Specifies the Ethernet priority assigned to a frame that has
arrived via this port, and that does not have a VLAN tag.
Priority will only be assigned to the frame if it should be
sent out tagged on another port. This object is not
affecting the traffic class assigned to the frame. The
traffic class will be assigned to the frame based on the
DSCP (if ethIfPriorityMode is set to `diffserv(2)') or to
the value of ethIfDefaultTrafficClass.