A method for configuring a first network node using a first autonomous system (AS) number in at least one session established with another node according to a dynamic routing protocol is described. The method is implemented by the first node and includes receiving a configuration message comprising at least one piece of information that is representative of a second AS number intended to be used by the first node as a replacement for the first number, configuring the first node with the second AS number, identifying at least one second node having at least one session according to the dynamic routing protocol, active with the first node, in which the first node is associated with the first AS number, and sending a control message to the at least one second node requesting the replacement of the first AS number with the second AS number by the at least one second node, such that, after the replacement, the first node is associated with the second AS number in the at least one active session.