Methodologies for bandwidth allocation, transmission scheduling, and congestion avoidance in broadband ATM networks

Abstract

The call types supported in high-speed packet networks vary widely in their bandwidth requirements and tolerance to message delay and loss. In this paper, we classify various traffic sources which are likely to be integrated in broadband ATM networks, and suggest schemes for bandwidth allocation and transmission scheduling to meet the quality and performance objectives. We propose ATM cell-multiplexing using a Dynamic Time-Slice (DTS) scheme which guarantees a required bandwidth for each traffic class and/or virtual circuit (VC), and is dynamic in that it allows the different traffic classes or VCs to share the bandwidth with a soft boundary. Any bandwidth momentarily unused by a class or a VC is made available to the other traffic present in the multiplexer. The scheme guarantees a desired bandwidth to connections which require a fixed wide bandwidth. Thus, it facilitates setting up circuit-like connections in a network using the ATM protocol for transport. The DTS scheme is an efficient way of combining constant bit-rate (CBR) services with variable bit-rate (VBR) stastically multiplexed services. We also described methodologies to schedule delivery of delay-tolerant data traffic within the framework of the DTS scheme. Important issues such as buffer allocations, guarantee of service quality, and ease of implementation are also discussed.