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88525ca373d6c27ca925fc02f42c683a | 23.007 | 5.2.3 Mobile Originated Activity for ProSe | When the ProSe Function receives a request for ProSe Service from a UE whose associated context is marked as "Subscriber Data Not Confirmed by HSS", it shall initiate a "ProSe Subscriber Information Retrieval" request to the HSS as described in the 3GPP TS 29.344 [34].
When the HSS receives a "ProSe Subscriber Information Retrieval" request from the ProSe Function, it shall proceed as described in the 3GPP TS 29.344 [34]. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 5.2.4 Procedures in the SGSN | Upon receipt of a HLR/HSS reset, the SGSN shall mark each relevant MM contexts as invalid and shall set the Non-GPRS Alert Flag (NGAF) if an SGSN - MSC/VLR association exists. After detection of any activity (either signalling or data) from a marked MS or any other implementation dependent trigger for a marked MS in PMM-CONNECTED state with Direct tunnel, the SGSN performs an update location to the HLR/HSS as in the attach or inter-SGSN RA update procedures and, if NGAF is set, the procedure of "Non-GPRS Alert" is followed (see clause 7 in 3GPP TS 29.018 [7]).
The update location procedure and the procedure towards the VLR may be delayed by the SGSN for a maximum operator configuration-depending time period to avoid high signalling load. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 5.2.5 Procedures in the MME | Upon receipt of a HSS reset, the MME shall mark each relevant MM contexts as invalid and shall set Non-EPS Alert Flag (NEAF) if an MME - MSC/VLR association exists. After detection of any activity (either signalling or data) from a marked UE or any other implementation dependent trigger for a marked UE in ECM-CONNECTED state, the MME performs an update location to the HSS as in the attach or inter-MME TA update procedures and, if NEAF is set, the procedure of "NON-EPS Alert" is followed (see clause 5.3 in 3GPP TS 29.118 [14]).
The update location procedure and the procedure towards the VLR may be delayed by the MME for a maximum operator configuration-depending time period to avoid high signalling load. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 5.2.6 Mobile Originated Activity for V2X | When the V2X Control Function receives a request for V2X Service from a UE whose associated context is marked as "Subscriber Data Not Confirmed by HSS", it shall initiate a "V2X Subscriber Information Retrieval" request to the HSS as described in the 3GPP TS 29.388 [41].
When the HSS receives a "V2X Subscriber Information Retrieval" request from the V2X Control Function, it shall proceed as described in the 3GPP TS 29.388 [41]. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 6 Periodic location updating | The time taken to confirm the location of an MS after location register failure is governed by the frequency with which the MS establishes radio contact with the network. The location information for an MS which remains silent for a long time will remain doubtful for a long time.
A method of reducing this time is to require the MS to establish radio contact with the network at intervals, purely to confirm its location, if the MS does not move to a new location area (which would lead to a normal location registration) or respond to paging for a mobile terminated call or request a mobile originated call or call-independent supplementary service activity.
The interval between successive periodic location updatings is controlled by a timer in the MS; this timer is reset to its initial value at the end of each successfully established radio contact between the MS and the network.
The use of the periodic location update timer is described in 3GPP TS 23.122 [27]. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 7 Periodic routeing area updating | All GPRS-attached MSs, except MSs in class-B mode of operation engaged in CS communication, shall perform periodic RA updates. For MSs that are both IMSI-attached and GPRS-attached, the periodic updates depend on whether the Gs interface is installed or not:
- If the Gs interface is installed, periodic RA updates shall be performed, and periodic LA updates shall not be performed. If the SGSN has the indicator "VLR-reliable" set to ´false´ the SGSN shall perform a location area update procedure towards the VLR
- If the Gs interface is not installed, both periodic RA updates and periodic LA updates shall be performed independently. RA updates are performed via the Gb interface, and LA updates are performed via the A interface.
The periodic routeing area update is described in 3GPP TS 23.060 [5]. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 8 Stand-alone operation of the VLR | In a 2G authentication regime, triplets, regardless of its nature (generated in a 2G AuC or derived from quintuplets in a 3G VLR or a 3G HLR), may be reused when no unused authentication triplets are available in the VLR for an IMSI record. It is an operator option to define how many times an authentication triplet may be reused in the VLR.
In a 3G authentication regime, quintuplets, regardless of its nature (generated in a 3G AuC or derived from triplets in a 3G VLR), shall not be reused when no unused authentication quintuplets are available in the VLR for an IMSI record.
If the Update Location response contains an error different from "Unknown Subscriber" or "Roaming Not Allowed" or if there is a parameter problem (e.g. no HLR number included), no error shall be indicated to the MSC and the IMSI record in the VLR shall not be affected, provided that the associated "Subscriber Data Confirmed by HLR" indicator is in the "Confirmed" status. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 9 Stand-alone operation of the SGSN | In a 2G authentication regime, triplets, regardless of their nature (generated in a 2G AuC or derived from quintuplets in a 3G SGSN or a 3G HLR), may be reused when no unused authentication triplets are available in the SGSN for an IMSI record. It is an operator option to define how many times an authentication triplet may be reused in the SGSN.
In a 3G authentication regime, quintuplets, regardless of their nature (generated in a 3G AuC or derived from triplets in a 3G SGSN), shall not be reused when no unused authentication quintuplets are available in the SGSN for an IMSI record.
9A Stand-alone operation of the MME
In a E-UTRAN authentication regime, EPS authentication vectors shall not be reused when no unused EPS authentication vectors are available in the MME for an IMSI record. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 10 Restoration of data in the GGSN | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 10.0 GGSN failure | When a GGSN fails, all its PDP contexts affected by the failure become invalid and may be deleted. GGSN storage of subscriber data is volatile.
When the GGSN receives a GTP‑U PDU for which no PDP context exists, it shall discard the GTP‑U PDU and return a a GTP error indication to the originating node (the SGSN or, if Direct Tunnel is established, the RNC).
The GGSN should ensure as far as possible that previously used TEID values are not immediately reused after a GGSN restart, in order to avoid inconsistent TEID allocation throughout the network. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 10.1 Restart of the GGSN | After a GGSN restart, all the PDP contexts, the MBMS UE contexts, and the MBMS Bearer contexts stored in the GGSN and affected by the restart become invalid and may be deleted.
When the SGSN detects a restart in a GGSN (see clause 18 "GTP-C based restart procedures") with which it has one or more PDP contexts activated, it shall deactivate all these PDP contexts and request the MS to reactivate them. When the SGSN detects a restart in a GGSN with which it has MBMS Bearer context(s) and/or MBMS UE context(s), it shall delete all these MBMS Bearer context(s) and/or MBMS UE context(s). |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 10.2 Restoration Procedures | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 10.2.0 General | The GGSN will receive the SGSN restart counters in GTPv1 echo response from the SGSN. When a GGSN detects that a peer SGSN has restarted it shall delete all PDP context(s), MBMS UE context(s), MBMS Bearer context(s) associated with the peer node that failed as well as freeing any internal GGSN resources associated with those PDP context(s), MBMS UE context(s) and MBMS Bearer context(s). The GGSN may optionally perform other implementation specific actions such as messages to clear other external resources (e.g. PCC messages).
If the GGSN needs to send a request for IP-CAN Session Modification procedure towards a PCRF which is known to have restarted since the IP-CAN session establishment, the GGSN may discard the request and may tear down all the PDP context(s) associated with the PDP address of the IP-CAN session, based on operator policy, by initiating a PDP Context Deactivation procedure towards the SGSN with the cause set to "Reactivation requested". This leads the UE to initiate PDP Context Activation procedure for the same APN. Emergency sessions should not be torn down.
NOTE: The procedure above just enables to clean up all the PDP Context(s) associated with the PDP address of the IP-CAN session, affected by the PCRF failure when a specific interaction with the PCRF is required. Prior to that interaction, PCC controlled services cannot be provided to the UE. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 10.2.1 Mobile terminated transmission | When the GGSN receives a mobile terminated PDU for which no valid PDP context exists the GGSN discards the received PDU and may also return an appropriate Error message depending on the protocol used. No further actions are performed by the GGSN. Alternatively, if the GGSN has static PDP information about the PDP address, the GGSN may try to deliver the PDU by initiating the Network-Requested PDP Context Activation procedure (see 3GPP TS 23.060 [5]). |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 10.2.2 Mobile originated transmission | When the GGSN receives a tunnel PDU for which no PDP context exists it discards the tunnel PDU and sends an Error indication message to the originating SGSN. The SGSN deactivates the PDP context and sends an Error indication to the MS. The MS may then re-activate the PDP context. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11 Restoration of data in the SGSN | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.0 SGSN Failure | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.0.1 Gn/Gp SGSN failure | When an SGSN fails, it deletes all MM and PDP contexts affected by the failure. SGSN storage of subscriber data is volatile. Based on configuration data, the SGSN may send a Reset message to each of its associated VLRs. If a Reset message is sent, the VLR may mark all associations containing the restarted SGSN as unreliable. See 3GPP TS 29.018 [7]. In the case of optional CAMEL interaction the failing SGSN shall invoke the CAMEL-GPRS-Exception procedure towards the GSM‑SCFs.
If data or signalling, except GPRS attach and RA update, is received in an SGSN from an MS for which no MM context exists in the SGSN, the SGSN shall discard the data or signalling.
If an RA update request is received in an SGSN from an MS for which no MM context exists in the SGSN, or in the old SGSN for the inter-SGSN RA update case, the SGSN shall reject the RA update with an appropriate cause. In order to remain GPRS-attached, the MS shall then perform a new GPRS attach and should (re‑)activate PDP contexts.
If a service request is received in a 3G‑SGSN from an MS for which no MM context exists in the 3G‑SGSN, the 3G‑SGSN shall reject the service request with an appropriate cause. In order to remain GPRS-attached, the MS shall then perform a new GPRS attach and should (re‑) activate PDP contexts.
NOTE: In some cases, user interaction may be required, and then the MS cannot (re‑)activate the PDP contexts automatically.
When the SGSN receives a PDU Notification Request message for which no MM context exists, the SGSN returns a PDU Notification Response message to the GGSN with an appropriate cause (see clause "Unsuccessful Network-Requested PDP Context Activation Procedure" in 3GPP TS 23.060 [5]), and the SGSN may search the MS by paging with the IMSI in the SGSN area. An MS that is paged for PS services with IMSI as the identifier shall perform a new GPRS attach and should (re‑)activate PDP contexts.
When the SGSN receives a GTP‑U PDU from the GGSN for which no PDP context exists, it shall discard the GTP‑U PDU and send a GTP error indication to the originating GGSN.
When the SGSN receives a GTP‑U PDU from the RNC for which no PDP context exists, the SGSN shall discard the GTP‑U PDU and send a GTP error indication to the originating RNC.
When the SGSN receives a mobile-terminated SM from the SMS‑GMSC for an IMSI unknown in the SGSN, it rejects the request.
When the SGSN receives a paging request over the Gs interface for an IMSI unknown in the SGSN and the SGSN has not completed recovery, the SGSN may page the MS for packet services with IMSI as identifier in the area specified by the location information provided by the MSC/VLR. If no such location information is provided, the SGSN may page the MS in the routeing areas corresponding to that MSC/VLR. After the MS performs a combined GPRS attach, the SGSN may continue serving the Gs interface paging request. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.0.2 SGSN Failure using S4 | When the SGSN receives a GTP‑U PDU from the Serving GW for which no Bearer context exists, it shall discard the GTP‑U PDU and send a GTP error indication to the originating Serving GW.
When the SGSN receives a GTP‑U PDU from the MBMS GW for which no MBMS Point to Point Bearer context exists, it shall discard the GTP‑U PDU and send a GTP Error Indication to the originating MBMS GW.
An S4-SGSN and an SGW supporting the optional network triggered service restoration procedure shall behave as specified in clause 25.
When the S4-SGSN which does not support the optional network triggered service restoration procedure as specified in clause 25 receives a Downlink Data Notification message for which no MM context exists, the S4-SGSN returns a Downlink Data Notification Acknowledge message to the Serving GW with an appropriate cause. The Serving GW shall delete the related Bearer context related to S4-SGSN; and if there is no ISR associated MME recorded on the related Bearer context the Serving GW shall also notify the PDN GW to delete the Bearer context. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.1 Restart of the SGSN | After an SGSN restart, the SGSN deletes all MM, PDP, MBMS UE, and MBMS Bearer contexts affected by the restart.
When the GGSN detects a restart in an SGSN (see clause 18 "GTP-C based restart procedures") with which it has PDP context(s) activated and/or MBMS UE context(s), it shall delete all these PDP context(s) and/or MBMS UE context(s). When the GGSN detects a restart in an SGSN with which it has any MBMS Bearer context, it shall not delete the MBMS bearer context unless all SGSNs connected to the GGSN restart.
When the MBMS GW detects a restart in an SGSN (see clause 18 "GTP-C based restart procedures") with which it has at least one MBMS Bearer context, the MBMS GW should re-establish the active MBMS bearer services affected by the SGSN restart by initiating MBMS Session Start procedure(s) towards the restarted SGSN (or an alternative SGSN in the same SGSN pool). The MBMS GW shall encode the contents of the MBMS Session Start Request with the same contents as in the original MBMS Session Start Request (or as per the last MBMS Session Update Request received from the BM-SC if the original parameters were updated) with the following exceptions:
- the MBMS GW shall set the "MBMS session re-establishment indication" flag to signal that this message is used to re-establish an MBMS session;
- the MBMS GW may change the relative start time ("time to MBMS data transfer" parameter) to fasten the restoration of the MBMS service in UTRAN;
- the MBMS GW should set the estimated session duration to a value corresponding to the remaining duration of the session.
NOTE: If the MBMS GW receives an MBMS Session Update Request from the BM-SC during the SGSN restart, the contents of the MBMS Session Start Request sent to the SGSN after the SGSN restart can also differ from the parameters sent to the SGSN before its restart for the parameters that can be modified by the MBMS session update procedure (i.e. MBMS Session Area, MBMS Time to Data Transfer).
The MBMS GW shall not delete the MBMS Bearer context unless all SGSNs/MMEs serving the MBMS bearer service and connected to the MBMS GW have restarted and the MBMS-GW does not support re-establishing MBMS bearer services after an SGSN restart. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.2 Restoration Procedures | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.2.1 Mobile terminated user data transmission | When a Gn-SGSN receives a tunnel PDU for which no PDP context or MBMS Bearer Context exists it discards the tunnel PDU and sends an Error indication message to the originating GGSN.
An S4-SGSN and an SGW supporting the optional network triggered service restoration procedure shall behave as specified in clause 25. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.2.2 Mobile terminated services requested by the MSC/VLR | When the SGSN receives a request for CS paging from an MSC/VLR for an IMSI unknown by the SGSN, if the "SGSN-Reset" indicator is set to "true", the SGSN sends the paging request with the location information provided by the VLR. If no such location information is provided, the SGSN should page for the MS in all the routeing areas corresponding to that SGSN.
If the "SGSN-Reset" indicator is set to "false" and the IMSI is unknown or the MS is marked as GPRS or non-GPRS detached by the SGSN, the paging request is rejected.
If the "SGSN-Reset" indicator is set to "false" and the IMSI is known and the MS is marked as GPRS and is non-GPRS attached by the SGSN, the paging request shall be sent to the MS. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.2.3 Mobile terminated SMS over GPRS | a) Send Routing Information for MT SMS (SMS-GMSC -> HLR):
The HLR returns the SGSN number as for normal operation.
b) Send Information for MT SMS:
- When the SGSN receives a mobile terminated SMS for an unknown MM context for the MS, or if the SGSN indicator "Subscriber Data Confirmed by HLR" is marked "Not Confirmed" it rejects the SMS request and returns a failure report with cause value "Unidentified Subscriber" to the SMS gateway MSC indicating unsuccessful delivery of the SMS. The Gateway MSC sends a "Report SM Delivery Status" request, with a cause of "Absent Subscriber", to the HLR. This causes the HLR to set the "Mobile Station Not Reachable for GPRS Flag" for the MS, as described in the Technical Specifications3GPP TS 23.040 [4] and 3GPP TS 29.002 [6].
- If the SGSN has the indicator "Subscriber Data Confirmed by HLR" set to "Confirmed", the SGSN handles the SMS request in the normal way.
The state of the indicator "Location Information Confirmed in HLR" does not affect the Mobile Terminated SMS procedure. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.2.4 Mobile originated Routeing Area Updating or Attach | For attach, where the MS is unknown in the SGSN (i.e. the SGSN has no MM context for the MS) the SGSN creates an MM context for the MS and sets the indicators "Location Information Confirmed in HLR", "Subscriber Data Confirmed by HLR", "Location Information Confirmed by CSS" and "Subscriber Data Confirmed by CSS" to "Not Confirmed". If authentication is required, the SGSN retrieves authentication data. The SGSN then performs an "Update GPRS Location" to the HLR. If this is successful, the SGSN sets the indicators "Location Information Confirmed in HLR" and "Subscriber Data Confirmed by HLR" to "Confirmed". If the VPLMN supports Autonomous CSG Roaming and the HPLMN has enabled Autonomous CSG Roaming in the VPLMN, the SGSN may perform an "Update VCSG Location" to the CSS if the requested cell is a CSG/hybrid cell. If this is successful, the SGSN sets the indicators "Location Information Confirmed by CSS" and "Subscriber Data Confirmed by CSS" if the CSS has the valid CSG subscription data to "Confirmed".
For routing area update, where the MS is unknown in the SGSN (i.e. the SGSN has no MM context for the MS) or for inter-SGSN routing area update, where the MS is unkown in the old SGSN, the SGSN shall reject the RA update with an appropriate cause. In order to remain GPRS-attached, the MS shall then perform a new GPRS attach and should (re‑)activate its PDP contexts.
If the SGSN has an MM context for the MS, and the indicators "Location Information Confirmed in HLR" or "Subscriber Data Confirmed by HLR" is set to "Not Confirmed" the SGSN performs an "Update GPRS Location" to the HLR. If this is successful, the SGSN sets the indicators "Location Information Confirmed in HLR" and "Subscriber Data Confirmed by HLR" to "Confirmed". If the indicators "Location Information Confirmed by CSS" or "Subscriber Data Confirmed by CSS" if the CSS has the valid CSG subscription data is set to "Not Confirmed", and the VPLMN supports Autonomous CSG Roaming and the HPLMN has enabled Autonomous CSG Roaming in the VPLMN, the SGSN may perform an "Update VCSG Location" to the CSS if the requested cell is a CSG/hybrid cell. If this is successful, the SGSN sets the indicators "Location Information Confirmed by CSS" and "Subscriber Data Confirmed by CSS" if the CSS has the valid CSG subscription data to "Confirmed".
If the SGSN has an MM context for the MS with the indicator "Subscriber Data Confirmed by HLR" marked "Confirmed" the originated transmission is handled in the normal way.
The SGSN retrieves subscriber data from the HLR by sending an "Update GPRS Location" request, which triggers one or more "Insert Subscriber Data" operations from the HLR.
The SGSN retrieves CSG subscriber data from the CSS by sending an "Update VCSG Location" request, which triggers one or more "Insert Subscriber Data" operations from the CSS if the CSS has the valid CSG subscription data. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.2.5 Mobile originated LLC frame | If an SGSN receives an LLC frame for which no MM context exists in the SGSN, and if the LLC frame does not contain an Attach Request or a Routeing Area Update Request signalling message, then the LLC frame shall be discarded. The MS may determine that the network is not responding and attempt to re-attach or eventually a periodic Routing Area Update message is sent by the MS which initiates the attach procedures. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.2.6 Mobile originated Service Request | For service request, where the MS is unknown in the SGSN (i.e. the SGSN has no MM context for the MS), the SGSN shall reject the service request with an appropriate cause. In order to remain GPRS-attached, the MS shall then perform a new GPRS attach and should (re‑)activate its PDP contexts.
