The value of tmnxOspfIfAdvtSubnet specifies the advertisement
method. When tmnxOspfIfAdvtSubnet is set to 'true', OSPF will
advertise the network number and netmask instead of the
individual host-routes of an active point-to-point interface.
Setting a value for this object has no effect when tmnxOspfVersion
has the value 'version3'.