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