Redundant networks can be used with OPC UA in either transparent or non-transparent Redundancy.

Network Redundancycan be combined with Serverand Client Redundancy.

In the transparent network use-case a single Server Endpointcan be reached through different network paths. This case is completely handled by the network infrastructure. The selected network path and Failoverare transparent to the Clientand the Server. Transparent network Redundancyis illustrated in Figure 34.

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Figure 34– Transparent network Redundancy

Examples:

  • A physical appliance/device such as a router or gateway which automatically changes the network routing to maintain communications.
  • A virtual adapter which automatically changes the network adapter to maintain communications.

In the non-transparent network use-case the Serverprovides different Endpointsfor the different network paths. This requires both the Serverand the Clientto support multiple network connections. In this case the Clientis responsible for selecting the Endpointand for Failover. For Failoverthe normal reconnect scenario described in 6.7can be used. Only the SecureChannelis created with another Endpoint. Sessionsand Subscriptionscan be reused. Non-transparent network Redundancyis illustrated in Figure 35.

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Figure 35– Non-transparent network Redundancy

The information about the different network paths is specified in NonTransparentRedundancyType ObjectTypedefined in OPC 10000-5.