Communication protocol designers are facing new challenges due to the development of high-speed networks and to the increasing demands of network applications. Gigabit networks pose a challenge to flow control techniques developed for traditional acknowledgment-based, and typically packet-switched, lower-speed networks. Network applications such as distributed databases, groupware and distributed multimedia, all of which require multicasting, have rendered insufficient existing point-to-point flow control methodologies. We examine the problem of flow control for multicasting in gigabit networks. Instead of feedback or rate adaptation techniques, we employ more active flow control mechanisms that use traffic information in protocol control frames. These techniques are very effective for the totally ordered multicast protocol we have developed for the QuickRing gigabit local-area network.