In this paper, we integrate the pipeline buffering mechanism with the DiffServ-capable OBS to schedule data burst (DB) at core nodes. And we improve a DiffServ-capable virtual scheduling technique (DiffServ-VST) to adapt our scheme. For performance evaluation, we propose a new model to revise the classic <i>Erlang-B</i> formula for calculating burst loss probability in OBS environment: the LAUC-VF-ed M/D/K/K. The simulation results shows that lower packet loss probability and higher link utilization is obtained when traffic load is less than 0.8 by using our scheme. However, the extra end to end delay of AF and BE is brought by pipeline buffer.