a flow in a network is identified and handled by using a virtual host address . a packet is received at a switch with a first virtual host address as its destination address . if the packet is the first packet of a flow received by the switch , then a second virtual host address is determined by the switch . the first virtual host address is stored in a packet forwarding table correlated with the second virtual host address . a subsequently received packet of the same flow has the same first virtual host address as its destination address , and is forwarded to the second virtual host address in accordance with the packet forwarding table .