Patent ID: 8089865

Claim:
A network system, comprising: a first network and a plurality of second networks for transferring multicast data, a first data transfer device connected to the first network, a plurality of second data transfer devices connected to the first network and the plurality of second networks, and a plurality of third data transfer devices each connected to a corresponding second network of the plurality of second networks, wherein the multicast data is transferred from the first data transfer device via the second data transfer devices to each of the third data transfer devices in response to a request for the multicast data, a currently used channel and a backup channel are set for a communication path between the first data transfer device and the second data transfer devices in the first network and for each communication path between the second data transfer devices and the third data transfer devices in the plurality of second networks, and the first data transfer device transmits to each third data transfer device via the second data transfer devices maintenance management data for: a communication path connecting the currently used channel of the first network to the currently used channel of the corresponding second network for the third data transfer device; a communication path connecting the currently used channel of the first network to the backup channel of the corresponding second network for the third data transfer device; a communication path connecting the backup channel of the first network to the currently used channel of the corresponding second network for the third data transfer device; and a communication path connecting the backup channel of the first network and the backup channel of the corresponding second network for the third data transfer device.