This paper deals with the analysis of small overflow probabilities in
single-server queues with batch arrivals. First, for the class of GI(X
)/G/1 queues we give analytical expressions for the decay rate (in the
buffer size) of these probabilities. In case of Poisson arrivals, eff
ective bandwidth results are deduced. Furthermore, we propose a change
of measure which enables the execution of importance sampling in an a
symptotically optimal way. Simulation results for a specific applicati
on show large speed-ups.