Virtual IP failover

When virtual IP failover is enabled, Content Gateway maintains a pool of virtual IP addresses that it assigns to the nodes in the cluster as necessary (see What are virtual IP addresses? for more information.) These addresses are virtual only in the sense that they are not tied to a specific machine; Content Gateway can assign them to any of its nodes. To the outside world, these virtual IP addresses are the addresses of Content Gateway servers.

Virtual IP failover assures that if a node in the cluster fails, other nodes can assume the failed node’s responsibilities. Content Gateway handles virtual IP failover in the following ways:

• The content_manager process maintains cluster communication. Nodes automatically exchange statistics and configuration information through multicast communication. If multicast heartbeats are not received from one of the cluster nodes, the other nodes recognize it as unavailable.
• The content_manager process reassigns the IP addresses of the failed node to the remaining operational nodes within approximately 30 seconds, so that service can continue without interruption.
• The IP addresses are assigned to new network interfaces, and the new assignment is broadcast to the local network. The IP address reassignment is done through a process called ARP rebinding.