Indicates the mask to be logical-ANDed with the
destination address before being compared to
the value in the wfIpForwardDest field. For
those systems that do not support arbitrary
subnet masks, an agent constructs the value of
the ipForwardMask 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
wfIpForwardDest object is not equal to wfIpForwardDest.