  The Available Bit Rate (ABR) service has been developed to support 21st
century data applications over Asynchronous Transfer Mode (ATM). The ABR
service uses a closed-loop rate-based traffic management framework where the
network divides left-over bandwidth among contending sources. The ATM Forum
traffic management group also incorporated open-loop control capabilities to
make the ABR service robust to temporary network failures and source
inactivity. An important problem addressed was whether rate allocations of
sources should be taken away if sources do not use them. The proposed
solutions, popularly known as the Use-It-or-Lose-It (UILI) policies, have had
significant impact on the ABR service capabilities. In this paper we discuss
the design, development, and the final shape of these policies and their impact
on the ABR service. We compare the various alternatives through a performance
evaluation.
