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Wireless Bridge

A while back, I tried to wirelessly extend my home network from one basement room to another, using my Linksys WRT54G and the modded Linksys firmware from Sveasoft (tutorials here and here, firmware here). My goal was not to extend wireless coverage, but to extend my cabled network using a wireless link between two wireless routers. In one room, I have a Topcom WBR 254g, which is connected to my cable modem. In another room, I have a couple of machines connected to the switch of the WRT54G.

The intended network setup: wireless link between two routers

I could not get it to work with the Sveasoft software. Probably because of some error on my part, but the WRT54G just never showed up on the radar of the other router.
A few days ago, I decided to give it another go and so I looked around for more information on the subject. The search led me to DD-WRT, another modification of the Linksys firmware. In addition to the WDS way of extending a wireless network (which is what the Sveasoft firmware does), the DD-WRT firmware also enables you to bridge a network using the WRT54G. The two approaches are similar, but the ‘Wireless Bridge’ (or ‘client-bridge’) mode of DD-WRT appears to be less complicated to configure, since it is completely transparent. If you look over the Sveasoft tutorials mentioned above, you will notice the discussions about network segmentation etc. Problems, such as these are absent with DD-WRT in bridge mode, which was why I was immediately interested.

The ‘client-bridge’ mode of DD-WRT is available in both version 2.2 (stable) and version 2.3 (beta). Version 2.3 supports setting and configuring the ‘client-bridge’ mode via the web based administration interface. In version 2.2 this can only be done by telnet’ing into the router and issuing commands.I downloaded the standard edition of the v2.3 firmware and followed this guide:

  • Reset router to factory defaults
  • Updated firmware
  • Reset to factory defaults again
  • Added WRT54G WAN MAC to main router MAC access list.
  • Set WRT54G LAN IP to something outside the main router’s DHCP range. I.e. if the main router assigne IP adresses in the range between 192.168.2.100 and 192.168.2.200, you should assign the WRT54G an adresse like 192.168.2.50. The wireless bridge is completely transparent and the WRT54G will not be visible anywhere, so this step is necessary to keep the WRT54G from interfering with the rest of the network. Note: this step is not mentioned in the guide referenced above.
  • Set WRT54G wireless settings, set SSID and channel to match main router.
  • Rebooted the WRT54G.

Note that the web based admin interface of DD-WRT v2.3 appears to have some issues with Firefox (the preferred browser experience of connoisseurs worldwide). Maybe these are just issues in general, and not specific to Firefox. The web interface supports multiple layouts (which can be selected in the ‘Administration’ tab) and with the default layout - ‘Kromo’ - some functionalities like text fields, pull down menues etc. were dimmed out, and thus not available to me. I switched to the ‘Brainslayer’ (!) layout, which made everything ok.

Update 29-11-2005

I enabled encryption on the wireless network yesterday and was a bit anxious as to how the wireless bridge would play a long. As it turned out, there were no problems at all.

What did turn out to be a problem though, were the issues between Firefox and the administration interface of the Topcom WBR 254g router. Using Firefox, I was not able to set the encryption keys, regardless of whether I copy-pasted them or typed them in manually. No matter what I did, the router would complain about “Key 1 is wrong, the legal key length is 10″ (as reported here). A switch to Internet Explorer fixed this.

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13 Responses to “Wireless Bridge”

  1. Gravatar Patrick Thomas Says:

    Hey, Christopher. I e-mailed you a bit ago asking about the MAC address and whether it was required or not, I see that it isn’t (if you have MAC filtering disabled).

    Anyway, I’ve run into another problem. First let me describe my current situation: I have the routers connected through AP/Client Bridge mode (host AP/client Client Bridge) and both have the same SSID, channel frequency number, wireless mode (Mixed). I am able to access each router’s control interface by using 192.168.1.1 (host) & 192.168.1.2 (client).

