This identifies the auto-sizing failure handler configured for this tunnel -- the policy governing what happens if a bandwidth resize attempt fails, such as when no additional capacity is available along the path. An admin checks this to know whether the tunnel will simply retry later, alarm, or fall back to its last successfully-reserved size if an upsize attempt is rejected. For example, a failure handler configured to alarm-and-retain would keep the tunnel at its last successful bandwidth while raising an alert, rather than silently failing with no notification.