ATM block transfer capability vs. available bit rate service
Fabrice M. Guillemin · European Transactions on Telecommunications · 1997
Abstract ATM Block Transfer is an ATM transfer capability, which has been standardized in the May 1996 version of ITU‐T Recommendation 1.371. Two transmission modes for ABT exist, namely the delayed and immediate transmission modes, giving rise to ABT/DT and ABT/IT, respectively, which can run in the elastic or rigid modes. The Available Bit Rate (ABR) service is an ATM layer service, which has been worked by the ATM Forum and specified in the UNI Spec. 4.0 voted in June 1996. The aim of this paper is to give the high level description of ABT and ABR and to draw attention to their common features and their differences. It turns out that the service offered by ABR is much more sophisticated but also more fragile than that offered by elastic ABT/DT. Since the implementation of ABR requires a deeper modification of the existing ATM switches and cross‐connects than elastic ABT/DT, an interworking scenario between these two capabilities, compatible with the cross‐connects used in the current ATM networks, is proposed.