According to one embodiment, a system on a chip includes multiple agents each corresponding to an intellectual property (IP) logic and a fabric to couple the agents. The fabric can include a primary message interface and a sideband message interface. The fabric further includes one or more routers to provide out-of-band communications between the agents via this sideband message interface. To effect such communication, the router can perform a subset of ordering rules of a personal computer (PC)-based specification for sideband messages. Other embodiments are described and claimed.