Cisco ASA 5505 Configuration Manual page 1194

Failover System Requirements
When the security appliance is configured for Active/Active Stateful Failover, you cannot enable IPsec
Note
or SSL VPN. Therefore, these features are unavailable. VPN failover is available for Active/Standby
failover configurations only.
Failover System Requirements
This section describes the hardware, software, and license requirements for adaptive security appliances
in a failover configuration.
This section includes the following topics:
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•
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Hardware Requirements
The two units in a failover configuration must be the same model, have the same number and types of
interfaces, the same SSMs installed (if any), and the same RAM installed.
If you are using units with different flash memory sizes in your failover configuration, make sure the
unit with the smaller flash memory has enough space to accommodate the software image files and the
configuration files. If it does not, configuration synchronization from the unit with the larger flash
memory to the unit with the smaller flash memory will fail.
Software Requirements
The two units in a failover configuration must be in the same operating modes (routed or transparent,
single or multiple context). They must have the same major (first number) and minor (second number)
software version. However, you can use different versions of the software during an upgrade process; for
example, you can upgrade one unit from Version 7.0(1) to Version 7.0(2) and have failover remain active.
We recommend upgrading both units to the same version to ensure long-term compatibility.
License Requirements
The two units in a failover configuration do not need to have identical licenses; the licenses combine to
make a failover cluster license. See the
Failover and Stateful Failover Links
This section describes the failover and the Stateful Failover links, which are dedicated connections
between the two units in a failover configuration. This section includes the following topics:
•
•
Cisco ASA 5500 Series Configuration Guide using ASDM
57-2
Hardware Requirements, page 57-2
Software Requirements, page 57-2
License Requirements, page 57-2
Failover Link, page 57-3
Stateful Failover Link, page 57-3
Chapter 57
"Failover Licenses" section on page 4-19
Information About High Availability
for more information.
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