Architecture for supporting service level agreements in an IP network

A method of controlling packet traffic in an IP network of originating, receiving and intermediate nodes to meet performance objectives established by service level agreements. Traffic statistics and performance data such as delay and loss rates relating to traffic flows are collected at intermediate nodes. A control server processes the collected data to determines data flow rates for different priorities of traffic. A static directory node is used to look up inter-node connections and determine initial traffic classes corresponding to those connections. The rates are combined with the initial traffic classes to define codes for encoding the headers of packets to determine their network priority.