COST 257 MID-TERM SEMINAR INTERIM REPORT ON AVAILABLE BIT RATE The Available Bit Rate Service Category in ATM Networks

Preface This report gives an overview of results on the Available Bit Rate Service Category (ABR) for ATM networks obtained in the COST 257 action on " Impacts of New Services on the Architecture and Performance of Broadband Networks ". First we give an overview of the ATM Forum specifications of the ABR service category. Examples of ABR switch mechanisms are given, including two new proposals, a weighted version of the ERICA algorithm (W-ERICA) and the Explicit Rate-Proportional Regulator Algorithm. Next three analytical models to evaluate the performance of different ABR flow control schemes are presented. Two are based on a fluid flow model and the other is using a discrete-time Markov chain approach. The suitability of ABR and UBR for the transport of TCP traffic is investigated through simulation. We also discuss conformance definition and policing of an ABR connection, based on a dynamic version of the GCRA scheme. Different approaches for usage-based pricing of ABR are analyzed. Finally, ABR as elastic traffic in a multiservice network is discussed. This report is based on technical documents of COST 257 members and experts. Contributions of the following authors have been used: