Among a group of ports this object per port says whether this ports is preferred or not. A preferred port in a redundant group (usually a pair of ports) will always be the active link if it has link, regardless of the link state of other ports in its group.

Only one port in a redundant group may be preferred. If other ports in the same redundant group are already designated yes(1), the system should automatically set them to no(2).

When a port is selected as preferred port, its redundant group is assumed to be in revertive mode.

When no port is selected as preferred port, its redundant group is assumed to be in non-revertive (a.k.a. sticky) mode.

Once selected, a port's actual active state be read via the SelectLink object.

Use caution in designating Preferred ports, because on flaky/intermittent lines, this may result in excessive failovers.

If read as notSupported(1), this port either does not belong to a redundant group, or its redundant group is always in non-revertive (a.k.a. sticky) mode.