Bandwidth Regulation of Real-time Traac 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 internetworks. Existing ow and congestion control mechanisms have been shown to be ineeec-tive 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 traac classes. The mechanism achieves regulation of link bandwidth at two levels. At one level, bandwidth is dynamically regulated between diierent traac classes. We introduce the concept of inter-class regulation which enforces that the bandwidth left unused by some traac classes is assigned equally to traac classes with high bandwidth demands. At the second level, bandwidth regulation is enforced on packet ows from the same class. Each end-to-end packet ow 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 intra-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 internetwork. The protocol does not require network gateways to maintain state information on individual traac ows, and adapts quickly to changes in the traac load. The eeectiveness of the protocol is demonstrated by simulation experiments.