Offload of TCP segmentation to a smart adapter

• US 5,937,169 A
• Filed: 10/29/1997
• Issued: 08/10/1999
• Est. Priority Date: 10/29/1997
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Sherer, W. Paul, Connery, Glenn William, Jaszewski, Gary, Binder, James S.
• Primary Examiner(s): Harrell, Robert B.
• Application Number:
  US08/960,238
• Time in Patent Office: 650 Days
• Field of Search: 364/DIG. 1, 364/DIG. 2, 395/200.3, 395/200.36, 395/200.37, 395/200.48, 395/200.5, 395/200.53, 395/200.55, 395/200.6, 395/200.66, 395/200.8
• US Class Current: 709/250
• CPC Class Codes: G06F 13/387 for adaptation of different data processing systems to different peripheral devices, e.g. protocol converters for incompatible systems, open system

Abstract

A method is provided for sending data from a data source executing a network protocol such as the TCP/IP protocol stack, which includes a process for generating headers for packets according to the network protocol. The method includes sending such data on a network through a smart network interface. The network protocol defines a datagram in the data source, including generating a header template and supplying a data payload. The datagram is supplied to the network interface. At the network interface, a plurality of packets of data are generated from the datagram. The plurality of packets include respective headers, such as TCP/IP headers, based on the header template, and include respective segments of the data payload. The network interface supports packets having a pre-specified length, and the data payload is greater than the pre-specified length, such as two to forty times larger or more. Thus, the higher layer processing specifies a very large datagram, which is automatically segmented at the network interface layer, instead of at the TCP layer.

Claims

1. A method for sending data on a network from a data source executing a network protocol which includes a process for generating packet control data for packets according to the network protocol, through a network interface including medium access control layer processes, comprising:

establishing a connection with a destination for a session according to the network protocol;

determining a window size from the destination according to the network protocol, which indicates an amount of data the destination is ready to receive;

defining a datagram in the data source, including generating a packet control data template and supplying a data payload having a size less than or equal to the window size;

supplying the datagram to the network interface;

generating in the network interface, a plurality of packets from the datagram, the plurality of packets including respective packet control data based on the packet control data template, and including respective segments of the data payload;

sending the plurality of packets to the destination; and

receiving acknowledgment from the destination of receipt of the plurality of packets according to the network protocol.

2. The method of claim 1, wherein the acknowledgment carries an indication of an updated window size for the destination.

3. The method of claim 2, including if a packet with data is received for the session before a last packet in the plurality of packets is sent, then abandoning the unsent packets in the plurality of packets, and resending the datagram.

4. The method of claim 1, including holding acknowledgment and window values for a given datagram session in a location accessible by the network interface, and reading in the network interface the values stored in said location during the sending of the plurality of packets.

5. The method of claim 1, including holding in the network interface, recieved packets during the sending of the plurality of packets, until the plurality of packets has been sent.

6. The method of claim 1, wherein the step of supplying includes providing a segment size parameter, and a segmentation request to the network interface.

7. The method of claims 1, wherein the step of supplying includes providing a segment size parameter outside the datagram.

8. The method of claim 1, wherein the packet control data template includes a reserved field, and the step of supplying includes providing a segment size parameter to the network interface by a path outside the datagram and a segmentation request to the network interface by setting a bit in the reserved field.

9. The method of claim 1, wherein the step of supplying includes providing a segment size parameter and a segmentation request to the network interface by a path outside the datagram.

10. The method of claim 1, wherein the packet control data template includes a packet header template.

11. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template.

12. The method of claim 1, wherein the network interface supports packets having a prespecified length, and the data payload is greater than the prespecified length.

13. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an IP total length field set to indicate the length of the data payload, and wherein the step of generating in the network interface includes setting IP total length fields in the plurality of packets, based on size or sizes of the respective segments of the data payload in the plurality of packets.

14. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an IP identification field set to an initial value for the datagram, and wherein the step of generating in the network interface includes setting IP identification values in the plurality of packets based on said initial value.

15. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an initial TCP sequence number set for the datagram, and wherein the step of generating in the network interface includes setting TCP sequence numbers for the plurality of packets based on the initial TCP sequence number and the size or sizes of the respective segments of the data payload in the plurality of packets.

16. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an IP header checksum field, and a TCP checksum field, and wherein the step of generating the plurality of packets in the network interface includes computing IP header checksums and TCP checksums for the plurality of packets.

17. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template having a TCP header PSH flag, and wherein the step of generating the plurality of packets in the network interface includes if the TCP header PSH flag is set to a no action state, setting the TCP header PSH flag in the packet headers to the no action state, and includes if the TCP header PSH flag is set to a push state, setting the TCP header PSH flag in a last packet in the plurality of packets to the push state, and for other packets in the plurality of packets to the no action state.

18. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having a TCP header acknowledgment number and window field, and wherein the step of generating the plurality of packets in the network interface includes setting the TCP header acknowledgment number and window field to the values in the TCP/IP header template.

19. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having a TCP header acknowledgment number and window field, and wherein the step of generating the plurality of packets in the network interface includes before sending each packet in the plurality of packets, if no more recent datagram has been supplied, then setting the TCP header acknowledgment number and window field to the values in the TCP/IP header template, and if a more recent datagram has been supplied, then setting the TCP header acknowledgment number and window field to the values in the TCP/IP header template of the more recent datagram.

20. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having a MF flag set to indicate no fragmentation, and a Fragment Offset field set to zero.

21. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an IP options field set to indicate no options.

22. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having TCP, URG, RST, SYN and FIN flags set to no action states, and the urgent pointer field set to zero.

23. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template having an URG flag and a URG pointer identifying a byte in the datagram, and including in the network interface flag and setting the URG pointer in a packet in the plurality of packets which includes said byte.

24. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template having an URG flag and a URG pointer identifying a byte in the datagram, and including in the network interface setting the URG flag and URG pointer in a packet in the plurality of packets which includes said byte.

25. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template having a FIN flag, and including in the network interface, if the FIN flag is set in the TCP/IP header template, setting the FIN flag in a last packet in the plurality of packets.

26. The method of claim 1, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template having a PSH flag, and including in the network interface, if the PSH flag is set in the TCP/IP header template, setting the PSH flag in at least one packet in the plurality of packets.

27. The method of claim 1, including sending a plurality of datagrams to the network interface for the same session, and wherein the step of generating the plurality of packets for a current datagram includes for a last packet in the plurality of packets, determining whether data from a following datagram falls in sequence, and if it does, then concatenating data from the current datagram with data from the following datagram in the last packet.

28. The method of claim 1, including sending a plurality of datagrams to the network interface for the same session, and wherein the step of generating the plurality of packets for a current datagram includes determining whether a more recent datagram has been supplied, and if it has, then updating the template for the current datagram based upon the more recent datagram.

29. The method of claim 1, including sending a plurality of datagrams to the network interface for the same session, and assigning sequence numbers to the plurality of datagrams, and wherein the step of generating the plurality of packets for a current datagram includes determining whether a more recent datagram has been supplied having a sequence number which precedes a sequence number in the current datagram, and if it has, then stopping the generating of the plurality of packets for the current datagram, and beginning the generating of the plurality of packets for the more recent datagram.

30. A method for sending data on a network from a data source executing a TCP/IP network protocol which includes a process for generating TCP/IP headers for packets according to the network protocol, through a network interface, comprising:

establishing a connection with a destination for a session according to the TCP/IP network protocol;

determining a TCP window size from the destination, which indicates an amount of data the destination is ready to receive;

defining a datagram in the data source, including generating a TCP/IP header template and supplying a data payload having a size less than or equal to the window size;

supplying the datagram, a segment size parameter, and a request to segment the datagram to the network interface;

generating in the network interface, in response to the segment size parameter and to the request to segment, a plurality of packets from the datagram, including executing processes in the network interface to provide respective TCP/IP headers based on the TCP/IP header template, to provide respective segments of the data payload having lengths equal to or less than the segment size parameter, and to compute IP header checksums and TCP checksums for the plurality of packets;

sending the plurality of packets to the destination; and

receiving acknowledgment from the destination of receipt of the plurality of packets according to the network protocol.

31. The method of claim 30, including if a TCP packet with a non-zero data payload is received before a last packet in the plurality of packets is sent, then abandoning the unsent packets in the plurality of packets, and resending the datagram.

32. The method of claim 30, wherein the step of supplying includes providing the segment size parameter outside the datagram.

33. The method of claim 30, wherein the TCP/IP header template includes a reserved field, and the step of supplying includes providing the segment size parameter to the network interface by a path outside the datagram, and the segmentation request to the network interface by setting a bit in the reserved field.

34. The method of claim 30, wherein the acknowledgment carries an indication of a updated window size for the destination.

35. The method of claim 30, wherein the TCP/IP header template includes an IP total length field set to indicate the length of the data payload, and wherein the step of generating in the network interface includes setting IP total length fields in the plurality of packets, based on size or sizes of the respective segments of the data payload in the plurality of packets.

36. The method of claim 30, wherein the TCP/IP header template includes an IP identification field set to an initial value for the datagram, and wherein the step of generating in the network interface includes setting IP identification values in the plurality of packets based on said initial value.

37. The method of claim 30, wherein TCP/IP header template includes an initial TCP sequence number set for the datagram, and wherein the step of generating in the network interface includes setting TCP sequence numbers for the plurality of packets based on the initial TCP sequence number and the size or sizes of the respective segments of the data payload in the plurality of packets.

