network supports cfm messages similarly to fig2 a combined network comprises a central ethernet based network 30 and an access ethernet based network 32 interconnected via an intermediate bridge 34 let the ethernet sender of a cfm message does not know the mac addresses of some specific destinations but according to the invention is able to address them in an alternative manner by inserting data in at least one proprietary tlv field of the cfm message the source 36 sends a multicast cfm message 33 with a specific alternative description of the destination in one or more proprietary tlv s for example a proprietary tlv comprises indication of a specific output port of the ib connected to the required destination optionally the alternative destination information can be a user id a service id a user name or any other attribute that can be mapped to a specific physical or virtual port in the ib the ib analyzes the cfm message 33 including its proprietary tlv contents and forwards the contents of the message as a single cfm message 35 via the specific output ib port if indicated in the tlv only to the specified destination 38 the destination 38 responds with a standard cfm unicast message 37 that then passes to the cfm message source 36 through the ib 34 without any specific processing it should be noted that ib may send either a unicast or a multicast single message to the peer 31 since the peer 31 has its associated end devices to which the message may be forwarded if required fig4 depicts the proposed messaging process for the case when the access.