On the fly header checksum processing using dedicated logic

• US 7,283,528 B1
• Filed: 03/22/2002
• Issued: 10/16/2007
• Est. Priority Date: 03/22/2002
• Status: Expired due to Fees

• Current Assignee: Juniper Networks Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Lim, Raymond Marcelino Manese, Libby, Jeffrey G.
• Primary Examiner(s): Sam; Phirin
• Application Number:
  US10/102,958
• Time in Patent Office: 2,034 Days
• Field of Search: 370/389, 370/392, 370/394, 370/412, 370/413, 370/415, 370/417, 370/465, 370/471, 370/474
• US Class Current: 370/392
• 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

Abstract

A packet header processing engine includes a packet processing unit that is configured to generate the packet header information based on the packet header data. A checksum generating unit is connected to the packet processing unit. The checksum generating unit is configured to compute and store a partial checksum for a packet header being processed by the packet processing unit. After all packet header information for a packet is stored in the buffer, the checksum generating unit contains a complete checksum for the packet header.

Claims

1. A packet header processing engine comprising:

a packet processing unit configured to construct packet header information according to a packet header protocol;

a buffer configured to receive the packet header information, wherein the packet processing unit is connected to the buffer and is configured to send the packet header information to the buffer;

a checksum accumulator configured to store a partial checksum for a packet header being processed by the packet processing unit; and

a checksum generator connected to the packet processing unit and the checksum accumulator, the checksum generator being configured to compute and store a new partial checksum from the packet header information and the stored partial checksum concurrently when the packet header information is sent by the packet processing unit to the buffer.

2. The packet header processing engine of claim 1, wherein the checksum generator is further configured to store the new partial checksum in the checksum accumulator.

3. The packet header processing engine of claim 1, wherein the packet processing unit is configured to load the checksum accumulator with an initial value when beginning construction of packet header information for a packet.

4. The packet header processing engine of claim 1, wherein the packet processing unit is configured to read the stored checksum from the checksum accumulator and write the stored checksum to the buffer when finishing construction of the packet header information for a packet.

5. The packet header processing engine of claim 1, wherein the packet header protocol is a layer 3 (L3) packet header protocol.

6. A packet header processing engine comprising:

a packet processing unit configured to construct packet header information according to a packet header protocol;

a buffer configured to receive the packet header information, wherein the packet processing unit is connected to the buffer and configured to send the packet header information to the buffer; and

a checksum generating unit connected to the packet processing unit, the checksum generating unit being configured to compute and store a partial checksum for a packet header being processed by the packet processing unit concurrently when the packet header information is sent by the packet processing unit to the buffer.

7. The packet header processing engine of claim 6, wherein the packet processing unit is configured to load the checksum generating unit with an initial value when beginning construction of packet header information for a packet.

8. The packet header processing engine of claim 6, wherein the packet processing unit is configured to read the stored checksum from the checksum generating unit and write the stored checksum to the buffer when finishing construction of packet header information for a packet.

9. The packet header processing engine of claim 6, wherein the checksum generating unit includes:

a checksum accumulator connected to the packet processing unit and configured to store the partial checksum, and

a checksum generator connected to the packet processing unit and the checksum accumulator, the checksum generator being configured to compute a new partial checksum from the packet header information and the stored partial checksum concurrently when the packet header information is sent by the packet processing unit to the buffer.

10. The packet header processing engine of claim 6, wherein the packet header protocol is a layer 3 (L3) packet header protocol.

11. A method comprising:

constructing packet header information for a packet according to a packet header protocol;

writing the packet header information to a buffer; and

computing a partial checksum for a packet header associated with the packet header information concurrently when the packet header information is written to the buffer.

12. The method of claim 11, further comprising:

storing the partial checksum.

13. The method of claim 11, further comprising:

storing an initial checksum when starting construction of the packet header.

14. The method of claim 11, wherein said computing includes:

computing the partial checksum based on the packet header information and a previously stored partial checksum.

15. The method of claim 13, wherein said computing includes:

computing the partial checksum based on the packet header information and the initial checksum.

16. The method of claim 12, further comprising:

reading the partial checksum as a completed checksum when completing construction of the packet header.

17. The method of claim 16, further comprising:

writing the completed checksum to the buffer.

18. The method of claim 11, further comprising:

recomputing the partial checksum for the packet header concurrently each time associated packet header information is written to the buffer.

19. The method of claim 11, wherein packet header protocol is a layer 3 (L3) packet header protocol.

20. A network device for processing packets comprising:

a buffer configured to store the packets, including header data and payload data for the packets;

a descriptor reader component coupled to the buffer, the descriptor reader component configured to receive the header data for the packets stored in the buffer and configured to look up descriptor information relating to the received packet header data; and

a packet header processing component coupled to the descriptor reader component, the packet header processing component configured to receive the packet header data and the descriptor information from the descriptor reader component, the packet header processing component additionally including;

a buffer configured to receive packet header information,

a packet processing unit connected to the buffer, the packet processing unit being configured to generate the packet header information based on the packet header data and to send the packet header information to the buffer, and

a checksum generating unit connected to the packet processing unit, the checksum generating unit being configured to compute and store a partial checksum for a packet header being processed by the packet processing unit.

21. The network device of claim 20, wherein the packet processing unit is further configured to generate the packet header information from the packet header data according to a layer 3 (L3) packet header protocol.

22. A device comprising:

means for constructing packet header information for a packet;

means for storing the packet header information;

means for computing a partial checksum for a packet header associated with the packet header information concurrently when the packet header information is stored in the means for storing; and

means for storing the partial checksum.