Internet protocol packets are statelessly identified as associated with a particular session-instance by identifying a key, or session-instance identifier, within the data (or payload) portion of a user plane packet. This identifier is specific to the session-instance and remains constant throughout the session-instance. Using this stateless identification, transmitted user plane packets are automatically routed at the transmission speed of the transmission link using a method that automatically balances the analysis processing load between network probes. The load is balanced by routing the user plane packet to a network probe that is either already analyzing the session-instance or by routing the user plane packet to a system that has processing capacity to analyze a new session-instance. The network probe then analyzes the user plane packet and the session-instance to measure the quality of the user experience of the session-instance and performance of the network.