PROGRAMMABLE DATA PACKET PARSER

• US 20030108038A1
• Filed: 06/30/1999
• Published: 06/12/2003
• Est. Priority Date: 06/30/1999
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: DEVANAGONDI, HARISH, SUN, JAMES
• Granted Patent: US 6,611,524 B2
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04L 2012/5651 Priority, marking, classes
• CPC Class Codes: H04L 49/90 Buffering arrangements
• CPC Class Codes: H04L 49/901 using storage descriptor, e.g. read or write pointers
• CPC Class Codes: H04L 49/9073 Early interruption upon arrival of a fraction of a packet
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

A data packet parser, for determining packet format, is substantially software controlled, to readily accommodate new or different formats, without the need for using a microprocessor for parsing. Comparisons are performed under the control of data stored in a database. By storing new or different data in the database, new or different packet formats can accommodated without the need for making hardware changes. In one embodiment, comparisons performed on various fields of the data packet result in setting or clearing bits of a signature word which identifies the packet format. The signature word can be used directly or indirectly such as forming the input argument of a ternary CAM, to provide a pointer to microcode which appropriately handles the data packet in the identified format.

Claims

1. Apparatus for facilitating parsing of a network data packet comprising:

a memory device for storing a plurality of database entries,

at least a first comparator which is controlled, at least partially in response to data from one or more of said database entries, to perform a comparison on at least a portion of said data packet and to output a first comparison result, said first comparison result being used for forming at least a first part of a signature word at least partially identifying a format of said data packet.

2. Apparatus, as claimed in claim 1, wherein said memory device comprises a plurality of registers.

3. Apparatus, as claimed in claim 1, wherein said comparator compares said portion of said data packet to data obtained from said database.

4. Apparatus, as claimed in claim 1, wherein said comparison result is used for setting or clearing a bit location of said signature word and wherein said bit location is selected using data from said database.

5. Apparatus, as claimed in claim 1, wherein said portion of said data packet is selected using data from said database.

6. Apparatus, as claimed in claim 1 wherein said comparator includes masking circuitry for masking said portion of said data packet, using mask data obtained from said database.

7. Apparatus, as claimed in claim 1, further comprising a second comparator which outputs a second comparison result used for forming at least a second part of said signature word.

8. Apparatus, as claimed in claim 1, further comprising a second comparator which outputs a second comparison result for combination with said first comparison result for forming said first part of said signature word.

9. Apparatus, as claimed in claim 1, further comprising a content-addressable memory (CAM) configured to receive said signature word and output a pointer to a microcode entry point.

10. Apparatus, as claimed in claim 1 further comprising a look-up table configured to output associated data in response to said signature word.

11. A method for identifying a format of a network data packet comprising:

storing a plurality of comparison control data in a database;

comparing, using a comparator, at least a first portion of said data packet with parsing data, said comparing including outputting at least a first comparison result, wherein said comparing is at least partly controlled using at least first control data from said database;

forming at least a first portion of a signature word using at least said first comparison result.

12. A method, as claimed in claim 11, wherein said step of storing comprises storing in at least a first of a plurality of registers.

13. A method, as claimed in claim 11, further comprising selecting said first portion of said data packet in response to data from said database.

14. A method, as claimed in claim 11, further comprising masking said first portion of said data packet with mask data from said database.

15. A method, as claimed in claim 11, wherein at least a portion of said parsing data is obtained from said database.

16. A method, as claimed in claim 11, further comprising selecting said first portion of said signature word in response to data from said database.

17. A method, as claimed in claim 11, wherein said comparing is selected from the group consisting of a less-than comparison, an equals comparison and a greater-than comparison.

18. A method, as claimed in claim 11, wherein a type of comparison is performed in response to data from said database.

19. A method, as claimed in claim 11, further comprising comparing at least a second portion of said data packet with parsing data and outputting at least a second comparison result.

20. A method as claimed in claim 19 further comprising combining said second comparison result with said first comparison result before said step of forming said first portion of said signature word.

