Method and apparatus to perform error control

• US 20030182614A1
• Filed: 03/22/2002
• Published: 09/25/2003
• Est. Priority Date: 03/22/2002
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Schroeder, Jacob J.
• Granted Patent: US 7,080,308 B2
• Time in Patent Office: Days
• US Class Current: 714/776
• CPC Class Codes: H03M 13/091 Parallel or block-wise CRC computation
• CPC Class Codes: H03M 13/6547 TCP, UDP, IP and associated protocols, e.g. RTP
• CPC Class Codes: H04L 1/0083 Formatting with frames or packets; Protocol or part of protocol for error control
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers

Abstract

Embodiments to perform improved error control using packet fragments are described.

Claims

1. A method for error control, comprising:

receiving a plurality of packet fragments for a packet;

determining a partial error control value for each packet fragment;

combining said partial error control values into an error control value; and

performing error control for said packet using said error control value.

2. The method of claim 1, wherein said determining comprises:

determining a number of bytes for said packet fragment;

adding a pad byte if said number of bytes is uneven; and

calculating said partial error control value.

3. The method of claim 2, wherein said packet fragment comprises a header section and a payload section, and said calculating comprises performing a 1-complement add of said payload section.

4. The method of claim 1, wherein said partial error control value comprises two bytes.

5. The method of claim 1, wherein said combining comprises:

determining whether each packet fragment has an even or uneven offset;

rotating each partial error control value by one byte for packet fragments having an uneven offset; and

adding each partial error control value to form said error control value.

6. The method of claim 5, further comprising:

creating a pseudo header for a packet comprising said packet fragments;

determining a partial error control value for said pseudo header; and

adding said partial error control value for said pseudo header to said error control value.

7. The method of claim 6, wherein said creating comprises:

retrieving a source address from a header field of a packet fragment;

retrieving a destination address from said header field;

retrieving a protocol identifier from said header field;

calculating a packet length; and

combining said source address, said destination address, said protocol identifier and said packet length into said pseudo header.

8. The method of claim 1, wherein said error control values are Transmission Control Protocol (TCP) checksum values.

9. The method of claim 1, wherein said packet comprises a TCP and Internet Protocol (IP) packet.

10. An apparatus to perform error control, comprising:

a padding module to add a pad byte to uneven packet fragments of a packet;

a partial checksum generator module to generate a partial error control value for each packet fragment;

a pseudo header generator module to generate a pseudo header for said packet; and

a partial checksum combiner module to combine said partial error control values into an error control value.

11. The apparatus of claim 10, wherein said partial checksum generator module generates a partial error control value using a 16-bit 1-complement add.

12. The apparatus of claim 10, wherein said packet is a TCP/IP packet.

13. The apparatus of claim 10, wherein said error control value is a TCP checksum.

14. The apparatus of claim 10, wherein said partial checksum combiner module rotates partial error control values by one byte for packet fragments having an uneven offset prior to combining.

15. A system to perform error control, comprising:

a first network node to perform packet fragmentation for a packet; and

a second network node to receive packet fragments and perform error control for said packet using partial error control values generated for said packet fragments.

16. The system of claim 15, wherein said second network node includes an error control manager comprising:

an padding module to add a pad byte to uneven packet fragments of said packet;

a partial checksum generator module to generate said partial error control values for said packet fragments;

a pseudo header generator module to generate a pseudo header for said packet; and

a partial checksum combiner module to combine said partial error control values into an error control value.

17. A system to perform error control, comprising:

a computer platform adapted to perform error control;

said platform being further adapted to receive a plurality of packet fragments for a packet, determine a partial error control value for each packet fragment, combine said partial error control values into an error control value, and perform error control for said packet using said error control value.

18. The system of claim 17, wherein said platform is further adapted to perform said determining by determining a number of bytes for said packet fragment, adding a pad byte if said number of bytes is uneven, and calculating said partial error control value.

19. The system of claim 17, wherein said platform is further adapted to perform said combining by determining whether each packet fragment has an even or uneven offset, rotating each partial error control value by one byte for packet fragments with an uneven offset, and adding each partial error control value to form said error control value.

20. The system of claim 19, wherein said platform is further adapted to create a pseudo header for a packet comprising said packet fragments, determine a partial error control value for said pseudo header, and add said partial error control value for said pseudo header to said error control value.

21. The system of claim 20, wherein said platform is further adapted to creating by retrieving a source address from a header field of a packet fragment, retrieving a destination address from said header field, retrieving a protocol identifier from said header field, calculating a packet length, and combining said source address, said destination address, said protocol identifier and said packet length into said pseudo header.

22. An article comprising:

a storage medium;

said storage medium including stored instructions that, when executed by a processor, result in performing error control by receiving a plurality of packet fragments for a packet, determining a partial error control value for each packet fragment, combining said partial error control values into an error control value, and performing error control for said packet using said error control value.

23. The article of claim 22, wherein the stored instructions, when executed by a processor, further result in said determining a partial error control value by determining a number of bytes for said packet fragment, adding a pad byte if said number of bytes is uneven, and calculating said partial error control value.

24. The article of claim 22, wherein the stored instructions, when executed by a processor, further result in said combining said partial error control values into said error control value by determining whether each packet fragment has an even or uneven offset, rotating each partial error control value by one byte for packet fragments having an uneven offset, and adding each partial error control value to form said error control value.

25. The article of claim 24, wherein the stored instructions, when executed by a processor, further result in creating a pseudo header for a packet comprising said packet fragments, determining a partial error control value for said pseudo header, and adding said partial error control value for said pseudo header to said error control value.

26. The article of claim 25, wherein the stored instructions, when executed by a processor, further result in creating said pseudo header by retrieving a source address from a header field of a packet fragment, retrieving a destination address from said header field, retrieving a protocol identifier from said header field, calculating a packet length, and combining said source address, said destination address, said protocol identifier and said packet length into said pseudo header.