6.1 Non-Call Related Procedures
23.3333GPPMultimedia Resource Function Controller (MRFC) - Multimedia Resource Function Processor (MRFP) Mp interface: Procedures descriptionsRelease 17TS
6.1.1 General
The non-call related procedures are based on corresponding procedures of 3GPP TS 23.205[7] when the MRFC takes the place of the MSC server and the MRFP takes the place of the MGW.
6.1.2 MRFP Unavailable
The MRFC recognises that the MRFP is unavailable in the following 4 cases:
1. The signalling connection is unavailable
Figure 6.1.2.1: Signalling connection failure
2. The MRFP indicates the failure condition to all connected MRFCs
Figure 6.1.2.2: MRFP indicates the Failure/Maintenance locking
The failure indication indicates that the MRFP will soon go out of service and that no new connections should be established using this MRFP. The MRFP can choose between the "graceful" and the "forced" method. In the graceful method the connections are cleared when the corresponding calls are disconnected. In the forced method all connection are cleared immediately.
3. The MRFC recognises that the MRFP is not functioning correctly, e.g. because there is no reply on periodic sending of Audits. The periodic sending of Audits by MRFC should persist.
4. The MRFP indicates the maintenance locking condition to all concerned MRFCs.
The maintenance locking indication indicates that the MRFP is locked for new calls and that no new connections shall be established using this MRFP. The MRFP can choose between the "graceful" and the "forced" method. In the graceful method the connections are cleared when the corresponding calls are disconnected. In the forced method all connection are cleared immediately
In all of the above cases the MRFC shall prevent the usage of the MRFP until the MRFP has recovered or the communication with the MRFP is restored.
6.1.3 MRFP Available
The MRFC discovers that the MRFP is available when it receives an MRFP Communication Up message or an MRFP Restoration message. When the MRFC discovers that the MRFP is available the following shall occur:
1. Signalling recovery
The MRFP indicates to all connected MRFCs that the signalling connection is restored.
Figure 6.1.3.1: Communication goes up
2. MRFP restoration/maintenance unlocking indication.
The MRFP indicates to all connected MRFCs that normal operation has resumed.
Figure 6.1.3.2: MRFP indicates recovery from a failure/or maintenance unlocking
NOTE: This procedure may be used after recovery from a signalling failure.
3. The MRFC recognises that the MRFP is now functioning correctly, e.g. because there is a reply on periodic sending of Audits.
After this the MRFC can use the MRFP. If none of 1,2, or 3 happens the MRFC can initiate the MRFC Ordered Re-register procedure.
6.1.4 MRFP Recovery
If the MRFP recovers from a failure, is maintenance unlocked, or it has been restarted, it registers to its known MRFCs using the MRFP Restoration procedure or the MRFP Registration procedure. The MRFP can indicate whether the Service has been restored or whether it has restarted with a cold or warm boot. The response sent to the MRFP indicates a signalling address to be used by the MRFP.
Figure 6.1.4.1: MRFP Restoration
Figure 6.1.4.2 MRFP Registration
After the recovery the MRFC can use the MRFP.
6.1.5 MRFC Recovery
6.1.5.1 General
If an MRFP-unavailable condition is provoked by a failure/recovery action, the MRFC recovery sequence will, from an information flow point of view, look like MRFP unavailable and then MRFP available. If an MRFP-unavailable condition is not provoked, the MRFC recovery sequence will look like MRFP available.
After the information flow, the terminations affected by the recovery action are released.
6.1.5.2 MRFC Restoration
Figure 6.1.5.2.1: MRFC Restoration
NOTE: Normal release procedure may also be initiated.
After the recovery action is complete and it is possible to signal to the MRFP the MRFC starts a timer Tw. If recovery indications are not received (MRFP Communication Up or MRFP Restoration) from the MRFP during Tw an Audit is sent. If the MRFC receives a recovery indication or MRFP communication up indication, it shall acknowledge the indication before the MRFC Restoration may be sent or the release procedure is initiated.
6.1.6 MRFP Re-register
When the MRFC requests an MRFP to perform a registration (see clause 6.1.7), the MRFP performs a re-registration to the MRFC which is defined in the MRFC address.
Figure 6.1.6.1: Re-registration of an MRFP
6.1.7 MRFP Re-registration Ordered by MRFC
If the MRFC knows that communication is possible, but the MRFP has not registered, the MRFC can order re-registration of the MRFP.
Figure 6.1.7.1: Re-registration ordered by the MRFC
If the re-registration request is accepted the MRFP uses the MRFP Re-register procedure to register with the MRFC.
6.1.8 Audit of MRFP
6.1.8.1 Audit of Value
The MRFC may request the MRFP to report the current values assigned to distinct objects in the MRFP.
Figure 6.1.8.1.1: Audit Value
6.1.8.2 Audit of Capability
The MRFC may request the MRFP to report the capabilities of distinct objects in the MRFP.
Figure 6.1.8.2.1: Audit Capability
6.1.9 MRFP Capability Change
The MRFP reports a change of capability of distinct objects in the MRFP.
Figure 6.1.9.1: Capability Update
The MRFC can use the Audit Value and/or Audit Capability procedures to obtain further information, about the objects whose capabilities have changed.
6.1.10 MRFC Out of service
Figure 6.1.10.1: MRFC Out of Service
If an MRFC discovers that it wants to go out of service it starts an MRFC Out of Service procedure. The MRFC can indicate whether it requires the context to be cleared immediately (forced) or cleared when all terminations are released.(Graceful)
6.1.11 MRFP Resource Congestion Handling – Activate
When the MRFC requires that an MRFP congestion notification mechanism be applied in the MRFP, the MRFC shall use the MRFP Resource Congestion Handling – Activate procedure towards the MRFP.
Figure 6.1.11.1: MRFP Resource Congestion Handling – Activate
6.1.12 MRFP Resource Congestion Handling -Indication
When the MRFC receives a load reduction notification from the MRFP via the MRFP Resource Congestion Handling – Indication procedure, the MRFC tries to reduce the processing load that the MRFC creates on the MRFP. The MRFP shall decide the actual level of traffic reduction.
Figure 6.1.12.1: MRFP Resource Congestion Handling-Indication