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Bridged Connection Woes

Last response: in Networking
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July 5, 2012 5:07:53 AM

So I'm in a bit of an interesting networking situation.

I just moved in to a studio with the promise of internet included in utilities. Turns out that the internet is provided in the form of a wireless network in the main house. It works, but I have some wired devices that I need to set up. I have a desktop running Win7 with a usb wireless adapter that I have bridged to its Ethernet connection. On the Ethernet connection I have a wireless router configured as a switch.

For some reason, it seems like router in the house (actually a Qwest DSL gateway) is only seeing the MAC of the Win7 desktop and every device on the bridged Ethernet connection is getting the same IP as the desktop. I'm trying to get my web server up and running so I set a static IP on it and I can get to the internet from it, but anything trying to get to the Ethernet side of the bridge from the wireless side (in other words, any internet connection) can't connect. I can access my web server by IP from the desktop or my laptop connected to the same switch but when I connect to the wireless network and try to access the server, it can't connect.

It seems like a problem with the bridge? A limitation of the bridge implementation? A router configuration issue? (I do have access to the gateway configuration)

Any ideas would be greatly appreciated.
July 5, 2012 1:39:54 PM

Hopefully your wireless router (now configured as a switch) has its DHCP server DISABLED and is connected LAN to LAN w/ the bridged laptop (not ICS, just a simple bridge).

[primary wireless router]<-- wireless -->[bridged laptop](lan)<-- wire -->(lan)[switch (no dhcp, no radio)]<-- wire(s) -->[wired device(s)]

As long as the primary wireless router is using a private network (e.g., 192.168.1.x) and its own DHCP server, it should work. If it doesn’t, then there’s some other piece of missing information that would explain the problem.
July 10, 2012 9:53:43 PM

Thanks for the quick response, and sorry it took so long to reply.

The setup is as you have described. The connection is bridged, not ICS. I actually removed the router/switch from the scenario and connected a computer directly to the bridged Ethernet port and it still gets the same address as the bridge machine from the DHCP server.

[primary router]<--wireless-->[bridge computer]<--wire-->[laptop]
192.168.0.1------------------192.168.0.17---------------192.168.0.17

Those are the IPs given dynamically and even if I set a static, any device on the wireless side of the bridge cannot connect to it, even though it can ping out and receive a response.
July 10, 2012 10:17:15 PM

Can't be. Something is amiss here because this is a VERY basic configuration. It's done all the time. Make sure before you bridge the wireless and wired network connections, that each is set to DHCP, and THEN bridge them.

Once the bridge is created, it creates a single, logical ethernet connection for both the computer and laptop. As each device makes its respective DHCP requests, they'll be received by the primary router's DHCP server and each sent a unique response.

If that's not working, if somehow they end up w/ the same IP address, that's truly odd and maybe something funky (technical terms for "I don't know") is happening on the router. Again, this is a VERY simple configuration. It can only be screwed up if something else is being done here I'm unaware of (MAC filtering, static rather than DHCP config, etc.). If all else fails, have the primary router rebooted and try again.

!