Switchovers

A switchover occurs when the active Oracle® Enterprise Session Border Controller stops being the active system, and the standby system takes over that function. There are two kinds switchovers: automatic and manual.

Automatic Switchovers

Automatic switchovers are triggered without immediate intervention on your part. Oracle® Enterprise Session Border Controller s switch over automatically in the following circumstances:

• When the active Oracle® Enterprise Session Border Controller ’s health score of drops below the threshold you configure.
• When a time-out occurs, meaning that the active Oracle® Enterprise Session Border Controller has not has not sent checkpointing messages to the standby Oracle® Enterprise Session Border Controller within the allotted time.

  The active Oracle® Enterprise Session Border Controller might not send checkpointing messages for various reasons such as link failure, communication loss, or advertisement loss. Even if the active Oracle® Enterprise Session Border Controller has a perfect health score, it will give up the active role if it does not send a checkpoint message or otherwise advertise its status within the time-out window. Then the standby Oracle® Enterprise Session Border Controller takes over as the active system.

When an automatic switchover happens, the Oracle® Enterprise Session Border Controller that has just become active sends an ARP message to the switch. This message informs the switch to send future messages to its MAC address. The Oracle® Enterprise Session Border Controller that has just become standby ignores any messages sent to it.

Manual Switchovers

You can trigger a manual switchover in the HA node by using the ACLI notify berpd force command. This command forces the two Oracle® Enterprise Session Border Controllers in the HA node to trade roles. The active system becomes standby, and the standby becomes active.

In order to perform a successful manual switchover, the following conditions must be met.

• The Oracle® Enterprise Session Border Controller from which you trigger the switchover must be in one of the following states: active, standby, or becoming standby.
• A manual switchover to the active state is only allowed on a Oracle® Enterprise Session Border Controller in the standby or becoming standby state if it has achieved full media, signaling, and configuration synchronization.
• A manual switchover to the active state is only allowed on a Oracle® Enterprise Session Border Controller in the standby or becoming standby state if it has a health score above the value you configure for the threshold.