This object controls the system wide ability to manipulate
the physical link state of an interface when the interface's
ifOperStatus transitions into or out of the down(2) state.
A value of enabled(1) will cause an interface to drop physical
link when its ifOperStatus transitions to down(2). If the
interface would transition out of the down(2) state, assuming
it did have link, then physical link will be restored to the
interface. A value of disabled(2) will cause an interface to
not alter its physical link regardless of the value of
ifOperStatus. This object only affects those interfaces which
have a concept of physical link.