1. A router in a Network on Chip (NoC) comprising a plurality of routers, the router comprising: a plurality of ports, each of the plurality of ports configured with one or more virtual channels (VCs), each of the one or more VCs associated with a separate buffer, each of the one or more VCs configured to connect to specified one or more other ports or VCs of the plurality of ports based on a membership specified by a specification; wherein a number of the plurality of ports and a number of the one or more VCs for the each of the plurality of ports is specified by the specification; wherein a size of each of the one or more VCs and a size of the buffer is specified by the specification; wherein the connectivity between each of the one or more VCs is specified by the specification; wherein the one or more VCs are configured to operate in different clock domain as specified by the specification.