Hello,

how to set 2 vlans per one port one for specific vlan id and another for untagged frames (e.g. native vlan)? If I set one ip to interface for example vlan1 and second to ether1, is that configuration correct for encapsulation for tagged and untagged frames in one trunk port?

Alex

Untagged frames have nothing to do with VLAN or that mythical "native VLAN". Untagged means that there is no VLAN tags on the packets, so they are regular Ethernet packets without need to perform anything additional to support them. as they already are standard Ethernet packets.

IEEE 802.1Q specification allows to classify untagged frames as local default VLAN (native vlan reffered by cisco). Check this quote from IEEE 102.1Q specification

LAN segments are likely to carry VLAN-tagged frames belonging to various VLANs, but each such LAN
segment has its own “local default” VLAN. This “local default” defines the VLAN to which untagged or priority-tagged
frames are presumed to belong when received on the Ports of IEEE 802.1Q conformant bridges attached to that LAN
segment.

and cisco documentation

http://www.cisco.com/univercd/cc/td/doc ... fvl80q.htm
...
The IEEE 802.1Q protocol is used to interconnect multiple switches and routers, and for defining VLAN topologies. The IEEE 802.1Q standard is extremely restrictive to untagged frames. The standard provides only a per-port VLANs solution for untagged frames. For example, assigning untagged frames to VLANs takes into consideration only the port from which they have been received. Each port has a parameter called a permanent virtual identification (Native VLAN) that specifies the VLAN assigned to receive untagged frames

And what is so difficult to understand there? Doesn't the phrase "local default defines the VLAN to which untagged or priority-tagged frames are presumed to belong" mean there is no way to find out which VLAN do they belong except the presumptions administratively put on the port? I repeat once more, the "untagged" or "native VLAN" mean that it is plain and simple Ethernet that is connected to the port. The reason why they make up such terms except marketing, is to show that it is possible to assign the traffic received on the port to an administratively VLAN, which is obviously a basic functionality, which can not be unsupported. In fact, without this functionality having VLAN tags would have been pointless as the term really means that it is possible to mark plain Ethernet traffic with a VLAN tag.

So, yes it is possible with routeros, but you first have to know what are you looking for, and there is no parameters called "default vlan" or "native vlan", just when you make the configurationit will become apparent how to do that. moreover, you can send the same traffic with different VLAN IDs on different ethernet ports

It sounds like you would like to bridge untagged frames from one Ethernet port to another Ethernet port and exclude all tagged frames from that bridge group. I don't know if we have a bridge filter for VLAN tagged frames, but it is probably not too difficult to add.

Is that what you are looking for?

We will probably also be adding vlan in vlan support a little later.

John

I would like to extend this thread.

I have a MT router which has 2 Ethernet Ports and 2 WLAN Ports, I would like to tag each "untagged" packet coming from WLAN1 with VLAN ID 10 and each packet from WLAN2 with VLAN ID 20. The packets need to be forwarded via ETHER1 and should conserve the VLAN Tag. This host should not do routing rather bridging. A router at the other end of ETHER1 should do the routing and firewalling between VLAN 10 an VLAN 20 and of course the internet.

Can this be done with RouterOS and if so does someone know how?

Regards,

Marc

Basic functionality again... Yes it is possible. Just create the vlan interfaces on ethet1 with the appropiate VLAN IDs, and bride one of them with one of the WLAN interfaces, and the other one - with the second of the WLAN interfaces. Just remember that you can not bridge with WLAN interfaces in station mode (there are plenty of other threads explaining why and how to work around this problem)