38. The method of claim 30, wherein the TCP/IP header template includes a TCP header PSH flag, and wherein the step of generating the plurality of packets in the network interface includes if the TCP header PSH flag is set to a no action state, setting the TCP header PSH flag in the packet headers to the no action state, and includes if the TCP header PSH flag is set to a push state, setting the TCP header PSH flag in a last packet in the plurality of packets to the push state, and for other packets in the plurality of packets to the no action state.

39. The method of claim 30, wherein the TCP/IP header template includes a TCP header acknowledgment number and window field, and wherein the step of generating the plurality of packets in the network interface includes setting the TCP header acknowledgment number and window field to the values in the TCP/IP header template.

40. The method of claim 30, wherein the TCP/IP header template includes a TCP header acknowledgment number and window field, and wherein the step of generating the plurality of packets in the network interface includes before sending each packet in the plurality of packets if no more recent datagram has been supplied, then setting the TCP header acknowledgment number and window field to the values in the TCP/IP header template, and if a more recent datagram has been supplied, then setting the TCP header acknowledgment number and window field to the values in the TCP/IP header template of the more recent datagram.

41. The method of claim 30, wherein the TCP/IP header template includes a MF flag set to indicate no fragmentation, and a Fragment Offset field set to zero.

42. The method of claim 30, wherein the TCP/IP header template includes an IP options field set to indicate no options.

43. The method of claim 30, wherein the TCP/IP header template includes TCP, URG, RST, SYN and FIN flags set to no action states, and the urgent pointer field set to zero.

44. The method of claim 30, wherein the TCP/IP header template having an URG flag and a URG pointer identifying a byte in the datagram, and including in the network interface flag and setting the URG pointer in a packet in the plurality of packets which includes said byte.

45. The method of claim 30, wherein the TCP/IP header template having a FIN flag, and including in the network interface, if the FIN flag is set in the TCP/IP header template, setting the FIN flag in a last packet in the plurality of packets.

46. The method of claim 30, wherein the TCP/IP header template having a PSH flag, and including in the network interface, if the PSH flag is set in the TCP/IP header template, setting the PSH flag in at least one packet in the plurality of packets.

47. The method of claim 30, including sending a plurality of datagrams to the network interface for the same session, and wherein the step of generating the plurality of packets for a current datagram includes for a last packet in the plurality of packets, determining whether data from a following datagram falls in sequence, and if it does, then concatenating data from the current datagram with data from the following datagram in the last packet.

48. The method of claim 30, including sending a plurality of datagrams to the network interface for the same session, and wherein the step of generating the plurality of packets for a current datagram includes determining whether a more recent datagram has been supplied, and if it has, then updating the template for the current datagram based upon the more recent datagram.

49. The method of claim 30, including sending a plurality of datagrams to the network interface for the same session, and assigning sequence numbers to the plurality of datagrams, and wherein the step of generating the plurality of packets for a current datagram includes determining whether a more recent datagram has been supplied having a sequence number which precedes a sequence number in the current datagram, and if it has, then stopping the generating of the plurality of packets for the current datagram, and beginning the generating of the plurality of packets for the more recent datagram.

50. A network interface device coupled to a host system including a data source, the data source executing a network protocol which includes a process for generating packet control data for packets according to the network protocol and sending packet on the network, comprising:

a host interface coupled to the host system, adapted to receive a datagram in the data source, the datagram including a packet control data template and a data payload;

memory to store at least portions of the datagram to the network interface;

a processor that generates a plurality of packets from the datagram, the plurality of packets including respective packet control data based on the packet control data template, and including respective segments of the data payload; and

a medium access control unit coupled to the memory and to a network medium that manages transfer of the plurality of packets to the network from the memory.

51. The network interface device of claim 50, wherein the packet control data template includes a packet header template.

52. The network interface device of claim 50, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template.

53. The network interface device of claim 50, wherein the medium access control unit supports packets having a prespecified length, and the data payload is greater than the prespecified length.

54. The network interface device of claim 50, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an IP total length field set to indicate the length of the data payload, and wherein the process of generating the plurality of packets includes setting IP total length fields in the plurality of packets, based on size or sizes of the respective segments of the data payload in the plurality of packets.

55. The network interface device of claim 50, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an IP identification field set to an initial value for the datagram, and wherein the process of generating the plurality of packets includes setting IP identification values in the plurality of packets based on said initial value.

56. The network interface device of claim 50, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an initial TCP sequence number set for the datagram, and wherein the process of generating the plurality of packets includes setting TCP sequence numbers for the plurality of packets based on the initial TCP sequence number and the size or sizes of the respective segments of the data payload in the plurality of packets.

57. The network interface device of claim 50, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an IP header checksum field, and a TCP checksum field, and wherein the process of generating the plurality of packets includes computing IP header checksums and TCP checksums for the plurality of packets.

