A method for communication includes operating a network element, which includes multiple ports and multiple interconnected processing units, such that each processing unit is assigned to process packets that are communicated over a respective set of one or more of the ports. Each processing unit stores a respective list, which indicates one or more multicast packet streams that are permitted for forwarding by the network element, and further indicates a respective subset of the ports over which each of the multicast packet streams is permitted for forwarding. A request relating is disturbed among the multiple processing units, and the respective list in each processing unit is updated responsively to the request. Multicast packets associated with the given multicast packet stream are forwarded selectively by the processing units in accordance with the respective updated lists.