— We consider cell-based switch architectures, whose internal switching matrix does not provide enough speed to avoid input buffering. These architectures require a scheduling algorithm to select at each slot a subset of input buffered cells which can be transferred towards output ports. The stability properties of several classes of scheduling algorithms are studied in the paper, using analytical techniques mainly based upon Lyapunov functions. Original stability conditions are derived for some scheduling algorithms that are being used today in high-performance switch architectures.