Answer- CSA provides a mechanism for an AP to notify the stations connected to it of its intention to change channels. This mechanism will allow for the WLAN to continuously choose the channel that is the least noisy and the least likely to cause interference.
When an AP changes its channel, an existing wireless clients may “time out” while waiting to receive a new beacon from the AP; the client must begin scanning to discover the new channel on which the AP is operating.
If the disruption is long enough, the client may need to reassociate, reauthenticate, and request an IP address.
Channel Switch Announcement (CSA), as defined by IEEE 802.11h, enables an AP to announce that it is switching to a new channel before it begins transmitting on that channel. This allows the clients, who support
CSA, to transition to the new channel with minimal downtime.
When an AP changes channel, it advertises certain information in Element ID=37 to indicate which channel it is going to and when.
This information helps the client to jump to the same channel and saves scanning time.
When CSA is enabled, the AP does not change to a new channel immediately. Instead, it sends a number of beacons (the default is 4) which contain the CSA announcement before it switches to the new channel. You can
configure the number of announcements sent before the change.
rf radio-profile <profile-Name>
csa-count <number of beacons with channel announcement>