Product Documentation

Understanding the causes of failover

The following events can cause failover in a high availability configuration:

  1. If the secondary node does not receive a heartbeat packet from the primary node for a period of time that exceeds the dead interval set on the secondary. For more information about setting the dead interval, see Configuring Communication Intervals. Possible causes for a node not receiving heartbeat packets from a peer node include:
    • A network configuration problem prevents heartbeats from traversing the network between the high availability nodes.
    • The peer node experiences a hardware or software failure that causes it to freeze (hang), reboot, or otherwise stop processing and forwarding heartbeat packets.
  2. The primary node experiences a hardware failure of its SSL card.
  3. The primary node does not receive any heartbeat packets on its network interfaces for three seconds.
  4. On the primary node, a network interface that is not part of a Failover Interface Set (FIS) or a Link Aggregation (LA) channel and has the high availability Monitor (HAMON) enabled, fails. The interfaces are enabled, but go to a DOWN state.
  5. On the primary node, all interfaces in an FIS fail. The interfaces are enabled, but go to a DOWN state.
  6. On the primary node, an LA channel with HAMON enabled fails. The interfaces are enabled, but go to a DOWN state.
  7. On the primary node, all interfaces fail. In this case, failover occurs regardless of the HAMON configuration.
  8. On the primary node, all interfaces are manually disabled. In this case, failover occurs regardless of the HAMON configuration.
  9. You force a failover by issuing the force failover command on either node.
  10. A route monitor that is bound to the primary node goes DOWN.

Understanding the causes of failover

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