Patent ID: 8614941

Claim:
A method performed in a network element for maintaining an active-standby relationship between an active control card and a standby control card, the method comprising the steps of: receiving a data packet from a remote network element at an active transport control protocol (“TCP”) module in the active control card; communicating at least a portion of the data packet from the active TCP module to an active application (“APP”) module in the active control card; communicating an APP synchronization (“SYNC”) message from the active APP module to a standby APP module on the standby control card responsive to receiving the at least a portion of the data packet; receiving an APP SYNC acknowledgement (“ACK”) message from the standby APP module at the active APP module, wherein the APP SYNC ACK message indicates successful delivery of the APP SYNC message; communicating an APP ACK message from the active APP module to the active TCP module responsive to receiving the APP SYNC ACK message; communicating a data ACK message from the active TCP module to the remote network element responsive to receiving the APP ACK message, wherein the data ACK message indicates successful delivery of the data packet; retrieving TCP endpoint information from one or more TCP endpoints in the active TCP module; communicating the retrieved TCP endpoint information to a standby TCP module; detecting, at the standby APP module, a switchover event that initiates a hitless switchover; creating one or more TCP endpoints in the standby TCP module with the previously communicated TCP endpoint information; and in response to detecting the switchover event, performing a hitless switchover causing a standby control card to transition from a standby status to an active status wherein the transition is to be transparent the remote network element.