For real-time communication, we must be able to guarantee timely delivery of messages. In recent years, improvements in technology have made possible switch-based local area networks (LANs) and system area networks (SANs) that use wormhole switching, a pipelined switching technique which permits significantly shorter network latencies and higher throughputs than traditional store-and-forward packet switching. This paper proposes a model for real-time communication in such wormhole networks based on the use of real-time wormhole channels, which are simplex virtual circuits in wormhole networks with certain realtime guarantees. A distinguishing feature of our model is that it can be used in existing wormhole networks without any special hardware support. Preliminary delay analysis and properties are shown for the proposed real-time wormhole channel model. A practical quadratic time complexity algorithm is shown for determining the feasibility of a set of wormhole channels. Finally, as an example of the utility of our model, actual parameter values obtained from experiments on a Myrinet switch-based network are used to determine if real-time guarantees are possible for an example set of real-time traffic streams intermixed with nonreal-time traffic.