To map reserved VLANs to nonreserved VLANs or map 802.1Q VLANs to ISL VLANs, use the set vlan mapping command.
set vlan mapping reserved vlan non-reserved vlan
set vlan mapping dot1q 1q_vlan_num isl isl_vlan_num
Two condition might be occur when you are configuring VLAN mapping.
1.If outer-vlan of dot1q-tunnel is same as trans-vlan of other mapping config , upstream traffic is not transferred. And
2. If trans-vlan of dot1q-tunnel is same as origin-vlan of other mapping config, traffic is not transferred.