A generalized hierarchical fair service curve algorithm for high network utilization and link-sharing

The number of real-time applications, such as video-on-demand and video conferencing, is rapidly increasing. Real-time data now occupies a significant portion of network traffic. These applications require real-time service; as such, they need to bound end-to-end delays. Generally, real-time service is provided by reserving bandwidth in advance. Thus, to admit a large number of real-time applications, bandwidth needs to be reserved efficiently. In addition, to share limited bandwidth effectively among multiple agencies, a link-sharing service is required. A link-sharing service provides a guaranteed share of link bandwidth to each agency. To provide both real-time and link-sharing services simultaneously, several hierarchical link-sharing schemes have been proposed. However, existing hierarchical schemes still have problems in achieving a high level of network utilization, especially when variable-bit-rate (VBR) video sessions participate in a hierarchy. The problem is serious since a large portion of real-time applications transmit MPEG-coded VBR data. We propose a new scheduling algorithm that can achieve a high level of network utilization even with VBR video sessions. The proposed scheduling algorithm is a hierarchical link-sharing scheme; it is an extension of the H-FSC generalized with a new bandwidth reservation scheme. The new scheme provides tight bandwidth reservations for VBR video sessions. Even with the advantage in network utilization, the generalized H-FSC does not require high overhead for scheduling; the scheduling complexity remains the same as that of the H-FSC.