1. An anomaly detection method for link-state routing protocols, a link-state routing protocol providing for link-state update (LSU) messages to be exchanged between nodes in a packet-based network, wherein each link-state update message includes link-state advertisement (LSA) message(s) each having a respective header with a number of fields, the method comprising: monitoring link-state advertisement messages exchanged in the network; extracting and forming respective detection feature vectors with the values in at least some of the fields of the headers of at least some of the monitored link-state advertisement messages; and detecting an anomaly related to routing based on the detection feature vectors.