A flow based routing method and apparatus selects a path from a plurality of different paths for assignment to a flow. The path is selected based on a traffic performance measurements which identify relative congestion and performance of the different paths, so that traffic flows can be diverted away from network congestion points, thereby allowing network resources to be load balanced at a flow granularity. The present invention may be configured on physical or virtual links on an NE to enhance the forwarding of packets using the primary link and one or more alternate links to any given destination.