6 Recovery after SCC AS failure
23.3803GPPIMS Restoration ProceduresRelease 17TS
6.1 General
The following clauses show the requirements and information flows of IMS Restoration Procedures for the SCC-AS service interruption in each of the scenarios where they apply.
It is an optional feature to support SCC-AS restoration. If SCC-AS restoration is supported, it is required to support enhanced third part registration procedure described in 6.2.1 and enhanced service request procedure described in 6.2.2 together.
6.2 General Procedure
During the 3rd party registration, the SCC-AS should store extra SRVCC related information, i.e, ATCF-Path-URI, ATCF-Management-URI and g.3gpp.accesstype media feature tag if received as specified in 3GPP TS 24.237 [34] clause 6.3.2, in the HSS as Repository Data.
When a service request is received when assigned SCC-AS is down, the S-CSCF should forward the service request to a working SCC-AS and this SCC-AS should:
– download corresponding ATCF related information previously stored in the HSS and it should notify the ATCF with its own ATU-STI for SRVCC; and
– download corresponding g.3gpp.accesstype media feature tag (if exist) previously stored in the HSS and determine that PS to CS SRVCC is usable for UE as specified in 3GPP TS 24.237 [34] clause 6.3.2.
6.2.1 Enhanced Third Party Registration Procedure
6.2.1.1 Introduction
The restoration described in the clause 6.2.1 is an optional mechanism which applies for third party registration. The SCC-AS are optionally enhanced to store ATCF related information and g.3gpp.accesstype media feature tag (if received) in the HSS as Repository Data.
6.2.1.2 Description
Enhanced third party registration procedure is described in figure 6.2.1.2-1.
Figure 6.2.1.2-1 Enhanced Third Party Registration Procedure
21. For the first time the SCC-AS receives a third party registration of a served user, the SCC-AS shall store the ATCF-Path-URI, ATCF–Management-URI parameters and g.3gpp.accesstype media feature tag (if received) contained in the SIP REGISTER request as new Repository Data in the HSS. For the subsequent third party registration of that served user, the SCC-AS shall update the ATCF-Path-URI, the ATCF-Management-URI and the g.3gpp.accesstype media feature tag stored in the HSS as Repository Data with the new received value.
The SCC-AS may as well store this data locally, and then for the subsequent third party registration of that served user, if the ATCF-Path-URI, the ATCF-Management-URI and/or the g.3gpp.accesstype media feature tag (if received) contained in the SIP REGISTER request is different from previously stored one, the SCC-AS shall update the locally stored ATCF-Path-URI, the ATCF-Management-URI or the g.3gpp.accesstype media feature tag as well as that stored in the HSS as Repository Data with the new received value.
NOTE 1: The SCC-AS already updates STN-SR in the HSS using PUR/PUA command, then the SCC-AS may send the new Repository Data along with STN-SR in a single PUR (only if Update-Eff-Enhance feature is supported).
22. HSS updates data and responds back.
23 ~ 24. HSS sends the received STN-SR and C-MSISDN to update MME/SGSN as normal.
6.2.2 Enhanced Service Request Procedure
6.2.2.1 Introduction
The restoration described in the clause 6.2.2 is an optional mechanism which applies for service request. And SCC-AS is optionally enhanced to download SRVCC related information as Repository Data from the HSS and notify the ATCF with new ATU-STI.
Enhanced Service Request Procedure is based on enhanced third part registration procedure in 6.2.1.
6.2.2.2 Description
Enhanced service request procedure is described in figure 6.2.2.2-1.
Figure 6.2.2.2-1 Enhanced Service Request Procedure
1. The S-CSCF receives session service request message and it attempts to route the message towards the registered SCC-AS, that in the figure 6.2.2.2-1 is "SCC-AS1".
2. The S-CSCF detects the failure of SCC-AS1.
3. S-CSCF re-selects a new available SCC-AS, i.e. "SCC-AS2" e.g. by a DNS procedure or by configuration in the matched Filter Criteria of an alternative SCC-AS to provide services to the user.