If the SGSN has an MM context for the MS, and the indicators "Location Information Confirmed by CSS" or "Subscriber Data Confirmed by CSS" if the CSS has the valid CSG subscription data is set to "Not Confirmed", and the VPLMN supports Autonomous CSG Roaming and the HPLMN has enabled Autonomous CSG Roaming in the VPLMN, the SGSN may perform an "Update VCSG Location" to the CSS if the requested cell is a CSG/hybrid cell. If this is successful, the SGSN sets the indicators "Location Information Confirmed by CSS" and "Subscriber Data Confirmed by CSS" if the CSS has the valid CSG subscription data to "Confirmed".
The SGSN retrieves CSG subscriber data from the CSS by sending an "Update VCSG Location" request, which triggers one or more "Insert Subscriber Data" operations from the CSS if the CSS has the valid CSG subscription data. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.3 Use of TLLI | After the SGSN has restarted but before the next authenticated radio contact the P‑TMSI and TLLI known by the MS are invalid, as the P-TMSI was allocated before the SGSN restarted. The SGSN may request the MS to identify itself with the IMSI in order to make a relationship between the IMSI and the received old TLLI. The SGSN shall allocate a new P-TMSI for that MS.
If an MS identifies itself by a TLLI in an MS originating transmission, the SGSN proceeds as follows:
a) The SGSN checks the routing area identity (RAI) of the previous routing area sent by the MS. If this previous RAI belongs to a different SGSN, the request is handled in the normal way.
b) If the previous RAI belongs to the current SGSN, the status of the TLLI is checked.
- If the P‑TMSI derived from the TLLI was allocated after the SGSN restarted, and corresponds to a valid IMSI record, then the request is handled in the normal way.
- If the P‑TMSI derived from the TLLI was allocated before the SGSN restarted, or does not correspond to a valid IMSI record, then the SGSN requests the IMSI from the MS. If the MS returns an IMSI the SGSN proceeds in the normal way. If the MS does not return an IMSI the network aborts the originating transmission request or location registration procedure. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.4 VLR associations | All associations with VLRs affected by the restart of an SGSN are marked as unreliable and may be deleted. Based on configuration data, Reset messages may be sent on the Gs-interface to the VLRs served by the SGSN. If Reset messages are sent, the VLRs may mark all associations with the SGSN as unreliable by setting the restoration indicator "Confirmed by radio contact" to "Not Confirmed" for the MSs served by that SGSN. See 3GPP TS 29.018 [7]. The associations will be re-initiated one by one by the SGSN at the next Routing Area update, or combined RA/LA update from each MS. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.5 Restart of a peer node | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.5.1 SGW failure | When an SGSN detects that a peer SGW has failed with or without restart (relying on restart counter as specified in clause 18 "GTP-C based restart procedures" or implementation e.g. preconfigured path failure timer) it shall either:
- as a default delete all PDN connection table data/MM bearer contexts associated with the peer node that has failed as well as freeing any internal SGSN resources associated with those PDN connections. The SGSN may optionally perform other implementation specific actions such as to clear external resources (e.g. Iu messages to clear UTRAN resources) or more advanced forms of restoration;
or
- follow the procedures specified in clause 27 to restore the PDN connections affected by the SGW failure, if the SGSN and the PGW support these procedures.
NOTE: The SGSN will have the identity of the PGW and SGW currently in use for a PDN connection available in the SGSN's PDN connection table as part of existing EPC procedures as well as other peer state data. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 11.5.2 MBMS-GW failure | The behaviour of an SGSN when it detects that a peer MBMS GW has restarted is described in clause 17A.1. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 12 Restoration of Data in an SMLC (GSM only) | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 12.1 Restart of an SMLC | When an SMLC restarts after a failure, it performs the following actions for those of its associated LMUs whose records have been affected by the fault:
- Reload all administered LMU data from non-volatile back-up;
- Reinitialize other temporary data for each LMU to indicate no ongoing measurement or diagnostic activities;
- Perform data restoration for each affected Type A and Type B LMU as described below. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 12.2 Data Restoration for a Specific LMU | An SMLC may restore data for a specific LMU when the data in the SMLC or LMU is considered unreliable (e.g. if there is no communication between the SMLC and LMU for a long time or if messages received by the SMLC are inconsistent with the LMU state kept by the SMLC). To restore data for a specific LMU, the SMLC shall open a signalling connection to the LMU if this is Type A, as described in 3GPP TS 23.071 [10]. For both a Type A LMU and a Type B LMU, the SMLC shall then send an LLP Reset message to the LMU. On receiving an LLP Reset, an LMU shall cancel any LCS measurement and O&M tasks previously ordered by the SMLC and shall return an LLP Reset acknowledgement to the SMLC. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 13 Restoration of Data in an LMU (GSM only) | When an LMU restarts following a failure, it shall reinitialize all data concerning LCS measurement and O&M tasks to indicate that no tasks ordered by an SMLC are active. A Type A LMU shall then perform an "IMSI Attach". A Type A LMU shall then open a signalling connection to its controlling SMLC as described in 3GPP TS 23.071 [10]. Both a Type A LMU and a Type B LMU shall send an LLP Status Update message to their controlling SMLC containing an indication that the LMU has restarted following a failure. The SMLC shall update its data regarding the state of the LMU and shall return an LLP Update Status acknowledgment to the LMU. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14 Restoration of data in the MME | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14.1 Restart of the MME | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14.1.1 Restoration Procedures | After an MME restart, the MME shall delete all MM Bearer contexts affected by the restart that it may have stored.
When the MBMS GW detects a restart in an MME (see clause 18 "GTP-C based restart procedures") with which it has at least one MBMS Bearer context, the MBMS-GW should re-establish the active MBMS bearer services affected by the MME restart by initiating MBMS Session Start procedure(s) towards the restarted MME (or an alternative MME in the same MME pool). The MBMS GW shall encode the MBMS Session Start Request with the same contents as in the original MBMS Session Start Request (or as per the last MBMS Session Update Request received from the BM-SC if the original parameters were updated) with the following exceptions:
- the MBMS GW shall set the "MBMS session re-establishment indication" flag to signal that this message is used to re-establish an MBMS session;
- if no absolute start time ("MBMS data transfer start" parameter) has been received, the MBMS GW may change the relative start time ("time to MBMS data transfer" parameter) to fasten the restoration of the MBMS service in E-UTRAN;
- the MBMS GW should set the estimated session duration to a value corresponding to the remaining duration of the session.
The MCE shall be able to accept MBMS session requests with an absolute start time ("MBMS data transfer start" parameter) in the past.
NOTE: If the MBMS GW receives an MBMS Session Update Request from the BM-SC during the MME restart, the contents of the MBMS Session Start Request sent to the MME after the MME restart can also differ from the parameters sent to the MME before its restart for the parameters that can be modified by the MBMS session update procedure (i.e. MBMS Session Area, MBMS Time to Data Transfer, MBMS Data Transfer Start).
The MBMS GW shall not delete the MBMS Bearer context unless all SGSNs/MMEs serving the MBMS bearer service and connected to the MBMS GW have restarted and the MBMS-GW does not support re-establishing MBMS bearer services after an MME restart.
If the MCE receives an M3 Reset message from the MME (i.e. in case the restart event has resulted in loss of some or all M3 transactions reference information) with which it has at least one MBMS Bearer context, the MCE shall deactivate all the related MBMS Bearer contexts locally and towards E-UTRAN within which the MBMS bearer service is active, either immediately or after a pre-configured time period if the corresponding MBMS Bearer contexts are not re-established via any MME.
An MME and an SGW supporting the optional network triggered service restoration procedure shall behave as specified in clause 25.
When the MME which does not support the optional network triggered service restoration procedure as specified in clause 25 receives a Downlink Data Notification message for which no MM context exists, the MME returns a Downlink Data Notification Acknowledge message to the Serving GW with an appropriate cause. The Serving GW shall delete the related Bearer context related to MME; and if there is no ISR associated S4-SGSN recorded on the related Bearer context the Serving GW shall also notify the PDN GW to delete the Bearer context. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14.1.2 Mobile originated Tracking Area Updating or E-UTRAN Attach | For attach, where the UE is unknown in the MME (i.e. the MME has no MM context for the UE) the MME shall create an MM context for the UE and shall set the indicators "Location Information Confirmed in HSS", "Subscriber Data Confirmed by HSS", "Location Information Confirmed by CSS" and "Subscriber Data Confirmed by CSS" to "Not Confirmed". If authentication is required, the MME shall retrieve the authentication data. The MME then performs an "Update Location" to the HSS. If this is successful, the MME shall set the indicators "Location Information Confirmed in HSS" and "Subscriber Data Confirmed by HSS" to "Confirmed". If the VPLMN supports Autonomous CSG Roaming and the HPLMN has enabled Autonomous CSG Roaming in the VPLMN, the MME may perform an "Update VCSG Location" to the CSS if the requested cell is a CSG/hybrid cell. If this is successful, the MME shall set the indicators "Location Information Confirmed by CSS" and "Subscriber Data Confirmed by CSS" if the CSS has the valid CSG subscription data to "Confirmed".
For tracking area update, where the UE is unknown in the MME (i.e. the MME has no MM context for the UE) or for inter-MME tracking area update, where the UE is unkown in the old MME, the MME shall reject the TA update with an appropriate cause. In order to remain attached, the UE shall then perform a new attach and should (re‑)activate its EPS Bearer contexts.
If the MME has an MM context for the UE, and the indicator "Location Information Confirmed in HSS" or "Subscriber Data Confirmed by HSS" is set to "Not Confirmed" the MME shall perform an "Update Location" to the HSS. If this is successful, the MME shall set the indicators "Location Information Confirmed in HSS" and "Subscriber Data Confirmed by HSS" to "Confirmed". If the indicators "Location Information Confirmed by CSS" or "Subscriber Data Confirmed by CSS" is set to "Not Confirmed", and the VPLMN supports Autonomous CSG Roaming and the HPLMN has enabled Autonomous CSG Roaming in the VPLMN, the MME may perform an "Update VCSG Location" to the CSS if the requested cell is a CSG/hybrid cell. If this is successful, the MME shall set the indicators "Location Information Confirmed by CSS" and "Subscriber Data Confirmed by CSS" if the CSS has the valid CSG subscription data to "Confirmed".
If the MME has an MM context for the UE with the indicator "Subscriber Data Confirmed by HSS" marked "Confirmed" the originated transmission shall be handled in the normal way.
The MME retrieves subscriber data from the HSS by sending an "Update Location" request, which triggers an "Update Location" answer which contains the subscriber data.
The MME retrieves CSG subscriber data from the CSS by sending an "Update VCSG Location" request, which triggers an "Update VCSG Location" answer which may contain the valid CSG subscription data. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14.1.3 Mobile terminated services requested by the MSC/VLR | An MME and a VLR supporting mobile terminated CS service delivery via an alternative MME in MME pool shall behave as specified in clause 26.
When the MME receives a request for CS paging from an MSC/VLR for an IMSI unknown by the MME, if the "MME-Reset" indicator is set to "true", the MME sends the paging request with the location information provided by the VLR. If no such location information is provided, the MME should page for the UE in all the tracking areas corresponding to that MME. The MME may support and apply this procedure to a UE using extended idle mode DRX for MT-SMS service.
NOTE: How the restarted MME knows the UE's DRX parameter or the extended DRX parameters to page the UE is implementation dependent.
If the "MME-Reset" indicator is set to "false" and the IMSI is unknown or the UE is marked as EMM-DEREGISTERED by the MME, the paging request is rejected.
If the "MME-Reset" indicator is set to "false" and the IMSI is known and the UE is marked as EMM-REGISTERED by the MME, the paging request shall be sent to the UE. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14.1.4 Mobile terminated user data transmission | An MME and an SGW supporting the optional network triggered service restoration procedure shall behave as specified in clause 25. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14.1.5 Mobile originated Service Request | For service request, where the UE is unknown in the MME (i.e. the MME has no MM context for the UE), the MME shall reject the service request with an appropriate cause. In order to remain attached, the UE shall then perform a new attach and should (re‑)activate its EPS Bearer contexts.
If the MME has an MM context for the UE, and the indicators "Location Information Confirmed by CSS" or "Subscriber Data Confirmed by CSS" is set to "Not Confirmed", and the VPLMN supports Autonomous CSG Roaming and the HPLMN has enabled Autonomous CSG Roaming in the VPLMN, the MME may perform an "Update VCSG Location" to the CSS if the requested cell is a CSG/hybrid cell. If this is successful, the MME shall set the indicators "Location Information Confirmed by CSS" and "Subscriber Data Confirmed by CSS" if the CSS has the valid CSG subscription data to "Confirmed".
The MME retrieves CSG subscriber data from the CSS by sending an "Update VCSG Location" request, which triggers an "Update VCSG Location" answer which may contain the valid CSG subscription data. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14.1.6 Mobile Terminated NIDD procedure | During the Mobile Terminated NIDD procedure, if the SCEF receives a MT-Data-Answer from the MME/SGSN with a failure cause that UE cannot be found, the SCEF shall delete all the bearer contexts of this UE and may notify the Operation and Maintenance network element.
NOTE: After that, if the SCEF receives a following NIDD Submit request from the SCS/AS for the deleted bearer, the SCEF behaves as specified in clause 5.13.3 of TS 23.682[38] step 2.
14.1A Restart of a peer node
14.1A.1 SGW Failure
When an MME detects that a peer SGW has failed with or without restart (relying on restart counter as specified in clause 18 "GTP-C based restart procedures" or implementation e.g. preconfigured path failure timer) it shall either:
- as a default delete all PDN connection table data/MM bearer contexts associated with the peer node that has failed as well as freeing any internal MME resources associated with those PDN connections. The MME may optionally perform other implementation specific actions such as to clear external resources (e.g. S1-MME messages to clear eNodeB resources) or more advanced forms of restoration;
or
- follow the procedures specified in clause 27 to restore the PDN connections affected by the SGW failure, if the MME and the PGW support these procedures.
NOTE: The MME will have the identity of the PGW and SGW currently in use for a PDN connection available in the MME's PDN connection table as part of existing EPC procedures as well as other peer state data.
14.1A.2 MBMS GW failure
The behaviour of an MME when it detects that a peer MBMS GW hast restarted is described in clause 17A.1.
14.1A.3 MCE Restart
When the MME detects a restart in an MCE (i.e. when the MME receives an M3 Reset or M3 Setup Request message from the MCE) with which it has at least one MBMS Bearer context, the MME shall behave as specified in clause 15A.3.
14.1A.4 UCMF Failure
When an MME detects that a peer UCMF has failed with or without restart (relying on restart counter as specified in clause 19B "URCMP based restart procedures" or implementation e.g. a preconfigured path failure timer as specified in clause 20 "Path management procedures"), it shall consider the dictionary mapping information received from the failed UCMF is deprecated, the subscription to get notifications from the UCMF become invalid; the MME may retrieve such mapping information upon subsequent UE - AMF signalling e.g. at registration procedure. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14.2 VLR associations | All associations with VLRs affected by the restart of an MME are marked as unreliable and may be deleted. Based on configuration data, Reset messages may be sent on the SGs interface to the VLRs served by the MME. If Reset messages are sent, the VLRs may mark all associations with the MME as unreliable by setting the restoration indicator "Confirmed by radio contact" to "Not Confirmed" for the UEs served by that MME. See 3GPP TS 29.118 [14]. The associations will be re-initiated one by one by the MME at the next Combined TA/LA update from each UE. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14.3 Partial Failure Handling at MME | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14.3.1 General | See Clause 23. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14.3.2 Procedures during PDN Connection Establishment | If the MME supports the feature, the following procedures apply.
During a PDN connection establishment, the MME shall provide one MME FQ-CSID containing exactly one CSID for that particular PDN connection to the SGW in the S11 Create Session Request. The MME shall store the Node-ID and CSID values from the FQ-CSID provided by the SGW and the PGW in the S11 Create Session Response in its PDN Connection table maintained as part of MME MM and EPS Bearer Contexts as specified in Table 5.6.2-15.7.2-1 in 3GPP TS 23.401 [15].
The MME should ensure as far as possible that previously used FQ-CSIDs are not immediately reused after a partial/full failure of an MME.
The MME determines that the SGW supports partial failure handling by the presence of the SGW FQ-CSID in the S11 Create Session Response. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14.3.3 Procedures during MME Partial Failure | If the MME supports the feature the following procedures apply.
When an MME detects that it has undergone a partial failure, it shall verify that one or more corresponding CSID(s) are present for the component(s) undergoing a partial fault. If there is no such CSID, then the following does not apply. When one or more CSIDs are currently assigned, the MME shall perform the following.
The MME may perform implementation-specific operations to clean up any residual state associated with the CSID(s).
The MME shall send a GTPv2 Delete PDN Connection Set Request containing all the MME CSID(s) of the component(s) failing in MME FQ-CSID(s) to the SGW peers that support the feature.
Upon receiving a GTPv2 Delete PDN Connection Set Response message with Cause value "Success", the MME shall conclude that the SGW peer has initiated the internal deletion of the PDN connections corresponding to the FQ-CSID(s) present in the GTPv2 Delete PDN Connection Set Request message.
Regardless of the "Cause" value in the response, the MME is not required to perform any further recovery actions towards SGW and PGW peers for PDN connections in the connection set identified by the MME FQ-CSID(s). |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14.3.4 Procedures during a Peer's Partial Failure | If the MME supports the feature, the following procedures apply.
When an MME receives a GTPv2 Delete PDN Connection Set Request message from an SGW, the MME shall retrieve all the PDN connections corresponding to each of the FQ-CSID(s) present in the message. The MME shall delete all the retrieved PDN connections and the associated resources. Other implementation-specific actions may be performed.
As a response, the MME shall send a GTPv2 Delete PDN Connection Set Response message with appropriate Cause value immediately to the SGW. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 14.3.5 Procedures during PDN Connection Removal or Modification | If an MME and an SGW support the feature, the following procedures apply.
During an S11 procedure, impacting an existing PDN connection removal or modification the following apply:
1) If the SGW is being relocated then the MME shall clear the currently stored SGW FQ‑CSID .
2) If an MME relocation occurs (for example, TAU with MME change), or if an SGW relocation occurs, (for example, TAU with SGW change), the MME shall include its MME FQ-CSID in the S11 Create Session Request for SGW change and the S11 Modify Bearer Request for MME change without SGW change.
3) Additionally, if MME decides to change own FQ-CSID, the MME shall include MME FQ-CSID in other S11 messages.
4) If the MME receives a FQ-CSID value of an SGW over S11, the MME shall overwrite the current stored SGW FQ‑CSID value with the received value.
5) If the MME receives a FQ-CSID value of a PGW over S11, the MME shall overwrite the current stored PGW FQ‑CSID value with the received value.
6) During a S11 procedure removing an existing PDN connection the MME removes the PDN data as well as any stored FQ-CSID values(s) of the PGW FQ-CSID and SGW FQ-CSID. The same actions are done on the old MME if there is an MME relocation.
The MME determines that the SGW supports partial failure handling by the presence of the SGW FQ-CSID in the S11 Create Session Response with SGW change; and S11 Modify Bearer Response without SGW change. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 15 Restoration of data in GERAN/UTRAN | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 15.1 BSS Failure (A/Gb mode) | When a BSS fails, all its BSS contexts affected by the failure become invalid and shall be deleted. BSS storage of data is volatile. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 15.2 RNC/BSC Failure (Iu mode) | When an RNC/BSC fails, all its RNC/BSC contexts affected by the failure become invalid and shall be deleted. RNC/BSC storage of data is volatile. An SGSN that recognises unavailability of an RNC/BSC or receives a Reset from an RNC/BSC, shall locally release the RABs for all affected PDP contexts.
Any affected PDP contexts that use Direct Tunnel and have an invalid tunnel in GGSN will be recovered when the SGSN receives an Iu connection establishment request from the MS or when the GGSN informed the SGSN that the GGSN has received a GTP error indication from RNC.
