Before you configure fault tolerance check whether you have bound the desired NIC. If not, go to Binding Protocols to do so.
Load INETCFG and select Protocols.
Select TCP/IP from the list of Protocols.
Select Fault Tolerance and enable it.
This switch is for the complete system. You still have to configure fault tolerance on your network.
Select Fault Tolerance Configuration.
Configure Fault Detection Interval, Minimum Error Level and Configure Individual Groups.
In the Configure Individual Groups, select the network listed and enable fault tolerance.