A method for providing authoritative application-based routing and an improved application firewall, as well as a method for application classification, is described. The first embodiment, which provides a method for authoritative application-based routing, comprises tagging packets with an application identifier, and pushing the tagged packets to the network to enable the application identifier to be used in routing and priority decisions. In the second embodiment, a method for improving application firewall comprises using the application identifier to minimize the amount of processing required by the firewall when analyzing packet information.