4.4 SSTP Layer Teardown

This protocol uses forceful teardown through the Call Abort message in addition to graceful shutdown through the Call Disconnect message.

The Call Abort message is used in situations in which the SSTP control channel negotiation has encountered a problem such as a time-out, an invalid message, or other similar problems. The Call Abort-based shutdown uses short timers for quick cleanup.

Graceful shutdown occurs when the Call Disconnect message is sent to the far end. The far end responds by sending a Call Disconnect Acknowledge message in order to signal the end of data transfer.

SSTP graceful shutdown

Figure 7: SSTP graceful shutdown