The distributed algorithms that constitute the basis of several popular approaches to admission control for real-time (i.e., guaranteed-performance) connections in packet-switching networks are described. Separate descriptions are given for the cases of unicast connections and multicast connections, which require different algorithms for some of the parts of the procedure. Real-time connections are expected to be needed for good-quality transmission of continuous-media (audio and video) streams, and will be subject to controlled admission so as to avoid congestion.