In general, techniques are described for measuring packet data unit (PDU) loss in a L2 virtual private network (L2VPN) service, such as a VPLS instance. In one example of the techniques, provider edge (PE) routers that participate in the L2VPN measure known unicast and multicast PDU traffic at the service endpoints for the instance to determine unicast PDU loss within the service provider network. As the routers learn the outbound service (i.e., core-facing) interfaces and outbound local (i.e., customer-facing) interfaces for L2 addresses of customer devices that issue packets to the VPLS instance, the routers establish respective unicast transmit and receipt counters for the service endpoints that serve the customer devices. In another example, PE routers that participate in the L2VPN measure multicast PDU traffic at the service endpoints for the instance and account for internal replication by intermediate service nodes to determine multicast PDU loss within the service.