In a network arrangement implementing a virtual interface scheme to execute various types of application processes using plural control units, the routing tables of the control units may be synchronized without having to execute a complicated process sequence. In a network apparatus including a forwarding unit corresponding to a base point for conducting packet transmission/reception with an external network, and plural control units for operating plural applications that are arranged to access virtual interfaces of the control units that correspond to actual interfaces of the forwarding unit so that the network apparatus appears from the outside to be functioning as a single unit. A routing process of generating a routing table is executed at a master control unit corresponding to one of the control units, and if the routing table of the master control unit is updated, a routing table of the forwarding unit is updated by a routing synchronization process that operates independently from the routing process. One or more routing tables of one or more slave control units corresponding to the control units other than the master control unit are updated through the forwarding unit.