Potential-master state kicks in when the existing Master goes down or becomes unreachable.
- The IAP waits for election wait time to move from slave to Potential master.
- If it hears any beacon during this time, it moves back to salve.
- If it does not hear any master beacon it becomes a potential master.
- As soon as an IAP becomes a potential master, it starts sending Master-beacon as Broadcast packets in the subnet. These packets are sent with a parameter mentioning that these packets are being sent by a pot-master.
- Pot-master also tries to reach the last known master through unicast messages for the election wait time.
- If the previous master is still not reachable and the election wait time is over, it transitions into the Master.
Environment : When Multiple IAPs are part of the same subnet and on failure of master a slave transitions to Pot-master and then to Master.
Master election process is built in to the code. No specific configuration required.
As the AP becomes a Pot-master, it starts sending Master beacon with pot-master flag state set. Below master election related messages can be seen by using “debug-master-beacon”.
Potential master also tries to reach its last known Master through unicast (00:24:6c:cb:a5:3f).
In the above screen shot it can been seen that events “Slave->Pot-Master : 1 time” and “Pot-master->Master: 1 time” have taken place once each.
Troubleshooting can be done using command "debug-master-beacon", "show election" and "show summary"