SSID signal idle mode?
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Hello,
I have a quick question about the signal level of multile SSIDs on the same EAP.
I ran Netspot to check the WIFI network in my surrounding and the signal strenght of my own network. And I made a strange observation. My EAPs have two active SSIDs, one for the private network and one guest network.
In Netspot the signal level of the guest network was always or almost every time on the same level. On the same EAP the private SSID had very intermittent signal strenghts/levels oing down to zero or no signal in Netspot. Again, at the same time the gust network SSID on the same EAP has had a constant signal level. Both on 2.4G.
The guest netwok has no client connected. The private SSID only one client with almost no traffic.
When I truned off the 5G frequency on this EAP and forcing all clients to the 2.4G network then suddenly the sinal level in the 2.4G netwok went up and was running without interruptions.
Could it be that the EAP (or the controller) idles SSIDs in certain frequencies if there is no traffic? If so, why is the Guest SSID still on the same contant high level with no client connected?
Thanks
Regards
P.S. The EAP and the controller are on the latest firmware version.
Yes and no (depends on how you define a SSID being »idle«).
WiFi signals are pulsed signals and a WiFi network is a shared medium. APs don't send WiFi signals constantly nor are the signals on a (strictly) constant level.
Multi-SSID networks are Virtual APs, which means that the same physical radio just emits beacons with each of the configured SSID alternately.
Depending on when and how long an analyzer scans the frequency bands it collects several beacons from surrounding APs for a certain (very short) time. Thus, it can see the SSID in question at one time, but doesn't see it at another time when doing scans.
Below is a NetSpot scan showing two SSIDs from an EAP225-Outdoor, one guest SSID and one private SSID, one client (running NetSpot) connected to the private WLAN. As you can see, the SSIDs seem to »go away« alternately (the green and red graphs) for as long as 55 sec. at the time the screenshot was made, but this just means that the beacon for the private (or the guest) SSID couldn't be captured in the short time window of NetSpot's scan. Consequently, the signal level seems to go to 0% for one of the SSID.
The WiFi network is not really »idle« or »away« in the long run, except if you consider the time between occupation of the WiFi channel by the AP for sending data (which includes the beacon carrying the SSID) as idle. Then yes, it always idles between acquisitions of the WiFi channel, but data could be received anyway by some radio associated with the AP while the AP doesn't need to send data for itself, be it the beacon carrying the SSID or any other data.
Every radio (not only APs) always releases the WiFi channel regularily to give other radios a change to send something. The time a radio can acquire the channel is called »AirTime«. The more radios are actively using the same channel, the smaller is the amount of AirTime each radio can acquire. Noise (the dashed lines in the graphs) can also have an impact on availability of the WiFi channel for the radio. Signal levels might change over time due to interferences, changes in the environment and/or transmit power control.
Thus, nothing to worry about.
