Figure 9: Connection Teardown Procedure
The connection teardowns are initiated currently only by the sender application (source-initiated teardown). This can be later extended to having receiver-initiated teardowns also. The actions involved in a connection-teardown are illustrated in Figure 9.
The application initiates a teardown by invoking the Teardown_Request() call of the MyRTP library and provides with the connection identifier. The library then frames an Appl_Teardown_Src message and sends the message to the sender HEC. This contains as its payload the identifier of the connection to be torn down.
On receiving the Appl_Teardown_Src message, the HEC dispatches it to the Sender state machine, which invokes the Teardown procedure of the algorithm. It then frames a Net_Teardown_Src message with the LCID of the connection in the payload and forwards it to the connected SEC.
The SEC on receiving a Net_Teardown_Src message dispatches it to the correct state machine, after determining the output port from the LCID value. This then invokes the Teardown procedure and forwards the message to the next SEC, after reframing it with new header information and LCID local to this SEC.
The destination HEC on receiving the Net_Teardown_Src message finally dispatches it to the Receiver state machine which again invokes its Teardown procedure. Once the destination HEC is finished processing the teardown request, the teardown procedure is complete.