In DoIP, endpoints (optionally) are associated with a particular namespace (as indicated by the namespace attribute in the file). Normally, devices are identified by their unique ID or service ID on the network. This however is a problem for devices that are mobile and can be connected to the network in different ways. Bluetooth devices, for instance, can be introduced on the network through TJBluetoothServer, but there can be multiple gateways on the network that do so (and the device may switch gateways at any time).

To still be able to uniquely identify such devices, you would normally rely on the id of the device (which, in the case of TJBluetoothServer, equals the unique Bluetooth address). However, this would clash with other series of unique addresses (Bluetooth addresses look very much like Ethernet MAC addresses, for instance). Therefore, namespaces were introduced. The full unique identifier of a device is simply the namespace concatenated with the id and a '.' in between, or just the id if there is no namespace specified.