In a virtual ring configuration method and a virtual ring system, a plurality of nodes are set on a plurality of rings and the rings are cross-connected. Each node has a transmitting unit and a receiving unit for sending and receiving service information between the nodes by the SONET path....http://www.google.com.au/patents/US5754528?utm_source=gb-gplus-sharePatent US5754528 - Virtual ring configuration method and virtual ring system
