Timer for the loop-back mode. The loop-back mode is reset to
its normal mode none(0) after the specified number of
seconds. A timer value of 0 indicates infinite time, which
means that the interface stays in loop-back mode until it is
specifically changed.
If the value of itsIfLoopTime is set while an interface is in
loop-back mode, the interface's timer will be reinitialized
with the new value.