Patent ID: 6237111
Filing Date: 2001-05-22
Classification: H04L

Abstract:
A method of resynchronizing message traffic between a first data processing system and a second data processing system connected by a data communications network after a failure of said first data processing system, where said message traffic travels over a logical connection linking said first and second data processing systems, where each message in said message traffic includes a SYNC number and a byte sequence number, and wherein a recipient of each said message tests to determine whether said message has a next expected byte sequence number and discards any byte sequence number older than the next expected byte sequence number, said method comprising:retrieving a stored SYNC number and byte sequence number (BSN) from an external memory;incrementing said SYNC number by a predetermined amount to obtain a new SYNC number, said predetermined amount being sufficient to ensure said new SYNC number comprises a current SYNC number;sending a status request message from said first data processing system to said second data processing system, said status request including said new SYNC number, and said BSN read from said external memory;receiving at the first data processing system a response message to said status request message, wherein said response message contains a BSN of a next piece of data that said second data processing system is expecting; andupdating logical connection control information at said first data processing system with said BSN value for said next piece of data expected by said second data processing system.