When the RNC/BSC receives a GTP‑U PDU for which no RAB context exists, the RNC/BSC shall discard the GTP‑U PDU and return a GTP error indication to the originating node that may be SGSN or GGSN if Direct Tunnel is established.
The RNC should ensure as far as possible that previously used TEID values are not immediately reused after an RNC restart, in order to avoid inconsistent TEID allocation throughout the network. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 15.3 RNC/BSC Failure (Iu mode) using S4 | When an RNC/BSC fails, all its RNC/BSC contexts affected by the failure become invalid and shall be deleted. RNC/BSC storage of data is volatile. An SGSN that recognises unavailability of an RNC/BSC or receives a Reset from an RNC/BSC, shall locally release the RABs for all affected PDP contexts. If ISR is activated or direct tunnel is established, the S4-SGSN shall initiate release of the access bearer for all bearers towards the Serving GW as defined in Iu Release Procedure Using S4 in 3GPP TS 23.060 [5]. For the other cases, the S4-SGSN may send the Release Access Bearers Request message to the Serving GW to remove the downlink user plane address and TEID as specified in 3GPP TS 23.060 [5]. In addition, based on operator policy, the SGSN may initiate the Dedicated Bearer Deactivation procedure for bearers using streaming or conversational traffic class. Any affected EPS bearers contexts in Serving GW are recovered when the SGSN receives an Iu connection establishment request from the MS or when the Serving GW initiates the Network Triggered Service Request procedure as specified in 3GPP TS 23.060 [5].
When the RNC/BSC receives a GTP‑U PDU for which no RAB Context exists, the RNC/BSC shall discard the GTP‑U PDU and return a GTP Error Indication to the originating node that may be SGSN or Serving GW if Direct Tunnel is established.
An S4-SGSN that recognises unavailability of an RNC (e.g. no more SCTP association in service) or receives a Reset message from an RNC shall maintain the related MBMS bearer contexts but shall locally delete the RNC related information (i.e. Iu related resources) for all MBMS service association(s) or those indicated in the Reset message. See clause 8.26 of 3GPP TS 25.413 [29].
Upon receipt of a Reset message from the RNC, the S4-SGSN should then subsequently re-establish the MBMS bearer services affected by the RNC failure by initiating MBMS Session Start procedure(s) towards the RNC. The S4-SGSN shall encode the contents of the MBMS Session Start Request with the same contents as in the original MBMS Session Start Request (or per the last MBMS Session Update Request received from the MBMS GW if the original parameters were updated) with the following exceptions:
- if the S4-SGSN has received recently an MBMS session re-establishment indication from the MBMS GW (i.e. within a past short period covering the time during which the same MBMS session may exist simultaneously in two S4-SGSNs of the S4-SGSN pool), the S4-SGSN shall set the "MBMS session re-establishment indication" flag to signal that this message is used to re-establish an MBMS session. Otherwise, the S4-SGSN shall not set "MBMS session re-establishment indication" flag;
- the S4-SGSN should set the estimated session duration to a value corresponding to the remaining duration of the session.
NOTE 1: During an Sn path failure when the MBMS GW moves the control of an MBMS session to an alternative S4-SGSN in the S4-SGSN pool (see clause 20.2.3.2), the MBMS session can exist in the old and in the new S4-SGSN for a short period of time. This time period is not bigger than the value of the maximum Sm path failure timer configured at the S4-SGSN. If an RNC happens to restart during this time, both S4-SGSNs will try to re-establish the MBMS session. In this case, it needs to be ensured that the control of the MBMS session remains at the new S4-SGSN, whatever the order of the MBMS Session Start Request messages the RNC will receive from both S4-SGSNs. The setting of the "MBMS session re-establishment indication" flag by the new S4-SGSN as specified above ensures that the new S4-SGSN, which has acquired the control of the MBMS session in the recent past, will get the control of the MBMS session.
NOTE 2: If the S4-SGSN receives an MBMS Session Update Request from the MBMS GW during the RNC failure, the contents of the MBMS Session Start Request sent to the RNC after the RNC recovery can also differ from the parameters sent to the RNC before its failure for the parameters that can be modified by the MBMS session update procedure (i.e. MBMS Session Area, MBMS Time to Data Transfer). |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 15.4 Other RNC functionality for MBMS restoration | The RNC should accept an MBMS Session Start Request received for an ongoing MBMS session (i.e. with the same TMGI)
- from the same or a different SGSN than the SGSN that currently controls the MBMS session, if the message contains the "MBMS session re-establishment indication" flag; or
- from the SGSN that currently controls the MBMS session, if the RNC supports the option to maintain MBMS bearer contexts during a pre-configured time period after an Iu path failure and the message is received during that period without the "MBMS session re-establishment indication" flag.
If it accepts the request from the SGSN, and if the message contains the "MBMS session re-establishment indication" flag, the RNC shall:
- replace the Iu related resources for this MBMS service associated to the previous SGSN by those assigned in the MBMS Session Request (if different) and consider that the MBMS session is now being controlled by the new SGSN (if different from the previous SGSN); for IP Unicast over Iu, the RNC receives the user plane data for this MBMS session via the new SGSN (if different from the previous SGSN);
- the RNC shall leave the former M1 transport network IP multicast address and join the new M1 transport network IP multicast address (including the IP address of the multicast source) if the MBMS Session Start Request contains a different transport network IP multicast distribution address and/or a different IP multicast source address; the RNC shall also use the C-TEID received in the MBMS Session Start Request
NOTE: This can also result in a change from IP Multicast to IP unicast or vice versa for the Iu userplane. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 15.5 Iu path failure using S4 | Upon detection of an Iu path failure (i.e. no more SCTP association in service),
- the RNC shall release all the MBMS services affected by the Iu path failure either immediately or after a pre-configured time period if the corresponding MBMS bearer contexts are not re-established via any S4-SGSN;
- the S4-SGSN shall maintain the related MBMS bearer contexts but shall locally delete the RNC related information (i.e. Iu related resources) for all MBMS service association(s).
Upon recovery of the Iu path, the RNC should initiate a Reset procedure towards the related S4-SGSN. Upon receipt of the Reset message from the RNC, the S4-SGSN should behave as specified for RNC failure in clause 15.3.
15A Restoration of data in E-UTRAN
15A.1 eNodeB Failure
15A.1.1 General
An MME which does not support UE context retention at SCTP recovery and recognises unavailability of an eNodeB (e.g. no more SCTP association in service) or an MME which receives a Reset or a S1 Setup message with UE Retention Information not set to "ues-retained" from an eNodeB, shall locally delete the eNodeB related information ("eNodeB Address in Use for S1-MME" and "eNodeB UE S1AP ID"). In this case, the MME initiates release of all S1 bearers towards the Serving GW by sending a Release Access Bearer Request message as defined in the S1 Release procedure in 3GPP TS 23.401 [15]. The MME shall initiate the Dedicated Bearer Deactivation procedure to deactivate the GBR bearers in the packet core; as an option, the MME may defer the deactivation of the GBR bearers for a short period (e.g. in the order of seconds) so as to allow the re-establishment of the corresponding radio and S1 bearers and thus avoid the GBR bearers deactivation if the MME receives a NAS Service Request or a GTP-C Downlink Data Notification message as a result of the SGW having received an Error Indication message from the eNodeB (see clause 22).
If the Serving GW receives Release Access Bearers Request message, the Serving GW shall release all eNodeB related information (address and TEIDs) for the UE, but other elements of the UE's Serving GW context shall not be affected. Any Bearer contexts affected by eNodeB failure that have no valid S1-U tunnel in Serving GW are recovered during the UE Triggered Service Request or during the Network Triggered Service Request procedure as specified in 3GPP TS 23.401 [15].
An MME, which supports UE context retention at SCTP recovery and recognises unavailability of an eNodeB (e.g. no more SCTP association in service), shall keep the UEs in ECM-CONNECTED and suspended UE Context data for UEs in ECM-IDLE, which have used the S1 signalling connection before it was broken. Upon the subsequent S1 Setup procedure, the MME and the eNB may agree that UE-related contexts and related signalling connection that have been existing before the S1 Setup shall not be affected as specified in the clause 19.2.2.8 of 3GPP TS 36.300 [32].
The eNodeB should ensure as far as possible that previously used TEID values are not immediately reused after an eNodeB restart, in order to avoid inconsistent TEID allocation throughout the network.
15A.1.2 PWS restoration
After an (H)eNodeB has restarted, it shall delete all its warning message data. If the warning message service is operational in one or more cell(s) of the (H)eNodeB, the (H)eNodeB shall send a PWS Restart Indication message, which shall include the identity of the (H)eNodeB, the identity of the restarted cell(s), and the TAI(s) and EAI(s) with which the restarted cell(s) are configured, to the CBC to request the CBC to re-load its warning message data if applicable.
The (H)eNB should send the PWS Restart Indication message via two MMEs of the MME pool, if possible, to ensure that the CBC receives the message even if one MME cannot propagate it to the CBC (e.g. due to an SBc path failure).
For HeNBs, the HeNB GW (respectively the MME) shall check the cell identity (respectively the HeNB identity) received in the PWS Restart Indication, as specified in clause 4.6.2 of 3GPP TS 36.300 [32].
Upon receipt of a PWS Restart Indication message, the CBC shall consider that the warning message service is restarted in the reported cell(s), i.e. the service is operational and no warning messages are being broadcast in the cell(s). The CBC shall then re-send the warning message data (with the same message identifier and serial number) to the (H)eNodeB for these cells, if any. When doing so, the CBC:
- shall include the identity of the (H)eNodeB received in the PWS Restart Indication into the Write-Replace-Warning-Request message(s) to enable the MME to forward the message(s) only to the (H)eNodeB (or HeNB GW) involved in the restart;
- should set the warning area list to the identities of the cell(s) to be reloaded which are relevant to the warning message data being reloaded; and
- may update the number of broadcasts requested, if necessary.
NOTE 1: Setting the warning area list to the identities of the cell(s) to be reloaded enables, for example, the HeNB GW to forward the message only to the involved HeNB when the restarted HeNB is connected to a HeNB GW.
The CBC shall consider a PWS Restart Indication message received shortly after a preceding one for the same cell identity as a duplicate restart indication for that cell which it shall ignore.
NOTE 2: The broadcast of warning messages can be configured in the network per individual cell, TAI and/or EAI. The CBC can use the list of cell(s), the TAI(s) and EAI(s) received in the PWS Restart Indication to derive the list of warning messages to be broadcast in the respective cell(s), TAI(s) and EAI(s).
Likewise, in other scenarios where the (H)eNodeB may need to reload its warning message data (e.g. when an individual cell is restarted), the (H)eNodeB shall send a PWS Restart Indication message (including the identity of the (H)eNodeB, the identity of the restarted cell(s), and the TAI(s) and EAI(s) with which the restarted cell(s) are configured) to the CBC to request the CBC to re-load its warning message data if applicable. The (H)eNodeB, MME and CBC shall then proceed as specified above for an (H)eNodeB restart.
15A.2 S1-AP path failure
Upon detection of an S1-AP path failure (i.e. no more SCTP association in service),
- the eNodeB shall either release the RRC connection of the affected UEs, or if UE context retention at SCTP recovery is supported, the eNodeB shall keep those UEs in RRC_CONNECTED and suspended UE Context data for UEs in ECM-IDLE, which have used the S1 signalling connection before it was broken;
- the MME shall proceed as specified for the eNodeB failure in clause 15A.1.
The eNodeB shall continue to broadcast warning messages, if any, during an S1AP path failure. Upon recovery of the S1AP path, the eNodeB shall proceed as if no S1AP path failure had occurred.
During an S1AP path failure, the warning message data stored in the eNodeB may become desynchronized with the CBC, e.g. if the CBC attempts to modify the warning message data during the S1AP path failure. The CBC and MME(s) should support the Write-Replace-Warning-Indication and Stop-Warning-Indication procedures (see 3GPP TS 23.041 [30]) to keep the warning message data synchronized in the eNodeB and the CBC.
15A.3 MCE Failure
When an MCE fails, the MCE shall release all the MBMS services affected by the failure locally and towards E-UTRAN within which the MBMS bearer services are active, either immediately or after a pre-configured time period if the corresponding MBMS bearer contexts are not re-established via any MME.
An MME that recognises unavailability of an MCE (e.g. no more SCTP association in service) or receives a Reset or a M3 Setup Request message from an MCE shall maintain the related MBMS bearer contexts but shall locally delete the MCE related information (i.e. M3 related resources) for all MBMS service association(s) or those indicated in the RESET message. See clauses 8.5 and 8.7 of 3GPP TS 36.444 [28].
Upon receipt of a Reset or M3 Setup Request message from the MCE, the MME should then subsequently re-establish the MBMS bearer services affected by the MCE failure by initiating MBMS Session Start procedure(s) towards the MCE. The MME shall encode the contents of the MBMS Session Start Request with the same contents as in the original MBMS Session Start Request (or per the last MBMS Session Update Request received from the MBMS GW if the original parameters were updated) with the following exceptions:
- if the MME has received recently an MBMS session re-establishment indication from the MBMS GW (i.e. within a past short period covering the time during which the same MBMS session may exist simultaneously in two MMEs of the MME pool), the MME shall set the "MBMS session re-establishment indication" flag to signal that this message is used to re-establish an MBMS session. Otherwise, the MME shall not set "MBMS session re-establishment indication" flag;
- if no absolute start time ("MBMS data transfer start" parameter) has been received, the MME may change the relative start time ("time to MBMS data transfer" parameter) to fasten the restoration of the MBMS service in E-UTRAN;
- the MME should set the estimated session duration to a value corresponding to the remaining duration of the session.
The MCE shall be able to accept MBMS session requests with an absolute start time ("MBMS data transfer start" parameter) in the past.
NOTE 1: During an Sm path failure when the MBMS GW moves the control of an MBMS session to an alternative MME in the MME pool (see clause 20.2.3.1), the MBMS session can exist in the old and in the new MME for a short period of time. This time period is not bigger than the value of the maximum Sm path failure timer configured at the MME. If an MCE happens to restart during this time, both MMEs will try to re-establish the MBMS session. In this case, it needs to be ensured that the control of the MBMS session remains at the new MME, whatever the order of the MBMS Session Start Request messages the MCE will receive from both MMEs. The setting of the "MBMS session re-establishment indication" flag by the new MME as specified above ensures that the new MME, which has acquired the control of the MBMS session in the recent past, will get the control of the MBMS session.
NOTE 2: If the MME receives an MBMS Session Update Request from the MBMS GW during the MCE failure, the contents of the MBMS Session Start Request sent to the MCE after the MCE recovery can also differ from the parameters sent to the MCE before its failure for the parameters that can be modified by the MBMS session update procedure (i.e. MBMS Session Area, MBMS Time to Data Transfer, MBMS Data Transfer Start).
15A.4 M3AP path failure
Upon detection of an M3AP path failure (i.e. no more SCTP association in service),
- the MCE shall release all the MBMS services affected by the M3AP path failure locally and towards E-UTRAN within which the MBMS bearer services are active, either immediately or after a pre-configured time period if the corresponding MBMS bearer contexts are not re-established via any MME;
- the MME shall maintain the related MBMS bearer contexts but shall locally delete the MCE related information (i.e. M3 related resources) for all MBMS service association(s).
Upon recovery of the M3AP path, the MCE should initiate a Reset or M3 Setup Request procedure towards the related MME. Upon receipt of the Reset or M3 Setup Request message from the MCE, the MME should then subsequently re-establish the MBMS bearer services affected by the M3AP path failure by initiating MBMS Session Start procedure(s) towards the MCE. The MME shall encode the MBMS Session Start Request with the same contents as in the original MBMS Session Start Request (or per the last MBMS Session Update Request received from the MBMS GW if the original parameters were updated) with the following exceptions:
- if the MME has received recently an MBMS session re-establishment indication from the MBMS GW (i.e. within a past short period covering the time during which the same MBMS session may exist simultaneously in two MMEs of the MME pool), the MME shall set the "MBMS session re-establishment indication" flag to signal that this message is used to re-establish an MBMS session. Otherwise, the MME shall not set "MBMS session re-establishment indication" flag;
- if no absolute start time ("MBMS data transfer start" parameter) has been received, the MME may change the relative start time ("time to MBMS data transfer" parameter) to fasten the restoration of the MBMS service in E-UTRAN;
- the MME should set the estimated session duration to a value corresponding to the remaining duration of the session.
The MCE shall be able to accept MBMS session requests with an absolute start time ("MBMS data transfer start" parameter) in the past.
NOTE 1: During an Sm path failure when the MBMS GW moves the control of an MBMS session to an alternative MME in the MME pool (see clause 20.2.3.1), the MBMS session can exist in the old and in the new MME for a short period of time. This time period is not bigger than the value of the maximum Sm path failure timer configured at the MME. If an M3AP path failure and recovery happens during this time, both MMEs will try to re-establish the MBMS session. In this case, it needs to be ensured that the control of the MBMS session remains at the new MME, whatever the order of the MBMS Session Start Request messages the MCE will receive from both MMEs. The setting of the "MBMS session re-establishment indication" flag by the new MME as specified above ensures that the new MME, which has acquired the control of the MBMS session in the recent past, will get the control of the MBMS session.
NOTE 2: If the MME receives an MBMS Session Update Request from the MBMS GW during the M3AP path failure, the contents of the MBMS Session Start Request sent to the MCE after the M3AP path recovery can also differ from the parameters sent to the MCE before the M3AP path failure for the parameters that can be modified by the MBMS session update procedure (i.e. MBMS Session Area, MBMS Time to Data Transfer, MBMS Data Transfer Start).
15A.5 Other MCE functionality for MBMS restoration
The MCE should accept an MBMS Session Start Request received for an on-going MBMS session (i.e. with the same TMGI)
- from the same or a different MME than the MME that currently controls the MBMS session, if the message includes the "MBMS session re-establishment indication" flag; or
- from the MME that currently controls the MBMS session, if the MCE supports the option to maintain MBMS bearer contexts during a pre-configured time period after an M3AP path failure, MME restart or MCE failure, and the message is received during that period without the "MBMS session re-establishment indication" flag.
If the MCE accepts the request from the MME, and if the message contains the "MBMS session re-establishment indication" flag,
- the MCE shall replace the M3 related resources for this MBMS service associated to the previous MME by those assigned in the MBMS Session Start Request (if different) and consider that the MBMS session is now being controlled by the new MME (if different from the previous MME);
- the eNodeB(s) involved in the broadcast of the MBMS session shall leave the former M1 transport network IP multicast address and join the new M1 transport network IP multicast address (including the IP address of the multicast source) if the MBMS Session Start Request contains a different transport network IP multicast distribution address and/or a different IP multicast source address; the eNodeB(s) shall also use the C-TEID received in the MBMS Session Start Request.
The MCE shall be able to accept MBMS session start/update/stop requests with an absolute start time ("MBMS data transfer start" or "MBMS data transfer stop" parameter) in the past.
15A.6 Other MME related functionality for MBMS restoration
When establishing MBMS bearer services in an MCE to ensure the distribution of content from ongoing MBMS sessions to an MCE which modifies the lists of the MBMS Service Areas it serves via the MCE Configuration Update procedure (see clause 5.9.2 of 3GPP TS 23.246 [12]), the MME shall encode the MBMS Session Start Request as specified in clause 15A.3 upon receipt of a Reset or M3 Setup Request message from the MCE. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 16 Restoration of data in the SGW | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 16.1 Restart of the SGW | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 16.1.0 SGW Failure | When a SGW fails, all its Bearer contexts affected by the failure become invalid and may be deleted. SGW storage of subscriber data is volatile.
When the SGW receives a GTP‑U PDU for which no Bearer context exists, it shall discard the GTP‑U PDU and return a GTP error indication to the originating node (the PGW, the eNodeB, the S4-SGSN, or if Direct Tunnel is established, the RNC) or follow the procedures specified in clause 27.2.2.5 if the restoration of PDN connections after an SGW failure is supported.