4. The S-CSCF sends the message to the selected SCC-AS2.
5. After receiving the service request message, if no subscriber data is found, SCC-AS2 starts implicit registration procedure as normal (not displayed in figure 6.2.2.2-1). After retrieving required subscriber data from the HSS, the SCC-AS2 shall request the ATCF related information and the g.3gpp.accesstype media feature tag stored as Repository Data (if present).
6. If ATCF related Repository Data is stored in the HSS, it is received back by the SCC-AS2.
7. If ATCF related Repository Data is received by the SCC-AS2, it shall send a MESSAGE with its own ATU-STI towards the ATCF that is identified by received ATCF-Management-URI. If the g.3gpp.accesstype media feature tag is present, the SCC-AS2 shall determine that PS to CS SRVCC is usable for UE as specified in 3GPP TS 24.237 [34] clause 6.3.2.
8. The SCC-AS2 continues the session as normal.
Annex A (informative):
Change history
|
Date |
TSG # |
TSG Doc. |
CR |
Rev |
Cat |
Subject/Comment |
New |
|
CT#41 |
V1.0.0 was approved in CT#41 |
8.0.0 |
|||||
|
2008-12 |
CT#42 |
CP-080698 |
0003 |
– |
Re-selection of S-CSCF at de-registration |
8.1.0 |
|
|
2008-12 |
CT#42 |
CP-080698 |
0004 |
1 |
Subscription to registration information recover |
8.1.0 |
|
|
2008-12 |
CT#42 |
CP-080963 |
0007 |
3 |
AS originating procedures |
8.1.0 |
|
|
2008-12 |
CT#42 |
CP-080698 |
0008 |
– |
Multiple contacts restoration at re-registration |
8.1.0 |
|
|
2008-12 |
CT#42 |
CP-080698 |
0009 |
1 |
Multiple contacts restoration at de-registration |
8.1.0 |
|
|
2009-03 |
CT#43 |
CP-090026 |
0010 |
– |
Multiple Registrations in De-Registration |
8.2.0 |
|
|
2009-03 |
CT#43 |
CP-090026 |
0011 |
– |
Multiple Registrations in Registration |
8.2.0 |
|
|
2009-06 |
CT#44 |
CP-090303 |
0019 |
– |
Contact storage in reg event subscription |
8.3.0 |
|
|
2009-12 |
CT#46 |
CP-090796 |
0020 |
1 |
P-CSCF restoration procedures: stage 2 |
9.0.0 |
|
|
2010-03 |
CT#47 |
CP-100045 |
0022 |
1 |
P-CSCF failure indication removal |
9.1.0 |
|
|
2010-03 |
CT#47 |
CP-100045 |
0023 |
1 |
P-CSCF failure handling for DHCP based scenarios |
9.1.0 |
|
|
2010-03 |
CT#47 |
CP-100045 |
0024 |
1 |
P-CSCF monitoring performed by UE |
9.1.0 |
|
|
2010-03 |
CT#47 |
CP-100045 |
0025 |
1 |
S9 interface procedures |
9.1.0 |
|
|
2010-06 |
CT#48 |
CP-100285 |
0027 |
– |
Notification is to be sent to all UEs sharing the IMPU |
9.2.0 |
|
|
2010-09 |
CT#49 |
CP-100462 |
0030 |
1 |
Restoration Data Backup |
9.3.0 |
|
|
2011-03 |
– |
Update to Rel-10 version (MCC) |
10.0.0 |
||||
|
2011-06 |
CT#52 |
CP-110356 |
0033 |
– |
Emergency Restoration |
10.1.0 |
|
|
2012-09 |
CT#57 |
CP-120440 |
0040 |
1 |
Emergency registrations do not affect registration status |
