A method is disclosed for interconnecting an MS-SP ring network and an SNCP ring network in a Dual Node and Bridge and Switch architecture through a primary interconnection node and a secondary interconnection node connected by an optical fiber span, said primary interconnection node comprising means for carrying out a Drop and Continue operation and a service selector for each circuit. The architecture provides for closing said SNCP ring network through the service selector of the primary node of the MS-SP ring network. In this way the management of the selectors is simplified, less I/O interfaces as well as less optical fiber are used and the available band is better exploited.