The SGW should ensure as far as possible that previously used TEID values are not immediately reused after a SGW restart, in order to avoid inconsistent TEID allocation throughout the network. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 16.1.1 Restoration Procedures | After an SGW restart, the SGW shall delete all MM Bearer contexts affected by the restart that it may have stored.
During or immediately after an SGW Restart the SGW shall place local SGW restart counter value in all GTPv2 Echo requests/responses messages and PMIPv6 heartbeat responses the SGW sends.
16.1a Restart of the SGW-C
16.1a.1 SGW-C failure
When a SGW-C fails, all its Bearer and Session contexts, Sx Association(s) affected by the failure become invalid and may be deleted.
If F-TEID allocation is performed in the SGW-C, the SGW-C should ensure as far as possible that previously used F-TEID values are not immediately reused after a SGW-C restart, in order to avoid inconsistent TEID allocation throughout the network.
NOTE: This is to ensure that F-TEIDs are not reused until earlier PDN connections using them are released e.g. in eNB or PGW.
16.1a.2 Restoration procedure
During or immediately after an SGW-C Restart, the SGW-C shall place local SGW-C Recovery Time Stamp value in all Heartbeat Request/Response and Sx Association Setup Request/Response Messages.
16.1b Restart of the SGW-U
16.1b.1 SGW-U failure
When a SGW-U fails, all its Sx session contexts and Sx Association(s) affected by the failure become invalid and may be deleted.
If F-TEID allocation is performed in the SGW-U, the SGW-U shall ensure that previously used F-TEID values are not immediately reused after a SGW-U restart, in order to avoid inconsistent TEID allocation throughout the network and to enable the restoration of Sx sessions affected by the failure. How this is ensured is implementation specific.
NOTE: As the user plane F-TEID pool is partitioned in the SGW-U across the multiple SGW-Cs controlling the SGW-U, the SGW-U does not need to wait for the re-establishment of all the Sx associations from all SGW-Cs to start assigning new F-TEID for new Sx sessions for a particular SGW-C.
16.1b.2 Restoration procedure
During or immediately after an SGW-U Restart, the SGW-U shall place local SGW-U Recovery Time Stamp value in all Heartbeat Request/Response and Sx Association Setup Request/Response Messages.
16.1A Restart of a peer node
16.1A.1 MME/S4-SGSN Failure
16.1A.1.1 General
The SGW will receive the MME/S4-SGSN restart counter in GTPv2 Echo requests and Echo response messages that the SGW receives from the MME/S4-SGSN.
When an SGW detects that a peer MME /S4-SGSN has restarted (see clause 18 "GTP-C based restart procedures") it shall either:
- delete all PDN connection table data/MM bearer contexts associated with the peer node that fails as well as freeing any internal SGW resources associated with those PDN connections. The SGW may optionally perform other implementation specific actions such as messages to clear other external resources (e.g. PCC messages to clear the resources in the PCRF or GTP/PMIP messages to release the corresponding PDN connection in the PGW);
or
- follow the network triggered service restoration procedure as specified in clause 25 if the MME, the S4-SGSN and the SGW support this procedure.
16.1A.2 PGW Failure
The SGW will receive the PGW restart counter in GTPv2 Echo requests/ responses and PMIPv6 heartbeat responses that the SGW receives from the PGW.
When an SGW detects that a peer PGW has restarted (see clause 18 "GTP-C based restart procedures") it shall delete all PDN connection table data/MM bearer contexts associated with the peer node that fails as well as freeing any internal SGW resources associated with those PDN connections. In addition, if the optional feature PGW Restart Notification is supported by the SGW and MME/S4-SGSN as specified in clause 8.83 in 3GPP TS 29.274[13], the SGW shall initiate the cleanup of the hanging PDN connections associated with the SGW and the restarted PGW at the corresponding MMEs/S4-SGSNs by sending GTPv2 message(s) PGW Restart Notification, with the control plane IP address of the restarted PGW and the control plane IP address of the SGW on the S11/S4 interface included. The SGW may optionally perform other implementation specific actions such as messages to clear other external resources (e.g. PCC messages).
If an SGW detects that a peer PGW has failed and not restarted, it may delete all PDN connection table data/MM bearer contexts associated with the peer node that fails as well as freeing any internal SGW resources associated with those PDN connections. In addition, if the optional feature PGW Restart Notification is supported by the SGW and MME/S4-SGSN as specified in clause 8.83 in 3GPP TS 29.274[13], the SGW may also send a PGW Restart Notification message to the MME or S4-SGSN. The PGW Restart Notification message shall include the control plane IP address of the PGW, the control plane IP address of the SGW on the S11/S4 interface and the cause value "PGW not responding". It is an implementation matter how an SGW becomes aware that a PGW has failed and has not restarted, e.g. the SGW detects a signalling path failure with the PGW for a duration exceeding the maximum path failure duration timer (see clause 20.2.1).
When the MME/S4-SGSN receives this message, according to the control plane IP address of the restarted PGW and the control plane IP address of the SGW on the S11/S4 interface included in the message, the MME/S4 SGSN should delete all PDN connection table data/MM bearer contexts associated with the SGW and the restarted PGW as well as freeing any internal MME/S4-SGSN resources associated with those PDN connections. Additionally the MME/S4-SGSN may decide to restore certain PDN connections based on operator's policy e.g. based on the QCI and/or ARP and/or APN. If so,
- the S4-SGSN shall deactivate the corresponding PDN connections using the "reactivation requested" cause value as specified in clause 9.2.4.2 of 3GPP TS 23.060 [5];
- the MME shall deactivate the corresponding PDN connections using the "reactivation requested" cause value as specified in clause 5.10.3 of 3GPP TS 23.401 [15] if only a subset of the PDN connections of the UE need to be restored or if the UE has a SCEF PDN connection or if the UE supports Attach without PDN connectivity as specified in clause 5.3.8.3 of 3GPP TS 23.401 [15]; if all the PDN connections of the UE need to be restored and the UE does not have a SCEF PDN connection and the UE does not support Attach without PDN connectivity, the MME shall initiate the "explicit detach with reattach required" procedure as specified in clause 5.3.8.3 of 3GPP TS 23.401 [15].
The MME/S4-SGSN may prioritize the PDN connections to restore based on operator's policy e.g. based on the QCI and/or APN. Besides, the MME/SGSN may use the subscribed Restoration Priority per APN, if received from the HSS, and if permitted by service level agreements for in-bound roamers, to determine the relative restoration priority among PDN connections to the same APN. The MME/SGSN may use a locally configured value as default restoration priority if the restoration priority for a user's PDN connection is not received from the HSS or not permitted by service level agreement for in-bound roamers.
NOTE 1: The Restoration Priority can e.g. allow to restore with a higher priority users with an IMS voice subscription over IMS users without an IMS voice subscription.
The MME/S4-SGSN may optionally perform other implementation specific actions such as to clear external resources (e.g. S1-MME messages to clear eNodeB resources or Iu messages to clear RNC resources) or more advanced forms of restoration.
NOTE 2: The SGW will have the identity of the MME/S4-SGSN and PGW currently in use for a PDN connection available in the SGW's PDN connection table as part of existing EPC procedure.
If PMIPv6 based S5/S8 interface is used and if the SGW needs to send a request for Gateway Control and QoS Policy Rules Provision procedure towards a PCRF which is known to have restarted since the Gateway Control Session Establishment, the SGW may discard the request and may tear down the associated PDN connection, based on operator policy, by sending a Delete Bearer Request message for the default bearer towards the MME/S4-SGSN with the cause set to "Reactivation requested". Additionally, SGW initiates an SGW initiated PDN Disconnection procedure towards PGW. This leads the UE to initiate a UE requested PDN connectivity procedure for the same APN. Emergency and eMPS sessions should not be torn down.
NOTE 3: The procedure above just enables to clean up the PDN connection affected by the PCRF failure when a specific interaction with the PCRF is required. Prior to that interaction, PCC controlled services cannot be provided to the UE.
For a split SGW, if the SGW-C detects a PGW failure, it shall initiate a Sx Session Deletion procedure towards the SGW-U.
16.1A.3 SGW-C Failure
The SGW-U will receive the recovery time stamps of the PFCP entity(ies) in the SGW-C in PFCP heartbeat request/response messages.
When an SGW-U detects that a peer PFCP entity in the SGW-C has restarted, the SGW-U shall delete all its Sx session contexts affected by the restart. When the SGW-U receives a GTP‑U PDU not matching any PDRs, it shall discard the GTP‑U PDU and return a GTP error indication to the originating node (the PGW, the eNodeB, the S4-SGSN, or if Direct Tunnel is established, the RNC); as an exception, if the restoration of PDN connections after an SGW failure is supported as specified in clause 27, the SGW-U shall not send Error indication message for a configurable period after the restart in the SGW-C.
NOTE: The period needs to be longer than the time required for the peer node to detect the restart of the SGW-C, e.g. the interval between two echo request messages. This ensures that the MME/SGSN or PGW does not deactivate the bearers before it detects the SGW-C failure and triggers the restoration procedure.
When a SGW-U detects that a peer PFCP entity in the SGW-C is not reachable for a preconfigured time, the SGW-U shall delete all session contexts affected by the unreachability of the peer PFCP entity in the SGW-C that it may have stored.
16.1A.4 SGW-U Failure
The SGW-C will receive the recovery time stamps of the PFCP entity(ies) in the SGW-U in PFCP heartbeat request/response messages.
After an SGW-U restart, the Sx association between SGW-C(s) and the SGW-U has to be re-established.
NOTE: The SGW-C can determine to re-establish the Sx Association if it receives the cause code "No established PFCP Association" in a response message, or if it detects all peer PFCP entities in the SGW-U have restarted.
Restoration of Sx sessions includes:
- if re-establishment of Sx association is required, the SGW-C may start immediately the Sx association setup procedure, and then;
- when re-establishing a Sx session and if F-TEID allocation is performed in the SGW-U by network configuration, the SGW-C shall include a restoration indication in the PFCP Session Establishment Request message to indicate to the SGW-U it is for a restoration of an existing PFCP session and the SGW-U shall accept SGW-C allocated F-TEID if possible.
- if the restoration is supported in the SGW-C on a proactive basis, the SGW-C may start re-establishing Sx sessions matching any PDRs.
- if the restoration is supported in the SGW-C on a reactive basis:
- the SGW-C shall establish an Sx session with a wildcarded PDR to instruct the UP function to forward G-PDU packets which are not matching any other PDRs to the CP function (to a F-TEID uniquely assigned in the CP function for this Sx-u tunnel);
- upon receipt of G-PDUs from this Sx-u tunnel, the CP function shall then check if it has an active session for each received G-PDU packet:
- if so, the CP function shall perform Sx Session establishment procedures to re-establish the corresponding Sx sessions in the SGW-U;
- otherwise the CP function shall generate a GTP-U Error Indication with a destination address set to the source IP address of the received G-PDU, and send it to the UP function. The UP function shall forward this GTP-U Error Indication transparently. The CP function shall delete the G-PDU after the check for active sessions.
NOTE 1: The SGW-U can filter the G-PDU packets with same target F-TEID and send only one such G-PDU to the CP function.
NOTE 2: Such Sx-u tunnel to forward GTP-U Error Indication can be established per UP function and can also be used to send End Marker packets generated by the CP function. See clause 5.3.2 of TS 29.244 [43]
The SGW-U shall not send Error indication message for a configurable period after a PFCP entity restart in the SGW-U when the SGW-U receives G-PDU not matching any PDRs.
NOTE 3: If restoration on a reactive basis is used, the period needs to be longer than the time required by the SGW-C to detect the SGW-U restart, establish the Sx association and provision the wildcarded PDR. Otherwise, the period needs to be longer than the time required by the SGW-C to restore all the Sx sessions on a proactive basis.
When the SGW-C detects the failure of an SGW-U without a restart, the SGW-C may select an alternative SGW-U which can take over the IP addresses of the failed one to restore the Sx sessions in the UP function. How this is performed is implementation specific. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 16.2 Partial Failure Handling at SGW | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 16.2.1 General | See Clause 23.
In addition, the following applies. If an SGW, which supports the feature receives Delete PDN Connection Set Request/Reply messages from MME or the PGW it shall forward the messages to the appropriate peer.
If the SGW does not support the feature then partial failure handling does not apply to that specific PDN connection. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 16.2.2 Procedures during PDN Connection Establishment | If the SGW supports the feature, the following procedures apply.
During a PDN connection establishment, the SGW shall provide one SGW FQ-CSID for that particular PDN connection to the PGW. Similarly, the SGW shall provide one SGW FQ-CSID for that particular PDN connection to the MME if the MME supports partial failure handling. The SGW shall store the Node-ID and CSID from the FQ-CSID provided by the PGW and the MME respectively for that particular PDN connection in its PDN Connection table maintained as part of "EPS Bearer Contexts" table as specified in Table 5.7.3-1 in 3GPP TS 23.401 [15].
The SGW shall forward the MME FQ-CSID provided by the MME on S11 to the PGW in the S5/S8 Create Session Request (Proxy Binding Update for PMIPv6) for that PDN connection. Similarly, the SGW shall forward the PGW FQ-CSID provided by the PGW on S5/S8 to the MME in the S11 Create Session Response for that PDN connection if the MME supports partial failure handling.
The SGW determines that the MME supports partial failure handling by the presence of the MME FQ-CSID in the S11 Create Session Request.
The SGW determines that the PGW supports partial failure handling by the presence of the PGW FQ-CSID in the S5/S8 Create Session Response for GTPv2 based S5/S8 and the Proxy Binding Acknowledgement for PMIPv6 based S5/S8. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 16.2.3 Procedures during SGW Partial Failure | If the SGW supports the feature, the following procedures apply.
When an SGW detects that it has undergone a partial failure, it shall verify that one or more corresponding CSID(s) are present for the component undergoing a partial fault. If there is no such CSID, then the following does not apply. When one or more CSIDs are currently assigned, the SGW shall perform the following.
The SGW may perform implementation-specific operations to clean up any residual state associated with the CSID(s).
The SGW shall send the GTPv2 Delete PDN Connection Set Request containing all the SGW CSIDs of the component(s) failing in SGW FQ-CSID to MME peers supporting the feature. The SGW shall send the GTPv2 Delete PDN Connection Set Request (or PMIP6 Binding Revocation Indication with G bit set) message containing the equivalent SGW FQ-CSID(s) to PGW peers supporting the feature.
Upon receiving a GTPv2 Delete PDN Connection Set Response message with Cause value "Success", the SGW shall conclude that the PGW (for GTPv2 S5/S8) or the MME (for S11) has initiated the internal deletion of the PDN connections corresponding to the FQ-CSID(s) present in the GTPv2 Delete PDN Connection Set Request message. Similarly, upon receiving a successful PMIP6 Binding Revocation Acknowledgment message with G bit set, the SGW shall conclude that the PGW has initiated the internal deletion of the PDN connections corresponding to the CSID(s) present in the PMIP6 Binding Revocation Indication message.
The SGW is not required to perform any further recovery actions towards MME and PGW peers for PDN connections in the connection set identified by the SGW FQ-CSID(s). |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 16.2.4 Procedures during a Peer's Partial Failure | If the SGW supports the feature, the following procedures apply.
When an SGW receives a S11 GTPv2 Delete PDN Connection Set Request message from an MME, the SGW shall retrieve all the PDN connections corresponding to each of the FQ-CSID(s) present in the message. The SGW shall send a S5/S8 GTPv2 Delete PDN Connection Set Request (or PMIP6 Binding Revocation Indication with G bit set) message containing the FQ-CSID(s) provided by the MME to PGW peers supporting the feature. The SGW shall delete all the retrieved PDN connections and the associated resources. Other implementation-specific actions may be performed.
As a response, the SGW shall send a S11 GTPv2 Delete PDN Connection Set Response message with an appropriate Cause value immediately to the MME.
When an SGW receives a S5/S8 GTPv2 Delete PDN Connection Set Request (or PMIP6 Binding Revocation Indication with G bit set) message from a PGW, the SGW shall retrieve all the PDN connections corresponding to each of the FQ-CSID(s) present in the message. The SGW shall send a S11 GTPv2 Delete PDN Connection Set Request message containing the FQ-CSID(s) provided by the PGW to MME peers supporting the feature. The SGW shall delete all the retrieved PDN connections and the associated resources. Other implementation-specific actions may be performed.
As a response, the SGW shall send a S5/S8 GTPv2 Delete PDN Connection Set Response message with an appropriate Cause value to the PGW. On PMIP6-based S5/S8 interface, the SGW shall send a PMIP6 Binding Revocation Acknowledgment message with G bit set.
If the SGW detects the full/complete failure of an MME or PGW, e.g., through the Echo Request/Echo Response procedure, it may send a Delete PDN Connection Set Request (or PMIP6 Binding Revocation Indication with G bit set) message, containing all of the FQ-CSIDs of the associated hanging PDN connections of the failed node, to the corresponding remote node (MME or PGW). |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 16.2.5 Procedures during PDN Connection Removal or Modification | Only if the SGW supports the feature, the following procedures apply.
During a S11 or an S5/S8 procedure, impacting an existing PDN connection removal or modification the following apply:
1) If the MME is being relocated then the SGW shall clear the currently stored MME FQ‑CSID value (if any).
2) For inter MME and intra SGW HO/TAU, and if the new MME supports the feature, then the SGW shall:
- include SGW FQ-CSID in the S11 Modify Bearer Response. If PGW supports the feature, the SGW shall also include PGW FQ-CSID into the message.
- inform the feature supporting PGW about the change of FQ-CSID values with the following messages:
- Modify Bearer Request, when Modify Bearer Request message needs to be sent to the PGW as specified in the 3GPP TS 23.401 [15], e.g. if the sending of this message is triggered by user location reporting procedure. The message shall contain both SGW FQ-CSID and MME FQ-CSID.
- Update PDN Connection Set Request message, only if Modify Bearer Request is not sent. The message shall contain both SGW FQ-CSID and MME FQ-CSID.
- Proxy Binding Update (if PMIPv6 is used). The message shall contain both SGW FQ-CSID and MME FQ-CSID.
3) For inter MME and intra SGW HO/TAU, and if the new MME does not support the feature, then the SGW shall:
- not include any FQ-CSID in the S11 Modify Bearer Response.
- inform the feature supporting PGW with the following messages:
- Modify Bearer Request when Modify Bearer Request message needs to be sent to the PGW as specified in the 3GPP TS 23.401 [15], e.g. if the sending of this message is triggered by user location reporting procedure. The message shall contain only SGW FQ-CSID.
- Update PDN Connection Set Request message, only if Modify Bearer Request is not sent. The message shall contain only SGW FQ-CSID.
- Proxy Binding Update (if PMIPv6 is used). The message shall contain only the SGW FQ-CSID.
NOTE: The patial failure handling is not supported by the S4-SGSN, therefore, during the RAU/HO to S4-SGSN procedure, the SGW can behave in the same way as the TAU/HO to a MME which does not support the feature.
4) For inter SGW HO/TAU, if the new MME supports the feature, then the new SGW shall:
- include SGW FQ-CSID in the S11 Create Session Response. If PGW supports the feature, the SGW shall also include PGW FQ-CSID into the message.
- inform the feature supporting PGW about the change of FQ-CSID values with the following messages:
- Modify Bearer Request. The message shall contain both SGW FQ-CSID and MME FQ-CSID.
- Proxy Binding Update (if PMIPv6 is used). The message shall contain both SGW FQ-CSID and MME FQ-CSID.
5) For inter SGW HO/TAU, if the MME does not support the feature, then the SGW shall:
- not include any FQ-CSID in the S11 Create Session Response.
- inform the feature supporting PGW about the change of SGW FQ-CSID value with the following messages:
- Modify Bearer Request. The message shall contain only SGW FQ-CSID
- Proxy Binding Update (if PMIPv6 is used). The message shall contain only the SGW FQ-CSID.
6) If the SGW receives a FQ-CSID value of a PGW over S5/S8, or a FQ-CSID value of a MME over S11, the SGW shall overwrite the current stored FQ‑CSID value with the received value.
