Multiple access point with same SSID but all connections goes to only one access point

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4

So I have three multiple access points with same SSID, installed within 60 ft of each other.

AP1 - Ch 1 - Linksys WAP4400N
AP2 - Ch 6 - Linksys WAP4400N
AP3 - Ch 11 - HP V-M200

95% ~ 100% of client connections seem to connect to HP V-M200 AP. I've tried switching around channels. But majority(19 of 20 client stations) connect to HP V-M200 AP.

Any thoughts on why this would be, and how it determines which AP channel to connect to?

takethephil

Posted 2011-12-13T16:48:07.447

Reputation: 91

2The HP has a stronger signal... Just a guess. You should get a wifi analyzer to see what is putting out the stronger signal 60ft is pretty close. Also what clients? – Supercereal – 2011-12-13T17:17:59.700

Client devices are ranging from windows, mac, iphone, ipad... even eprinter =] – takethephil – 2011-12-15T00:42:35.457

Answers

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The IEEE 802.11 standard does not specify how a client should determine which AP it should connect to; it's left up to the equipment vendors as an implementation detail.

Clients usually just connect to whichever AP has the strongest signal coverage where the client is. It might be interesting to use a tool that does 802.11 scans and reports the signal strength (RSSI) for each AP it sees (and breaks them out separately even if they're all publishing the same SSID), and see if your HP AP's signal is stronger from the client's perspective.

Enterprise-class equipment vendors understand your predicament. If you want to maximize bandwidth for a lot of clients in a small area, you want to put APs on 1, 6, and 11 in that area, and have roughly equal load on each of the APs. But there's no way in the standard to guarantee that clients will do what you want unless you set separate SSIDs. Some vendors of enterprise-class APs have shipped features that try to work around this from the AP side, and some vendors have tried to get client card vendors to be sure to work with their system (example: Cisco's CCX program), but I'm not sure how well any of these attempted solutions really work. There's even been some work on addenda to the 802.11 spec to help clients make better roaming decisions, but I'm not sure how well those things have been adopted.

Spiff

Posted 2011-12-13T16:48:07.447

Reputation: 84 656

I'm using wavemon under linux to see how strong which access point is received. You need to run it with root priviliges to be able to use the scan feature. – Christoph Grimmer-Dietrich – 2015-09-18T14:19:59.163

1Excellent answer. Side note: we switched to Ruckus from Cisco to combat this issue with barcode scanners. They offer a device called a zone director which manages the aps and will actually lower or increase signal to based on client location. It also accepts CAD drawings to make coverage very precise. – Supercereal – 2011-12-13T19:29:24.833

Great answers. Zone director sounds very interesting, and wonder how other vendors are addressing this issue. I know most of major vendors have "centralized" access point managing system. Wonder if they address this issue. – takethephil – 2011-12-15T00:49:31.607