58. The network interface device of claim 50, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having a TCP header PSH flag, and wherein the process of generating the plurality of packets includes if the TCP header PSH flag is set to a no action state, setting the TCP header PSH flag in the packet headers to the no action state, and includes if the TCP header PSH flag is set to a push state, setting the TCP header PSH flag in a last packet in the plurality of packets to the push state, and for other packets in the plurality of packets to the no action state.

59. The network interface device of claim 50, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having a TCP header acknowledgment number and window field, and wherein the process of generating the plurality of packets includes setting the TCP header acknowledgment number and window field to the values in the TCP/IP header template.

60. The network interface device of claim 50, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having a MF flag set to indicate no fragmentation, and a Fragment Offset field set to zero.

61. The network interface device of claim 50, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an IP options field set to indicate no options.

62. The network interface device of claim 50, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having TCP, URG, RST, SYN and FIN flags set to no action states, and the urgent pointer field set to zero.

63. The network interface device of claim 50, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template having an URG flag and a URG pointer identifying a byte in the datagram, and including in the network interface resource to set the URG flag and pointer in a packet in the plurality of packets which includes said byte.

64. The network interface device of claim 50, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template having a FIN flag, and including in the network interface, resources which if the FIN flag is set in the TCP/IP header template, set the FIN flag in a last packet in the plurality of packets.

65. The network interface device of claim 50, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template having a PSH flag, and including in the network interface, resources which if the PSH flag is set in the TCP/IP header template, set the PSH flag in at least one packet in the plurality of packets.

66. The network interface device of claim 50, including resources in the network interface to read acknowledgment and window values stored in a predetermined location during the sending of the plurality of packets.

67. The network interface device of claim 50, including resources to hold in the network interface, received packets during the sending of the plurality of packets, until the plurality of packets has been sent.

68. A method for sending data on a network from a data source executing a network protocol which includes a process for generating packet control data for packets according to the network protocol, through a network interface, comprising:

defining a datagram in the data source, including generating a packet control data template and supplying a data payload;

supplying the datagram to the network interface;

generating in the network interface at the medium access control layer, a plurality of packets from the datagram, the plurality of packets including respective packet control data based on the packet control data template, and including respective segments of the data payload.

69. The method of claim 68, wherein the packet control data template includes a packet header template.

70. The method of claim 68, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template.

71. The method of claim 68, wherein the network interface supports packets having a prespecified length, and the data payload is greater than the prespecified length.

72. The method of claim 68, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an IP total length field set to indicate the length of the data payload, and wherein the step of generating in the network interface includes setting IP total length fields in the plurality of packets, based on size or sizes of the respective segments of the data payload in the plurality of packets.

73. The method of claim 68, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an IP identification field set to an initial value for the datagram, and wherein the step of generating in the network interface includes setting IP identification values in the plurality of packets based on said initial value.

74. The method of claim 68, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an initial TCP sequence number set for the datagram, and wherein the step of generating in the network interface includes setting TCP sequence numbers for the plurality of packets based on the initial TCP sequence number and the size or sizes of the respective segments of the data payload in the plurality of packets.

75. The method of claim 68, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an IP header checksum field, and a TCP checksum field, and wherein the step of generating the plurality of packets in the network interface includes computing IP header checksums and TCP checksums for the plurality of packets.

76. The method of claim 68, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having a TCP header PSH flag, and wherein the step of generating the plurality of packets in the network interface includes if the TCP header PSH flag is set to a no action state, setting the TCP header PSH flag in the packet headers to the no action state, and includes if the TCP header PSH flag is set to a push state, setting the TCP header PSH flag in a last packet in the plurality of packets to the push state, and for other packets in the plurality of packets to the no action state.

77. The method of claim 68, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having a TCP header acknowledgment number and window field, and wherein the step of generating the plurality of packets in the network interface includes setting the TCP header acknowledgment number and window field to the values in the TCP/IP header template.

78. The method of claim 68, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having a MF flag set to indicate no fragmentation, and a Fragment Offset field set to zero.

79. The method of claim 68, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having an IP options field set to indicate no options.

80. The method of claim 68, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template including having TCP, URG, RST, SYN and FIN flags set to no action states, and the urgent pointer field set to zero.

81. The method of claim 68, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template having an URG flag and a URG pointer identifying a byte in the datagram, and including in the network interface setting the URG flag and URG pointer in a packet in the plurality of packets which includes said byte.

82. The method of claim 68, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template having a FIN flag, and including in the network interface, if the FIN flag is set in the TCP/IP header template, setting the FIN flag in a last packet in the plurality of packets.

83. The method of claim 68, wherein the network protocol comprises TCP/IP, and the packet control data template comprises a TCP/IP header template having a PSH flag, and including in the network interface, if the PSH flag is set in the TCP/IP header template, setting the PSH flag in at least one packet in the plurality of packets.