A technique for testing peer nodes in a multicast domain (such as an access network) interconnected with an Ethernet network via an Intermediate Bridge (IB), especially helpful when an individual MAC address of a destination peer node is unknown. The technique comprises a) issuing a Connectivity Fault Management (CFM) message from the Ethernet network, and introducing into the CFM message alternative destination data being different than the individual MAC address of the destination peer node; b) utilizing the alternative destination data, at the IB, for determining topological position or address of the destination peer node, and c) forwarding contents of the CFM message only to the destination peer node.