    My problem starts here, I have the client router plugged in at a remote location of the house and accordingly, when I view the control interface, the Wireless -> Rate (Status -> SysInfo) it shows 36 Mbps, signifying that there is indeed a remote link with true signal degradation. However, I have a wireless laptop sitting right next to the client router (in the remote location) and it is still showing only two bars of connectivity, when it should be showing five (right?) as there is beside it the wireless client router (connected to the main router). I know that the data rate will still be 36 Mbps, but if I had a computer connected to one of the LAN ports on the client router, would the data still flow from the laptop into the client router and to the computer (connected to client) at 56 Mbps?

    And that’s another problem, I am not able to plug anything into the LAN ports on my Belkin F5D7230-4 (which, of course, does have the modified DD-WRT firmware on it). I have read [http://www.dd-wrt.com/phpBB2/viewtopic.php?p=11886] that perhaps you must Telnet into the router to enable access to the LAN ports..there is a issue between the firmware and the model of router.
    Do you know anything about this?

    Anyway, I hope that I have been clear enough. I’ve tried to explain my situation in the fullest way but if I haven’t please let me know and I’ll get more detailed =)
    Thanks.

  2. Chris Says:

    Hello again, Patrick
    I’m glad things are (sort of) working out for you.

    In the following, I’ll refer to your ‘host AP’ router as the ‘main’ router and your Client Bridge router as the ‘bridge’.

    I’m pretty sure a router running DD-WRT stops being a wireless AP when it is set to ‘client-bridge’ mode (it essentially becomes a switch). This explains the difference between the signal quality reported by the ‘bridge’ and your laptop. Both get their network connections from your ‘main’ router and the ‘bridge’ probably has better reception because of more powerful hardware and DD-WRT firmware optimazation.

    This also answers your second question. No, data will most likely not be transferred at 56 Mbps. If the above is correct, data will flow from the laptop to the ‘main’ router and from there to the ‘bridge’ and on to the computer connected to one of the ‘bridge’s LAN ports. So the laptop’s weak wireless connection becomes the bottleneck.

    I cannot help you much with your third question since I have zero experience with Belkin routers. I can give you some pointers with regards to the Telnet stuff:

    - To telnet to the router, open a terminal and type ‘telnet 192.168.1.2′. This cause the router to prompt you for username and password.

    - Remember that DD-WRT turns your router into a Linux box. Your username for telnet sessions is ‘root’ and not the ‘admin’ username used for accessing the router by web. The password is the same.

    I hope this helps you out a bit.

    /christopher

  3. Gravatar Patrick Thomas Says:

    “This also answers your second question. No, data will most likely not be transferred at 56 Mbps. If the above is correct, data will flow from the laptop to the ‘main’ router and from there to the ‘bridge’ and on to the computer connected to one of the ‘bridge’s LAN ports. So the laptop’s weak wireless connection becomes the bottleneck.”

    If the laptop is sitting right next to the ‘bridge’, won’t the data go from the laptop, to the ‘bridge’, and then to the computer connected to the bridge? Will the ‘main’ router be used at all? It doesn’t need to be, does it? I mean, it’s kind of like a small sub-network that only gets it’s DHCP from the ‘main’ router.

    What do you think of WDS? How is this very different from Client Bridging? Have you any experience with the newst (alpha) verson of DD-WRT, v24? I’m told it may have a feature called repeater in the firmware that will give another option to what I’m trying to accomplish.

  4. Chris Says:

    If the laptop has a wireless connection to your network, I’ll maintain that data flows as I stated in my previous comment. If both the laptop and the other computer connect with the ‘bridge’ by cable, the situation is different and data will flow like you say (but most likely at a different rate, since the switch-part of your router is probably 100 Mbps?)

    I think you are trying to accomplish something different from what I have done with the wireless bridge: I think you are trying to extend your wireless coverage, no?

    I have adequate wireless coverage all over my house, I just need cabled connections for one room full of computers - it is not convenient to run cables between that room and my ‘main’ router and I don’t want to buy wireless adaptors for every computer in the room.

    For your purposes, WDS may be what you are looking for. I considered WDS when I decided on what to do about my ‘cables-are-not-convenient’ situation. As far as I know, WDS does extend wireless coverage, but the setup is more complicated than the wireless bridge setup. Furthermore, with WDS the different routers each maintain their separate network subnets and machines connected to different routers cannot ’see’ each other. NAT wizardry can compensate for this segmentation, but adds to the overall complexity of the setup.

