QoS Profile Restrictions
In stacking mode, CoS level 6 (hardware queue 6) is reserved for stacking, so you cannot create quality profile QP7.
Because QP7 cannot be created, you cannot use hardware queue 6 to assign CoS level 6 to a packet. However, you can assign packets received with 802.1p priority 6 to a QoS profile using the technique described in Processing of Packets Received With 802.1p Priority 6
NoteThis restriction is applicable only when the stackable switch is operating in stacking mode.