Devices residing in different networks communicate with one another using inter-network communication. A host may transmit a first packet to a gateway and the gateway may transform it into a second packet. When creating the second packet, the gateway may transmit a request to an address mapper for a mapped address. The mapped address includes a native address or a system address. The system address includes another native address as well as a reference value. The reference value is associated with the host, includes an opaque binary value of an arbitrary size, and is subdivided into multiple fields associated with the host. In response to the mapped address being the system address, the address mapping engine obtains the system address. In response to the mapped address being the native address, the address mapping engine obtains the native address. The native address is determined in view of an existing network protocol.