A communication network is operated by detecting an anomaly in the communication traffic at a plurality of nodes in a communication network. A first blocking measure A is independently applied at respective ones of the plurality of nodes to the anomalous traffic that stops the anomalous traffic. A second blocking measure B is independently determined at the respective ones of the plurality of nodes such that application of a logical combination of the first blocking measure A and the second blocking measure B to the anomalous traffic stops the anomalous traffic.