Indicate the mask to be logical-ANDed with the destination
address before being compared to the value in the
cIpForwardDest field. For those systems that do not
support arbitrary subnet masks, an agent constructs the
value of the cIpForwardMask by reference to the IP
Address Class.
Any assignment (implicit or otherwise) of an instance of
this object to a value x must be rejected if the bitwise
logical-AND of x with the value of the corresponding
instance of the cIpForwardDest object is not equal to
cIpForwardDest.