Patent ID: 7000121

Claim:
A method of operating a computer system comprising a first node connectable to a second node by way of any of a plurality of gateway nodes, wherein: (a) the first node initially establishes a first virtual private network (VPN) connection with the second node by way of one of the gateway nodes, using a session key which is held in a cache store in the first node to encrypt communications between the first node and said one of the gateway nodes; (b) the first node monitors said one of the gateway nodes for failure; (c) in the event of failure of said one of the gateway nodes, the first node deletes the session key from the cache store and searches the cache store to determine whether another session key has been cached allowing a new VPN connection to be established with the second node by way of another of the gateway nodes; (d) in the event that another session key has not been cached, the first node initiates a key establishment protocol exchange with a selected one of the gateway nodes, other than the failed node, to establish a new session key allowing a new VPN connection to be established with the second node by way of said selected one of the gateway nodes, the new session key being saved in the cache store.