This network node comprises: a reception unit that receives, from a first network node, a message including information about a first
satellite that newly accommodates a terminal; a
control unit that, on the basis of the information about the first
satellite, information about a second
satellite that accommodates another network-side terminal, and information indicating whether the own network is an originating network or a terminating network, determines that the first satellite and the second satellite are different and that it is impossible to continue setting an inter-satellite
optimum route, and further configures a second network node on the ground; and a transmission unit that transmits, to the first network node, a message including a termination point for a terminal in the second network node on the ground and information requesting an update of a packet filter of the terminal, and transmits, to a third network node, a message including a termination point for the other network in the second network node on the ground and information requesting transmission of a message for session update to the other network.