You can use the FORWARD.COND parameter to forward the specified network route exclusively over a specified interface.
If the specified interface is inactive, RouteD forwards the network over all of the other interfaces.
Specify a network as both an IP address and a mask or as both an IP address and a bit number. The bit number n indicates which bit in the 0 – n bits of the IP address (counting left to right) is the last bit of the network portion of the IP address. If the MASK and bit number are missing, the system calculates a network by using the subnet mask of the interface specified through the ADDTCPIFC CL command.