Error detection/correction and fault detection/recovery – Pulse or data error handling – Error/fault detection technique
Reexamination Certificate
1999-01-07
2001-08-21
DeCady, Albert (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Error/fault detection technique
Reexamination Certificate
active
06279140
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the data processing field, and more particularly, relates to a method and apparatus for checksum verification with receive packet processing for data communications.
DESCRIPTION OF THE RELATED ART
In any communication system, it is desirable to detect data transmission errors. Packets transmitted across a communications network between nodes contain data and a header that describes the data. Typically, such as with known communication systems utilizing an internet protocol (IP), a sending computer or node sends a header and then data.
One known method called TCP/IP checksum assist has proven to be very beneficial to server systems in terms of CPU utilization and overall throughput. Checksum assist is the process of generating a partial protocol checksum with minimal user intervention. This process is done concurrently with the DMA process when the data is traversed when being moved to a host. The partial sum is exposed to the user, and the user then does more work to verify the eventual checksum using values from the IP protocol header. This method does not address the IP header checksum, the overhead of completing the sum, or the checksum process when the data is not being DMAed, such as when a data frame is sent to on-chip processor.
U.S. Pat. No. 5,815,516 issued Sep. 29, 1998 to Aaker et al., and assigned to the present assignee discloses a method and apparatus for producing transmission control protocol (TCP) checksums using internet protocol (IP) fragmentation. The transmission communication protocol (TCP) uses a checksum to protect the data which is transmitted. This checksum is located in the TCP header of the internet datagram packet. In the disclosed method, a transmission control protocol module receives packet data to be transmitted and prepares a first internet protocol data fragment without a checksum for the received packet data. The first internet protocol data fragment is transmitted. Collecting checksum is performed during the transmission of the first internet protocol data fragment. Then an internet protocol header fragment including the collected checksum is transmitted.
A need exists for an improved method and apparatus for checksum verification with receive packet processing for data communications. It is desirable to provide full checksum verification on the currently used IP version 4 for data communications and new and different protocols including the proposed protocol IP version 6 for data communications.
SUMMARY OF THE INVENTION
A principal object of the present invention is to provide an improved method and apparatus for checksum verification with receive packet processing for data communications. Other important objects of the present invention are to provide such method and apparatus for checksum verification with receive packet processing for use with a variety of modes for communications and to provide such method and apparatus that overcome disadvantages of prior art arrangements.
In brief, a method and apparatus are provided for checksum verification with receive packet processing for communications over a data communications network. First a data communications connection is identified. Responsive to an identified data communications connection, a start of data packet is identified. Then a header checksum is calculated and a protocol checksum including a protocol pseudo header and data is calculated. In accordance with features of the invention, an embedded processor structure is used for tracking packet state and running CRC calculations across received packets, and performing full checksum verification.
REFERENCES:
patent: 5260936 (1993-11-01), Bardet et al.
patent: 5430842 (1995-07-01), Thompson
patent: 5500864 (1996-03-01), Gonie et al.
patent: 5675591 (1997-10-01), Salzwedel et al.
patent: 5701316 (1997-12-01), Alferness et al.
patent: 5815516 (1998-09-01), Aaker et al.
patent: 5987022 (1999-11-01), Geiger et al.
patent: 6084859 (2000-07-01), Ratcliff
patent: 6105160 (2000-08-01), Fukumoto et al.
RFC 768, “User Datagram Protocol”, by J. Postel, Aug. 28, 1980, pps. 1-3.
RFC 791, “Internet Protocol”, by USC/Information Sciences Institute, Sep. 1981, pps. 1-45.
RFC 792, “Internet Control Message Protocol”, by J. Postel, Sep. 1981, pps. 1-21.
RFC 793, “Transmission Control Protocol”, by USC/Information Sciences Institute, Sep. 1981, pps. 1-85.
RFC 1883, “Internet Protocol, Version 6 (IPv6) Specification”, by S. Deering and R. Hinden, Dec. 1995, pps. 1-37.
De'cady Albert
International Business Machines - Corporation
Pennington Joan
Torres Joseph
LandOfFree
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