7) During the PDN connection removing procedures, a PGW removes the PDN data as well as any stored FQ-CSID values(s) of the MME and SGW FQ-CSIDs.
8) For the following procedures, if the procedures as specified in 3GPP TS 23.401 [15] e.g. Location Change reporting is enabled, the SGW shall send its own FQ-CSID and the MME FQ-CSID in Modify Bearer Request and Proxy Binding Update across S5/S8 interface to the respective PGW even if the MME did not update its FQ-CSID, e.g.:
- X2-based Handover without SGW relocation
- TAU without MME and without SGW relocation
- UE Triggered Service Request
During a S11 or S5/S8 procedure removing an existing PDN connection the SGW simply removes the PDN data as well as any stored FQ-CSID values(s) of the PGW FQ-CSID and MME FQ-CSID or pointers to such data. The same actions are done on the old SGW if there is an SGW relocation.
An SGW determines that the MME supports partial failure handling if MME FQ-CSID is present in the received S11 Modify Bearer Request or S11 Create Session Request (with both MME and SGW change) messages.
A new SGW determines that the PGW supports partial failure handling if PGW FQ-CSID is present in the S5/S8 Modify Bearer Response for GTPv2 based S5/S8 or in the Proxy Binding Acknowledgement for PMIPv6 based S5/S8. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 17 Restoration of data in the PGW | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 17.1 Restart of the PGW | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 17.1.0 PGW Failure | When a PGW fails, all its Bearer contexts affected by the failure become invalid and may be deleted. PGW storage of subscriber data is volatile.
When the PGW receives a GTP‑U PDU for which no Bearer context exists, it shall discard the GTP‑U PDU and return a GTP error indication to the originating node i.e. the SGW/ePDG/TWAN.
The PGW should ensure as far as possible that previously used TEID values are not immediately reused after a PGW restart, in order to avoid inconsistent TEID allocation throughout the network. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 17.1.1 Restoration Procedures | After a PGW restart, the PGW shall delete all MM Bearer contexts affected by the restart that it may have stored.
During or immediately after a PGW Restart, the PGW shall place this PGW restart counter value in all GTPv2 echo requests/responses and PMIPv6 heartbeat responses the PGW sends.
17.1a Restart of the PGW-C
17.1a.1 PGW-C failure
When a PGW-C fails, all its Bearer, session contexts and Sx associations affected by the failure become invalid and may be deleted.
If F-TEID allocation is performed in the PGW-C, the PGW-C should ensure as far as possible that previously used F-TEID values are not immediately reused after a PGW-C restart, in order to avoid inconsistent TEID allocation throughout the network.
NOTE: This is to ensure that F-TEIDs are not reused until earlier PDN connections using them are released.
17.1a.2 Restoration Procedures
After a PGW-C restart, the PGW-C shall delete all MM Bearer and session contexts, and Sx Associations affected by the restart that it may have stored.
During or immediately after a PGW-C Restart, the PGW-C shall place local PGW-C Recovery Time Stamp value in all Heartbeat Request/Response and Sx Association Setup Request/Response Messages.
17.1b Restart of the PGW-U
17.1b.1 PGW-U failure
When a PGW-U fails, all its Session contexts and Sx associations affected by the failure become invalid and may be deleted.
If F-TEID allocation is performed in the PGW-U, the PGW-U shall ensure that previously used F-TEID values are not immediately reused after a PGW-U restart, in order to avoid inconsistent TEID allocation throughout the network and to enable the restoration of Sx sessions affected by the failure. How this is ensured is implementation specific.
The PGW-U shall not send Error indication message for a configurable period after an PGW-U restart when the PGW-U receives G-PDU not matching any PDRs.
17.1b.2 Restoration Procedures
During or immediately after an PGW-U Restart, the PGW-U shall place local PGW-U Recovery Time Stamp value in all Heartbeat Request/Response and Sx Association Setup Request/Response Messages.
Immediately after the re-establishment of an Sx association between the PGW-C and the PGW-U, the PGW-C may start restoring Sx sessions in the PGW-U.
NOTE : Restoring Sx sessions in a PGW-U on a reactive basis (like defined for an SGW-U restart in clause 16.1A.4) is not supported in this release. In some cases, a restarted PGW-U cannot determine from the UE IP address the CP function reponsible for an incoming packet for which no session exists, e.g. when a UP function is controlled by multiple CP function for the same APN and when the UE IP address was assigned by the PDN.
17.1A Restart of a peer node
17.1A.1 SGW/ePDG/TWAN Failure
The PGW will receive the SGW/ePDG/TWAN restart counters in GTPv2 echo requests/responses and PMIPv6 heartbeat responses that the PGW receives from the SGW/ePDG/TWAN.
When a PGW detects that a peer ePDG/peer TWAN has restarted it shall delete all PDN connection table data/MM bearer contexts associated with the peer node that fails as well as freeing any internal PGW resources associated with those PDN connections. The PGW may optionally perform other implementation specific actions such as messages to clear other external resources (e.g. PCC messages).
When a PGW detects that a peer SGW has failed with or without restart it shall either:
- proceed as specified above when the PGW detects that a peer ePDG/TWAN fails; or
- follow the procedures specified in clause 27 to restore the PDN connections affected by the SGW failure, if the MME/S4-SGSN and the PGW support these procedures.
NOTE: The PGW will have the identity of SGW/ePDG/TWAN currently in use for a PDN connection available in the PGW's PDN connection table as part of existing EPC procedure.
For multi-access PDN connection in the Network-initiated NBIFOM mode, when the PGW detects ePDG/TWAN has failed, the PGW may:
- maintain the PDN connection on the 3GPP access and notify the PCRF the removal of Non-3GPP access. Then the PCRF can determine to move the affected traffic to the 3GPP access by updating the PCC rules as specified in the clause 5.8 in the 3GPP TS 23.161 [39].
For multi-access PDN connection in the Network-initiated NBIFOM mode, when the PGW detects that the SGW has failed, the PGW may:
- maintain the PDN connection on the Non-3GPP access and notify the PCRF the removal of 3GPP access. Then the PCRF can determine to move the affected traffic to the 3GPP access by updating the PCC rules as specified in the clause 5.8 in the 3GPP TS 23.161 [39], if the SGW restoration procedures as specified in clause 27 are not supported; or,
- follow the SGW restoration procedures specified in clause 27, e.g. maintain the PDN connection on both non-3GPP access and 3GPP access without notify the PCRF about SGW failure, if the SGW restoration procedures are supported.
17.1A.2 PCRF Failure
If the PGW needs to send a request for IP-CAN Session Modification procedure towards a PCRF which is known to have restarted since the IP-CAN session establishment, the PGW may discard the request and may tear down the associated PDN connection, based on operator policy, by initiating a PGW initiated bearer deactivation procedure for the default bearer towards the MME/S4-SGSN with the cause set to "Reactivation requested". This leads the UE to initiate a UE requested PDN connectivity procedure for the same APN. Emergency and eMPS sessions should not be torn down.
NOTE: The procedure above just enables to clean up the PDN connection affected by the PCRF failure when a specific interaction with the PCRF is required. Prior to that interaction, PCC controlled services cannot be provided to the UE.
17.1A.3 PGW-C Failure
The PGW-U will receive the recovery time stamps of the PFCP entity(ies) in the PGW-C in PFCP heartbeat requests/responses.
When a PGW-U detects that a peer PFCP entity in the PGW-C has restarted, the PGW-U shall delete all session contexts affected by the restart that it may have stored.
When a PGW-U detects that a peer PFCP entity in the PGW-C is not reachable for a preconfigured time, the PGW-U shall delete all session contexts affected by the unreachability of the peer PFCP entity in the PGW-C that it may have stored.
17.1A.4 PGW-U Failure
The PGW-C will receive the recovery time stamps of the PFCP entity(ies) in the PGW-U in and PFCP heartbeat requests/responses.
The PGW-C may start restoring Sx sessions in the PGW-U and it may:
- if re-establishment of Sx association is required, immediately re-establish the Sx association between the PGW-C and the PGW-U;
- re-establish Sx sessions affected by the PGW-U failure. .
- when re-establishing a Sx session and if F-TEID allocation is performed in the PGW-U by network configuration, the PGW-C shall include a restoration indication in the PFCP Session Establishment Request message to indicate to the PGW-U it is for a restoration of an existing PFCP session and the PGW-U shall accept PGW-C allocated F-TEID if possible.
NOTE: The PGW-C can determine to re-establish the Sx Association if it receives the cause code "No established PFCP Association" in a response message, or if it detects all peer PFCP entities in the PGW-U have restarted. When a PGW-C detects the failure of a PGW-U without a restart, the PGW-C may select an alternative PGW-U to restore the Sx sessions in the UP function. How this is performed is implementation specific. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 17.2 Partial Failure Handling at PGW | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 17.2.1 General | See Clause 23. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 17.2.2 Procedures during PDN Connection Establishment | If the PGW supports the feature, the following procedures apply.
During a PDN connection establishment, the PGW shall provide one FQ-CSID containing exactly one CSID for that particular PDN connection to the SGW, the ePDG or the TWAN. The PGW shall store the FQ-CSID provided by the SGW and the MME in the PDN Connection table maintained as part of P-GW Context as specified in Table 5.7.3-1 in 3GPP TS 23.401 [15]. Similarly, the PGW shall store the FQ-CSID received from the ePDG or the TWAN.
The PGW should ensure as far as possible that previously used FQ-CSIDs are not immediately reused after a partial/full failure of a PGW.
PGW determines that the partial failure handling does not apply to this PDN connection if it does not receive an SGW FQ-CSID in the S5/S8 Create Session Request (for GTP based interface) or in Proxy Binding Update (for PMIPv6 based interface), or if it does not receive a TWAN FQ-CSID in the S2a Create Session Request (for GTP based S2a) or in Proxy Binding Update (for PMIPv6 based S2a), or if it does not receive an ePDG FQ-CSID in the S2b Create Session Request (for GTP based S2b) or in Proxy Binding Update (for PMIPv6 based S2b). |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 17.2.3 Procedures during PGW Partial Failure | If the PGW supports the feature, the following procedures apply.
When a PGW detects that it has undergone a partial failure, it shall verify that one or more corresponding CSID(s) are present for the component(s) undergoing a partial fault. If there is no such CSID, then the following does not apply. When one or more CSIDs are currently assigned, the PGW shall perform the following:
- The PGW may perform implementation-specific operations to clean up any residual state associated with the CSID(s).
- The PGW shall send the GTPv2 Delete PDN Connection Set Request (or PMIPv6 Binding Revocation Indication with G bit set) message containing all the PGW FQ-CSID(s) of the component(s) failing to the SGW, the TWAN or the ePDG that support the feature.
Upon receiving a GTPv2 Delete PDN Connection Set Response message with Cause value "Success", the PGW shall conclude that the SGW, the ePDG peer or the TWAN peer has initiated the internal deletion of the PDN connections corresponding to the FQ-CSID(s) present in the GTPv2 Delete PDN Connection Set Request message. Similarly, upon receiving a PMIP6 Binding Revocation Acknowledgment message with G bit set, the PGW shall conclude that the SGW, the ePDG or the TWAN has initiated the internal deletion of the PDN connections corresponding to the CSID(s) present in the PMIPv6 Binding Revocation Indication message with G bit set.
The PGW is not required to perform any further recovery actions towards SGW, MME peers, an ePDG peer or a TWAN peer for PDN connections in the connection set identified by the PGW FQ-CSID regardless of the "Cause" value in the response. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 17.2.4 Procedures during a Peer's Partial Failure | If the PGW supports the feature, the following procedures apply.
When a PGW receives a GTPv2 Delete PDN Connection Set Request (or PMIPv6 Binding Revocation Indication with G bit set) message from an SGW, an ePDG or a TWAN, the PGW shall retrieve all the PDN connections corresponding to each of the FQ-CSIDs present in the message. The PGW shall delete all the retrieved PDN connections and the associated resources. Other implementation-specific actions may be performed.
As a response, the PGW shall send a GTPv2 Delete PDN Connection Set Response message. On PMIPv6-based S5/S8 interface, the PGW shall send a PMIPv6 Binding Revocation Acknowledgment message with G bit set. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 17.2.5 Procedures during PDN Connection Removal or Modification | If the PGW supports the feature, the following procedures apply.
During a S5/S8 procedure, impacting an existing PDN connection Removal or Modification the following apply:
1) If an SGW is being relocated then the PGW shall clear the currently stored MME and SGW FQ‑CSID values.
2) If the SGW includes a SGW FQ-CSID in the S5/S8 Modify Bearer Request (Proxy Binding Update for PMIPv6), or Update PDN Connection Request message, then the PGW shall include PGW FQ-CSID in the S5/S8 Modify Bearer Response (Proxy Binding Acknowledgement for PMIPv6), or Update PDN Connection Response message.
3) If the new SGW does not include a SGW FQ-CSID in the S5/S8 Modify Bearer Request (Proxy Binding Update for PMIPv6), then the new SGW does not support the feature and the feature does not apply for this PDN connection. In such case, PGW shall not include PGW FQ-CSID in the S5/S8 Modify Bearer Response (Proxy Binding Acknowledgement for PMIPv6).
4) If the PGW receives an SGW FQ-CSID and/or an MME FQ-CSID value of a SGW over S5/S8 then the PGW shall overwrite the respective stored FQ-CSID value with the received value.
5) If the PGW receives an Update PDN Connection Request, a Modify Bearer Request or Proxy Binding Update with an SGW FQ-CSID but without an MME FQ-CSID then the PGW shall erase the MME FQ-CSID value (i.e. the current MME does not support the feature).
6) During a S5/S8 procedure removing an existing PDN connection the PGW simply removes the PDN data as well as any stored FQ-CSID values(s) of the MME and SGW or pointers to such data.
During an S2a/S2b procedure, impacting an existing PDN connection Removal or Modification the following apply:
1) If the PGW receives a TWAN or an ePDG FQ-CSID value then the PGW shall overwrite the respective stored FQ-CSID value with the received value;
2) During an S2a/S2b procedure removing an existing PDN connection, the PGW removes the corresponding PDN data as well as any stored FQ-CSID value of the TWAN or the ePDG FQ-CSID.
17A Restoration of data in the MBMS GW
17A.1 Restart of the MBMS GW
When a MBMS GW fails, all its MBMS Bearer contexts affected by the failure become invalid and will be deleted. MBMS GW storage of subscriber data is volatile.
After a MBMS GW restart, all the MBMS Bearer contexts stored in the MBMS GW and affected by the restart become invalid and will be deleted. All the SGmb Diameter sessions affected by the restart are also lost in the MBMS GW.
When the SGSN/MME detects a restart in a MBMS GW (see clause 18 "GTP-C based restart procedures") with which it has MBMS Bearer contexts activated, it shall deactivate all the related MBMS Bearer contexts locally and towards E-UTRAN/UTRAN in which the MBMS bearer service is active. The MME shall initiate a M3AP Reset procedure (see clause 8.5 of 3GPP TS 36.444 [28]), or an MBMS Session Stop procedure per affected MBMS service (see clause 8.3 of 3GPP TS 36.444 [28]), towards the MCE(s) to deactivate the related MBMS services in E-UTRAN. The SGSN shall initiate an MBMS Session Stop procedure per affected MBMS service (see clause 8.38 of 3GPP TS 25.413 [29]), towards the RNC(s) to deactivate the related MBMS services in UTRAN.
If the MBMS GW receives a non-initial message (i.e. MBMS session update or MBMS session stop request) from the BM-SC for which no SGmb Diameter session exists, the MBMW GW shall discard the message and return a Diameter error indication to the originating BM-SC.
In deployments without a Diameter Agent between the BM-SC and the MBMS GW, the BM-SC shall detect a restart in the MBMS GW using either:
- the Diameter Origin-State-Id AVP as specified in the Diameter Base Protocol. To enable fast detection of restart, the Diameter Origin-State-Id AVP shall be included (at least) in Capabilities-Exchange-Request and Capabilities-Exchange-Answer commands; or
- the Diameter Restart-Counter AVP as specified in the MBMS Heartbeat procedure (see clause 29), if this procedure is supported.
In deployments with a Diameter Agent between the BM-SC and the MBMS GW, the BM-SC shall detect a restart in the MBMS GW using the Diameter Restart-Counter AVP as specified in the MBMS Heartbeat procedure (see clause 29).
NOTE 1: The intermediate Diameter Agent can remove or update the Diameter Origin-State-Id AVP, e.g. if it needs to modify the Origin-Host-ID. Thus the Diameter Origin-State-Id AVP, if received by the BM-SC or MBMS GW, does not reflect the state of the remote MBMS peer but the state of the Diameter Agent.
When the BM-SC detects a restart in a MBMS GW with which it has at least one MBMS Bearer context, the BM-SC shall maintain the related MBMS bearer context(s), assume that all related SGmb Diameter session(s) have been terminated and clean-up internal resources associated with these lost session(s). The BM-SC should then re-establish the active MBMS bearer services affected by the MBMS GW restart by initiating MBMS Session Start procedure(s) towards the restarted MBMS GW (or an alternative MBMS GW). The BM-SC shall encode the MBMS Session Start Request with the same contents as in the original MBMS Session Start Request (or per the last MBMS Session Update Request sent by the BM-SC if the original parameters were updated) with the following exceptions:
- the BM-SC shall set the "MBMS session re-establishment indication" flag to signal that this message is used to re-establish an MBMS session;
- if no absolute start time ("MBMS data transfer start" parameter) has been sent, the BM-SC may change the relative start time ("time to MBMS data transfer" parameter) to fasten the restoration of the MBMS service in E-UTRAN;
- the BM-SC should set the estimated session duration to a value corresponding to the remaining duration of the session.
NOTE 2: If the BM-SC is instructed to modify an MBMS Session during the MBMS GW failure/restart, the contents of the MBMS Session Start Request sent to the MBMS GW after the MBMS GW restart can also differ from the parameters sent to the MBMS GW before its restart for the parameters that can be modified by the MBMS session update procedure (i.e. MBMS Session Area, MBMS Time to Data Transfer, MBMS Data Transfer Start).
17A.2 Restart of a peer node
17A.2.1 MME failure
The behaviour of an MBMS GW when it detects that a peer MME has restarted is described in clause 14.1.1.
17A.2.2 SGSN failure
The behaviour of an MBMS GW when it detects that a peer SGSN has restarted is described in clause 11.1.
17A.2.3 BM-SC failure
In deployments without a Diameter Agent between the BM-SC and the MBMS GW, the MBMS GW shall detect a restart in the BM-SC using either:
- the Diameter Origin-State-Id AVP as specified in the Diameter Base Protocol. To enable fast detection of restart, the Diameter Origin-State-Id AVP shall be included (at least) in Capabilities-Exchange-Request and Capabilities-Exchange-Answer commands; or
- the Diameter Restart-Counter AVP as specified in the MBMS Heartbeat procedure (see clause 29), if this procedure is supported.
In deployments with a Diameter Agent between the BM-SC and the MBMS GW, the MBMS GW shall detect a restart in the BM-SC using the Diameter Restart-Counter AVP as specified in the MBMS Heartbeat procedure (see clause 29).
NOTE: The intermediate Diameter Agent can remove or update the Diameter Origin-State-Id AVP, e.g. if it needs to modify the Origin-Host-ID. Thus the Diameter Origin-State-Id AVP, if received by the BM-SC or MBMS GW, does not reflect the state of the remote MBMS peer but the state of the Diameter Agent.
When the MBMS GW detects a restart of the BM-SC with which it has at least one MBMS Bearer context, the MBMS GW shall assume that all related SGmb Diameter session(s) have been terminated and shall deactivate all the related MBMS Bearer contexts locally and towards E-UTRAN/UTRAN in which the MBMS bearer service is active by sending MBMS Session Stop messages to their controlling MME/SGSNs.
