This paper deals with the problem of reliable group communication for distributed applications, in the context of the Reliable Broadcast class of protocols. An atomic multicast protocol for token passing Lans is presented. The actual implementation is on an 8802/4 Token-bus, although it is applicable to 8802/5 Token-rings and the FDDI Fibre-Optic network. The simplicity and efficiency of reliable broadcast protocols may be considerably improved, if the system fault model is restricted or convenient architectures are used. Fail-controlled communication components are used here to build an efficient reliable multicast protocol on top of the exposed MAC interface of a VLSI Lan controller. The architecture is built on standard Lans, in view of taking advantage of the availability of communications hardware and the possibility of coexistence with standard stations, in the same network. The service offered allows transparent multicasting inside logical groups, which are dynamically created and updated. The primitive is highly parallel and provides atomic agreement and consistent delivery order, respecting logical precedence. These features are an important contribution for the implementation of high performance distributed computing systems.