Client Mode

Using the wireless device built-in to the WRT54GS in client mode allows it to be connected to the host AP just like any normal Linux machine. Once connected, standard Linux tools can be used to configure the network logistics. Possible tools include a bridge device from bridge-utils, proxy arp settings built-in to the kernel, and standard routing built-in to the kernel.

Unfortunately, using a bridge device does not appear to work for us no matter how we change the configuration settings. The default br0 device set up by OpenWrt on the WRT54GS should logically bridge the lan ports (vlan0) with the wireless adapter (eth1), but it does not appear to work. Placing vlan0 on its own bridge works fine and placing eth1 on its own bridge works fine, but when put into the same bridge, packets from eth1 cannot be seen on vlan0 and packets from vlan0 cannot be seen on eth1, effectively defeating the purpose of a bridge. Please let us know if anyone can get this configuration working.

The following example uses proxy arp settings to simulate the functionality of a bridge so that the WRT54GS and the host AP can operate on the same local subnet.

Assume there exists a main wireless AP that is already connected to the Internet with an internal IP of 192.168.1.1/255.255.255.0 using a SSID of mynet, and a 128 bit wep key of hex 11111111112222222222abcdef. The WRT54GS device will be assigned an IP of 192.168.1.17 with allowable local addresses in the subnet 192.168.1.16/255.255.255.240 (192.168.1.18-30 assignable)

Detach the wireless device (eth1) from the default bridge (br0) containing the lan ports (vlan0):

nvram set lan_ifname=br0
nvram set lan_ifnames=vlan0

Configure wireless device (eth1):

nvram set wl0_mode=sta
nvram set wl0_ssid=mynet
nvram set wl0_wep=on
nvram set wl0_wep_bit=128
nvram set wl0_key1=11111111112222222222abcdef
nvram set wl0_key=1
nvram set wifi_ifname=eth1
nvram set wifi_proto=static
nvram set wifi_ipaddr=192.168.1.17
nvram set wifi_netmask=255.255.255.0

Configure local IP address for lan (br0):

nvram set lan_proto=static
nvram set lan_ipaddr=192.168.1.17
nvram set lan_netmask=255.255.255.240

Modify default gateway and dns (modify IPs as appropriate):

nvram set wan_gateway=192.168.1.1
nvram set wan_dns=192.168.1.1

Set up arp proxy to simulate bridge (add a new script to /etc/init.d, or possibly append to the end of /etc/init.d/S40network):

echo 1 > /proc/sys/net/ipv4/conf/eth1/proxy_arp

Update DHCP server by modifying /etc/dnsmasq.conf:

dhcp-range=192.168.1.18,192.168.1.30,255.255.255.240,12h

Commit and reboot the WRT54GS:

nvram commit
reboot

This example can easily be modified to use different subnets on the two devices with simple routing used to connect the subnets. If interested, here is another HOWTO that provides a specific example of the routing configuration.

WET Mode

Setting the wireless device on the WRT54GS to WET mode is supposed to allow it to be easily configured to bridge the WRT54GS to an existing wireless AP. However, our experiences show no difference between setting wl0_mode=wet and setting wl0_mode=sta. Others have reported problems with attempts at using WET mode. We would be interested to hear from anyone successful in getting WET mode to work properly.

WDS Mode

The Wireless Distribution System, or WDS, allows two or more wireless devices to sync with each other to effectively bridge all of the wireless segments into one logical segment. As with a regular bridge, WDS connections are based on MAC addresses to avoid polluting the IP address space. A disadvantage of WDS mode is that the separate wireless devices communicate with each other via the same channel and radio, so the space must be shared and the bandwidth available reduced as a result. Another disadvantage is that the WDS implemented by different chipsets may or may not be compatible with each other, so using the same or similar wireless device for each of the segments is recommended.

Assuming two WRT54GS devices, device1 with internal IP address 192.168.1.1 and MAC address xx:xx:xx:xx:xx:x1, and device2 with internal IP address 192.168.1.2 and MAC address xx:xx:xx:xx:xx:x2, using wireless channel 6, the required settings to use WDS are:

At device1:

nvram set wl0_mode=ap
nvram set wl0_wds=xx:xx:xx:xx:xx:x2
nvram set wl0_channel=6
nvram set lan_ipaddr=192.168.1.1
nvram commit
reboot

At device2:

nvram set wl0_mode=ap
nvram set wl0_wds=xx:xx:xx:xx:xx:x1
nvram set wl0_channel=6
nvram set lan_ipaddr=192.168.1.2
nvram commit
reboot

Additional information on WDS Bridging can be found in the article from Tom's Networking.