Asynchronous Configuration
Asynchronous messages may need to be sent to multiple controllers. An asynchronous
message is duplicated for each eligible OpenFlow channel, and each message is sent
when the respective controller connection allows it.
A controller can also control which types of switch asynchronous messages are sent over its OpenFlow channel. This is done using an asynchronous configuration message that has the filter setting for all the messages.
Different controllers can receive different notifications. A controller in the Master role can selectively disable notifications, and a controller in the Slave role can enable notifications it wants to monitor.
Each controller configuration block for active connection maintains its own asynchronous configuration setting for every role. The default initial configuration is shown in the following table.