Installing the Network Load Balancer (NLB)
OCI cannot recognize a [VIP protected by IP resource] in an OCI VCN. As a result, network communication using [VIP protected by IP resource] normally used in LifeKeeper for Windows cannot be performed. In this configuration, install NLB as follows and set [VIP set by NLB] as the network communication path.
Connection from the client
- Since the SIOS20-BASTION (the bastion server is also used as a client) connects to the application (Oracle Listener in the figure above), a connection is attempted using the virtual IP address and application port number (10.0.2.21:1521).
- SIOS20-NODE1 and SIOS20-NODE2 are registered as the backend pool of the NLB. The NLB healthcheck checks which node has opened the healthcheck port (12345). The Generic ARK for Load Balancer probe reply (GenLB), which is provided as generic application scripts, responds to the NLB healthcheck. Since LifeKeeper ensures that the GenLB is only active on either machine, the NLB health probe always detects that only the active side is healthy. As a result, NLB always allocates requests to the active side of the nodes (in the figure above, SIOS20-NODE1 is active).
- The NLB forwards the connection requests from client to the active side of the nodes without applying network address translation. Then, the requests arrive to the active side of the nodes with the destination address set to 10.0.2.21.
- A LifeKeeper IP resource (10.0.2.21) is necessary in order to receive the connection requests. However, 10.0.2.21 cannot be active on the NIC on Subnet #2 because the NLB on Subnet #2 is already using the same IP address as shown above. Therefore, for convenience, set the NIC on Subnet #3 to [VIP protected by IP resource]. The application waits for requests on the application port on the IP addresses (10.0.2.21). Lastly, connection requests to the virtual IP address and application port number (10.0.2.21:1521) on the client are delivered to the application.