Mapping of DCPS Domains to DDSI Domains

In Data-Centric Publish-Subscribe (DCPS), a domain is uniquely identified by a non-negative integer, the domain ID. In the UDP/IP mapping, this domain ID is mapped to port numbers that are used for communicating with the peer nodes. These port numbers are of significance for the discovery protocol. This mapping of domain IDs to UDP/IP port numbers ensures that accidental cross-domain communication is impossible with the default mapping.

In DCPS there is a one-to-many mapping of domain ID to port numbers. In DDSI, there is a one-to-one mapping of domain ID to a port number, which is why DDSI does not communicate the DCPS port number in the discovery protocol; it assumes that each domain ID maps to a unique port number.

Note

While it is unusual to change the mapping, the specification requires this to be possible, which means that two different DCPS domain IDs can be mapped to a single DDSI domain.