In an Active/Passive configuration, the PCS uses a Virtual IP (VIP) that is owned by only one node (considered the active node) at any given time. The other node in the cluster would be the passive node. Each node in a cluster is in near-constant communication with the other to ensure each node is reachable. This task is performed by sending Address Resolution Protocol (ARP) pings and confirming a successful response is received.
In the event that a node does fails (timeout being the gateway's ARPing timeout + 5 seconds), the passive node will assume ownership of the VIP and sends a gratuitous ARP message notifying other networking devices that it now owns the VIP address.
When the VIP is flapping between two nodes, this can occur due to the following reasons:
To resolve this issue, ensure both nodes can reach the default gateway.