Abstract: A method for detection of an anomaly in paths for routing data to an address prefix in a network composed of autonomous systems, where the paths are announced to a local autonomous system by neighboring autonomous systems. The method includes: a) receiving information representative of at least one part of the paths during a time interval; b) generating a matrix comprising elements representative of path segments respectively connecting pairs of autonomous systems located on the paths; c) repeating a) and b) to obtain a sequence of matrices according to b); d) analyzing a similarity between the matrices; and e) in a case where at least one of the matrices differs from other matrices, detecting a routing anomaly.