TV Box, VLANs, is this possible?

Discussion in 'Tomato Firmware' started by foukevin, May 3, 2012.

  1. foukevin

    foukevin Serious Server Member

    Hello everyone!

    First thanks to everyone involved in developing and/or supporting the Tomato firmware, I've been using it for years now, and it's a blast, really, thank you :)

    I've searched the web to resolve this but did not find any thread close enough to my problem to resolve mine. I'm pretty sure someone already have this issue, so if a thread already exists, please forgive me.

    The context

    My house as 4 wall Ethernet plugs (each in different room), each one ends in my main router LAN ports. My router is connected to the VDSL modem via its WAN port, using PPPoE. Both router and modem are sitting in the wiring closet.

    My TV set is next to wall plug 1, so is the TV Set Top Box (which you can't access or configure). The TV Box requires a direct connection to the VDSL modem to work. Previously I configured my main router so that port 1 (therefore everything connected to wall plug 1) is on a different VLAN (VID1), bridged to WAN. This way the TV service works, and everything but plug 1 is on the same network.

    The problem

    Besides the TV set top box, I'd like to connected other devices to plug 1, so that they can access my LAN.
    As an example of concrete use, I'd like to be able to use my game system as a media player, while my computer, plugged to plug 4 in another room acts as a DLNA server.
    For this to work, I added another router (the "Access Point" router) in plug 1, and have it be on the same network than the main router so everything is on the same network.
    Here is how my installation actually looks like:

                                |||                  |
                                |||                  |
                          +----+||| +-------+        |
                          |    |||| |       |        |
                          |  +-####-#-+   +-#UUU-+   |
                          |  | 1234 W |   | 1234 |   |
                          |  |  Main  |   | VDSL |   |
                          |  | Router |   +------+   |
                          |  +--------+              |
                          |                          |
                          |                          |
                          #(Plug1)                   #(Plug4)
                          |                          |
                          |                          |
    (Game System)#-----+  |                          +---#(Desktop PC/Media Server)
    (Media Player)#---+|  |
    (TV Box)#--------+||  |
                     |||  |
                     |||  |
                   | 1234 W |
                   | Access |
                   | Point  |
    • # stands for plugged ports/plugs, U stands for unplugged/free ports/plugs
    • 1, 2, 3 and 4 are LAN ports on the routers/VDSL modem
    • W is the WAN port
    But that obviously prevents the TV Box from having its own VLAN bridged connection to the main router's WAN, as it first goes through the Access Point and the packects gets "merged" into plug 1 with the other devices' ones.

    After some further googling, I found that the solution may lie in VLAN trunking and 802.1q tagging. I tried to configure the VLANs so my routers will tag the packets from the TV Box, but not luck for now.

    How I think it should work (I'm probably being wrong here :))

    It is possible to have access point router (as pictured above) tagging the packets coming into its LAN port 1 (from the TV Box) with a different LAN id, so they can travel through plug 1 along with packets from others devices, and end up into the main router, being sorted here (thanks to the previously inserted tag), and everything should be fine?

    My questions are:
    1. Is the previous assumption right ?
    2. Is this the right way to do this ?
    3. How would you configure your VLANs (or network if the solution is not VLANs) to achieve this result ?

    The hardware

    Here are some information about my routers hardware and configurations:
    • Linksys WRT54G v2.0
    • Asus WL520GU
    Both of them are running Tomato; toastman builds (latest version, with VLAN support)
    Important note: while the Asus WL520GU does support 802.1q tagging, the WRT54G v2.0 does not seem to officially support it (but this settings can be override by clicking some "experimental" option in the VLAN settings page). I suspect this lack of support being the cause of my issue.


    Here are my routers network configurations, which work nice for the LAN and wired/wireless Internet Access, but prevent the TV from working.

    Main Router configuration:
    WAN: PPPoE
    Gateway mode
    IP address:
    DHCP server enabled (range to 149)
    NAT enabled
    Wireless disabled

    Access Point Router configuration:
    WAN: Disabled (bridge WAN to LAN enabled)
    Router mode
    IP address:
    Default gateway:
    Default DNS:
    DHCP server disabled
    NAT disabled
    Wireless enabled (Access Point)

    I don't post my VLANs settings because I'm not home and don't remember them precisely, and I don't really master the subject, so they are probably wrong anyway :)

    I strongly suspect I might not achieve what I want without having both routers supporting VLAN tagging (one does, the other doesn't), can someone confirm this?

    I already tried both of these setups:
    1. WL520GU as main router, and WRT54G as access point router
    2. WRT54G as main router, and WL520GU as access point router
    Same results so far.

    Thanks for your help!

  2. foukevin

    foukevin Serious Server Member

    I'm starting to doubt about my VLAN setup :)

    I used wireshark to listen to what the TV Box was outputing on startup, here's what it says:
    No.     Time        Source                Destination           Protocol Length Info
          1 0.000000    fe80::223:54ff:fe8f:1f75 ff02::2               ICMPv6   70     Router Solicitation
          2 0.685220    Pegatron_bc:5d:a0     Broadcast             ARP      60     Who has  Tell
          3 1.685391    Pegatron_bc:5d:a0     Broadcast             ARP      60     Who has  Tell
          4 2.686382    Pegatron_bc:5d:a0     Broadcast             ARP      60     Who has  Tell
          5 3.687404    Pegatron_bc:5d:a0     Broadcast             ARP      60     Who has  Tell
          6 4.013363    fe80::223:54ff:fe8f:1f75 ff02::16              ICMPv6   90     Multicast Listener Report Message v2
          7 4.013424    fe80::223:54ff:fe8f:1f75 ff02::2               ICMPv6   70     Router Solicitation
          8 4.688415    Pegatron_bc:5d:a0     Broadcast             ARP      60     Who has  Tell
    It seems to try connect its server with IPv6 first then fallback to IPv4.

    I always just managed my local network and my routing knowledge is limited :/
    Do you think there might be a very simple way to route this from my lan to the outside world without all this VLAN stuff?

  3. teaman

    teaman LI Guru Member

    Any specific port? Or just any? Does it expect tagged frames? Do you know Which VLAN ID/PVID/VID should be used? This whole thing probably should involve having a couple of 802.1Q trunks between them at some point - knowing which VIDs should be configured on each port is sorta... imperative.

    That being said - this won't be 'just that simple' - it can be tricky, but possibly do-able.

    1. Yes.
    2. Don't know, there could be many ways to do this.
    3. You need to setup 802.1Q trunks between each pair of devices you wish to carry/transport frames that would be tagged (more than one VLAN running isolated, on the same wire).

    I guess you should be probably just fine with the Asus WL520GU, but I'm afraid the Linksys WRT54G v2.0 won't be able to run/support 802.1Q VLAN trunks, only port-based VLANs. See for more info.

    Best of luck!
  4. foukevin

    foukevin Serious Server Member

    Hi teaman!

    Thank you for yours answers! and the great work you do on tomato!
    The TV Box can be plugged into any port of the VDSL Modem. As far as I know it doesn't seem to expect tagged frames.
    I've no idea about the VLAN ID than should be used. I thought I could use VLANs tagging just inside my physical home network to carry and sort both the frames of my LAN (the classic and the one of the TV thing (which apparently is expecting something like
    My configuration might be ok, but one of the router probably does not support it. I think my best bet is perhaps to find another cheap router supporting tomato and tagged frames to figure this out.

    Thanks again for the help!

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