| 13.1 |  | Understanding Failover |
| 13.1.3 |  | Configuration replication |

| Configuration replication is the term that describes the configuration of the primary PIX Security Appliance being replicated to the secondary PIX Security Appliance. To perform configuration replication, both the primary and secondary PIX Security Appliances must be configured exactly the same and run the same software release. Configuration replication takes place between the active PIX Security Appliance and the standby PIX Security Appliance in one of three ways:

1. When the standby PIX Security Appliance completes its initial boot up, the active PIX Security Appliance replicates its entire configuration to the standby PIX Security Appliance.
2. As commands are entered on the active PIX Security Appliance, they are sent across the failover cable to the standby PIX Security Appliance.
3. Entering the write standby command on the active PIX Security Appliance forces the entire configuration in memory to be sent to the standby PIX Security Appliance.

Configuration replication occurs only from memory to memory. Because this is not a permanent place to store configurations, the administrator must use the write memory command to write the configuration into Flash memory. If a failover occurs during the replication, the newly active PIX Security Appliance will have only a partial configuration.

The newly active PIX Security Appliance will then reboot itself to recover the configuration from the Flash memory or resynchronize with the new standby PIX Security Appliance. When replication starts, the PIX Security Appliance console displays the following message:

> Sync Started

When replication is complete, the PIX Security Appliance console displays the following message:

> Sync Completed

Replication can take a long time to complete with serial cable failover for a large configuration, because configuration replication occurs over the failover cable. Information cannot be entered on the PIX Security Appliance console during replication.