QoS Controls. The fourth research area encompasses the mapping of the Service Level Specification (the technical parameters such as a delay bound, a guaranteed throughput, etc.) described in an SLA to QoS controls, mechanisms or components (such as schedulers, queues, policers, etc.) needed in providing the specification defined in such SLA. An example of such QoS mapping is found in [62]. The paper proposes a hierarchical multilayer QoS routing system with dynamic SLA management for large-scale IP networks, by augmenting the existing OSPF and CR-LDP protocols to support hierarchical QoS routing, QoS aggregation, and QoS reservation in a MPLS-DiffServ based hierarchical routing network. A policy server is also proposed that is capable of dynamically handling SLAs between the networks and providing load balancing management within the network. The proposed hierarchical QoS routing reduces the MPLS LSP blocking probability and significantly reduces the control overhead. Another example could be found in [65,66]. The papers present a framework for dynamic management of SLAs in MPLS networks. In the proposed framework, the ingress router of the MPLS backbone performs admission control as well as path selection. For path computation different advanced routing algorithms are used. In the paper, the MPLS SLA is mapped to finding an MPLS LSP that can support the SLA by finding an appropriate path for the LSP. Three routing algorithms were inspected, Lowest-Cost (LC) routing algorithm, Widest Bandwidth (WB) routing algorithm and Minimum Interference Routing Algorithm (MIRA), where performance was judged based on average end-to-end delay, average throughput, average packet dropping probability, average link load and number of utilized links. The paper found through simulations that although LC and WB perform well when the number of requests is small, the MIRA algorithm proves to show more stable values and better performance of these parameters at high network loads. MIRA results in smaller average end-to-end delay and smaller average number of dropped packets whereas still utilizing a smaller number of links in the network. Finally, [38] discusses a QoS mapping at the application level to label packets relatively to each other. The paper proposes a framework for QoS mapping between practically categorized packet video and relative DiffServ network employing unified priority index and adaptive packet forwarding mechanism. In this framework, for example, a video application at the...
