This invention pertains to a method for protecting a telecommunication network comprising at least one secure router (100) equipped with a topology map (103) of that network in order to determine the intermediate routers which constitute an optimal pathway for routing information, said secure router and said intermediate routers generating this topological map by sharing the lists of links (LSA1, LSA2, LSAn) using a communications protocol, characterized in that the secure router (100) performs the following steps: The step (109) of calculating and then saving, when a list of links (LSA1, LSA2, . . . LSAn) is received, at least one receiving fingerprint (hash(LSA1), hash(LSA2), . . . hash(LSAn)) of the lists received (LSA1, LSA2, . . . LSAn), The step (120) of calculating and then saving, when a list of links (LSA′1, LSA′2, . . . LSA′n) is transmitted, at least one sending fingerprint (hash(LSA′1), hash(LSA′2), . . . hash(LSA′n)) of the lists to be transmitted, and The step of comparing the receiving fingerprint (hash(LSA1), hash(LSA2), . . . hash(LSAn)) to the sending fingerprint (hash(LSA′1), hash(LSA′2), . . . hash(LSA′n) such that the sending of a list of links (LSA1, LSA2, LSAn) is inhibited if the receiving fingerprint is different from the sending fingerprint.