A network element and method for marking traffic in a packet-switched data network which comprises a distributed hierarchical naming system and the network element. The network element comprises a marking rule store for storing marking rules, in which each marking rule is indicative of a quality of service level allocated to traffic on a connection impinging on the network element. The network element derives from the distributed hierarchical naming system quality of service level data for a connection, stores in the marking rule store a marking rule for the connection based on the retrieved quality of service level data and marks traffic on the connection in accordance with the marking rule.