IP multicasting is an extension of the Inter- net Protocol that efficiently delivers a single data- gram to multiple hosts instead of a single host. Its benefits for applications such as live audio and video conferencing among Internet sites around the world have been clearly demonstrated over the past three years in an experimental deployment called the "Multicast Backbone". or MBone. The time has now come for the next step-bringing IP multicast service up to production quality and ex- tending deployment to the entire Internet so that the MBone ceases to exist as a separate entity. This paper discusses some of the enhancements that are underway to make the MBone and IP multicast real: scalable routing. congestion man- agement, and diagnostic tools.