One of the Quality of Service (QoS) routing problems is link-constrained, path constrained routing.

and example of such problem is delay and bandwidth-constrained routing. Here, the proposed solution is presented through our proposal routing algorithms DCUR-AB (Delay Constraint Unicast Routing at Available Bandwidth) and ADCUR-AB (Adaptive Delay Constraint Unicast Routing at Available Bandwidth).

DCUR-AB and ADCUR-AB routing algorithms are proposed to solve the most popular QoS problem (Delay-constrained routing problem). Our proposed algorithms solve this problem in addition to take into account one of the important network resource (bandwidth). From experimental results for DCUR-AB it is found that this algorithm has a limitation searching to find the optimal path with taking into account the bandwidth constrained, therefore, it is proposed here another routing algorithm called ADCUR-AB that has a wide search to find the optimal path, then a practical comparison between the two proposed algorithms results is applied and it is found that the second algorithm is better than the first one.