21. A method, as claimed in claim 20, wherein said step of combining said second comparison result with said first comparison result includes performing an OR operation.

22. A method, as claimed in claim 19 further comprising forming a second portion of said signature word, different from said first portion, using said second comparison result.

23. A method, as claimed in claim 11, further comprising selecting one of a plurality of packet handling procedures for handling said packet, wherein said selecting is performed in response to said signature word.

24. A method, as claimed in claim 11, further comprising selecting a microcode entry point at least partially in response to said signature word.

25. A method, as claimed in claim 11 further comprising providing a content-addressable memory (CAM) and outputting a microcode pointer from said CAM in response to said signature word.

26. A method, as claimed in claim 11, further comprising storing new data in said database facilitating the handling of a different packet format.

27. Apparatus for identifying a format of a network data packet comprising:

means for storing a plurality of comparison control data;

means for comparing at least a first portion of said data packet with parsing data, and outputting at least a first comparison result, wherein said means for comparing is at least partly controlled using at least first control data from said means for storing;

means for forming at least a first portion of a signature word using at least said first comparison result.

28. Apparatus, as claimed in claim 27, wherein said means for storing comprises a plurality of registers.

29. Apparatus, as claimed in claim 27, further comprising means for selecting said first portion of said data packet in response to data from said means for storing.

30. Apparatus, as claimed in claim 27, further comprising means for masking said first portion of said data packet with mask data from said means for storing.

31. Apparatus, as claimed in claim 27, wherein at least a portion of said parsing data is obtained from said means for storing.

32. Apparatus, as claimed in claim 27, further comprising means for selecting said first portion of said signature word in response to data from said means for storing.

33. Apparatus, as claimed in claim 27, further comprising means for selecting a type of comparison in response to data from said means for storing.

34. Apparatus, as claimed in claim 27, further comprising second means for comparing at least a second portion of said data packet with parsing data and outputting at least a second comparison result.

35. Apparatus as claimed in claim 34 further comprising means for combining said second comparison result with said first comparison result.

36. Apparatus, as claimed in claim 35, wherein said means for combining said second comparison result with said first comparison result includes an OR gate.

37. Apparatus, as claimed in claim 34 further comprising means for forming a second portion of said signature word, different from said first portion, using said second comparison result.

38. Apparatus, as claimed in claim 27, further comprising means for selecting one of a plurality of packet handling procedures for handling said packet, in response to said signature word.

39. Apparatus, as claimed in claim 27, further comprising means for selecting a microcode entry point at least partially in response to said signature word.

40. Apparatus, as claimed in claim 27 further comprising a content-addressable memory (CAM) configured to output a microcode pointer from said CAM in response to said signature word.

41. A method for handling a network data packet having a first format, comprising:

storing, in at least a first of a plurality of registers, a plurality of comparison control data, forming a database;

selecting a first portion of said data packet in response to data from said database;

masking said first portion of said data packet with mask data from said database, to provide masked packet data;

comparing, using a comparator, said masked packet data with parsing data obtained from said database, and outputting a first comparison result;

forming at least a first portion of a signature word using at least said first comparison result wherein said first portion of said signature word is selected in response to data from said database;

comparing at least a second portion of said data packet with parsing data and outputting at least a second comparison result;

forming a second portion of said signature word, different from said first portion, using said second comparison result;

providing associated data in response to said signature word; and

handling said data packet in accordance with said associated data.

42. A method, as claimed in claim 41, further comprising providing a content-addressable memory (CAM) and wherein said step of providing associated data comprises outputting a microcode pointer from said CAM in response to said signature word.

43. A method, as claimed in claim 42, further comprising:

using said microcode pointer to select a microcode entry point; and

executing microcode, beginning at said entry pont, in a microprocessor, for said handling of said data packet.

44. A method, as claimed in claim 41, wherein said outputting said second comparison result is performed substantially simultaneously with said outputting said first comparison result.