SMP Gateway User Manual • 191
any SMP Tools, Telnet or Internet Explorer for any SMP Gateway, these applications will
use the second IP address.
To switch back to the first IP address:
From the Tools menu, click Use First Address.
Note that once a tool has been launched, it never switches IP addresses regardless of how many
times you toggle the address selection. Address switching applies only to commands that take
place after you instruct SMP Manager to switch addresses.
Note further, that if there are other models in your SMP Gateway list that support only one IP
address, such as the SMP 4 or the SMP 4-20, toggling back and forth between the first and second
IP address will have no effect. You will see the same logs, traces and statistics, regardless of
which address you specify.
19.4 Hot Standby
The SMP Gateway software has the possibility to maintain a complete up-to-date image of the
active SMP Gateway’s data on the standby SMP Gateway. This feature is called “hot standby”. It
is available for the most common master protocols.
Whenever a transition occurs on a hot-standby data point, data point information is first updated in
the real-time database of the active SMP Gateway; it is then transmitted to the standby
SMP Gateway, which updates its own database. Using hot standby, integrity scans are not always
required, since the hot-standby data points are already synchronized, reducing the failover time
significantly.
To configure a master protocol instance for hot standby, refer to the specific protocol manual
found on the SMP Gateway Software & Tools CD-ROM.
To take full advantage of the hot standby, the slave protocol should be configured to be active
anytime, even on standby. Proceed as follows:
In SMP Config, select the General node of the slave protocol instance.
Under Hot-Standby Support, Disabled should appear. Instead, select the slave component’s
expected behavior between the following:
Acquisition.
The slave protocol will receive data from its masters without accepting control
commands from the control center.
Acquisition and control.
The slave protocol will receive data from its masters and it will accept control commands
from the control center. These commands will be forwarded to the active SMP Gateway,
which will forward the control commands to the devices.
The following illustration presents the acquisition’s data flow for an SMP Gateway redundancy
group that supports hot standby.
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