The aggregation protocol type for the interface.
On some platforms, aggregation protocol may be assigned per
group. The group can be a collection of the ports which belong
to a module or system. If the aggregation protocol is assigned
to any of the ports in such group then the aggregation protocol
will apply to all ports in the same group.
On some platforms, aggregation protocol type can be assigned
per aggregator. If multiple ports belong to a aggregator,
the aggregation protocol assigned to any of the ports in such
aggregator will apply to all ports in the same.