Since I got the new ASUS RT-N16, the old Linksys WRT54GL v1.1 router has been sitting there and collecting dust. There is only one phone line at home at one corner of the house, so I have been thinking of using the idle router as a WiFi repeater so that I can get decent WiFi coverage for each room.
Finally I found some time this weekend and studied about it. Many online tutorials cover how to do it using DD-WRT, another great customized firmware for WiFi routers. Since my RT-N16 already runs Tomato, I'd want to find a way to have Tomato on WRT54GL and work as the repeater as well.
After digging into the Web searches, finally I found Tomator author's FAQ for WDS, it is very straightforward. Basically, both both master and repeater routers need to set "Wireless Mode" into "AP and WDS". You also need to turn off dhcp and wan (turn WAN/Internet type into "disabled") on the repeater. Then you configure WDS to "Link with..." each other's MAC address (note this is the Wireless MAC address, not router's MAC address).
WDS stands for Wireless Distribution System, it enables interconnections between access points (AP). Wikipedia definition has more technical details. Ideally, using WDS we can chain more APs together, just make sure you don't keep any loop ;-)
The beautify of this is that it uses the same ssid, so when you move around, it switches to the router with the best signal strength automatically.
To test the signal strength, there is a nice free tool for Mac called AP Grapher, very handy indeed.