My company has a SCADA control system comprising of 2 industrial Windows PCs within a cabinet. These operate in a hot-standby configuration. One PC is designated as the online machine and this communicates with a number of remote PLCs etc. The other PC is designated as the standby and simple waits for the online PC to fail, which will then cause it to become the online PC. In addition, it is possible to manually force a PC switchover.
We have a situation where a Modbus client wishes to connect to our system. Ideally I would like to provide the vendor with a single IP address to connect to our system. However, I really need to provide 2 addresses, 1 for the online PC and another for the standby PC, which could be promoted to the online and thereby resume communications to the Modbus client. Which ever PC is online will server as the Modbus server.
I have been looking at ways of presenting our system as a single IP address. One potential option is Network Load Balancing using the features of Windows Server 2012. Ideally we would like to avoid introducing addition hardware into the cabinet. We have a Cisco L3 switch connecting PC1 and PC2 and this will also be used to connect the Modbus client.
What is the best way to do this?