7.3 Mobility Management Messages

29.2743GPP3GPP Evolved Packet System (EPS)Evolved General Packet Radio Service (GPRS) Tunnelling Protocol for Control plane (GTPv2-C)Release 16Stage 3TS

7.3.1 Forward Relocation Request

A Forward Relocation Request message shall be sent from:

– the source MME to the target MME over the S10 interface as part of an S1-based handover relocation procedure;

– the source MME to the target SGSN, or from the source SGSN to the target MME over the S3 interface as part of an Inter RAT handover and combined hard handover and SRNS relocation procedures;

– the source SGSN to the target SGSN over the S16 interface as part of an SRNS Relocation and PS handover procedures;

– the source MME to the target SGSN over the S3 interface as part of an SRVCC from E-UTRAN to UTRAN or GERAN with DTM HO support procedures and from the source SGSN to the target SGSN over the S16 interface as part of SRVCC from UTRAN (HSPA) to UTRAN or GERAN with DTM HO support;

– the source MME to the target AMF, or from the source AMF to the target MME over the N26 interface as part of the EPS to 5GS handover and 5GS to EPS handover procedures.

– the source AMF to the target MME_SRVCC over the N26 interface as part of the 5G-SRVCC from NG-RAN to UTRAN procedure.

A source MME/SGSN which supports CIoT knows whether the target MME/SGSN pool or target AMF (5GS) supports some CIoT optimisations either by using DNS procedures enhanced for DCNs or by local configuration, as specified in clause 5.9 of 3GPP TS 29.303 [32]. A source AMF knows whether the target MME pool supports SGi Non-IP or Ethernet PDN connections either by using DNS procedures enhanced for DCNs or by local configuration, as specified in clause 5.9 and 5.13 of 3GPP TS 29.303 [32]. The target MME/SGSN may forward the Forward Relocation Request to another MME/SGSN in the target MME/SGSN pool which is more suitable to serve the UE, based on the information received in the Forward Relocation Request message, e.g. required CIoT EPS optimisation(s) applicable to the given UE’s attachment.

NOTE 1: The source MME/SGSN/AMF does not need to know each individual CIoT feature the target MME/SGSN pool or target AMF (5GS) supports. The source MME/SGSN/AMF can behave as if the target MME/SGSN/AMF pool supports all CIoT features when the target MME/SGSN pool is known to support CIoT; the source MME/SGSN/AMF determines then which bearer contexts were successfully transferred as specified in sunclause 7.3.2.

NOTE 2: Among the CIoT optimization features, only the support of SCEF Non-IP PDN connection and the support of SGi Non-IP PDN connection are applicable to a SGSN.

NOTE 3: 5GS supports Attach without PDU session. 5GS can also support Unstructured and Ethernet PDU session types, which are assimilated to "SGi Non-IP PDN connections" over N26.

Forward Relocation procedure across S10 interface (when KASME is taken into use) shall be performed according to the Rules on Concurrent Running of Security Procedures, which are specified in 3GPP TS 33.401 [12].

When the source MME/SGSN supports one or more of the CIoT optimization features as specified in clause 8.125, the source MME/SGSN shall transfer EPS bearer context(s) for SGi Non-IP PDN connections or for PDN connections to a SCEF only if the target serving node is known to support SGi Non-IP PDN connections or SCEF Non-IP PDN connections respectively, as specified in clause 5.5.1.2.1 and 5.5.2 of 3GPP TS 23.401 [3]. Likewise, a source AMF shall transfer EPS bearer context(s) for SGi Non-IP PDN connections only if the target MME is known to support SGi Non-IP PDN connections. The source MME/SGSN/AMF shall not proceed with the Forward Relocation Request procedure if the UE does not have any EPS bearer context(s) for SGi IP or Non-IP PDN connections that can be transferred to the target serving node, i.e. under the following conditions:

– If the UE is attached to the source MME/SGSN with only the PDN connection(s) of PDN type "non-IP" through the SGW and the PGW, with or without SCEF PDN connections, and the target serving node is known to not support SGi Non-IP PDN Connection (as specified in clause 4.3.17.8.3.3 of 3GPP TS 23.401 [3] and in clause 5.3.13.8 of 3GPP TS 23 060 [35]); or

– If the UE is attached to the source AMF (5GS) with only PDU session(s) of type "Ethernet" or "Unstructured", and the target MME is known to not support SGi Non-IP and Ethernet PDN Connection.

