Abstract: The invention relates to a monitoring system and method for performing a connectivity check and a trace routing test in Ethernet based networks built around VLAN switching. For the connectivity check, a beacon frame is inserted at an originating point by an initiating test unit for transmission to a destination point provided with a loop for returning a response frame to the initiating test unit whenever the beacon frame is received, thereby confirming connectivity between the originating and destination points. For the trace routing test, a marker frame is inserted at the originating point by the initiating test unit and monitored as it passes through network nodes along its way towards the destination point. At any node where the beacon frame is detected, a tracing frame containing a copy of the marker frame is returned to the initiating test unit to build a sequential list of every node where the marker frame is detected.