To a Client the transparent Redundant Server Set appears as if it is just a single Server and the Client has no Failover actions to perform. All Servers in the Redundant Server Set have an identical ServerUri and an identical EndpointUrl.
Figure 26 shows a typical transparent Redundancy setup.
Figure 26 – Transparent Redundancy setup example
For transparent Redundancy, OPC UA provides data structures to allow Clients to identify which Servers are in the Redundant Server Set, the ServiceLevel of each Server, and which Server is currently responsible for the Client Session. This information is specified in TransparentRedundancyType ObjectType defined in OPC 10000-5. Since the ServerUri is identical for all Servers in the Redundant Server Set, the Servers are identified with a ServerId contained in the information provided in the TransparentRedundancyType Object.
In transparent Redundancy, a Client is not able to control which physical Server it actually connects to. Failover is controlled by the Redundant Server Set and a Client is also not able to actively Failover to another Server in the Redundant Server Set.