VLANs
Create a vlan
Other devices (routers, switches) between the router and the computer must be configured appropriately.
Add an IP address for the vlan interface (optional)
Two interfaces one vlan
Create the vlans for the interfaces
/interface vlan add interface=ether4 name=e4.20 vlan-id=20
/interface vlan add interface=ether5 name=e5.20 vlan-id=20
Create the bridge and add the previously created vlans
/interface bridge add name=b20
/interface bridge port add bridge=b.20 interface=e4.20
/interface bridge port add bridge=b.20 interface=e5.20
Add an IP address to the interface if needed.
Access port
Vlan 20 on ether5 tagged and ether4 untagged.
/interface vlan add interface=ether5 name=e5.20 vlan-id=20
/interface bridge add name=b20
/interface bridge port add bridge=b20 interface=e5.20
/interface bridge port add bridge=b20 interface=ether4
Example
Vlan with DHCP
/interface vlan add arp=enabled disabled=no loop-protect=off name=e4.110 interface=ether4 vlan-id=110
/ip address add address=10.0.11.1/24 comment=vlan110 network=10.0.11.0 interface=e4.110
/ip pool add name=e4.110 range=10.0.11.200-10.0.11.240
/ip dhcp-server add address-pool=e4.110 interface=e4.110 lease-time=1d name=e4.110
/ip dhcp-server network add address=10.0.11.0/24 comment=e4.110 gateway=10.0.11.1 netmask=24 dns-server=1.1.1.1
Notes
The DHCP server goes on the bridge.