Evaluation of required queue size to support ABR service

The objective of the ABR service is to provide data transfer via ATM network with the cell loss ratio as small as possible. In order to achieve this goal many traffic control algorithms are discussed, e.g. EFCI, ERICA, CAPC. This paper presents approximation methods to evaluate the upper bound for the queue size in the switch. For this purpose, we assume the worst case of VBR+CBR traffic in the form of the step unit function. The method was applied to evaluate the required buffer size in case of EFCI, ERICA and ER-PR. The ER-PR method (Explicit Rate with Proportional Regulator) is the authors proposition and will be briefly described in the text. The numerical results are also included and compared with simulation.