A system enabling inter-ring network connection when a plurality of ring networks are connected via a redundancy network, that is, a packet network system configured by a plurality of ring networks and redundancy networks linking the plurality of ring networks. This system virtually defines a plurality of virtual resilient packet ring networks among all of these packet networks and transfers packets on a designated virtual resilient packet ring network. Here, each virtual resilient packet ring network is identified by a virtual resilient packet ring network identifier allocated to each.