Bandwidth Regulation of Real-Time Traffic Classes in Internetworks

New network applications which involve transmission of continuous media data, such as audio and video conferencing, introduce immense challenges for the design of packet-switching intemetworks. Existing flow and congestion control mechanisms have been shown to be ineffective for supporting the real-time requirements of continuous media data transfers. We propose a novel bandwidth regulation mechanism which improves the ability of the network to cope with multiple real-time and non real-time traffic classes. The mechanism achieves regulation of link bandwidth at two levels. At one level, bandwidth is dynamically regulated between different traffic classes. We introduce the concept of inter-class regulation which enforces that the bandwidth left unused by some traffic classes is assigned equally to traffic classes with high bandwidth demands. At the second level, bandwidth regulation is enforced on packet flows from the same class. Each end-to-end packet flow from the same class has identical bandwidth constraints if their routes share the link with the smallest capacity for this class. This concept is referred to as intru-class regulation. We show that a bandwidth assignment which provides both intra-class and inter-class regulation without unnecessary waste of bandwidth is uniquely determined. We present a simple distributed protocol that achieves intra-class and inter-class regulation in a general intemetwork. The protocol does not require network gateways to maintain state information on individual traffic flows, and adapts quickly to changes in the traffic load. The effectiveness of the protocol is demonstrated by simulation experiments.