10.2.0 |
|
|
2012-09 |
CT#57 |
CP-120458 |
0037 |
1 |
P-CSCF failure procedure with S5 PMIP |
11.0.0 |
|
|
2012-09 |
CT#57 |
CP-120458 |
0041 |
1 |
Reference list correction to align with the corrected TS 29.212 title |
11.0.0 |
|
|
2012-12 |
CT#58 |
CP-120745 |
0042 |
1 |
Alignment on the Network recovery procedure at P-CSCF failure |
11.1.0 |
|
|
2012-12 |
CT#58 |
CP-120743 |
0046 |
1 |
PSI direct routing with restoration procedures |
11.1.0 |
|
|
2013-12 |
CT#62 |
CP-130609 |
0047 |
1 |
Correction of reference to Update Notifications for Proxy Mobile IPv6 |
11.2.0 |
|
|
2014-03 |
CT#63 |
CP-140017 |
0051 |
1 |
Update the reference of draft-ietf-sipcore-keep-01 to RFC 6223 |
11.3.0 |
|
|
2014-03 |
CT#63 |
CP-140020 |
0048 |
1 |
Update the reference of IETF draft Update Notifications for Proxy Mobile IPv6 to RFC 7077 |
11.3.0 |
|
|
2014-09 |
CT#65 |
CP-140515 |
0053 |
1 |
T-GRUU restoration |
12.0.0 |
|
|
2014-09 |
CT#65 |
CP-140506 |
0054 |
3 |
HSS-based P-CSCF restoration |
12.0.0 |
|
|
2014-09 |
CT#65 |
CP-140506 |
0055 |
2 |
P-CSCF restoration in roaming scenarios for the HSS based mechanism |
12.0.0 |
|
|
2014-09 |
CT#65 |
CP-140506 |
0056 |
5 |
PCRF based P-CSCF restoration |
12.0.0 |
|
|
2014-09 |
CT#65 |
CP-140506 |
0057 |
3 |
P-CSCF restoration in roaming scenarios for PCRF based solution |
12.0.0 |
|
|
2014-12 |
CT#66 |
CP-140794 |
0059 |
1 |
HSS-based P-CSCF restoration, ISR implications |
12.1.0 |
|
|
2014-12 |
CT#66 |
CP-140794 |
0060 |
3 |
HSS-based P-CSCF restoration, MME/SGSN lack of support |
12.1.0 |
|
|
2014-12 |
CT#66 |
CP-140794 |
0061 |
1 |
HSS-based P-CSCF restoration, response back to UE with retry option |
12.1.0 |
|
|
2014-12 |
CT#66 |
CP-140794 |
0062 |
2 |
P-CSCF Restoration for single IMS APN |
12.1.0 |
|
|
2014-12 |
CT#66 |
CP-140794 |
0065 |
1 |
P-CSCF restoration in a roaming scenario that P-GW and P-CSCF are in HPLMN for PCRF based solution |
12.1.0 |
|
|
2014-12 |
CT#66 |
CP-140794 |
0066 |
1 |
A correction in figure of PCRF based P-CSCF restoration |
12.1.0 |
|
|
2014-12 |
CT#66 |
CP-140794 |
0069 |
2 |
P-CSCF Restart |
12.1.0 |
|
|
2014-12 |
CT#66 |
CP-140794 |
0070 |
– |
Addition of P-CSCF restoration in the scope |
12.1.0 |
|
|
2014-12 |
CT#66 |
CP-140794 |
0071 |
2 |
P-CSCF as non-reachable clarification |
12.1.0 |
|
|
2015-03 |
CT#67 |
CP-150033 |
0073 |
1 |
P-CSCF restoration failure when UE is temporarily out of coverage |
12.2.0 |
|
|
2015-06 |
CT#68 |
CP-150261 |
0074 |
1 |
S-CSCF hanlding in PCRF based solution when UE is temporarily out of coverage |
12.3.0 |
|
|
2015-09 |
CT#69 |
CP-150458 |
0075 |
1 |
Basic P-CSCF restoration mechanism for WLAN |
13.0.0 |
|
|
2015-09 |
CT#69 |
CP-150458 |
0076 |
2 |
P-CSCF restoration supported features |
