
Configuring a Redundant System
BIG-IP® Reference Guide 6-1
Introduction
A BIG-IP redundant system consists of two identically configured BIG-IP
units, only one of which is active at a given time (unless a special
active-active configuration is chosen). The inactive unit serves as a standby
which becomes active only in case of failure of the active system, a process
called failover.
BIG-IP redundant systems have special settings that you need to configure,
such as VLAN fail-safe settings. One convenient aspect of configuring a
redundant system is that once you have configured one of the BIG-IP units,
you can simply copy the configuration to the other BIG-IP in the system by
using the configuration synchronization feature.
There are two basic aspects about working with redundant systems:
• Synchronizing configurations between two BIG-IP units
• Configuring fail-safe settings for the VLANs
In addition to the simple redundant features available on the BIG-IP, several
advanced redundant features are available. Advanced redundant system
features provide additional assurance that your content is available if a
BIG-IP experiences a problem. These advanced redundant system options
include:
• Mirroring connection and persistence information
• Gateway fail-safe
• Network-based fail-over
• Setting a specific BIG-IP to be the active unit
• Setting up active-active redundant systems
The attributes you can configure for a redundant systems are shown in
Table 6.1.
Attributes Description
Synchronizing
configurations
This feature allows you to configure one BIG-IP and then synchronize the configuration with
the other BIG-IP.
Fail-safe for VLANs Fail-safe for VLANs provides the ability to cause a BIG-IP to fail over if a VLAN is no longer
generating traffic.
Mirroring connections
and persistence
information
You can mirror connection and/or persistence information between redundant units. This
enables you to provide seamless fail-over of client connections.
Gateway fail-safe This feature allows you to fail-over between two gateway routers.
Network-based
fail-over
You can configure the BIG-IP to use the network to determine the status of the active unit.
Table 6.1 The attributes you can configure for redundant systems
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