TABLE OF CONTENTS Many enterprises require high availability, and have no tolerance for disruption to network operations. In many environments, providing 99.99 percent uptime is part of the service-level agreement (SLA), which equals fewer than 53 minutes of planned and unplanned downtime a year. For this uptime requirement to be met, high availability through redundancy and failover must be implemented. To support high availability, the PIX firewall provides stateless and stateful failover capabilities. New in version 7.0, the PIX now supports active/active failover in addition to active/standby. This chapter explains the meaning and importance of these terms, and how failover works on the PIX firewall. We provide several examples to demonstrate failover use and configuration.
With the different variations and types of failover features that the PIX firewall supports, it is important to understand the basic failover concepts. A good grasp of failover concepts is fundamental to configuring it successfully.
The failover feature on the Cisco PIX firewall handles and adapts to firewall failures by running two, and exactly two, firewalls in a mirrored tandem. Failover is only supported on the high-end models of the PIX firewall, such as the PIX 515, 515E, 520, 525, and 535. It is not supported on the PIX 501, 506, and 506E. Failover works with all interface types, but the two firewalls must be identical in the following ways:
Same model of firewall
Same amount of flash memory
Same amount of RAM
Same major and minor software version
Same operating mode...
