Configuring your routers

The exact configuration of your routers is determined by what purpose the link is to be used for. In our example we are going to create a simple point to point link using WDS. Although the DD-WRT firmware is capable of far more imaginative things than WDS some readers will elect to use the standard firmware that ships with the router they have chosen to use and WDS is a common thread in most decent firmware. Our intention will be to join two geographically seperate networks together in such a way that computers in one location will be able to use file shares, printers and even internet access available in the other location and vice versa.

To create a simple link using WDS we really only need to attend to a few things in the routers configuration for the link to work. For the link to join successfully the routers must use the same WEP key, SSID and channel. They must also be assigned IP addresses that dont conflict with each other and we should disable the DHCP server on at least one of them to avoid a conflict. If you are unsure of what these things are once again we must direct you to our sister site's basic networking guide to do some study before you attempt your configuration.

We shall start with router no 1 and log into its web interface. Make notes of the settings you choose because most of them will need to go into the second router. The DD-WRT firmware has two rows of tabs up the top. On the top row click on set up and make sure you are on the basic setup tab on the second row. We need to change the following configuration options-
  • Set the Internet Connection Type to Disabled
  • Change the IP address from the default, we have chosen
  • Disable the DHCP server
  • You may elect to assign the WAN port to the switch, which will give you an extra ethernet port
Click on Save Settings at the bottom of the page and the router will most likely reboot. Once it has rebooted click on Wireless on the top row of tabs and ensure you are in the Basics Settings tab on the second row.
  • Select AP as the Wireless Mode
  • Set Wireless Network Mode as Mixed
  • Change the SSID to something you like, we chose diywireless. Avoid capitals and spaces for simplicity's sake
  • Select a channel, we selected 10 as a lot of devices that work on 2.4Ghz default to 6. This can reduce noise.
  • Wireless SSID broadcast can be enable or disabled and determines if your link can be seen on a scan for networks. I suggest leaving this on during configuration and disabling it once the link is running, preventing it from being seen so readily.
Click on the save settings button down the bottom and then navigate to the Security tab on the second row. Unfortunately we are limited to WEP encryption as WPA encryption is not compatible with WDS, regardless of what type of router you choose.
  • Set the Security Mode to WEP
  • Ensure the Default Transmit Key is one
  • Select 128 Bits Encryption
  • Type your WEP key into Key 1. It should be Hexadecimal (numbers 0-9, letters A-F). Make a note of it as the other router will need the exact same key.
Click Save Settings on the bottom of the page. The next step is to go to the advanced settings tab on the second row of tabs. Changing the TX and RX antennas to right means that they will transmit and recieve on the same antenna which allows us to connect the cable to the external to only one fitting on the back of the router. Nominally on the WRT54GL this is the connector on the right facing the front of the router.
  • Change the TX Power to 100
  • Change the TX antenna to right
  • Change the RX antenna to right
Click Save Settings on the bottom of the page. Now the router is set up as a basic Access Point we can repeat the above process on router No 2. The only difference between the two routers at this point should be the IP address, which should be different to avoid a conflict. In our example we shall set router no 2 to

All that remains is to create the WDS link itself. Seeing that both routers now have IP addresses that wont conflict with each other we can open their web interfaces up concurrently and do the WDS configuration easily, particularly if you have a browser with tabs such as IE 7 or firefox. On each router go to the Wireless tab on the first row and WDS on the second row. You will see that the routers display their own Wireless MAC address at the top of the page. Select LAN on the first WDS configuration and type in the MAC address of the other router, ie type router no 1's MAC address into router no 2 and vice versa. Click save settings down the bottom of the page. Wait for the settings to save and then restart both routers, disconnecting one from the network. When they have both restarted your link should be functional and you should be able to ping both routers and visit their respective configuration pages. If you go to the status tab up the top and select wireless on the second row you will come to the wireless status page. At the bottom of this page is a section marked WDS nodes that displays the signal strength of each node attached to the router you are looking at. When installed they should have a SNR (Signal to Noise Ratio) of at least 20 to be considered a good quality link.

Although we have our link functioning on the bench there are a few further things we need to consider. As they are currently configured the routers are pure bridges and they will pass all traffic between the two points. They will also accept connections from other wireless devices other than each other which may not be highly desirable on a long link. So consider the following points as good practice for tightening up your network or adding functionality.

MAC filtering will allow you to control who connects to the link by ignoring MAC addresses that you have not specified as being allowed to connect. On the DD-WRT firmware this is access by clicking on the Wireless tab on the first row of tabs and selecting MAC Filter on the second row.

Maximum Associated Clients in the Wireless Advanced Settings tab when set to 1 will prevent additional connections.

Change the routers admin password in the administration tab to prevent them from being reconfigured by anyone other than yourself. Make sure you remember this password!

DHCP or Dynamic Host Configuration Protocol allows devices on the networks that you have bridged to receive an IP address automatically. You can enable the DHCP server on ONE of the routers to provide this service to computers or devices on the network. If one of the locations has a broadband connection that both locations will use to access the internet then using the DHCP server built into the router that performs this connection will allow all clients to easily get an appropriate IP address to access the net. Avoid having more than one active DHCP server on your network or the results may be interesting.

Explore the DD-WRT firmware if you feel you have suitable knowledge to do so. DD-WRT is powerfull stuff and we have barely scratched the surface of what it can do. Additional functionality is there and just needs to be unlocked.