The Control End Point is used to connect, maintain and disconnect the Tunnel Connection. To be more precise, Control of the Tunnel Connection is the only thing the Control End Point does. The Control End Point sees very little traffic, only 2 or 3 messages to connect or disconnect and 1 or 2 messages per minute to maintain the connection.
The Maximum Received Packets Que Size (see Knx Device/Comms Connections) controls the size of the Control End Point’s receive queue and it has a default of 5. If this value were too small, there would be an indication of lost frames in the hidden Rx Frames Lost Queue Full Communications Counter (see Knx Device/Comms Connections/Comms Counters).