1. A method of balancing loads in a communication network, said method comprising: tracking active network flows by adding flow identifiers for the active network flows to a Bloom filter; creating a snapshot of the Bloom filter responsive to a scaling event, the snapshot being indicative of a set of network flows active prior to the scaling event; comparing flow identifiers for incoming packets with the Bloom filter snapshot to differentiate between pre-existing network flows active prior to the scaling event and new network flows active only after the scaling event; distributing packets for pre-existing network flows among a first set of service instances according to a first mapping function; and distributing packets for new network flows among a second set of service instances according to a second mapping function.