I'm having a hard time trying to configure VLAN tagging in a Mikrotik router. The same has 5 interfaces which I'll describe below:
Interface 1 and Interface 2 --> ISPs
Interface 3 --> Uplink to a Cisco core switch with VLAN 1 in access mode, no trunking
Interface 4 --> Uplink to a Cisco core switch with VLAN 2 in access mode, no trunking (DHCP enabled here, also configured on Mikrotik)
Interface 5 --> Uplink to a Cisco core switch with VLAN 3 in access mode, no trunking (DHCP enabled here, also configured on Mikrotik)
So, what I wanted to do is to use one interface for all my LAN traffic so I thought about using VLANs, first of all in my cisco switch I configure this:
interface GigabitEthernet1/0/5 description uplinkToMikrotikiface5 switchport trunk encapsulation dot1q switchport trunk allowed vlan 1-3 switchport mode trunk !
As far as I'm concerned there is nothing weird there.
So in Mikrotik I created a VLAN interface tagging VLAN 3 and mapping that to Interface 5, this didn't work so after some research I discovered that I have to use bridges instead of mapping to the interface, so I create a bridge, I create a port for this bridge to the VLAN and I've also created a port for this bridge to the Interface. This didn't work, honestly I'm not so sure if using bridges is a good approach but it's all I found online. At some point the configuration went well but the DHCP server was refusing to accept the configuration, if I configure the DHCP server to use the VLAN interface it will just greyed out that.