    WDS is much too complex for my purposes - the wireless bridge is transparent so all my machines are on the same subnet. And the setup is stable. Since putting up the bridge in November last year, I have had to reestablish the connection between the ‘bridge’ and the ‘main’ router twice: once when I reconfigured the bridge and once because of a power failure.

    I am not familiar with DD-WRT v24, but repeater functionality sounds most interesting!

    /christopher

  5. Gravatar Patrick Thomas Says:

    Ah well, thanks Christopher for all of your help. I’m sorry that I wasn’t able to get the network up and running =/
    I’ll use WDS for the time being until I can purchase another WRT54G to match with the one I have now. I’ve deduced that the problem is with my Belkin F5D7230-4, as I’ve been notifed that there are problems between the firmware/hardware on DD-WRT.com’s forums.
    Thanks again, good luck with your network =)

  6. Gravatar AJ Wilcox Says:

    I saw the same results as Patrick while trying to configure my linksys 54G dd-wrt router to pick up my neighbor’s signal at an apartment complex to share his connection. I followed all the steps to set up a client bridge thinking it would extend the wireless coverage to my apartment, and was sorely confused when it didnt work. Thanks Chris for your explanation why it doesnt work. I will further look into the new v24 firmware’s repeater function. The problems i saw were that the only signal i actually picked up was the original from the host, and the client went completely under the radar.

  7. Gravatar david Says:

    I am a little confused.. I am using DD-WRT as well and have it set up correctly as a bridge to my main router (both WRT54Gs) but once I have it in client-bridge mode I have no idea how to open the administration panel (I can’t even telnet into the bridged router). Does the router (which I gave it’s own IP) still exist on the internet somewhere or is it essentially transparent? Is the only way to fix it reset the firmware and reset it up?

    I’ll check back here but if someone could ping me at david.g.yang at gmail dot com I’d appreciate it a lot.

  8. Chris Says:

    David, which IP did you assign (static) the WRT54G in client-bridge mode and are you sure: 1) DHCP is disabled on this router and 2) The assigned IP is outside the IP range used by DHCP on the other router?

    You should be able to just enter the IP address in a browser and access the admin panel.

    ‘Transparent’ does not mean that you cannot access the router - it means that clients communicating with each other across the bridge are oblivious to the bridge (technically, this does not appear to be true - see discussion in the DD-WRT forum - but if you are “just” running a home network it should not affect you. I have not experienced any problems).

    /christopher

  9. Gravatar Eric Says:

    Chris,

    Thanks! Your instructions were the simplest I found and they worked! I have one small problem, though, the computer I have connected to the bridge is recognized only when I set it up as a DHCP client. If I manually assign it an IP address it loses connectivity - can’t get out and it is not found on the network by other computers. Any suggestions would be appreciated.

    Thanks, again.

    Eric

  10. Chris Says:

    Hi Eric, thank you for your feedback - I’m really glad if this stuff is useful to you.

    Off the top of my head it sounds as if the IP address assigned statically to the computer clashes with the IP of another client on the network. That is, the same IP address is being assigned to two different clients.

    Have you double checked the addresses you assign statically and the addresses assigned by the DHCP server?

    /chris

  11. Gravatar naisioxerloro Says:

    Hi.
    Good design, who make it?

  12. Chris Says:

    @naisioxerloro: I am not sure I understand your question: who made what?
    But thanks for stopping by :-)

  13. Gravatar MOZ Says:

    I setup my wireless bridge for my xbox 360 using these instructions..http://www.wi-fiplanet.com/tutorials/article.php/3639271 .. hooked up the DD WRT router to the 360 and Presto .. everything works fine.. but i went downstairs to turn on my lap top and check some stuff online.. the lap top usess a wireless connection as well to the mian router.. but when i turned it on it would not connect to the internet..till i unplugged the DD WRT router that was connected to the xbox? any ideas Thankyou

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