6.2.6 Hanging Termination Detection

23.3343GPPIP Multimedia Subsystem (IMS) Application Level Gateway (IMS-ALG) - IMS Access Gateway (IMS-AGW) interface: Procedures descriptionsRelease 17TS

This procedure is identical to that of clause 6.2.1 apart from the IMS-ALG requesting the IMS-AGW to periodically report termination heartbeat indications to detect hanging context and termination in the IMS-AGW that may result e.g. from a loss of communication between the IMS-ALG and the IMS-AGW.

When the IMS-ALG receives a termination heartbeat notification from the IMS-AGW via the Termination heartbeat – Indication procedure, the IMS-ALG shall return a Termination heartbeat –Indication Ack (without an error) if the context id / termination identity combination exists in the IMS-ALG. If it does not exist, the IMS-ALG shall return an error and shall correct the mismatch, e.g. by requesting the IMS-AGW to subtract the indicated termination and to clear any associated context.

Figure 6.2.6.1: Termination heartbeat – Indication