Figure 5.

Connection handshaking mechanism of the 4g kernel. By executing connect, NEST calls add_connection of the corresponding connector in the connection infrastructure. This function creates a new instance for the connection, sets its parameters and starts the connection handshaking by calling check_connection. This function creates an instance of the check_helper class and calls send_test_event of the source node twice to send test events to the synapse represented by check_helper and to the target node, respectively. Both instances execute handles_test_event which, if the event cannot be handled, ends in the base-class implementation throwing an exception.