Patent ID: 8169895
Filing Date: 2012-05-01
Classification: H04J

Abstract:
1. A network system comprising: first and second ring networks that make a pair each of which has a mutually opposite transmission direction and is constructed in the form of a ring; a ring interface that connects nodes constituting the ring network; a user interface that connects a user terminal or other node not constituting the ring network; and a node equipped with switching means for forwarding a frame inputted from the each interface to a desired destination according to its header information, wherein, for each multicast flow that forwards multicast data, a multipoint logical path serving as a working path is formed on the first ring network, and the multipoint logical path serving as a backup path is formed on the second ring network, wherein each of the multipoint logical paths serving as the working path and the backup path contains: wherein, if defects occur both in the working path and in the backup path, the multicast data is copied by-the multicast transmitting end node, and the multicast data is forwarded both to the working path and to the backup path, and wherein, when the multicast transmitting end node detects a defect, if the defect occurs in the multipoint logical path serving as the working path, the multipoint logical path is switched from the multipoint logical path serving as the working path to the multipoint logical path serving as the backup path to forward a multicast frame, and if the defect occurs in the multipoint logical path serving as the backup path, the multicast frame continues to be forwarded via the working path.