Bandwidth Regulation of Real Time Tra c Classes in Internetworks

New network applications which involve transmission of continuous media data such as au dio and video conferencing introduce immense challenges for the design of packet switching internetworks Existing ow and congestion control mechanisms have been shown to be ine ec 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 tra c classes The mechanism achieves regulation of link bandwidth at two levels At one level bandwidth is dynamically regulated between di erent tra c classes We introduce the concept of inter class regulation which enforces that the bandwidth left unused by some tra c classes is assigned equally to tra c 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 main tain state information on individual tra c ows and adapts quickly to changes in the tra c load The e ectiveness of the protocol is demonstrated by simulation experiments