Open Flow Control Messages are based on TCP. To set up Open Flow communication, Open Flow Controller listens TCP ports 6633/6653.
There are five main parts in Open Flow Messages. These are given below:
• Message Lenght
• Transaction ID (A unique value section used to match requests for response)
• Controller to Switch
Controller to Switch Messages are the massages that is used to manage and configure the switches . They managed the Flow Tables. Switch capability exchange is also done with these messages. Controller to Switch Messages are initiated from the Controller.
Asyncronous Messages are sent to inform the Control about any events and state changes. Asyncronous Messages are sent by Switches.
Symmetric Messages are used to diagnose any problems between Controller and Switches. Symmetric Messages can be sent both from Contoller and Switches.