and wherein said no marker results indicate whether or not a no marker CRC check is good.

9. The apparatus as recited in claim 8, wherein said no marker results further indicate whether or not said TCP segment comprises multiple framed protocol data units (FPDUs).

10. The apparatus as recited in claim 9, wherein said no marker results further indicate whether or not said TCP segment comprises one or more partial FPDUs.

11. The apparatus as recited in claim 7, wherein said packet parser further comprises:

a minimum marker CRC engine, configured to perform a second CRC check to generate a second CRC corresponding to a second case where MPA protocol is employed with said markers enabled, and wherein said packet parser considers that a minimum number of said markers are placed within said TCP segment.

12. The apparatus as recited in claim 11, wherein said minimum marker CRC engine generates minimum marker results, and wherein said minimum marker results indicate whether or not a minimum marker CRC check is good.

13. The apparatus as recited in claim 12, wherein said minimum marker results further indicate whether or not said TCP segment comprises multiple framed protocol data units (FPDUs).

14. The apparatus as recited in claim 13, wherein said minimum marker results further indicate whether or not said TCP segment comprises one or more partial FPDUs.

15. The apparatus as recited in claim 11, wherein said packet parser further comprises:

a maximum marker CRC engine, configured to perform a third CRC check to generate a third CRC corresponding to a third case where MPA protocol is employed with said markers enabled, and wherein said packet parser considers that a maximum number of said markers are placed within said TCP segment.

16. The apparatus as recited in claim 15, wherein said maximum marker CRC engine generates maximum marker results, and wherein said maximum marker results indicate whether or not a maximum marker CRC check is good.

17. The apparatus as recited in claim 16 wherein said maximum marker results further indicate whether or not said TCP segment comprises multiple framed protocol data units (FPDUs).

18. The apparatus as recited in claim 17 wherein said maximum marker results further indicate whether or not said TCP segment comprises one or more partial FPDUs.

19. The apparatus as recited in claim 15, wherein said minimum marker CRC engine and said maximum marker CRC engine are coupled to allow for cross-feedback of respectively generated results and wherein said respectively generated results are employed to determine a start location of a following framed protocol data unit (FPDU) when it is speculated that multiple FPDUs are contained within said TCP segment.

20. The apparatus as recited in claim 1, wherein said network fabric comprises one or more 1-Gigabit Ethernet links.

21. The apparatus as recited in claim 1, wherein said network fabric comprises one or more 10-Gigabit Ethernet links.

22. The apparatus as recited in claim 1, wherein said packet parser and said protocol engine logic is embodied within a network adapter corresponding to the first server.

23. An apparatus, for performing remote direct memory access (RDMA) operations between a first server and a second server over a network fabric, the apparatus comprising:

a first network adapter, configured to access work queue elements, and configured to receive framed protocol data units (FPDUs) corresponding to the RDMA operations over a TCP/IP interface between the second and first servers, wherein the RDMA operations are responsive to said work queue elements, said first network adapter comprising;

a packet parser, configured to process a TCP segment within an arriving network frame, wherein said packet parser performs one or more speculative CRC checks according to an upper layer protocol (ULP), and wherein said one or more speculative CRC checks are performed concurrent with arrival of said network frame; and

a protocol engine, coupled to said packet parser, configured to receive results of said one or more speculative CRC checks, and configured to selectively employ said results for validation of an FPDU within said TCP segment according to said ULP.

a second network adapter, configured to transmit said FPDUs.

24. The apparatus as recited in claim 23, wherein said one or more speculative CRC checks are performed simultaneously.

25. The apparatus as recited in claim 23, wherein said packet parser considers that said TCP segment comprises an aligned framed protocol data unit (FPDU), and wherein said aligned FPDU comprises a 2-byte FPDU length field at the beginning of said aligned FPDU.

26. The apparatus as recited in claim 23, wherein said ULP comprises the Marker PDU aligned protocol.

27. The apparatus as recited in claim 26, wherein said packet parser comprises:

a no marker CRC engine, configured to perform a first CRC check to generate a first CRC corresponding to a first case where MPA protocol is employed with no markers enabled;

a minimum marker CRC engine, configured to perform a second CRC check to generate a second CRC corresponding to a second case where MPA protocol is employed with said markers enabled, and wherein said packet parser considers that a minimum number of said markers are placed within said TCP segment; and

a maximum marker CRC engine, configured to perform a third CRC check to generate a third CRC corresponding to a third case where MPA protocol is employed with said markers enabled, and wherein said packet parser considers that a maximum number of said markers are placed within said TCP segment.

28. The apparatus as recited in claim 27, wherein said CRC engines generate said results, and wherein said results indicate respective results of said first, second, and third CRC checks.

29. The apparatus as recited in claim 27, wherein said minimum marker CRC engine and said maximum marker CRC engine are coupled to allow for cross-feedback of respectively generated results and wherein said respectively generated results are employed to determine a start location of a following FPDU contained within said TCP segment.

30. A method for performing remote direct memory access (RDMA) operations between a first server and a second server over a network fabric, the method comprising:

processing work queue elements, wherein the work queue elements reside within a work queue that is within first host memory corresponding to the first server; and

accomplishing the RDMA operations over a TCP/IP interface between the first and second servers, wherein said accomplishing comprises;

receiving a network frame; and

concurrently generating and validating one or more speculative CRCs associated with a TCP segment within the network frame, wherein the speculative CRCs correspond to one or more types of CRC checks according to an upper layer protocol (ULP).

31. The apparatus as recited in claim 30, wherein said concurrently generating and validating comprises:

performing the one or more speculative CRC checks in parallel.

32. The apparatus as recited in claim 31, wherein said concurrently generating and validating comprises:

assuming that the TCP segment comprises an aligned framed protocol data unit (FPDU), and wherein the aligned FPDU comprises a 2-byte FPDU length field at the beginning of the aligned FPDU.

33. The apparatus as recited in claim 32, wherein the ULP comprises the Marker PDU aligned protocol.

34. The apparatus as recited in claim 32, wherein performing comprises:

first generating a first CRC corresponding to a first case where MPA protocol is employed with no markers enabled;

second generating a second CRC corresponding to a second case where MPA protocol is employed with markers enabled, wherein a minimum number of the markers are placed within the TCP segment; and

third generating a third CRC corresponding to a third case where MPA protocol is employed with markers enabled, wherein a maximum number of the markers are placed within the TCP segment.

35. The apparatus as recited in claim 34, wherein said accomplishing further comprises:

selectively employing results of said concurrently generating and validating to resolve a state of the TCP segment according to a corresponding connection context.