This paper addresses the issue of providing QoS services for optical burst switching (OBS) systems. We propose a linear predictive filter (LPF)-based forward resource reservation method to reduce the burst delay at edge routers. An aggressive reservation method is proposed to increase the successful forward reservation probability and to improve the delay reduction performance. We also discuss a QoS strategy that achieves burst delay differentiation for different classes of traffic by extending the FRR scheme. We analyze the latency reduction improvement gained by our FRR scheme, and evaluate the bandwidth cost of the FRR-based QoS strategy. Our scheme yields significant delay reduction for time-critical traffic, while maintaining the bandwidth overhead within limits.