The source MME shall transfer the EPS bearer context(s) for the Ethernet PDN connection only if the target serving node is known to support the Ethernet PDN connection, as specified in clause 5.3.3.1 of 3GPP TS 23.401 [3]. The source MME shall not proceed with the Forward Relocation Request procedure if the UE does not have any EPS bearer context(s) that can be transferred to the target serving node, i.e. under the following conditions:

– If the UE is attached to the source MME with only the PDN connection(s) of PDN type "Ethernet" through the SGW and the PGW, and the target serving node is known to not support the Ethernet PDN connection.

Table 7.3.1-1 specifies the presence requirements and conditions of the IEs in the message.

Table 7.3.1-1: Information Elements in a Forward Relocation Request

Information elements

P

Condition / Comment

IE Type

Ins.

IMSI

C

The IMSI shall be included in the message, except if the UE is emergency or RLOS attached and the UE is UICCless.

The IMSI shall be included in the message but not used as an identifier if UE is emergency or RLOS attached but IMSI is not authenticated.

IMSI

0

Sender’s F-TEID for Control Plane

M

F-TEID

0

MME/SGSN/AMF UE EPS PDN Connections

C

This IE shall be present, except:

– over the S16 interface if there is no active PDP context and the source and target SGSNs supports SRNS relocation w/o PDN connection over GTPv2 (see NOTE 2); or

– over the N26 interface, during 5G SRVCC handover procedure from 5GS to UTRAN, as specified in clause 6.5 of 3GPP TS 23.216 [43].

If the target MME/SGSN is known to not support SGi Non-IP PDN Connection (as specified in clause 4.3.17.8.3.3 of 3GPP TS 23.401 [3] and in clause 5.3.13.8 of 3GPP TS 23 060 [35]), then the source MME/SGSN/AMF shall only include PDN Connections of IP PDN type.

If the target MME is known to not support Ethernet PDN connections, or the target is an SGSN, then the source MME shall not include any Ethernet PDN connection. (See NOTE 10)

Several IEs with this type and instance values shall be included as necessary to represent a list of PDN Connections

PDN Connection

0

SGW S11/S4 IP Address and TEID for Control Plane

C

This IE shall be present, except over the S16 interface if there is no active PDP context and the source and target SGSNs supports SRNS relocation w/o PDN connection over GTPv2 (see NOTE 2).

Over the N26 interface, the source AMF shall set the IP address and TEID to the following values:

– any reserved TEID (e.g. all 0’s, or all 1’s);

– IPv4 address set to 0.0.0.0, or IPv6 Prefix Length and IPv6 prefix and Interface Identifier all set to zero.

F-TEID

1

SGW node name

C

This IE identifies the SGW that was used by the old MME/S4-SGSN. It shall be included by the source MME/S4-SGSN, except over the S16 interface if there is no active PDP context and the source and target SGSNs supports SRNS relocation w/o PDN connection over GTPv2 (see NOTE 2).

FQDN

0

MME/SGSN/AMF UE MM Context

M

MM Context

0

Indication Flags

C

This IE shall be included if any of the flags are set to 1.

