A control device (D) for a node (LCR3) in an Ethernet communications network having a GMPLS control plan and through which node a connection for setting up is to pass, includes control means (MC) arranged, in the event of said node (LCR3) receiving a connection setup message containing at least one first value representative of the sum since the beginning of the connection for setting up of the local values of an additive parameter as introduced in each of the preceding nodes (LCR3) in the connection, to determine a second value that is a function of the first value and of the local value as introduced by the node (LCR3), and then to compare the second value with a selected threshold so as to determine whether the connection can accept a maximum value for the additive parameter at the node, and to replace the first value in the received message with the second value as determined, at least when the connection can accept the maximum value.