High Availability Nodes

ESBCs can be deployed in pairs to deliver high availability (HA). Two ESBCs operating in this way are called an HA node. Over the HA node, media and call state are shared, keeping sessions/calls from being dropped in the event of a failure.

Two ESBCs work together in an HA node, one in active mode and one in standby mode.

• The active ESBC checks itself for internal process and IP connectivity issues. If it detects that it is experiencing certain faults, it will hand over its role as the active system to the standby ESBC in the node.
• The standby ESBC is the backup system, fully synchronized with active ESBCs session status. The standby ESBC monitors the status of the active system so that, if needed, it can assume the active role without the active system having to instruct it to do so. If the standby system takes over the active role, it notifies network management using an SNMP trap.

In addition to providing instructions for how to configure HA nodes and their features, this chapter explains how to configure special parameters to support HA for all protocols.

The ESBC uses SSH keys to manage the switchover. When you enable HA, you'll see new known-host keys and new authorized keys added to the configuration of both the active and standby configuration.