  • Direct Forwarding Indication: This flag shall be set to 1 if direct forwarding is supported in the S1 based handover procedure or during an inter-system handover between 5GS and EPS. This flag shall not be set to 1 if the message is used for other handover procedures.
  • Idle mode Signalling Reduction Supported Indication flag: This flag shall be set to 1 if the source MME/SGSN and associated SGW are capable to establish ISR for the UE.
  • Unauthenticated IMSI: This flag shall be set to 1 if the IMSI present in the message is not authenticated and is for an emergency or RLOS attached UE.
  • Change Reporting support indication flag: This flag shall be set to 1 if the Source S4-SGSN/MME supports Location Change Reporting mechanism. See NOTE1. See NOTE 3.
  • CSG Change Reporting Support Indication flag: This flag shall be set to 1 if the Source S4-SGSN/MME supports CSG Information Change Reporting mechanism. See NOTE1. See NOTE 3.
  • Management Based MDT allowed flag: This flag shall be set to 1 for the S1 based inter-MME handover procedure over the S10 interface, if Management Based Minimization of Drive Tests (MDT) is allowed. See 3GPP TS 36.413 [10] and 3GPP TS 32.422 [18].
  • CSFB Indication: when configured to support the return to the last used PLMN after CSFB, the MME shall set this flag to 1 on the S3 interface if the PS handover procedure is due to CSFB (see clause 4.3.2 of 3GPP TS 23.272 [21]). See NOTE 5.
  • Pending MT Short Message Indication: This flag shall be set to 1 on the S10/S16/S3 interface if the source S4-SGSN/MME knows that there is one (or more) pending MT Short Message(s) in the SMS-GMSC for the UE as specified in clause 10.1 of 3GPP TS 23.040 [75], Figure 17c). See NOTE 8.
  • LTE-M UE Indication (LTEMUI): This flag shall be set to 1 if the MME/AMF knows that the UE is an LTE-M UE.
  • Return Preferred Indication (REPREFI): the MME or the AMF may set this flag to 1 on the N26 interface to indicate a preferred return of the UE to the last used EPS or 5GS PLMN (respectively) at a later access change to an EPS or 5GS shared network. See NOTE 5.
  • 5G-SRVCC HO Indication (5SRHOI): the AMF may set this flag to 1 on the N26 interface to indicate the HO is used for 5G-SRVCC as specified in 3GPP TS 23.216 [43].
  • Emergency PDU Session Indication (EMCI): the AMF may set this flag to 1 on the N26 interface to indicate that the UE has emergency PDU session, as specified in 3GPP TS 23.126 [43]. The EMCI bit shall be set together with the 5SRHOI bit.

Indication

0

E-UTRAN Transparent Container

C

This IE shall be included to contain the "Source to Target Transparent Container", if the message is used for UTRAN/GERAN to E-UTRAN inter RAT handover procedure, E-UTRAN intra RAT handover procedure, 3G SGSN to MME combined hard handover and SRNS relocation procedure, 5GS to EPS handover and EPS to 5GS handover. The Container Type shall be set to 3.

F-Container

0

UTRAN Transparent Container

C

This IE shall be included to contain the "Source to Target Transparent Container", if the message is used for PS handover to UTRAN Iu mode procedures, SRNS relocation procedure and E-UTRAN to UTRAN inter RAT handover procedure. The Container Type shall be set to 1.

F-Container

1

BSS Container

C

This IE shall be included to contain the "Source BSS to Target BSS Transparent Container" if the message is used for PS handover to GERAN A/Gb mode and E-UTRAN to GERAN A/Gb mode inter RAT handover procedure. The Container Type shall be set to 2.

F-Container

2

Target Identification

C

This IE shall be included if the message is used for SRNS relocation procedure, handover to UTRAN/E-UTRAN, 5GS to EPS handover and EPS to 5GS handover procedures.

Target Identification

0

CO

This IE shall be included on the S3 interface if the message is used for PS handover from E-UTRAN to GERAN A/Gb mode.

HRPD access node S101 IP address

C

This IE shall be included only if the HRPD pre-registration was performed at the source MME.

IP-Address

0

1xIWS S102 IP address

C

This IE shall be included only if the 1xRTT CS fallback pre- registration was performed at the source MME.

IP-Address

1

S1-AP Cause

C

This IE is the information received from the source eNodeB or derived from the information received from the source NG-RAN. The source MME or AMF shall include this IE in the message. Refer to 3GPP TS 29.010 [42] for the mapping of cause values between S1AP, RANAP, BSSGP and NGAP.

F-Cause

0

RANAP Cause

C

This IE is the information from the source RNC. The source SGSN shall include this IE in the message. Refer to the 3GPP TS 29.010 [42] for the mapping of cause values between S1AP, RANAP and BSSGP.

F-Cause

1

BSSGP Cause

C

This IE is the information received from source BSS. The source SGSN shall include this IE in the message. Refer to 3GPP TS 29.010 [42] for the mapping of cause values between S1AP, RANAP and BSSGP.

F-Cause

2

Source Identification

C

This IE shall be included on the S16 interface if the message is used for PS handover from GERAN/UTRAN to GERAN A/Gb mode.

Source Identification

0

Selected PLMN ID

C

The old MME/SGSN/AMF shall include this IE if the selected PLMN identity is available. The Selected PLMN ID IE indicates the target core network operator selected for the UE in a shared network.

PLMN ID

0

Recovery

C

This IE shall be present when contacting the peer for the first time.

Recovery

0

Trace Information

C

This IE shall be included over S10/S16/S3 when session trace is active for this IMSI/IMEI.

Trace Information

0

Subscribed RFSP Index

CO

This IE shall be included by the source MME/SGSN/AMF, if received from the HSS or UDM.

