So Cal Free Net.org

Common problem: coverage is great at a window facing an antenna, but lousy inside. Our simple, cheap and effective solution: wireless to ethernet bridge hooked up to a cheap AP. We've been doing a lot of these recently. Here's a description of today's install for $130.

Background: As wireless support is becoming standard in laptops, more residents using our neighborhood wireless lan are requesting solutions that allow them to use their laptop wherever they want in the house, instead of 'by the window' which views the rooftop antenna. Or they want to 'break the tether' to the ethernet cable hooked to the 802.11b to our ethernet bridge kit perched on their window sill.

Something has happened in the past 12 months that makes this simple, cheap and effective - consumer grade access points are now very cheap. So, we've been installing an increasing number of 'mini relays'. These consist of:

• wireless to ethernet bridge, such as the D-Link 810+ ($60) and matching mini panel antenna ($30)
• consumer grade access point, typically including a four port hub, e.g. the D-Link DI-514 for $20-40

Total price, about $130. In the rest of this article, we'll talk about some of the installation gotchas.

First get the bridge working

In our typical install, there will already be a known good reception spot, and often a bridge already installed (usually one of our kits). This is a great position to start in, so get this going first.

Once the bridge is working, set the MAC address to match the access point its connected to. Some bridges, like the Linksys Wet-11, don't provide this feature. If it doesn't, that's ok, but as we'll see below its better if it does. The D-Link 810+ does provide this, so log into the web admin and configure it appropriately. (The simplest way to do this is via the built-in site survey tool. Upgrade to the March 2004 2.0 firmware if this doesn't seem to work for you.)

Configure the AP

The 'obvious' way to configure the AP is to plug the bridge into the WAN port and proceed as usual. However, we recommend not using the WAN port at all. Why? Because it adds another layer of NAT and generally more complications, especially with captive portals.

Instead, we suggest you plug the bridge into one of the (typically) four LAN ports. But before you do that, change the settings to:

• disable DHCP services, so your AP won't be handing out leases
• set the SSID. We have two standards for this. If we have a bridge that provides MAC configuration, we set the SSID to the same as the source, i.e. socalfreenet.org in our case. If you can't set the MAC, then you'll need a different SSID to stop the bridge from locking on to your new AP. We recommend socalfreenet.org/name.
• set LAN IP outside of range to ensure that the AP doesn't try and route or generally get in the way. For example, most consumer APs are set to 192.168.0.1 or similar. Our network mostly runs in the 10.12.x.x range, so we just leave the APs at their factory defaults. We've learnt the hard way that setting them to some IP in range, say, 10.12.nn.mm, causes routing problems.
• set the channel to channel 6 (different from the main AP). Our rooftop APs are typically on channel 1 or 11. We use these because they are less congested than channel 6. However we recommend channel 6 for these mini-repeaters because: a) we don't need much range from them, typically 50 feet through a couple of walls, b) we don't want to interfere with the rooftop APs.

Once you've done this, you should be able to plug the bridge into the AP and be online. Note that every new node you add to the network like this, extends the coverage. It also adds noise, so be judicious.

After you've got it working, its good to position the boxes as far apart as practical, but at least 3 feet and preferably at least 5. And, of course, put the bridge closer to the rooftop antenna than the new AP.