A system and method for multicast delivery of messages using a configurable directional 2D router for Networks on Chips (NOCs) is disclosed. The router is well suited for implementation in programmable logic in FPGAs and achieves theoretical lower bounds on FPGA resource consumption. A NOC comprising a plurality of routers may be configured as a directional 2D torus, or in diverse ways, network sizes and topologies, data widths, routing functions, performance-energy tradeoffs, and other options. The NOC may transmit a unicast message from one source client core to one destination client core, or a multicast message from one source client core to a plurality of destination client cores, or an arbitrary mix of unicast and multicast messages, simultaneously. A multicast message destination may include all client cores of routers with a particular first or second dimension coordinate, or all client cores, or some arbitrary subsets of client cores.