RFSP Index

0

RFSP Index in Use

CO

This IE shall be included by the source MME/SGSN/AMF, if it supports the feature.

RFSP Index

1

CSG ID

CO

This IE shall be included on the S3/S10/S16 interfaces if the source MME/SGSN receives it from the source eNodeB/RNC. It indicates the target CSG ID in case of a handover to a CSG cell or hybrid cell.

CSG ID

0

CSG Membership Indication

CO

This IE shall be included on the S3/S10/S16 interfaces by the source MME/SGSN if the CSG access mode is received from the source eNodeB/RNC and indicates the target cell is a hybrid cell, or if the UE has emergency bearer(s) and the target cell is a CSG cell.

CMI

0

UE Time Zone

CO

When available, this IE shall be included by the source MME/S4-SGSN/AMF.

UE Time Zone

0

Serving Network

CO

This IE shall be included to indicate the current Serving Network.

Serving Network

0

MME/S4-SGSN LDN

O

T his IE shall be sent by the source MME/S4-SGSN to the target MME/S4-SGSN on the S3/S10/S16 interfaces if MS Classmark2, MS Classmark3 and the Supported Codec are available in the source MME/S4-SGSN, or by the source AMF to the target MME_SRVCC on the N26 interface if MS Classmark2 and the Supported Codec are available in the source AMF.

Local Distinguished Name (LDN)

0

Additional MM context for SRVCC

CO

This IE shall be sent by the source MME/S4-SGSN to the target MME/S4-SGSN on the S3/S10/S16 interfaces if MS Classmark2, MS Classmark3 and the Supported Codec are available in the source MME/S4-SGSN.

Additional MM context for SRVCC

0

Additional flags for SRVCC

CO

This IE shall be included if any one of the applicable flags needs to be forwarded.

Applicable flags:

  • ICS Indicator: This IE shall be sent by the source MME/S4-SGSN to the target MME/S4-SGSN on the S3/S10/S16 interfaces if ICS Indicator is available in the source MME/S4-SGSN.
  • vSRVCC flag: This IE shall be sent by the source MME to the target MME on the S10 interface if vSRVCC flag is available in the source MME.

Additional flags for SRVCC

0

STN-SR

CO

This IE shall be sent by the source MME/S4-SGSN to the target MME/S4-SGSN on the S3/S10/S16 interfaces if STN-SR is available in the source MME/S4-SGSN, or by the source AMF to the target MME_SRVCC on the N26 interface if STN-SR is available in the source AMF.

STN-SR

0

C-MSISDN

CO

This IE shall be sent by the source MME/S4-SGSN to the target MME/S4-SGSN on the S3/S10/S16 interfaces if C-MSISDN is available in the source MME/S4-SGSN, or by the source AMF to the target MME_SRVCC on the N26 interface if C-MSISDN is available in the source AMF. The C-MSISDN is defined in 3GPP TS 23.003 [2].

MSISDN

0

MDT Configuration

CO

This IE shall be sent by the source MME to the target MME on the S10 interface for the S1-based handover relocation procedure, if the Job Type indicates Immediate MDT. See 3GPP TS 32.422 [18] clause 4.4.

MDT Configuration

0

SGSN node name

CO

This IE shall be sent by the source SGSN on the S3 interface if both source SGSN and associated SGW support ISR. See NOTE 4.

FQDN

1

MME node name

CO

This IE shall be sent by the source MME on the S3 interface if both source MME and associated SGW support ISR. See NOTE 4.

FQDN

2

User CSG Information (UCI)

CO

This IE shall be sent by the source MME/S4-SGSN on the S3/S10/S16 interfaces if the source MME/SGSN has reported to the PGW that the UE is in a CSG or hybrid cell. It shall then contain the last User CSG information that the source MME/S4-SGSN has reported to the PGW.

The absence of this IE indicates that the UE has not been reported to the PGW as being in a CSG or hybrid cell.

See NOTE 6.

UCI

0

Monitoring Event Information

CO

This IE shall be sent by the source MME/S4-SGSN on the S3/S10/S16 interfaces if monitoring events are to be continued in the target MME/S4-SGSN.

More than one IE with this type and instance values may be included to represent multiple monitoring events.

Monitoring Event Information

0

Monitoring Event Extension Information

CO

This IE shall be sent by the source MME/S4-SGSN on the S3/S10/S16 interfaces if monitoring event extensions are to be sent to the target MME/S4-SGSN.

