Multi-Level Rate-Based Flow Control for ABR Traffic

The rate control mechanism for available-bit-rate (ABR) traffic as defined by the ATM Forum does not distinguish between different types of ABR connections. However, since ABR traffic may result from a heterogeneous set of applications, there is an apparent need for a flow control scheme that can distinguish between and give differential treatment to different classes of ABR connections. In this study, a multi-level flow control scheme for ABR traffic is proposed that performs flow control of ABR traffic simultaneously at three levels: At the first level, the scheme determines the total available ABR bandwidth at a link. At the second level, the ABR bandwidth is distributed to different ABR traffic classes. At the third level, the scheme determines the bandwidth available to connections in same traffic class. It is shown that the multi-level flow control method completely decouples the explicit rate calculation of distinct traffic classes while achieving a high network utilization. Extensive silmulations demonstrate that the multi-level flow control quickly adapts to load changes in the network.