A method for balancing load among firewall security devices in a network is disclosed. According to one embodiment, a switch causes firewall security devices (FSDs) of a cluster to enter into a load balancing mode. Responsive to receiving a heartbeat signal from an FSD, information regarding the FSD and the port on which the heartbeat signal was received are added to a table maintained by the switch that maps outputs of a load balancing function to ports of the switch. A received packet is forwarded to an FSD of the cluster by: (i) extracting a configurable number of bit values from a configurable set of bit positions within the packet; (ii) determining the output of the load balancing function; (iii) identifying the port to which the FSD is coupled based on the output and the table; and (iv) transmitting the packet to the FSD via the identified port.