17B Restoration of data in the ePDG
17B.1 Restart of the ePDG
17B.1.1 ePDG Failure
When an ePDG fails, all its Bearer contexts/PDN connections affected by the failure become invalid and may be deleted. ePDG storage of subscriber data is volatile.
When the ePDG receives a GTP‑U PDU over GTPv2 based S2b for which no Bearer context exists, it shall discard the GTP‑U PDU and return a GTP error indication to the originating node (i.e. the PGW).
The ePDG should ensure as far as possible that previously used TEID values are not immediately reused after an ePDG restart, in order to avoid inconsistent TEID allocation throughout the network.
When the ePDG receives a user packet with an unknown GRE Key over PMIPv6 based S2b, the ePDG shall discard the packet and optionally response back with an ICMP message, as specified in Clauses 8.2 and 8.3 of IETF RFC2473 [31] for the node unreachable error case.
17B.1.2 Restoration Procedures
After an ePDG restart, the ePDG shall delete all MM Bearer contexts affected by the restart that it may have stored.
During or immediately after an ePDG Restart the ePDG shall place local ePDG restart counter value in all GTPv2 Echo requests/responses messages and PMIPv6 heartbeat responses the ePDG sends to the PGW.
17B.1A Restart of a peer node
17B.1A.1 PGW Failure
The ePDG will receive the PGW restart counter in GTPv2 Echo requests/ responses and PMIPv6 heartbeat responses that the ePDG receives from the PGW.
When an ePDG detects that a peer PGW has restarted (see clause 18 "GTP-C based restart procedures" and clause 19 "PMIPv6 based restart procedures") it shall delete all PDN connection table data/MM bearer contexts associated with the peer node that fails, free any internal ePDG resources associated with those PDN connections and initiate the release of the corresponding SWu instances (i.e. IKEv2 tunnels).
17B.2 Partial Failure Handling at ePDG
17B.2.1 General
See clause 23.
The partial failure feature is optional for ePDG.
If the ePDG does not support the feature then partial failure handling does not apply to that specific PDN connection.
17B.2.2 Procedures during PDN Connection Establishment
If the ePDG supports the feature, the following procedures apply.
During a PDN connection establishment, the ePDG shall provide one ePDG FQ-CSID containing exactly one CSID for that particular PDN connection to the PGW. The ePDG shall store the Node-ID and CSID from the FQ-CSID provided by the PGW for that particular PDN connection in its PDN Connection table.
The ePDG determines that the PGW supports partial failure handling by the presence of the PGW FQ-CSID in the Create Session Response for GTPv2 based S2b and/or Proxy Binding Acknowledgement message for PMIPv6 based S2b.
17B.2.3 Procedures during ePDG Partial Failure
If the ePDG supports the feature, the following procedures apply.
When an ePDG detects that it has undergone a partial failure, it shall verify that one or more corresponding CSID(s) are present for the component undergoing a partial fault. If there is no such CSID, then the following does not apply. When one or more CSIDs are currently assigned, the ePDG shall perform the following.
The ePDG may perform implementation-specific operations to clean up any residual state associated with the CSID(s).
The ePDG shall send Delete PDN Connection Set Request containing all the ePDG CSIDs of the component(s) failing in ePDG FQ-CSID over the GTPv2 based S2b interface or PMIPv6 Binding Revocation Indication with G bit set message containing the equivalent ePDG FQ-CSID(s) over the PMIPv6 based S2b interface to PGW peers supporting the feature.
On the GTPv2 based S2b interface, upon receiving a GTPv2 Delete PDN Connection Set Response message with Cause value "Success", the ePDG shall conclude that the PGW has initiated the internal deletion of the PDN connections corresponding to the FQ-CSID(s) present in the GTPv2 Delete PDN Connection Set Request message. Similarly, on the PMIPv6 based S2b interface, upon receiving a successful PMIP6 Binding Revocation Acknowledgment message with G bit set, the ePDG shall conclude that the PGW has initiated the internal deletion of the PDN connections corresponding to the CSID(s) present in the PMIP6 Binding Revocation Indication message.
The ePDG is not required to perform any further recovery actions towards PGW peers for PDN connections in the connection set identified by the PGW FQ-CSID(s).
17B.2.4 Procedures during PGW Partial Failure
If the ePDG supports the feature, the following procedures apply.
When an ePDG receives a GTPv2 Delete PDN Connection Set Request or PMIP6 Binding Revocation Indication with G bit set message from a PGW, the ePDG shall retrieve all the PDN connections corresponding to each of the FQ-CSID(s) present in the message. The ePDG shall delete all the retrieved PDN connections, free the associated internal resources and initiate the release of the corresponding SWu instances (i.e. IKEv2 tunnels). Other implementation-specific actions may be performed.
As a response, the ePDG shall send a GTPv2 Delete PDN Connection Set Response message with an appropriate Cause value or a PMIPv6 Binding Revocation Acknowledgment message with G bit set to the PGW.
17B.2.5 Procedures during PDN Connection Removal or Modification
For the modification of an existing PDN connection established over 2b, if the corresponding ePDG and PGW support the partial failure feature, when the ePDG receives an FQ-CSID value of a PGW over S2b, the ePDG shall overwrite the currently stored FQ CSID value with the received value.
For the removal of an existing PDN connection established over S2b, if the corresponding ePDG and PGW support the partial failure feature, an ePDG removes the corresponding PDN data as well as any relevant stored FQ-CSID value of the PGW FQ-CSID.
17C Restoration of data in the TWAN
17C.1 Restart of the TWAN
17C.1.1 TWAN Failure
When a TWAN fails, all its Bearer contexts/PDN connections affected by the failure become invalid and may be deleted. TWAN storage of subscriber data is volatile.
When the TWAN receives a GTP‑U PDU over GTPv2 based S2a for which no Bearer context exists, it shall discard the GTP‑U PDU and return a GTP error indication to the originating node (i.e. the PGW).
The TWAN should ensure as far as possible that previously used TEID values are not immediately reused after a TWAN restart, in order to avoid inconsistent TEID allocation throughout the network.
When the TWAN receives a user packet with an unknown GRE Key over PMIPv6 based S2a, the TWAN shall discard the packet and optionally respond back with an ICMP message, as specified in Clauses 8.2 and 8.3 of IETF RFC2473 [31] for the node unreachable error case.
17C.1.2 Restoration Procedures
After a TWAN restart, the TWAN shall delete all Bearer contexts affected by the restart that it may have stored and place local TWAN restart counter value in all GTPv2 Echo requests/responses messages and PMIPv6 heartbeat responses the TWAN sends to the PGW.
17C.1A Restart of a peer node
17C.1A.1 PGW Failure
The TWAN will receive the PGW restart counter in GTPv2 Echo requests/ responses and PMIPv6 heartbeat responses that the TWAN receives from the PGW.
When a TWAN detects that a peer PGW has restarted (see clause 18 "GTP-C based restart procedures" and clause 19 "PMIPv6 based restart procedures") it shall delete all PDN connection table data/bearer contexts associated with the peer node that fails, and may free the associated internal TWAN resources.
17C.2 Partial Failure Handling at TWAN
17C.2.1 General
See clause 23.
The partial failure feature is optional for TWAN.
If the TWAN does not support the feature then partial failure handling does not apply to that specific PDN connection.
17C.2.2 Procedures during PDN Connection Establishment
If the TWAN supports the feature, the following procedures apply.
During a PDN connection establishment, the TWAN shall provide one TWAN FQ-CSID containing exactly one CSID for that particular PDN connection to the PGW. The TWAN shall store the Node-ID and CSID from the FQ-CSID provided by the PGW for that particular PDN connection in its PDN Connection table.
The TWAN determines that the PGW supports partial failure handling by the presence of the PGW FQ-CSID in the Create Session Response for GTPv2 based S2a and/or Proxy Binding Acknowledgement message for PMIPv6 based S2a.
17C.2.3 Procedures during TWAN Partial Failure
If the TWAN supports the feature, the following procedures apply.
When a TWAN detects that it has undergone a partial failure, it shall verify that one or more corresponding CSID(s) are present for the component undergoing a partial fault. If there is no such CSID, then the following does not apply. When one or more CSIDs are currently assigned, the TWAN shall perform the following.
The TWAN may perform implementation-specific operations to clean up any residual state associated with the CSID(s).
The TWAN shall send Delete PDN Connection Set Request containing all the TWAN CSIDs of the component(s) failing in TWAN FQ-CSID over the GTPv2 based S2a interface or PMIPv6 Binding Revocation Indication with G bit set message containing the equivalent TWAN FQ-CSID(s) over the PMIPv6 based S2a interface to PGW peers supporting the feature.
On the GTPv2 based S2a interface, upon receiving a GTPv2 Delete PDN Connection Set Response message with Cause value "Success", the TWAN shall conclude that the PGW has initiated the internal deletion of the PDN connections corresponding to the FQ-CSID(s) present in the GTPv2 Delete PDN Connection Set Request message. Similarly, on the PMIPv6 based S2a interface, upon receiving a successful PMIPv6 Binding Revocation Acknowledgment message with G bit set, the TWAN shall conclude that the PGW has initiated the internal deletion of the PDN connections corresponding to the CSID(s) present in the PMIPv6 Binding Revocation Indication message.
The TWAN is not required to perform any further recovery actions towards PGW peers for PDN connections in the connection set identified by the PGW FQ-CSID(s).
17C.2.4 Procedures during PGW Partial Failure
If the TWAN supports the feature, the following procedures apply.
When an TWAN receives a GTPv2 Delete PDN Connection Set Request or PMIP6 Binding Revocation Indication with G bit set message from a PGW, the TWAN shall retrieve all the PDN connections corresponding to each of the FQ-CSID(s) present in the message. The TWAN shall delete all the retrieved PDN connections, and may free the associated internal TWAN resources.
As a response, the TWAN shall send a GTPv2 Delete PDN Connection Set Response message with an appropriate Cause value or a PMIPv6 Binding Revocation Acknowledgment message with G bit set to the PGW.
17C.2.5 Procedures during PDN Connection Removal or Modification
For the modification of an existing PDN connection established over S2a, if the corresponding TWAN and PGW support the partial failure feature, when the TWAN receives an FQ-CSID value of a PGW over S2a, the TWAN shall overwrite the currently stored FQ CSID value with the received value.
For the removal of an existing PDN connection established over S2a, if the corresponding TWAN and PGW support the partial failure feature, a TWAN removes the corresponding PDN data as well as any relevant stored FQ-CSID value of the PGW FQ-CSID.
17D Restoration of data in the BM-SC
17D.1 Restart of the BM-SC
When a BM-SC fails, all its MBMS Bearer contexts affected by the failure become invalid and will be deleted.
After a BM-SC restart, all the MBMS Bearer contexts stored in the BM-SC and affected by the restart become invalid and will be deleted. All the SGmb Diameter sessions affected by the restart are also lost in the BM-SC. If Group Communication Service (GCS) is supported, the BM-SC also loses the knowledge of the TMGIs it had allocated to the Group Communication Service Application Server(s) (GCS AS) before restarting.
When the MBMS GW detects the restart of a BM-SC, it shall behave as described in clause 17A.2.3.
When the GCS AS detects the restart of a BM-SC, it shall behave as described in clause 17E.1. The restoration of MBMS services by content providers other than GCS AS after a BM-SC failure or restart is out of scope of 3GPP.
NOTE: The reference point from content providers other than GCS AS to the BM-SC is not standardised by 3GPP.
17D.2 Restart of the GCS AS
In deployments without a Diameter Agent between the GCS AS and the BM-SC, the BM-SC shall detect a restart in the GCS AS using either:
- the Diameter Origin-State-Id AVP as specified in the Diameter Base Protocol. To enable fast detection of restart, the Diameter Origin-State-Id AVP shall be included (at least) in Capabilities-Exchange-Request and Capabilities-Exchange-Answer commands; or
- the Diameter Restart-Counter AVP as specified in the MBMS Heartbeat procedure (see clause 29), if this procedure is supported.
In deployments with a Diameter Agent between the GCS AS and the BM-SC, the BM-SC shall detect a restart in the GCS AS using the Diameter Restart-Counter AVP as specified in the MBMS Heartbeat procedure (see clause 29).
NOTE: The intermediate Diameter Agent can remove or update the Diameter Origin-State-Id AVP, e.g. if it needs to modify the Origin-Host-ID. Thus the Diameter Origin-State-Id AVP, if received by the BM-SC or GCS AS, does not reflect the state of the remote MBMS peer but the state of the Diameter Agent.
When the BM-SC detects a restart of the GCS AS, the BM-SC shall deallocate (locally) all the TMGIs that had been assigned to the restarted GCS AS and the BM-SC shall stop all the related MBMS bearers to free the corresponding resources in E-UTRAN.
17E Restoration of data in the GCS AS
17E.1 Restart of the GCS-AS
After a GCS AS restart, the GCS AS loses its MBMS bearer contexts and the knowledge of the TMGIs it had been allocated by the BM-SC(s) before restarting.
When the BM-SC detects the restart of a GCS AS, it shall behave as described in clause 17D.2.
17E.2 Restart of the BM-SC
In deployments without a Diameter Agent between the GCS AS and the BM-SC, the GCS AS shall detect a restart in the BM-SC using either:
- the Diameter Origin-State-Id AVP as specified in the Diameter Base Protocol. To enable fast detection of restart, the Diameter Origin-State-Id AVP shall be included (at least) in Capabilities-Exchange-Request and Capabilities-Exchange-Answer commands; or
- the Diameter Restart-Counter AVP as specified in the MBMS Heartbeat procedure (see clause 29), if this procedure is supported.
In deployments with a Diameter Agent between the GCS AS and the BM-SC, the GCS AS shall detect a restart in the BM-SC using the Diameter Restart-Counter AVP as specified in the MBMS Heartbeat procedure (see clause 29).
NOTE: The intermediate Diameter Agent can remove or update the Diameter Origin-State-Id AVP, e.g. if it needs to modify the Origin-Host-ID. Thus the Diameter Origin-State-Id AVP, if received by the BM-SC or GCS AS, does not reflect the state of the remote MBMS peer but the state of the Diameter Agent.
When the GCS AS detects a restart of the BM-SC, the GCS AS shall assume that all the TMGIs that had been assigned by the restarted BM-SC have been de-allocated and that all the related MBMS bearers have been deactivated.
The GCS AS may restore the MBMS delivery using the MB2-C procedures specified in 3GPP TS 29.468 [35].
17F Restoration of data in the UCMF
17F.1 Restart of the UCMF
The UCMF is assumed as a front-end application function with a persistent database connected. The UCMF may restart but all dictionary mapping information between UE Radio Capability and UE Radio Capability IDs can be retained, hence, in this case, a UCMF shall not update its Recovery Time Stamp if the UCMF has restarted.
Editor' Note: The handling of Version ID within PLMN assigned UE Radio Capability IDs at UCMF Restart is ffs.
17F.2 Restart of the MME
When a UCMF detects that a peer MME has failed with or without restart (relying on restart counter as specified in clause 19B "URCMP based restart procedures" or implementation e.g. a preconfigured path failure timer as specified in clause 20 "Path management procedures"), it shall delete the subscription created by the failed MME. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 18 GTP-C based restart procedures | Across GTP-C based interfaces an SGSN, GGSN, MME, SGW, PGW, TWAN, ePDG and HRPD Access Node utilize either GTPv1-C or GTPv2-C Echo Request and Echo Response messages or GTP-C messages containing the Recovery Information Element to detect and handle a restart.
A GTP-C entity shall maintain two Restart counters:
- in volatile memory a remote Restart counter of a peer with which the entity is in contact;
- in non-volatile memory own, or local Restart counter that was sent to a peer.
After a GTP-C entity has restarted, it shall immediately increment all local Restart counters and shall clear all remote Restart counters.
A GTP-C entity may have a common local Restart counter for all peers, or it may have a separate local Restart counter for each peer.
A GTP-C entity may probe the liveliness of each peer with which it is in contact by sending an Echo Request message (see clause 20 "Path management procedures") . The presence of the Restart counter in Echo Request or in a GTP-C message depends on the GTP-C version and therefore is specified in 3GPP TS 29.060 [8] and 3GPP TS 29.274 [13], respectively. The restart counter signalled in the GTP-C message is associated with the GTP-C entity identified by the sender's F-TEID or SGSN/GGSN IP address for control plane if present in the message, otherwise (e.g. in echo request message) it is associated with the GTP-C entity identified by the source IP address of the message.
The GTP-C entity that receives a Recovery Information Element in an Echo Response or in another GTP-C message from a peer, shall compare the received remote Restart counter value with the previous Restart counter value stored for that peer entity.
- If no previous value was stored the Restart counter value received in the Echo Response or in the GTP-C message shall be stored for the peer.
- If the value of a Restart counter previously stored for a peer is smaller than the Restart counter value received in the Echo Response message or the GTP-C message, taking the integer roll-over into account, this indicates that the entity that sent the Echo Response or the GTP-C message has restarted. The received, new Restart counter value shall be stored by the receiving entity, replacing the value previously stored for the peer.
- If the value of a Restart counter previously stored for a peer is larger than the Restart counter value received in the Echo Response message or the GTP-C message, taking the integer roll-over into account, this indicates a possible race condition (newer message arriving before the older one). The received new Restart counter value shall be discarded and an error may be logged.
Based on operator's policy, when a Recovery IE is received in an Echo Request or in any incoming GTP-C request message (which includes a Recovery IE) from a peer GTP-C entity, with a Restart counter value larger than the value of the Restart counter previously stored for the peer GTP-C entity, the GTP-C entity may verify whether the peer GTP-C entity has really restarted by:
- sending one or more Echo Request message(s) towards the peer GTP-C entity, or by monitoring other GTP-C request messages it may have sent for any PDN connections (e.g. Update Bearer Request message) towards the peer GTP-C entity; and
- determining that the peer GTP-C entity has restarted if the value of the restart counter received in the Recovery IE in the Echo Response message or in the corresponding GTP-C response messages (e.g. Update Bearer Response) is larger than the value of the Restart counter previously stored for the peer GTP-C entity.
NOTE: This can be used e.g. when two GTP-C entities are connected via a roaming interface and Network Domain Security (e.g. IPsec ESP) is not applied or may not provide sufficient protection of the GTP-C signalling, e.g. against IP address spoofing.
18A GTP-U based restart procedure
The support of GTP-U based restart procedure is optional for a GTP-U entity.
When the feature is supported, across GTP-U based interfaces, i.e. the S1-U, S11-U, S2a, S2b, X2, S4, S5, S8, S12, M1 and Sn interfaces of the Evolved Packet System in EPS, and the F1-U, Xn, N3, N9, N19, N3mb and N19mb interfaces of the 5G System in 5GS, a GTP-U entity shall utilize GTP-U Echo Request, Echo Response messages and GTP-U Error Indication message containing the Recovery Time Stamp Information Element to detect and handle a restart.
A GTP-U entity shall be prepared to receive an Echo Request message at any time (even from unknown peers), and it shall reply with an Echo Response message.
A GTP-U entity shall maintain two Recovery Time Stamps:
- in volatile memory a remote Recovery Time Stamp of a peer GTP-U entity with which the entity is in contact;
- in non-volatile memory own, or local Recovery Time Stamp that was sent to a peer GTP-U entity.
After a GTP-U entity has (re)started and all its GTP-U contexts have been lost, and if the GTP-U entity knows these GTP-U contexts are not to be restored, e.g., by its Control Plane function, it shall immediately update all local Recovery Time Stamps and shall clear all remote Recovery Time Stamps. When peer GTP-U entities information is available, e.g. when the first GTP-U tunnel towards the peer GTP-U entity is established, the (re)started GTP-U entity may send its (updated) Recovery Time Stamps in an Echo Request message to the peer GTP-U entity before sending GTP-U packets.
NOTE: The GTP-U entity needs to be configured to know if the GTP-U contexts can be restored or not. It is implemention specific how to handle the scenario that the GTP-U entity interworks with some control plane nodes supporting restoration of GTP-U contexts while others not supporting, for example, it can use different IP addresses.
