There are 4 states in which an Instant AP can be with respect to Master Election. They are
- Local or Slave
- Pot-Master (Potential Master)
Environment : Multiple IAPs with same image version connected to a single subnet.
Master election happens by default. No specific configuration required. If configured for standalone, that IAP will not take part in Master election process though its part of the same subnet.
Initial – This is the state of the IAP when it boots up or listens for master beacon initially.
Local or Slave – As soon as the AP hears a Master beacon during its wait period, it becomes a Local or Slave IAP.
Pot-Master – An IAP becomes a potential master if it does not hear any Master Beacon during the initial wait time. This State helps multiple IAP from becoming Master simultaneously and helps in conducting an election for competing potential masters.
IAPs in Potential master state send out Master Beacon with a flag mentioning they are currently potential master.
Master – Post Successful election of an IAP as master, the IAP takes up the functionality of the Virtual Controller. If any master beacon is heard on the subnet by the Master, then an election is triggered. Whoever has the highest priority wins the election and becomes the master.
Below command can be run on a master to check information pertaining to master election and master beacons sent.
On running the same command on local provides the number of received master beacons and election wait time.
If the original Master goes down and a new IAP is elected as master, below will be the show election output. It can be seen from the output that the IAP has transitioned from Slave to Pot-master once and from Pot-master to Master once.