Abstract: In a communication network, a system and method allow cooperating probes/access units at each end of a network connection, to mark, detect, and calculate the data delivery efficiency of the network connection for data transmitted in multiple service classifications. A trailer, which corresponds to the service classification of the data, is appended to the data at the ingress point of the network. The data, including the trailer, is then transmitted to the communication network. At the egress point of the network, the trailer is examined to determine the service classification of the data transmitted. The received data is then compared to the transmitted data for the service classification indicated by the trailer to determine the data delivery efficiency of the network connection with respect to that service classification.