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How can I change the way Macbooks roam on the WiFi network? I would like to speedup the roaming of Macs (and maybe other devices).

Is there a setting on the Airport base stations or in Mac OS to speedup AP switching for example?

Currently the network is built around 1 main Switch interconnecting 1 router and 4 Airport base stations using the same SSID:

  • 3 dual band Airport base stations
  • 1 Airport 2.4GHz base station

On the 5GHz band, there is no overlap as each base station uses its own channel.

On the 2.4GHz band there is a very slight overlap between 2 base stations which are at opposite sides and at different stories of the building.

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What exactly is the problem you are experiencing? Is switching networks slow for you? Under which conditions are you switching networks? –  Gerry Oct 10 '12 at 11:59
    
@Gerry: When moving from one room to another I loose the connection just long enough for airplay to stop, file shares to stop responding, and Time Machine sometimes manages to keep on going but sometimes not. It will be a major issue for the users using the WiFi network. –  Coyote Oct 10 '12 at 12:02
    
Are you moving between access points with different names, or do the different access points all have the same names? –  nthonygreen Oct 10 '12 at 13:31
    
@anthonyg I updated the question with more details. Yes they use the same SSID each is setup to different channels, on the 2.4GHz band there is no or negligible overlap. –  Coyote Oct 10 '12 at 14:16
    
Thanks for pinging this - 10.10 now roams automagically and I've updated my wrong answer. –  bmike Apr 12 at 16:55

5 Answers 5

up vote 10 down vote accepted

You can change the system preferences for JoinMode and JoinModeFallback to be the following:

    JoinMode (String)
        Automatic
        Preferred
        Ranked
        Recent
        Strongest
    JoinModeFallback (String)
        Prompt
        JoinOpen
        KeepLooking
        DoNothing

Do this using the airport command:

/System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/airport

Run the command to see the options, up the top you'll see a section on how to sec preferences.

For instance:

sudo /System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/airport prefs joinMode=Strongest
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Just used joinMode=Strongest and this fixed any issues I had with slow Wifi switch! Thanks a lot. –  Nivco Jan 26 at 1:48
    
This should be the approved answer btw :) –  Nivco Jan 26 at 1:48
1  
@Nivco - Did you run a command from Termianl to set joinMode=Strongest? I'm not sure if I did it right and not sure how to check. Any help would rock! –  Koby Jan 26 at 17:55
    
Yes I just ran the command on the terminal. You can check values have changed by using /System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/air‌​port prefs it should print out a line that says JoinMode=Strongest –  Nivco Jan 29 at 1:05
    
Does this only apply if you're using Apple Airport products, or with any wifi routers? Does it work in Yosemite? (I'm finding it has no effect with Netgear/TP Link routers in Yosemite) –  Stephen Lead Mar 31 at 8:27

Apple has introduced roaming across it's ecosystem with iOS 8 and OS X 10.10. You don't need to do anything as it's turned on by default. So, you can just update your OS on the Airport basestations as well as install Yosemite to take advantage of the changes.

Prior Yosemite, I've not seen instructions on how to enable this so I believe it's part of the drivers that were updated for 10.10.

The software was designed to keep a fair connection alive as long as possible rather than hop around always looking for a better connection. Now that AirPlay and AirDrop and continuity exploit the MIMO antennas that are shipping across the Apple hardware ecosystem, we now get better roaming since the hardware is more capable.

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I have the same problem but don't have an answer. However, I may have a path for further exploration. The airport utility on ML still has a legacy option to perform a WiFi network scan.

airport -s           # full scan
airport -s<SSID>     # scan only for SSID

The tool is under

/System/Library/PrivateFrameworks/Apple80211.framework/Resources/airport

and my suspicion is that triggering a scan also triggers a handover if another base station is better since the results are sorted by signal strength. Having said that one could write a tool which pings the default gw and triggers a scan on packet loss. If I have some time I will give it a shot.

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If you get some good results with that keep me posted. –  Coyote Jun 23 '13 at 11:55

Try a same channel setup - configure all APs to the same channel. That way the device can pick up the signal strengths of the other APs without having to scan all channels. You will limit the maximum throughout though, depending on the number of clients

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This sounds counter productive, all recommendations (CISCO, Apple, Alcatel...) are to setup all APs to avoid geographical overlap. But in areas where I have 2 to 4 devices per AP I will try your suggestion and see how this works out. –  Coyote Dec 28 '14 at 14:12
    
I know - that's why I always had configured different channels, but ended up with poor signal quality all the time when running around. I made a small iOS app displaying the MAC of the currently connected access point and noticed that wifi clients (at least the iphone) seem to like to stick to the current AP as long as possible. When I changed the setup to same-channel I noticed that the AP roaming is much more aggressive. –  Moritz Feb 9 at 14:44

I face this issue in small businesses that with OS X. I have yet to find a good solution other than disconnect and reconnect to grab the closer IP.

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In my setup the IP is assigned by the same DHCP server for all APs. All devices are on the same network with the same IP range. –  Coyote Apr 25 '14 at 21:40

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