Although multicasting has been recognized as a valuable service for packet networks in general, since existing architectures do not support it directly, many ways of providing such a service are under examination, from both theoretical and experimental standpoints. In this section we first look at the main issues in multicasting which are relevant for any application, such as group dynamics, routing support and feedback control, and discuss some of the proposed approaches. We conclude with a short look at existing hardware support for multicasting. Since space does not permit a more detailed exposition of all issues relevant to multicasting, the reader can refer also to specialized surveys[29], research compilations[30], or start from detailed bibliographies[31]; here we try to limit our scope to issues that are most relevant for continuous media communications.