Class-based service differentiation is provided in DiffServ networks. However, this differentiation will be disordered under dynamic traffic loads due to the fixed weighted scheduling. An adaptive weighted scheduling scheme is proposed in this paper to achieve fair bandwidth allocation among different service classes. In this scheme, the number of active flows and the subscribed bandwidth are estimated based on the measurement of local queue metrics, then the scheduling weights of each service class are adjusted for the per-flow fairness of excess bandwidth allocation. This adaptive scheme can be combined with any weighted scheduling algorithm. Simulation results show that, comparing with fixed weighted scheduling, it effectively improve the fairness of excess bandwidth allocation.
Ensuring minimum quality-of-service levels to traffic flows and groups of flows is an important challenge for future packet networks. Admission control is an important measure for QoS provision. However, the problem of multicast admission control was much less investigated. In this paper, a reservation-based edge multicast admission control scheme is investigated, which targets high QoS level and scalability. Using a new concept, virtual link, a virtual-link-oriented quota-based resource management mechanism is proposed. Besides, a hierarchical distributed bandwidth broker architecture is also employed. In this scheme, a central bandwidth broker manages the physical link bandwidth, and allocates/reclaims the bandwidth to virtual links; edge bandwidth brokers manage the bandwidth of virtual links, make admission decisions and reserve bandwidth for each flow. Simulation results show that the scheme achieves high scalability. Furthermore, the impact of quota size on the performance and complexity is investigated. A bandwidth adaptive quota size scheme is proposed to further improve the performance and reduce the complexity.
Multicast is an efficient approach to save network bandwidth for multimedia streaming services. To provide Quality of Services (QoS) for the multimedia services while maintain the advantage of multicast in bandwidth efficiency, admission control for multicast sessions are expected. Probe-based multicast admission control (PBMAC) schemes are of a sort of scalable and simple admission control for multicast. Probing scheme is the essence of PBMAC. In this paper, after a detailed survey on three existing probing schemes, we evaluate these schemes using simulation and analysis approaches in two aspects: admission correctness and group scalability. Admission correctness of the schemes is compared by simulation investigation. Analytical models for group scalability are derived, and validated by simulation results. The evaluation results illustrate the advantages and weaknesses of each scheme, which are helpful for people to choose proper probing scheme for network.