Examples of LAN Redundancy Used with Enhanced Failover
The sections that follow describe examples of the recovery modes for the following configurations:
- Redundant Local Area Network (2 LANs) for Redundant iFIX networking and One Dedicated LAN between the SCADA failover pair as the primary network for data and alarm synchronization, that also uses the iFIX networking networks as the Secondary and Tertiary network for data and alarm synchronization
- Redundant Local Area Network (2 LANs) for iFIX networking and No Dedicated SCADA Network
Both of these recovery mode examples include computers configured with LAN Redundancy and Enhanced Failover.
When reviewing these configurations, be aware of the following terminology:
|
Term |
Description |
|
Active |
Fully functioning SCADA node. Sends synchronization data to standby node. All iClients will get their data and alarms from the active SCADA. |
|
Standby |
“Idle” SCADA·node. Updates data based on synchronization from the active node. |
|
Synchronization |
Database and Alarms. Includes the:
|
|
Switch to Active |
System message – node switch from Standby to Active· Start SAC block processing (Warm Restart). Allow data and alarm requests. Synchronization data from this node is sent to the standby (if available). |
|
Switch to Standby |
System message – node switch from Active to Standby · Stop SAC block processing· Reject data and alarm requests· Synchronization waits for data from Active node. |
|
iFIX Client node |
Obtains data and alarms from the active SCADA node. Automatically switches over to the newly active SCADA when the failover occurs. VBA script on the client continues to execute when the failover occurs. If the VBA script is reading data while the failover occurs, the VBA script may return an error.·The Alarm Summary shows the same number of alarm and acknowledge states after the failover occurs. The real-time trend shows some gap in the line chart. |
