The available bit rate (ABR) service is proposed to transport data traffic in asynchronous transfer mode (ATM) networks. ABR is unique because the network switches can indicate to the sources the rates at which they should be transmitting, thus avoiding congestion and efficiently utilizing network resources. A number of algorithms have been developed for extending ABR flow control algorithms for point-to-multipoint connections. In this case, feedback consolidation is required at the branch points to avoid overwhelming the sender with feedback. This paper discusses various design options and implementation alternatives for consolidation algorithms, and proposes a number of novel algorithms. The performance of the proposed algorithms and the original algorithms is compared under a variety of conditions. Results indicate that the algorithms we propose eliminate the consolidation noise (caused if the feedback is returned before all branches respond), while exhibiting a fast transient response.
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