Tavve zoneranger User Manual page 38

Redundancy
Redundancy is a more sophisticated form of multiple ZoneRanger configuration. When using
redundancy, a persistent relationship is configured between the redundant ZoneRangers, so that they
become aware of each other. When two or more ZoneRangers are configured to be redundant,
configuration changes to one of the ZoneRangers, including changes to configuration options associated
with managed devices, will automatically be propagated to the other ZoneRangers, making it easier to
keep the configurations of the redundant ZoneRangers in sync. Whenever a redundant ZoneRanger that
has been down or was otherwise unreachable is restored, and communication with its peers is
reestablished, the ZoneRanger will resynchronize its configuration with its peers in order to pick up any
configuration changes that may have occurred.
Redundant ZoneRangers perform discovery and polling independently. As such, discovery results and
device status information are not propagated between redundant ZoneRangers. If polling configuration
settings associated with discovered devices are modified on one ZoneRanger, the changes are
propagated to all redundant ZoneRangers, each of which will attempt to locate the corresponding device
in their own database of discovered devices, and make identical changes.
ZoneRangers can be configured to be redundant during initial configuration, or at a later time, using the
ZoneRanger web interface. Note that redundancy and pooling can be used simultaneously. That is, the
Proxy Map service on the Ranger Gateway can be configured to distribute management protocol traffic
across the set of redundant ZoneRangers, in the same way as across a simple pool of ZoneRangers. In
that sense, Redundancy provides all of the features of pooling, plus the added value of automatically
synchronizing the configurations of the redundant ZoneRangers. A redundant pool of ZoneRangers is
illustrated in the following figure.
Figure 13-2. Redundant ZoneRanger Pooling Example
ZoneRanger 5.5 User's Guide 38