Session load balancing and use of VIP as source address for inter-cluster traffic through the use of a session identifier

Abstract

A method and system for enhancing a load balancing network's ability to load balance sessions is presented. A session identifier is placed within the TCP packet to enable a new mechanism of load distribution and connection grouping within a load balancing system. Specifically, TCP is invoked by a user application to obtain a unique session identifier value. TCP places the session identifier as a sender session identifier within the OPTIONS field of the TCP header. As an alternative, a session identifier can be placed within a session header that is attached to the TCP packet. On receiving such a packet, the destination load balancing system hashes over at least the session identifier value, and the node corresponding to the results of the hash algorithm acquires the packet. This method of hashing ensures that the same node acquires all subsequently received TCP packets possessing the same session identifier regardless of the source IP address or source port information. The node then places an identical session identifier value in the form of a response session identifier in its TCP response packet. When the TCP packet with response session identifier is received at a load balancing system, the node whose session identifier matches the response session identifier acquires it. This ensures that a response to a node assigned to a virtual IP address is received by the proper node, thus preventing other member nodes assigned to the same VIP address from picking up the packet instead.

Dependencies are inferred from the claim text.