Low-level network services are provided by network-service-provider plugins. These plugins are controlled by an extensible service provider that is layered above the TCP or other protocol layer but below the Winsock-2 library and API. Policy servers determine priority of network traffic through control points on a network. Examining packets passing through these control points provides limited data such as the source and destination IP address and TCP ports. Many applications on a client machine may use the same IP address and TCP ports, so packet examination is ineffective for prioritizing data from different applications on one client machine. Often some applications such as videoconferencing or data-entry for corporate sales are more important than other applications such as web browsing. A application-classifier plugin to the extensible service provider intercepts network traffic at above the client's TCP/IP stack and associates applications and users with network packets. These associations and statistics such as maximum, average, and instantaneous data rates and start and stop time are consolidated into tables. The policy server can query these tables to find which application is generating network traffic and prioritize the traffic based on the high-level application. Bandwidth-hogging applications such as browsers can be identified from the statistics and given lower priority.