Hung N Luong

US Patent:

6728929, Apr 27, 2004

Filed:

Feb 16, 2001

Appl. No.:

09/788014

Inventors:

Hung Luong - Simi Valley CA

Assignee:

Spirent Communications of Calabasas, Inc. - Calabasas CA

International Classification:

G06F 1110

US Classification:

714807, 370465

Abstract:

A method and apparatus for calculating and inserting a TCP checksum neutralizing value into a network data packet in a manner which minimizes storage requirements and processing time used to process the data packet. In one embodiment, a checksum is calculated as a data packet is being received, up to the checksum field. The calculated checksum is then inserted into the checksum field. Then the remaining fields used to calculate the TCP checksum are summed. The inverse of this sum is then stored in a normally unused portion of the payload portion of the data packet near the end of the packet. When the packet is received and the TCP checksum is calculated, since the inverse of the fields which were not used to calculated the checksum in the TCP header is in the payload portion, their contribution to the checksum is negated so that a comparison of the calculated checksum and the stored TCP checksum will match, assuming the packet was properly received.