Many folks use a second wireless router as a bridge to expand the reach of their main Wi-Fi network. Apple makes such a setup painless; it takes just a few clicks in Airport Utility, for example, to make an Airport Express extend your Airport Extreme’s wireless network. When you bridge a network this way, both base stations share one network name, and your Mac (or other Wi-Fi device) automatically switches between the base stations based on signal strength. But what if you want to know which base station you’re on at a given moment? Since the two bases sport the same name, that would seem to be impossible. Thanks to a tip from Macworld senior contributor Glenn Fleishman, I now know just how to do it.
First, you need to determine your base stations’ BSSIDs—the Basic Service Set Identification code that’s unique to each base. If you’re using Apple base stations, fire up Airport Utility, and note the AirPort ID for each base station listed. (Mine were different enough that I needed only to remember the first two characters for each base station.)
Next, launch the hidden Wi-Fi Diagnostics app included with Lion (which is found in the /System/Library/CoreServices folder and which we’ve covered in a previous hint). Choose the Monitor Performance option and click on Continue.
(Image Caption: Wi-Fi Diagnostics makes it easy to spot the moment your laptop switches from one bridged base station to the other.)
The graph that appears monitors your Wi-Fi signal’s strength, but the chart above it lists details about the base station you’re connected to—including its BSSID. You can resize the window from its bottom right corner, and you can also click and drag the resizing dot to make the chart portion of the window larger. If you’re using a laptop (or if you’re feeling buff and your desktop Mac has a long extension cord), you can then move your Mac around your home and watch the Wi-Fi Diagnostics log change as you hop between base stations.
Of course, if you find that your Mac isn’t switching between base stations where you’d expect it to, it may be worth relocating one or both base stations.