aluExtPortEtherLoopbackCfmLbMode is to enable/disable an ethernet port to reply to an ethernet CFM Loopback Message (LBM) frame at the port level. If enabled then it indicates the desired egress QoS priority treatment for the CFM Loopback Reply (LBR) frame. - disabled (0) : disables the handling of LBM. - priority-low (1) : enables the handling of LBM by sending LBR using low priority QoS treatment. - priority-high (2) : enables the handling of LBM by sending LBR using high priority QoS treatment. - priority-dot1p (3) : enables the handling of LBM classification based on the Dot1p priority. LBR will be forwarded to the corresponding egress queues based on the policy configuration. When enabled, all imcoming layer 2 LBM's frames (i.e. not encapsulated within any tunnel/services), with MAC destination address matched with the port address, will be processed. An LBR will be generated, in reverse direction, back toward the sender. The LBR's contain the same content as the received LBM's, with the exception of the swapping for source and destination MAC addresses, and the CFM op code being set to indicate frame type being LBR. The Nokia 7705 SAR devices has the following restrictions: - Only one port per MDA can have the cfm-loopback enabled at a time. - aluExtPortEtherLoopbackCfmLbMode can only be 'disabled' if aluExtPortEtherLoopback is not set to 'none'. - aluExtPortEtherLoopbackCfmLbMode can not be changed from one priority to another, i.e. once it is enabled to a priority, it can only be modified to 'disabled'. - priority-dot1p is allowed only on physical ring ports. CFM LB frames destined to these physical ring ports with aluExtPortEtherLoopbackCfmLbMode being priority-dot1p will be processed and replied only if ithey have no Vlan tags, or with Vlan tags of Vlan IDs specified by aluExtPortEtherCfmLbVlanList.