OpenWrt /etc/config/network

#===========================================================
              ##----- Virtual Switches -----##
#===========================================================

    # vSwitches #
#-----------------------------------------------------------

  # Switch 0:
config switch
    option  name            'switch0'
    option  enable_vlan     1
    option  reset           1

    # vLANs #
#-----------------------------------------------------------

  # 1: LAN
config switch_vlan
    option  device          'switch0'
    option  vlan            1
    option  vid             1
    option  ports           '0 5t'
                            # 0 is LAN 4
                            # 5t is the CPU LAN ethernet interface
  # 2: WAN
config switch_vlan
    option  device          'switch0'
    option  vlan            2
    option  vid             2
    option  ports           '1 2 3 4 6t'
                            # 1 - 3 are LAN 3 - 1
                            # 4 is the dedicated WAN port on the router
                            # 6t is the CPU WAN ethernet interface