Services usually run across a combination of enterprise and service provider networks. A transport infrastructure that spans many networks and management domains must nevertheless be tracked and managed.
To manage data flows, a network administrator needs flow-through QoS, which is true end-to-end management that spans multiple management systems. Service quality must be accurately controlled across all boundaries: customer to business partner, customer to provider, and provider to provider. Flow-through QoS would ensure that the paths across a set of ISPs would always deliver the specified service quality. The flow would change ISPs in its path as needed to maintain the overall quality.