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I have installed OpenWrt on a MikroTik Routerboard RB750UP (AR7240 CPU with AR9330 built in switch). I have included additional details below, but my question is:

How do I configure an untagged and tagged vlan on the same port?

I have successfully configured non-tagged vlans and tagged vlans independently, but not for the same port. The reason why I want to do this is because I have a Ubiquiti NanoStation loco M2 plugged into a port providing a wireless lan (which requires untagged frames), but I also want to configure a tagged vlan for managing the loco (i.e. accessing its management ip via tagged van).

Here are some further details:

Hardware

  • MikroTik RouterBoard RB750UP
  • Ubiquiti NanoStation loco M2

swconfig output:

swconfig dev eth0 help
switch0: eth0(AR7240/AR9330 built-in switch), ports: 5 (cpu @ 0), vlans: 16
<snip>

Here's a link to a diagram of (what I believe to be) the layout of the RB750's AR7240/AR9330 switch.

Operating System

OpenWrt BARRIER BREAKER (Bleeding Edge, r36085), built with a custom configuration

# uname -a
Linux OpenWrt 3.8.3 #3 Wed Mar 27 04:09:04 PDT 2013 mips GNU/Linux

Network Diagram

Here's a link to a diagram of my Network Setup.

As the image shows, the NanoStation loco is plugged into port 3 and has a management IP of 192.168.20.10/24 configured on a vlan with vid=3. It also acts as a wireless bridge/access point for the 192.168.100.0/24 network.

Accordingly, port 3 on the router has an untagged vlan configured for the 192.168.100.0/24 network and a tagged vlan for the 192.168.20.0/24 management network (with vid=3).

Network Configuration

Here's what I'm trying to achieve with the below config:

  • Tagged VLAN 3 (vid=3) on port 3 (virtual interface eth0.3)
  • Untagged VLAN 4 on port 3 (virtual interface eth0.4)
  • Default vlan pvid=4 on port 3 (to handle incoming untagged frames)

And the actual contents of /etc/config/network:

<snip>

config interface 'loco'
        option proto 'static'
        option ifname 'eth0.3'
        option ipaddr '192.168.20.1'
        option netmask '255.255.255.0'

config interface 'locolan'
       option proto 'static'
       option ifname 'eth0.4'
       option ipaddr '192.168.100.1'
       option netmask '255.255.255.0'

<snip>

config switch
        option name 'switch0'
        option reset '1'
        option enable_vlan '1'

config switch_vlan
        option device 'switch0'
        option vlan '1'
        option vid '1'
        option ports '0t 2 4'

config switch_vlan
        option device 'switch0'
        option vlan '2'
        option vid '2'
        option ports '0t 1'

config switch_vlan
        option device 'switch0'
        option vlan '3'
        option vid '3'
        option ports '0t 3t'

config switch_vlan
       option device 'switch0'
       option vlan '4'
       option vid '4'
       option ports '0t 3'

config switch_port
    option port '3'
    option pvid '4'

After rebooting the router, swconfig shows the following switch configuration. Note the missing '3t' from VLAN 3.

# swconfig dev switch0 show
Global attributes:
    enable_vlan: 1
Port 0:
    pvid: 0
    link: port:0 link:up speed:1000baseT full-duplex txflow rxflow 
Port 1:
    pvid: 2
    link: port:1 link:up speed:100baseT full-duplex auto
Port 2:
    pvid: 1
    link: port:2 link:down
Port 3:
    pvid: 4
    link: port:3 link:up speed:100baseT full-duplex auto
Port 4:
    pvid: 1
    link: port:4 link:up speed:100baseT full-duplex auto
VLAN 0:
    vid: 0
    ports: 0t 
VLAN 1:
    vid: 1
    ports: 0t 2 4 
VLAN 2:
    vid: 2
    ports: 0t 1 
VLAN 3:
    vid: 3
    ports: 0t    <----- no tagged port 3!
VLAN 4:
    vid: 4
    ports: 0t 3

As a result, I cannot ping the loco's management IP.

I've also tried manually configuring the vlan/port assignment and tags using swconfig, but in each permutation, it either leaves port 3 out of one of the vlans, or it forces port 3 to be tagged in both vlans.

Questions

  1. How do I configure an untagged and tagged vlan on the same port? I'm specifically trying to configure this for OpenWrt, but even understanding how to do this for Linux in general would be helpful.
  2. Are there any known bugs/issues with swconfig or the AR7240/AR9330 OpenWrt switch driver that could be causing this? (None came up in my searches.)
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