CHAPT ER
15-1
Cisco ASDM User Guide
OL-16647-01
15
High Availability
This section contains the following topics:
Understanding Failover, page 15-1
Configuring Failover with the High Availability and Scalability Wizard, page 15-4
Field Information for the Failover Panes, page 15-14

Understanding Failover

The Failover pane contains the settings for configuring failover on the security appliance. However, the
Failover pane changes depending upon whether you are in multiple mode or single mode, and when you
are in multiple mode, it changes based on the security context you are in.
Failover allows you to configure two security appliances so that one will take over operation if the other
fails. Using a pair of security appliances, you can provide high availability with no operator intervention.
The security appliance communicates failover information over a dedicated failover link. This failover
link can be either a LAN-based connection or, on the PIX security appliance platform, a dedicated serial
failover cable. The following information is communicated over the failover link:
The failover state (active or standby).
Hello messages (keep-alives).
Network link status.
MAC address exchange.
Configuration replication.
Caution All information sent over the failover and Stateful Failover links is sent in clear text unless you secure
the communication with a failover key. If the security appliance is used to terminate VPN tunnels, this
information includes any usernames, passwords and preshared keys used for establishing the tunnels.
Transmitting this sensitive data in clear text could pose a significant security risk. We recommend
securing the failover communication with a failover key if you are using the security appliance to
terminate VPN tunnels.
The security appliance supports two types of failover, Active/Standby and Active/Active. Additionally,
failover can be stateful or stateless. For more information about the types of failover, see the following
topics:
Active/Standby Failover, pa ge 15-2