Establishing Active and Standby Roles

Oracle® Enterprise Session Border Controller s establish active and standby roles in the following ways.

• If an ESBC boots up and is alone in the network, it is automatically the active system. If you then pair a second ESBC with the first to form an HA node, then the second system to boot up will establish itself as the standby automatically.
• If both ESBCs in the HA node boot up at the same time, they negotiate with each other for the active role. If both systems have perfect health, then the ESBC with the lowest HA rear interface IPv4 address will become the active ESBC. The ESBC with the higher HA rear interface IPv4 address will become the standby ESBC.
• If the rear physical link between the two ESBCs fails during boot up or operation, both will attempt to become the active ESBC. In this case, processing will not work properly.

Health Score

HA Nodes use health scores to determine their active and standby status. Health scores are based on a 100-point system. When an ESBC is functioning properly, its health score is 100.

Generally, the ESBC with the higher health score is active, and the ESBC with the lower health score is standby. However, the fact that you can configure health score thresholds builds some flexibility into using health scores to determine active and standby roles. This could mean, for example, that the active ESBC might have a health score lower than that of the standby ESBC, but a switchover will not take place because the active ESBC's health score is still above the threshold you configured.

Alarms are key in determining health score. Some alarms have specific health score value that are subtracted from the ESBC's health score when they occur. When alarms are cleared, the value is added back to the ESBC's health score.

You can look at an ESBC's health score using the ACLI show health command.