A GTP-U entity may have a common local Recovery Time Stamp for all peer GTP-U entities, or it may have a separate local Recovery Time Stamp for each peer GTP-U entity.
A GTP-U entity may probe the liveliness of each peer GTP-U entity with which it is in contact by sending an Echo Request message.
The Recovery Time Stamp signalled in the GTP-U Echo Request and Response messages is associated with the GTP-U entity identified by the source IP address of the message.
The Recovery Time Stamp signalled in the GTP-U Error Indication is associated with the source IP address of the GTP-U Error Indication or associated with a list of IP address(es) which are sharing the same Recovery Time Stamp if those IP address(es) are explicitly included in the GTP-U Error Indication message.
The GTP-U entity that receives a Recovery Time Stamp Information Element from a peer GTP-U entity shall compare the received remote Recovery Time Stamp value with the previous Recovery Time Stamp value stored for that peer GTP-U entity.
- If no previous value was stored, the Recovery Time Stamp value received in the Echo Request or Response messages or the GTP Error Indication message shall be stored for the peer GTP-U entity.
- If the value of a Recovery Time Stamp previously stored for a peer GTP-U entity is smaller than the Recovery Time Stamp received in the Echo Request or Response messages or the GTP-U Error Indication messages, this indicates that the entity that sent the Echo Request or Response messages or the GTP-U Error Indication messages has restarted. The received, new Recovery Time Stamp value shall be stored by the receiving entity, replacing the value previously stored for the peer GTP-U entity.
- If the value of a Recovery Time Stamp previously stored for a peer GTP-U entity is larger than the Recovery Time Stamp value received in the Echo Request or Response messages or the GTP-U Error Indication messages, this indicates a possible race condition (newer message arriving before the older one). The received new Recovery Time Stamp value shall be discarded and an error may be logged.
Based on operator's policy, when a Recovery Time Stamp IE is received in an Echo Request from a peer GTP-U entity, with a Recovery Time Stamp larger than the value of the Recovery Time Stamp previously stored for the peer GTP-U entity, the GTP-U entity may verify whether the peer GTP-U entity has really restarted by:
- sending one or more Echo Request message(s) towards the peer GTP-U entity; and
- determining that the peer GTP-U entity has restarted if the Recovery Time Stamp in the Echo Response message is larger than the value of the Recovery Time Stamp previously stored for the peer GTP-U entity. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 19 PMIPv6 based restart procedures | Across PMIPv6 based interfaces, SGW, PGW, TWAN and ePDG utilize PMIPv6 Heartbeat mechanism for node restart detection as specified in 3GPP TS 29.275 [16].
A PMIPv6 entity shall maintain two restart counters:
- in volatile memory a remote restart counter of a peer with which the entity is in contact;
- in non-volatile memory an own, or local restart counter that was sent to a peer.
After a PMIPv6 entity has restarted, it shall immediately increment all local restart counters and shall clear all remote restart counters.
A PMIPv6 entity may have a common local restart counter for all peers, or it may have a separate local restart counter for each peer.
19A PFCP based restart procedures
Across PFCP based interfaces, an SGW-C, SGW-U, PGW-C and PGW-U Node shall utilize PFCP Heartbeat Request and Heartbeat Response messages to detect and handle a peer PFCP entity failure or restart. A PFCP entity shall be prepared to receive a Heartbeat Request message at any time (even from unknown peers), and it shall reply with a Heartbeat Response message.
A PFCP entity shall maintain two Recovery Time Stamps:
- in volatile memory a remote Recovery Time Stamp of a peer PFCP entity with which the entity is in contact;
- in non-volatile memory own, or local Recovery Time Stamp that was sent to a peer PFCP entity.
After a PFCP entity has restarted, it shall immediately update all local Recovery Time Stamps and shall clear all remote Recovery Time Stamps. When peer PFCP entities information is available, i.e. when the PFCP Association is still alive, the restarted PFCP entity shall send its updated Recovery Time Stamps in a Heartbeat Request message to the peer PFCP entities before initiating any PFCP session signalling.
A PFCP entity may have a common local Recovery Time Stamp for all peer PFCP entities, or it may have a separate local Recovery Time Stamp for each peer PFCP entity.
A PFCP entity may probe the liveliness of each peer PFCP entity with which it is in contact by sending a Heartbeat Request message (see clause 20 "Path management procedures").
The Recovery Time Stamp signalled in the PFCP Heartbeat Request and Response messages is associated with the PFCP entity identified by the source IP address of the message.
The Recovery Time Stamp signalled in the PFCP Session Establishment Request messages is associated with the IP address in the CP F-SEID IE.
The PFCP entity that receives a Recovery Time Stamp Information Element from a peer PFCP entity shall compare the received remote Recovery Time Stamp value with the previous Recovery Time Stamp value stored for that peer PFCP entity.
- If no previous value was stored, the Recovery Time Stamp value received in the Heartbeat Request or Response messages or the PFCP Session Establishment Request messages shall be stored for the peer PFCP entity.
- If the value of a Recovery Time Stamp previously stored for a peer PFCP entity is smaller than the Recovery Time Stamp value received in the Heartbeat Request or Response messages or the PFCP Session Establishment Request messages, this indicates that the entity that sent the Heartbeat Request or Response messages has restarted. The received, new Recovery Time Stamp value shall be stored by the receiving entity, replacing the value previously stored for the peer PFCP entity.
- If the value of a Recovery Time Stamp previously stored for a peer PFCP entity is larger than the Recovery Time Stamp value received in the Heartbeat Request or Response message or the PFCP Session Establishment Request messages, this indicates a possible race condition (newer message arriving before the older one). The received Sx node related message and the received new Recovery Time Stamp value shall be discarded and an error may be logged.
A PFCP function shall ignore the Recovery Timestamp received in PFCP Association Setup Request and PFCP Association Setup Response messages (see clause 6.2.6 of 3GPP TS 29.244 [43]).
When a NAT device is deployed between PFCP entities, e.g. between the CP function and UP function, the following requirements shall apply in addition to the above requirements:
- the Heartbeat Request message may include a Source IP Address IE;
- when the Source IP Address IE is present, the Recovery Time Stamp signalled in the Heartbeat Request message shall be associated with the Source IP Address IE, instead of the source IP address of the message.
19B URCMP based restart procedures
Across URCMP based interfaces, an MME and UCMF Node shall utilize URCMP Heartbeat Request and Heartbeat Response messages to detect and handle a peer URCMP entity failure or restart. A URCMP entity shall be prepared to receive a Heartbeat Request message at any time (even from unknown peers), and it shall reply with a Heartbeat Response message.
A URCMP entity shall maintain two Recovery Time Stamps:
- in volatile memory a remote Recovery Time Stamp of a peer URCMP entity with which the entity is in contact;
- in non-volatile memory own, or local Recovery Time Stamp that was sent to a peer URCMP entity.
After a URCMP entity has restarted and if it loses all dictionary mapping information between UE Radio Capability Information and UE Radio Capability IDs, it shall immediately update all local Recovery Time Stamps and shall clear all remote Recovery Time Stamps.
A URCMP entity may have a common local Recovery Time Stamp for all peer URCMP entities, or it may have a separate local Recovery Time Stamp for each peer URCMP entity.
A URCMP entity may probe the liveliness of each peer URCMP entity with which it is in contact by sending a Heartbeat Request message (see clause 20 "Path management procedures").
The Recovery Time Stamp signalled in the URCMP Heartbeat Request and Response messages is associated with the URCMP entity identified by the source IP address of the message.
The URCMP entity that receives a Recovery Time Stamp Information Element from a peer URCMP entity shall compare the received remote Recovery Time Stamp value with the previous Recovery Time Stamp value stored for that peer URCMP entity.
- If no previous value was stored, the Recovery Time Stamp value received in the Heartbeat Request or Response messages shall be stored for the peer URCMP entity.
- If the value of a Recovery Time Stamp previously stored for a peer URCMP entity is smaller than the Recovery Time Stamp value received in the Heartbeat Request or Response messages, this indicates that the entity that sent the Heartbeat Request or Response messages has restarted. The received, new Recovery Time Stamp value shall be stored by the receiving entity, replacing the value previously stored for the peer URCMP entity.
- If the value of a Recovery Time Stamp previously stored for a peer URCMP entity is larger than the Recovery Time Stamp value received in the Heartbeat Request or Response message, this indicates a possible race condition (newer message arriving before the older one). The received Sx node related message and the received new Recovery Time Stamp value shall be discarded and an error may be logged. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20 Path management procedures | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.1 General | This clause specifies path management procedures for GTP-C based, PMIP and PFCP based interfaces.
For GTP based interfaces, Echo Request / Response procedure is used. The usage depends on the GTP-C version in the following way:
- GTPv1-C entity may periodically send an Echo Request message as specified in 3GPP TS 29.060 [8].
- GTPv2 entity shall probe the liveliness of each peer with which it is in contact by sending an Echo Request messages (see TS 29.274 [13]). When and how often a GTPv2 Echo Request message may be sent is implementation specific but an Echo Request shall not be sent more often than every 60 s on each path. This does not prevent resending an Echo Request with the same sequence number according to the T3-RESPONSE timer.
It is recommended that GTPv2 Echo Request should be sent only when a GTP-C entity has not received any GTP response message for a previously sent request message on the GTP-C path for, an implementation dependent period of time.
A GTP-C entity (both GTPv1-C and GTPv2) shall be prepared to receive an Echo Request message at any time and it shall reply with an Echo Response message.
For the PMIP based S5/S8 interface, the SGW and PGW shall detect respectively a peer PGW and SGW as currently unavailable by sending a series of PMIPv6 Heartbeat Request messages, and not receiving within a period of time respectively a PMIPv6 Heartbeat Response message (see 3GPP TS 29.275 [16]).
For PFCP based Sxa/Sxb/Sxc interfaces, the CP function shall detect a peer UP function (or vice versa) as currently unavailable by sending a series of PFCP heartbeat Request messages, and not receiving within a period of time respectively a PFCP Heartbeat Response message (see 3GPP TS 29.244 [43]).
For URCMP based S17 interface, the URCMP entity shall detect a peer URCMP entity as currently unavailable by sending a series of URCMP heartbeat Request messages, and not receiving within a period of time respectively a URCMP Heartbeat Response message (see 3GPP TS 29.674 [44]). |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2 Signalling path failure detection and handling | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.1 General | GTP-C entities shall support detection of path failure by using Echo Request / Echo Response messages in the following way. A peer's IP address specific counter shall be reset each time an Echo Response message is received from that peer's IP address and incremented when the T3-RESPONSE timer expires for an Echo Request message sent to that peer's IP address. The path shall be considered to be down if the counter exceeds N3-REQUESTS.
PMIP entities shall support detection of path failure as specified for Failure Detection in IETF RFC 5847 [22].
Upon detecting a path failure, the network node should notify the failure via the Operation and Maintenance system and may either:
- delete the PDN connections (EPS bearer contexts) or PDP contexts associated with this peer's IP address; or
- maintain the PDN connections (EPS bearer contexts) or PDP contexts associated with the peer's IP address during an operator configurable maximum path failure duration. The network node shall delete the maintained resources if the path is still down when this duration expires. The network node may delete the maintained resources if control/user plane signalling is received across other interface(s) during the path failure and before the maximum path failure duration timer expires.
NOTE 1: During transient path failures (e.g. path failures not exceeding few minutes at most), maintaining the EPS bearer contexts or PDP contexts associated with the peer's IP address enables the delivery of end user services (when the path is reestablished again) and also avoids unnecessary signalling in the network for restoring those connections.
NOTE 2: It is not intended to maintain PDN connections during long path failures (e.g. exceeding few minutes at most) as this would imply undesirable effects like undue charging.
The following clauses specify further specific network element requirements. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.2 SGW functionality | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.2.1 S11/S4 path failure | It is optional for the SGW to maintain the S5/S8 bearer contexts when the SGW detects a path failure to the MME/S4-SGSN (see clause 20.2.1). However upon detecting a path failure to the MME/S4-SGSN, an SGW that supports the network triggered service restoration procedure (see clause 25) should maintain the S5/S8 bearer contexts eligible for network initiated service restoration and proceed with the network triggered service restoration procedure with the following modification:
- if the path to the MME/S4-SGSN is down for a duration exceeding the maximum path failure duration and if there is no alternative reachable path, e.g. another MME/S4-SGSN in the same pool or another control plane IP address belonging to the same MME/S4-SGSN, the SGW should locally delete the maintained PDN connections associated with the failed path.
In addition, for UEs in connected state associated with the failed path, the SGW should continue sending downlink packets to the eNodeB/RNC as long as the impacted PDN connections are maintained, regardless of whether the SGW supports the network triggered service restoration procedure or not. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.2.2 S5 path failure | The SGW may support the PGW triggered SGW restoration for an S5 path failure. If so, then the SGW should support the PGW Restart Notification procedure. After detecting a path failure to the PGW, the SGW may delete all the PDN connections affected by the path failure and should also send a PGW Restart Notification message to the MME or S4-SGSN if the the PGW Restart Notification procedure is supported by the SGW and MME/S4-SGSN (see clause 16.1A.2).
NOTE: The PGW Restart Notification procedure can help the MME to restore the PDN connections earlier since the SGW will detect the S5 path failure and send PGW Restart Notification triggering a PDN connection restoration at the MME, before the PGW sends the PGW Downlink Triggering Notification.
The SGW should proceed with the PGW triggered SGW restoration procedure (see clause 27.2.3.3) with the following modification:
- The SGW shall include the PGW F-TEID or PGW IP address and GRE key for control plane in the PGW Downlink Triggering Notification message that it sends to the MME/S4-SGSN, if this information is present in the PGW Downlink Triggering Notification/PMIP Update Notification message received from the PGW. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.3 MBMS GW functionality | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.3.1 Sm path failure | The MBMS GW may be provisioned with the list (or a sublist) of the MMEs pertaining to the MME pool.
NOTE 1: The MBMS GW expects only one MME of the MME pool in BM-SC requests received across the SGmb interface.
Upon detecting an Sm path failure, the MBMS GW should maintain the MBMS bearer contexts associated with the peer's MME IP address.
During a transient Sm path failure (e.g. before the maximum path failure duration timer expires), the MBMS GW may process MBMS requests from the BM-SC and intended for the MME for which the Sm path has failed as follows:
- for new MBMS Session Start Request, the MBMS GW may select an alternative MME in the same MME pool and send the MBMS Session Start Request to this alternative MME;
- for MBMS Session Update Request or MBMS Session Stop Request, the MBMS GW may select an alternative MME in the same MME pool, send a MBMS Session Start Request message to this alternative MME and, if successful, send subsequently the MBMS Session Update Request or MBMS Session Stop Request to this alternative MME.
After having selected an alternative MME, the MBMS GW shall consider the MME answering to the MBMS Start Request as the controlling MME for the MBMS session and send any subsequent MBMS Session Update or MBMS Session Stop for this MBMS Session to this MME.
NOTE 2: Each MME of the MME pool provisioned in the MBMS GW supports an M3 interface with the MCE(s).
When detecting a non-transient Sm path failure at the MBMS GW (e.g. the maximum path failure duration timer of the MBMS GW expires), the MBMS GW may move the control of all the affected active MBMS sessions to another MME in the same MME pool (if any other MME is reachable by the MBMS GW) by initiating new MBMS Session Start Request(s) to alternative MME(s).
NOTE 3: This allows to re-establish the MBMS sessions when a MME fails without restart.
The maximum path failure duration timer of the MBMS GW should be configured with a shorter value than the maximum path failure duration timer of the MME to avoid interrupting active MBMS sessions upon a non-transient Sm path failure. The MBMS GW timer should be shorter than the MME timer by at least the period between two Echo Request messages sent by the MME, to avoid that the MME timer expires before the MBMS GW timer if the MME starts its timer before the MBMS GW.
NOTE 4: This enables the MCE to receive a MBMS Session Start request from the new MME controlling the MBMS session before the MCE receives a request to stop the MBMS service from the previous controlling MME.
When sending an MBMS Session Start Request sent to an alternative MME, the MBMS GW shall encode the contents of the request with the same contents as in the original MBMS Session Start Request (or per the last MBMS Session Update Request sent by the MBMS GW if the original parameters were updated) with the following exceptions:
- the MBMS GW shall set the "MBMS session re-establishment indication" flag to signal that this message is used to re-establish an MBMS session;
- if no absolute start time ("MBMS data transfer start" parameter) has been received, the MBMS GW may change the relative start time ("time to MBMS data transfer" parameter) to fasten the restoration of the MBMS service in E-UTRAN;
- the MBMS GW should set the estimated session duration to a value corresponding to the remaining duration of the session.
NOTE 5: Per the requirements above, if the MBMS GW had started an MBMS session within an MME with the MBMS Service Area (1, 2, 3) and receives during an Sm path failure (towards this MME) an MBMS Session Update from the BM-SC modifying the MBMS Service Area to (3, 4, 5), the MBMS GW will encode the original MBMS Service Area (1, 2, 3) in the MBMS Session Start Request sent to the alternative MME and subsequently send an MBMS Session Update Request with the MBMS Service Area (3,4,5) to the new MME controlling the MBMS session.
NOTE 6: If the previous MME received an MBMS Session Update Request from the MBMS GW but could not propagate it to the MCE due to a M3AP path failure, the contents of the MBMS Session Start Request sent to the MCE via the new MME can also differ from the parameters sent to the MCE via the previous MME for the parameters that can be modified by the MBMS session update procedure (i.e. MBMS Session Area, MBMS Time to Data Transfer, MBMS Data Transfer Start).
After detecting an Sm path failure, the MBMS GW shall determine whether the failure is transient or non transient from the perpective of the MME (e.g. the MBMS GW is provisioned with the maximum path failure timer of the MME). The MBMS GW shall assume that the failure is non transient from the perspective of the MME if the Sm path recovers after a period longer than the maximum path failure timer of the MME plus the period between two Echo Request messages sent by the MME, to ensure that the MME also determines this is a non transient path failure if the MBMS GW starts its timer before the MME. The MBMS GW shall consider that the MBMS session has been released by the MME if the Sm path failure is non transient for the MME. If the Sm path failure remains transient for the MME, the MBMS GW shall behave as follows upon detecting the Sm path recovery:
- if the MBMS GW has already moved the control of the MBMS session to an alternative MME(s), the MBMS GW shall send an MBMS Session Stop Request message to the MME previously controlling the MBMS session with a "Local MBMS bearer context release" indication to instruct that MME to release its MBMS bearer context locally, without sending any message to the MCE(s).
- if the MBMS GW has not yet moved the control of the MBMS session to an alternative MME (e.g. if the MBMS restoration procedures are not supported in the network),
- if the Sm path failure is transient from the perspective of the MBMS GW, the MBMS GW shall consider that MBMS session is still controlled by the related MME and proceed as if there had been no Sm path failure;
- if the Sm path failure is non transient from the perspective of the MBMS GW, the MBMS GW shall send an MBMS Session Start Request to the MME for the session and encode it as specified above (for a message sent to an alternative MME).
NOTE 7: The MBMS GW cannot know whether the MME will see the Sm path failure as transient or non transient if the Sm path recovers in the period between the maximum path failure timer of the MME plus and minus the period between two Echo Request messages sent by the MME. This can possibly lead the MBMS GW to send an MBMS Session Stop request to the MME for a session that has already been terminated by the MME (if the MME determined the failure is non transient) or to send an MBMS Session Start request (with the "MBMS session re-establishment indication" flag) to the MME for a session that is still alive at the MME (if the MME determined the failure is transient). |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.3.2 Sn path failure | The MBMS GW may be provisioned with the list (or a sub list) of the SGSNs belonging to the SGSN pool.
NOTE: The MBMS GW expects only one SGSN of the SGSN pool in BM-SC requests received across the SGmb interface.
