Multiple WLANs/SSIDs, Different Signal Strengths

Unanswered Question
Jul 19th, 2007

Cisco WLC 4404 -

AP 1242

We have AP's that broadcast multiple SSIDs. In one specific area of the building, we have noticed the signal strengths are not the same for different WLANs/SSIDs. For example, a WLAN with SSID "Public WiFi" may have very poor signal strenth while SSID "Private" may have excellent strength... from the same AP. To add to the mix, it appears that different wireless chipsets/drivers see conflicting results.

Your ideas are most welcome!

I have this problem too.
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cespurgeon Fri, 07/20/2007 - 08:09

How is signal strength being measured on the client?

I have seen the same thing you report on Windows XP in the "show available wireless networks" with the reported signal strength bars showing different levels for two SSIDs from the same AP.

However, I noticed that the bars would re-adjust when the client was actively associated with the SSID. In my case, an SSID with 5 bars would suddenly reduce to 3 bars when associated. It pops back to 5 bars when not associated.

Checking the levels using netstumbler on the same laptop showed that both SSIDs were being seen by the client radio at approx the same power level, as you'd expect.

A Cognio spectrum analyzer on a separate laptop also confirmed the both SSIDs from the same AP were being seen at the same level at that location and that there was no signal interference other than the usual 802.11 activity on other channels.


sometechguy Mon, 07/23/2007 - 05:44


I have used the Cisco ADU utility for a survey as well as AirMagnet. There appears to be good, overlapping coverage (from the the different access points in the area) for the WLAN/SSIDs affected.

It seems to be an issue with older wireless chipsets and/or drivers. The strange part is that it does not seem to happen at other locations within the infrastructure.

We have a controller code upgrade scheduled this week. Though I doubt it will help with this issue, you never know...


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