Quality of Service (QoS) based routing provides QoS guarantees to multimedia applications and an efficient utilization of the network resources. Nevertheless, QoS routing is likely to be a costly process that does not scale when the number of nodes increases. Thus, the routing algorithm must be simple and a class-of-service routing is an alternative to provide QoS guarantees instead of per-flow routing. This paper proposes and analyzes the performance of a distance-vector QoS routing algorithm that takes into account three metrics: propagation delay, available bandwidth, and loss probability. Classes of service and metric-combination are used to turn the algorithm scalable and as complex as a two-metric one. The processing requirements of the proposed algorithm and those of an optimal approach are compared and the results show an improvement up to 50%.