/interface bridge
add name=bridge1
/interface bridge port
add bridge=bridge1 interface=ether1 hw=yes
add bridge=bridge1 interface=ether2 hw=yes
add bridge=bridge1 interface=ether3 hw=yes
/interface ethernet switch ingress-vlan-translation
add ports=ether2 customer-vid=0 new-customer-vid=20 sa-learning=yes
add ports=ether3 customer-vid=0 new-customer-vid=30 sa-learning=yes
/interface ethernet switch egress-vlan-tag
add tagged-ports=ether1 vlan-id=20
add tagged-ports=ether1 vlan-id=30
add tagged-ports=ether1,switch1-cpu vlan-id=99
/interface ethernet switch vlan
add ports=ether1,ether2 vlan-id=20 learn=yes
add ports=ether1,ether3 vlan-id=30 learn=yes
add ports=ether1,switch1-cpu vlan-id=99 learn=yes
/interface vlan
add interface=bridge1 vlan-id=99 name=MGMT
/ip address
add address=
192.168.99.1/24 interface=MGMT
/interface ethernet switch
set drop-if-invalid-or-src-port-not-member-of-vlan-on-ports=ether1,ether2,ether3