In this paper, we study a work-conserving multicast scheduling with fanout splitting in a switch, which routes incoming packets asynchronously without fragmentation into cells. A new switch architecture is proposed, which distributes the input links to P variable length packet switching fabrics (VPS) with every G input links sharing GR inlets of the VPS. The system performance is analyzed by queueing analysis to express the maximum throughput and packet delay in terms of the system parameters and traffic characteristics. A practical switch design is also proposed to realize almost the same scheduling as the work-conserving one. We have surveyed how the fanout distribution affects the performance of the switch through Fanout Function, which is defined and studied to help the design of a multicast switch. We show how Fanout Function determines the maximum throughput and packet delay. Various fanout distributions are compared. The mixed fanout distribution exhibits better performance while the deterministic fanout can be used as a bound in the design of a multicast switch. We optimize R and P to attain 100% maximum throughput under limited switch complexity. When the mean fanout size is large, we can use less hardware to achieve the optimal performance by using our architecture. The proposed realization of this switch can be implemented easily due to its modular design. It is scalable because distributed output contention resolution and routing are used instead of a central arbitrator. Its performance is verified by simulation. The result matches the theoretical work-conserving scheduling very well.