13.0.0 |
|
|
2015-09 |
CT#69 |
CP-150458 |
0077 |
1 |
P-CSCF restoration extension for trusted WLAN |
13.0.0 |
|
|
2015-09 |
CT#69 |
CP-150458 |
0078 |
1 |
P-CSCF restoration extension for untrusted WLAN |
13.0.0 |
|
|
2015-12 |
CT#70 |
CP-150780 |
0079 |
1 |
Interaction between P-CSCF Restoration and NBIFOM |
13.1.0 |
|
|
2015-12 |
CT#70 |
CP-150780 |
0080 |
– |
Reference correction and editorials |
13.1.0 |
|
|
2015-12 |
CT#70 |
CP-150780 |
0081 |
2 |
Extended P-CSCF restoration mechanism for WLAN and AA-Request |
13.1.0 |
|
|
2015-12 |
CT#70 |
CP-150780 |
0082 |
– |
Remove the need to inform the UE about ePDG support of P-CSCF restoration |
13.1.0 |
|
|
2016-03 |
CT#71 |
CP-160025 |
0083 |
1 |
P-CSCF restoration not prioritized for WLAN |
13.2.0 |
|
|
2016-03 |
CT#71 |
CP-160025 |
0084 |
1 |
Result-Codes for P-CSCF Restoration |
13.2.0 |
|
|
2016-03 |
CT#71 |
CP-160025 |
0085 |
– |
Indication of P-CSCF restoration extension support over IKEv2 |
13.2.0 |
|
|
2016-06 |
CT#72 |
CP-160231 |
0086 |
3 |
P-CSCF restoration for NBIFOM PDN connections |
13.3.0 |
|
|
2016-06 |
CT#72 |
CP-160216 |
0087 |
3 |
SCC AS restoration Mechanism |
13.3.0 |
|
|
2016-09 |
CT#73 |
CP-160415 |
0091 |
– |
Non REGISTER authentication after S-CSCF restart |
13.4.0 |
|
|
2016-09 |
CT#73 |
CP-160431 |
0088 |
S-CSCF Restoration during Registration enhancement |
14.0.0 |
||
|
2016-12 |
CT#74 |
CP-160656 |
0093 |
1 |
P-CSCF restoration for NBIFOM connections |
14.1.0 |
|
|
2018-06 |
CT#80 |
CP-181132 |
0096 |
5 |
New Clause for P-CSCF Restoration in 5G Access |
15.0.0 |
|
|
2018-12 |
CT#82 |
CP-183092 |
0102 |
1 |
Updates to PCF Based P-CSCF Restoration Solution |
15.1.0 |
|
|
2019-03 |
CT#83 |
CP-190015 |
0103 |
– |
Correction to clause numbering |
16.0.0 |
|
|
2019-09 |
CT#85 |
CP-192191 |
0107 |
– |
5G P-CSCF restoration using Nudm |
16.1.0 |
|
|
2019-09 |
CT#85 |
CP-192099 |
0109 |
1 |
P-CSCF restoration |
16.1.0 |
|
|
2019-09 |
CT#85 |
CP-192124 |
0105 |
5 |
Correction to P-CSCF Restoration Procedures |
16.1.0 |
|
|
2019-09 |
CT#85 |
CP-192125 |
0106 |
2 |
Add P-CSCF subscription info to Restoration information |
16.1.0 |
|
|
2019-12 |
CT#86 |
CP-193040 |
0110 |
1 |
S-CSCF restoration after registration timer expiry |
16.2.0 |
|
|
2021-03 |
CT#91e |
CP-210062 |
0113 |
– |
P-CSCF restoration alignment |
16.3.0 |
|
|
2021-06 |
CT#92e |
CP-211060 |
0115 |
S-CSCF reselection in eIMS |
16.4.0 |
||
|
2021-12 |
CT#94e |
CP-213119 |
0116 |
– |
B |
Store g.3gpp.accesstype media feature tag in the HSS as Repository Data |
17.0.0 |
|
2021-12 |
CT#94e |
CP-213119 |
0117 |
– |
F |
Correction to HSS-based and PCRF-based P-CSCF restoration |
17.0.0 |
|
2022-03 |
CT#95e |
CP-220054 |
0118 |
1 |
B |
P-CSCF restoration |
17.1.0 |