A method is provided that uses a consistent hashing technique to dispatch incoming packets in a stable system prior to adding of a node. The method uses a hash table and assigns hash buckets in the table to each network node. A set of fields in each incoming packet is hashed and is used to identify the corresponding hash bucket. The packets are then dispatched to the network nodes based on the nodes' hash buckets. During an observation period, the method identifies the ongoing sessions by creating a bit vector table that is used to identify the old and new sessions during a re-dispatching period. The method uses the consistent hashing method and the probabilistic method dispatch the incoming packets such that each packet that belongs to an old session is dispatched to the same old node that has been processing the other packets of the session.