An MBMS GW and SGSN shall handle Sn path failure similar to the Sm path failure as described in clause 20.2.3.1 For IP Unicast over Sn/Iu when the SGSN changes the MBMS GW has to move the user plane which is affected by the Sn-path failure additionally. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.3.3 SGmb path failure | In deployments without a Diameter Agent between the BM-SC and the MBMS GW, the MBMS GW shall detect an SGmb path failure using either:
- mechanisms as specified in the Diameter Base Protocol (e.g. transport connection failure, BM-SC peer not responding, Diameter Device-Watchdog-Request and Device-Watchdog-Answer messages during periods when there is no need for other MBMS signalling); or
- the MBMS Heartbeat procedure (see clause 29), if this procedure is supported.
In deployments with a Diameter Agent between the BM-SC and the MBMS GW, the MBMS GW shall detect an SGmb path failure using the MBMS Heartbeat procedure (see clause 29).
NOTE 1: A transport connection failure does not allow to identify a failure of the remote MBMS peer. Likewise, it is not possible to rely on Diameter Device-Watchdog-Request / Answer messages to test the responsiveness of the remote MBMS node during periods when there is no need for other MBMS signalling as these messages are only exchanged between Diameter peers with a direct transport connection.
Upon detecting an SGmb path failure, the MBMS GW should maintain the MBMS bearer contexts associated with the peer's BM-SC during an operator configurable maximum path failure duration.
If the SGmb path to the BM-SC is down for a duration exceeding the maximum path failure duration, the MBMS GW should deactivate all the related MBMS Bearer contexts locally and send MBMS Session Stop Requests towards all MME/SGSNs in which the MBMS bearer services are active.
NOTE 2: This enables to free corresponding radio resources in E-UTRAN/UTRAN for MBMS services if the BM-SC has failed without restart.
The MBMS GW shall pass on the "MBMS session re-establishment indication" flag in the MBMS Session Start Request it sends to MME/SGSNs if received from the BM-SC.
The MBMS GW shall pass on the "Local MBMS bearer context release" indication in the MBMS Session Stop Request it sends to MME/SGSNs if received from the BM-SC.
The MBMS GW shall accept an MBMS Session Start Request received for an on-going MBMS bearer service (i.e. with the same TMGI and, if provided, MBMS Flow Identifier) from the same BM-SC that currently controls the MBMS session if the message includes the "MBMS session re-establishment indication" flag. The MBMS GW shall replace the SGmb related resources for this MBMS service by those received in the MBMS Session Start Request (if different). The MBMS GW should not send MBMS Session Start Request message(s) towards the involved MME/SGSN(s) if no parameters other than the estimated duration and relative start time have changed. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.4 MME functionality | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.4.1 Sm path failure | Upon detecting an Sm path failure, the MME should maintain the MBMS bearer contexts associated with the peer's MBMS GW IP address during an operator configurable maximum path failure duration.
The MME should behave as specified for the case of an MBMS GW restart (see clause 17A.1) if the Sm path to the MBMS GW is down for a duration exceeding the maximum path failure.
NOTE 1: This enables to free corresponding radio resources in E-UTRAN for MBMS services if the MBMS GW has failed without restart.
The MME shall pass on the "MBMS session re-establishment indication" flag in the MBMS Session Start Request it sends to MCEs if received from the MBMS GW.
The MME should accept an MBMS Session Start Request received for an on-going MBMS bearer service (i.e. with the same TMGI and, if provided, MBMS Flow Identifier) from a different MBMS GW than the MBMS GW that currently controls the MBMS session if the message includes the "MBMS session re-establishment indication" flag. If it accepts the request from the new MBMS GW, the MME shall replace the Sm related resources (i.e. TEID-C) for this MBMS service associated to the previous MBMS GW by those associated to the new MBMS GW and consider that the MBMS session is now being controlled by the new MBMS GW. The MME shall then send an MBMS Session Start Request message including the "MBMS session re-establishment" flag (and the new M1 transport parameters) towards all involved MCE(s).
The MME may accept an MBMS Session Start Request received for an on-going MBMS bearer service (i.e. with the same TMGI and, if provided, MBMS Flow Identifier) from a different MBMS GW than the MBMS GW that currently controls the MBMS session even if the message does not include the "MBMS session re-establishment indication" flag. If it accepts the request from the new MBMS GW, the MME shall replace the Sm related resources (i.e. TEID-C) for this MBMS service associated to the previous MBMS GW by those associated to the new MBMS GW and consider that the MBMS session is now being controlled by the new MBMS GW; the MME shall then either:
- stop the on-going MBMS bearer service and then start the new MBMS bearer service (without including the "MBMS session re-establishment indication" flag in the MBMS Session Start Request sent to the MCE(s)); or
- behave as if it had received an MBMS Session Start Request including the "MBMS session re-establishment indication" flag (i.e. include the "MBMS session re-establishment indication" flag in the MBMS Session Start Request sent to the MCE(s)).
The MME shall accept an MBMS Session Start Request received for an on-going MBMS bearer service (i.e. with the same TMGI and, if provided, MBMS Flow Identifier) from the same MBMS GW that currently controls the MBMS session if the message includes the "MBMS session re-establishment indication" flag. The MME shall replace the Sm related resources (i.e. TEID-C) for this MBMS service by those received in the MBMS Session Start Request (if different). The MME should not send MBMS Session Start Request message(s) towards the involved MCE(s) if no parameters other than the estimated duration and relative start time have changed.
The MME shall reject an MBMS Session Stop Request received for an on-going MBMS bearer service from a different MBMS GW than the MBMS GW that currently controls the MBMS session.
NOTE 2: Upon a non-transient SGmb path failure, if the BM-SC moves the control of an MBMS session to an alternative MBMS GW, the same MME can receive an MBMS Session Stop Request from the old MBMS GW after an MBMS Session Start Request from the new MBMS GW.
The MME shall release the MBMS bearer context resources locally without sending any message to the MCE(s) if it receives a MBMS Session Stop Request with a "Local MBMS bearer context release" indication for an on-going MBMS bearer service from the MBMS GW currently controlling the MBMS session. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.4.2 S5 path failure | The MME may support invoking the PGW triggered SGW restoration (see clause 27.2.3) upon receiving a PGW Downlink Triggering Notification message when the S11 path for the related UE is still available (see clause 20.2.1). If so, upon receiving a PGW Downlink Triggering Notification while the S11 path for the related UE is still available, the MME should proceed with the PGW triggered SGW restoration procedure (see clauses 27.2.3.2 and 27.3.2.2) with the following modifications:
- if the PGW F-TEID or PGW IP address and GRE key for control plane received in the PGW Downlink Triggering Notification message does not match the stored PGW F-TEID or PGW IP address and GRE key for control plane of any PDN connection(s) for that UE, the MME shall not proceed with the PGW triggered SGW restoration procedure but just respond to the SGW with a PGW Downlink Triggering Acknowledge message with an acceptance cause code;
NOTE 1: This can happen e.g. if the PDN connection has already been restored by the MME upon receipt of a preceding PGW Restart Notification message. In this case, the PDN connection remains hanging in the PGW until the timer monitoring the maximum duration to restore the PDN connection expires in the PGW.
- if the PGW F-TEID or PGW IP address and GRE key for control plane received in the PGW Downlink Triggering Notification message matches the stored PGW F-TEID or PGW IP address and GRE key for control plane of any PDN connection(s) for that UE, the MME shall proceed with the PGW triggered SGW restoration procedure.
- if the related UE is in connected mode, the MME may restore the PDN connection(s) of that UE by performing the MME triggered Serving GW relocation procedure as defined in clause 5.10.4 of 3GPP TS 23.401 [15].
NOTE 2: This avoids to tear down the S1 connection of the UE and thus to negatively affect other PDN connections of that UE that would not be impacted by the S5 path failure. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.5 SGSN functionality | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.5.1 Sn path failure | Upon detecting an Sn path failure, the S4-SGSN should maintain the MBMS bearer contexts associated with the peer's MBMS GW IP address during an operator configurable maximum path failure duration.
The S4-SGSN should behave as specified for the case of an MBMS GW restart (see clause 17A.1) if the Sn path to the MBMS GW is down for a duration exceeding the maximum path failure.
NOTE 1: This enables to free corresponding radio resources in UTRAN for MBMS services if the MBMS GW has failed without restart.
The S4-SGSN shall pass on the "MBMS session re-establishment indication" flag in the MBMS Session Start Request it sends to RNCs if received from the MBMS GW.
The S4-SGSN should accept an MBMS Session Start Request received for an on-going MBMS bearer service (i.e. with the same TMGI and, if provided, MBMS Flow Identifier) from a different MBMS GW than the MBMS GW that currently controls the MBMS session if the message includes the "MBMS session re-establishment indication" flag. If it accepts the request from the new MBMS GW, the S4-SGSN shall replace the Sn related resources (i.e. TEID-C) for this MBMS service associated to the previous MBMS GW by those associated to the new MBMS GW and consider that the MBMS session is now being controlled by the new MBMS GW. The S4-SGSN shall then send an MBMS Session Start Request message including the "MBMS session re-establishment" flag (and the new M1 transport parameters) towards all involved RNC(s).
The S4-SGSN may accept an MBMS Session Start Request received for an on-going MBMS bearer service (i.e. with the same TMGI and, if provided, MBMS Flow Identifier) from a different MBMS GW than the MBMS GW that currently controls the MBMS session even if the message does not include the "MBMS session re-establishment indication" flag. If it accepts the request from the new MBMS GW, the S4-SGSN shall replace the Sn related resources (i.e. TEID-C) for this MBMS service associated to the previous MBMS GW by those associated to the new MBMS GW and consider that the MBMS session is now being controlled by the new MBMS GW; the S4-SGSN shall then either:
- stop the on-going MBMS bearer service and then start the new MBMS bearer service (without including the "MBMS session re-establishment indication" flag in the MBMS Session Start Request sent to the RNC(s)); or
- behave as if it had received an MBMS Session Start Request including the "MBMS session re-establishment indication" flag (i.e. include the "MBMS session re-establishment indication" flag in the MBMS Session Start Request sent to the RNC(s)).
The S4-SGSN shall accept an MBMS Session Start Request received for an on-going MBMS bearer service (i.e. with the same TMGI and, if provided, MBMS Flow Identifier) from the same MBMS GW that currently controls the MBMS session if the message includes the "MBMS session re-establishment indication" flag. The S4-SGSN shall replace the Sn related resources (i.e. TEID-C) for this MBMS service by those received in the MBMS Session Start Request (if different). The S4-SGSN should not send MBMS Session Start Request message(s) towards the involved RNC(s) if no parameters other than the estimated duration and relative start time have changed.
The S4-SGSN shall reject an MBMS Session Stop Request received for an on-going MBMS bearer service from a different MBMS GW than the MBMS GW that currently controls the MBMS session.
NOTE 2: Upon a non-transient SGmb path failure, if the BM-SC moves the control of an MBMS session to an alternative MBMS GW, the same S4-SGSN can receive an MBMS Session Stop Request from the old MBMS GW after an MBMS Session Start Request from the new MBMS GW.
The S4-SGSN shall release the MBMS bearer context resources locally without sending any message to the RNC(s) if it receives a MBMS Session Stop Request with a "Local MBMS bearer context release" indication for an on-going MBMS bearer service from the MBMS GW currently controlling the MBMS session. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.5.2 S5 path failure | The S4-SGSN may support invoking the PGW triggered SGW restoration (see clause 27.2.3) upon receiving a PGW Downlink Triggering Notification and the S4 path of the related UE is still available (see clause 20.2.1). If so, S4-SGSN shall proceed as defined for the MME in clause 20.2.4.2, with the following modification:
- if the related UE is in connected mode, the S4-SGSN may restore the PDN connection(s) of that UE by performing the S4-SGSN triggered Serving GW relocation procedure as defined in clause 9.2.2.4 of 3GPP TS 23.060 [5]. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.6 BM-SC functionality | |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.6.1 SGmb path failure | In deployments without a Diameter Agent between the BM-SC and the MBMS GW, the BM-SC shall detect an SGmb path failure using either:
- mechanisms as specified in the Diameter Base Protocol (e.g. transport connection failure, MBMS GW peer not responding, Diameter Device-Watchdog-Request and Device-Watchdog-Answer messages during periods when there is no need for other MBMS signalling); or
- the MBMS Heartbeat procedure (see clause 29), if this procedure is supported.
In deployments with a Diameter Agent between the BM-SC and the MBMS GW, the BM-SC shall detect an SGmb path failure using the MBMS Heartbeat procedure (see clause 29).
NOTE 1: A transport connection failure does not allow to identify a failure of the remote MBMS peer. Likewise, it is not possible to rely on Diameter Device-Watchdog-Request / Answer messages to test the responsiveness of the remote MBMS node during periods when there is no need for other MBMS signalling as these messages are only exchanged between Diameter peers with a direct transport connection.
Upon detecting an SGmb path failure, the BM-SC should maintain the related MBMS bearer contexts.
During a transient SGmb path failure (e.g. before the maximum path failure duration timer expires), the BM-SC should consider all related MBMS bearer contexts as active in the MBMS GW. The BM-SC may initiate new MBMS sessions via an alternative MBMS GW (if available). The BM-SC should defer any MBMS session update or stop procedure for on-going MBMS sessions in the MBMS GW affected by the SGmb path failure until the transient path failure ends.
NOTE 2: Re-establishing an MBMS session via an alternative MBMS GW can generate network signalling over many interfaces and interrupt transiently the delivery of the MBMS data stream due to the need for related eNB/RNCs to switch to the new IP multicast group over M1. Thus during a transient SGmb path failure it is recommended to defer any MBMS session update or stop procedure for on-going MBMS sessions in the MBMS GW affected by the SGmb path failure. However if the MBMS session update or stop procedure is for time critical services, the BM-SC can immediately re-establish the active MBMS bearer services affected by the SGmb path failure by initiating MBMS Session Start procedure(s) towards an alternative MBMS GW (if available) as specified below, and subsequently send the MBMS Session Update or Stop message.
When detecting a non-transient SGmb path failure (e.g. the maximum path failure duration timer of the BM-SC expires), the BM-SC should re-establish the active MBMS bearer services affected by the SGmb path failure by initiating MBMS Session Start procedure(s) towards an alternative MBMS GW (if available) or towards the same MBMS GW (once the SGmb path is recovered). If the MBMS session is not re-established and if it was activated by a Group Communication Service Application Server(s) (GCS AS), the BM-SC shall notify the GCS AS that the MBMS session has been deactivated.
NOTE 3: This enables to re-establish the MBMS sessions when a MBMS GW fails without restart.
The maximum path failure duration of the BM-SC should be configured with a shorter value than the maximum path failure duration timer of the MBMS GW to minimize the interruption of the active MBMS sessions upon a non-transient SGmb path failure. The BM-SC timer should be shorter than the MBMS GW timer by at least the period between two Diameter Device-Watchdog-Request messages or MBMS Heartbeat Request messages sent by the MBMS GW, to avoid that the MBMS GW timer expires before the BM-SC timer if the MBMS GW starts its timer before the BM-SC.
NOTE 4: This enables the MCE/RNC to receive a MBMS Session Start request from the new MME/SGSN (and MBMS GW) controlling the MBMS session before the MCE/RNC receives a request to stop the MBMS service from the previous controlling MME/SGSN (and MBMS GW).
When re-establishing the active MBMS bearer services affected by the SGmb path failure, the BM-SC shall encode the MBMS Session Start Request with the same contents as in the original MBMS Session Start Request (or per the last MBMS Session Update Request sent by the BM-SC if the original parameters were updated) with the following exceptions:
- the BM-SC shall set the "MBMS session re-establishment indication" flag to signal that this message is used to re-establish an MBMS session;
- if no absolute start time ("MBMS data transfer start" parameter) has been sent, the BM-SC may change the relative start time ("time to MBMS data transfer" parameter) to fasten the restoration of the MBMS service in E-UTRAN;
- the BM-SC should set the estimated session duration to a value corresponding to the remaining duration of the session.
NOTE 5: If the BM-SC is instructed to modify an MBMS Session during the SGmb path failure, the contents of the MBMS Session Start Request sent to the MBMS GW after the SGmb path failure can also differ from the parameters sent to the MBMS GW before the SGmb path failure for the parameters that can be modified by the MBMS session update procedure (i.e. MBMS Session Area, MBMS Time to Data Transfer, MBMS Data Transfer Start).
After detecting an SGmb path failure, the BM-SC shall determine whether the failure is transient or non transient from the perpective of the MBMS GW (e.g. the BM-SC is provisioned with the maximum path failure timer of the MBMS GW). The BM-SC shall assume that the failure is non transient from the perspective of the MBMS GW if the SGmb path recovers after a period longer than the maximum path failure timer of the MBMS GW plus the period between two Diameter Device-Watchdog-Request messages or MBMS Heartbeat Request messages sent by the MBMS GW, to ensure that the MBMS GW also determines this is a non transient path failure if the BM-SC starts its timer before the MBMS GW. The BM-SC shall consider that the MBMS session has been released by the MBMS GW if the SGmb path failure is non transient for the MBMS GW. If the SGmb path failure remains transient for the MBMS GW, the BM-SC shall behave as follows upon detecting the SGmb path recovery:
- if the BM-SC has already moved the control of the MBMS session to an alternative MBMS GW, the BM-SC shall send an MBMS Session Stop Request message to the MBMS GW previously controlling the MBMS session with a "Local MBMS bearer context release" indication to instruct that MBMS GW to release the MBMS bearer context locally in the MBMS GW and in the associated MME/SGSN(s) without sending any message to the MCE/RNC(s).
- if the BM-SC has not yet moved the control of the MBMS session to an alternative MBMS GW (e.g. if the MBMS restoration procedures are not supported in the network),
- if the SGmb path failure is transient from the perspective of the BM-SC, the BM-SC shall consider that the MBMS session is still controlled by the related MBMS GW and proceed as if there had been no SGmb path failure;
- if the SGmb path failure is non transient from the perspective of the BM-SC, the BM-SC shall send an MBMS Session Start Request to the MBMS GW for the session and encode it as specified above (for a message sent to an alternative MBMS GW).
NOTE 6: The BM-SC cannot know whether the MBMS GW will see the SGmb path failure as transient or non transient if the SGmb path recovers in the period between the maximum path failure timer of the MBMS GW plus and minus the period between two Diameter Device-Watchdog-Request messages or MBMS Heartbeat Request messages sent by the MBMS GW. This can possibly lead the BM-SC to send an MBMS Session Stop request to the MBMS GW for a session that has already been terminated by the MBMS GW (if the MBMS GW determined the failure is non transient) or to send an MBMS Session Start request (with the "MBMS session re-establishment indication" flag) to the MBMS GW for a session that is still alive at the MBMS GW (if the MBMS GW determined the failure is transient). |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.6.2 MB2-C path failure | In deployments without a Diameter Agent between the BM-SC and the GCS AS, the BM-SC shall detect an MB2-C path failure using either:
- mechanisms as specified in the Diameter Base Protocol (e.g. transport connection failure, GCS AS peer not responding, Diameter Device-Watchdog-Request and Device-Watchdog-Answer messages during periods when there is no need for other MB2 signalling); or
- the MBMS Heartbeat procedure (see clause 29), if this procedure is supported.
In deployments with a Diameter Agent between the BM-SC and the GCS AS, the BM-SC shall detect an MB2-C path failure using the MBMS Heartbeat procedure (see clause 29).
NOTE 1: A transport connection failure does not allow to identify a failure of the remote MBMS peer. Likewise, it is not possible to rely on Diameter Device-Watchdog-Request / Answer messages to test the responsiveness of the remote MBMS node during periods when there is no need for other MB2 signalling as these messages are only exchanged between Diameter peers with a direct transport connection.
Upon detecting a non-transient MB2-C path failure, the BM-SC shall deallocate (locally) all the TMGIs that had been assigned to the GCS AS and the BM-SC shall stop all the related MBMS bearers to free the corresponding resources in E-UTRAN. |
88525ca373d6c27ca925fc02f42c683a | 23.007 | 20.2.7 PGW functionality |
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