Wireless Controller
Dedicated Wi-Fi control and management for high density and mobility
yashaswinits_FTNT
Article Id 193829
Description
This article discusses some points which will affect the wireless performance with more SSID’s in WLAN.

Scope
WLAN - MC3200, MC4200

Firmware 5.3-164, 6.1-2-29

Solution
The more SSIDs on the network, the more advertisements or beacons that are constantly going out over the air for those SSID’s.  This takes up shared airtime on that channel, since wireless is an unlicensed spectrum.

As the number of devices needing to transmit frames increase on the channel, congestion can occur to the point where devices spend more time receiving than sending which leads to more retries.

Re-transmissions result in slower speeds because it takes longer to successfully send a single frame.

The downside of enabling more SSIDs is that it creates more channel utilization due to overhead.

Beacons and probe responses are two types of required wireless management frames that can increase channel utilization.
  • Beacon frames are used by the AP to advertise the SSID and inform connected clients that frames are waiting for delivery.
  • Each VAP must send a beacon every 100ms at the lowest supported data rate so all clients can receive it.
  • As the number of wireless networks operating on a specific channel increase so does the amount of beacon frames and probe responses.
Therefore it is always advisable to the limit the number of SSIDs configured on the WLAN in order to reduce the amount of overhead on the network and to maintain high performance.

Wi-Fi operates in unlicensed spectrum and everyone shares the airtime.

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