More than one IE with this type and instance values may be included to represent multiple monitoring event extensions.

Monitoring Event Extension Information

0

UE Usage Type

CO

This IE shall be set to the subscribed UE Usage Type, if received from the HSS, and sent by the old MME/SGSN if the old MME/SGSN supports the Dedicated Core Networks specified in TS 23.401 [3].

This IE shall also be set to the subscribed UE Usage Type, if received from the UDM, and sent by the old AMF on N26 interface.

If the UE Usage Type is not available in the old MME/SGSN/AMF, the length field of this IE shall be set to 0.

See NOTE 7.

Integer Number

0

MME/SGSN UE SCEF PDN Connections

CO

This IE shall be present over the S10/S3/S16 interface if there is at least one SCEF PDN connection for this UE at the source MME/SGSN and if the target MME/SGSN is known to support SCEF Non-IP PDN Connections (as specified in clause 5.13.1 of 3GPP TS 23.682 [74]).

Several IEs with this type and instance values shall be included as necessary to represent a list of SCEF PDN Connections.

SCEF PDN Connection

0

MSISDN

CO

This IE shall be present over the S10/S3/S16 interface if the UE’s MSISDN is available and if there is at least one instance of the MME/SGSN UE SCEF PDN Connection IE included in the message.

MSISDN

1

Source UDP Port Number

CO

If the target MME/SGSN/AMF, selected by the source MME/SGSN/AMF, decides to forward the Forward Relocation Request message to another more suitable MME/SGSN/AMF in the same MME/SGSN pool or AMF set, the MME/SGSN/AMF shall include this IE, set to the Source UDP Port number of the received message from the source MME/SGSN/AMF. The new target MME/SGSN/AMF shall use this UDP port as the UDP destination port in the Forward Relocation Response message.

Port Number

0

Serving PLMN Rate Control

CO

This IE shall be included by the old MME on S10 interface if the Serving PLMN Rate control was enabled when there is at least one SCEF PDN connection. See NOTE 9.

Serving PLMN Rate Control

0

Extended Trace Information

C

This IE shall be included over N26 when session trace is active for this user.

Extended Trace Information

0

Subscribed Additional RRM Policy Index

CO

This IE shall be included by the MME over the S10 interface if received from the HSS.

Additional RRM Policy Index

0

Additional RRM Policy Index in Use

CO

This IE shall be included by the MME over the S10 interface if the feature is supported by the MME.

Additional RRM Policy Index

1

Subscribed V2X Information

CO

This IE shall be present over the N26 interface if available, and sent by the old MME/AMF if the old MME/AMF supports the V2X services specified in 3GPP TS 23.287 [89].

V2X Context

0

IWK SCEF ID for Monitoring Event

CO

This IE shall be included on the S3/S10 interface if the source MME/SGSN has selected the IWK-SCEF to relay Monitoring Events.

Node Identifier

0

Private Extension

O

Private Extension

VS

NOTE 1: 3GPP TS 23.401 [3] (e.g. clause 5.3.2.1) and 3GPP TS 23.060 [35] (e.g. clause 9.2.2.1) defines the MME/SGSN shall send the MS Info Change Reporting Support Indication to the PGW. In such case MME/SGSN shall use the Change Reporting Support Indication and/or CSG Change Reporting Support Indication (whichever is applicable), even if stage 2 refers to MS Info Change Reporting Support Indication.

NOTE 2: GTPv2 shall be used for SRNS relocation w/o PDN connection if all the S4-SGSNs (between which SRNS relocation can take place) support this optional GTPv2 procedure. Otherwise GTPv1 shall be used for that procedure (see clause 7.10). The S4-SGSN can know by local configuration whether all peer S4-SGSNs support this procedure.

NOTE 3: The receiver shall ignore the per UE Change Reporting Support Indication and CSG Change Reporting Support Indication flags, as included within the Indication Flags IE above, if these flags are included per PDN connection i.e. within the Indication Flags IE of the MME/SGSN UE EPS PDN Connections IE.

NOTE 4: According to the 3GPP TS 23.401 [3], during an inter-RAT handover procedure for a UE with ISR activated, the source MME/SGSN should select the ISR associated CN node for this UE as the target CN node for the inter RAT HO when the ISR associated CN node can serve the target access. This parameter is exchanged when ISR is being activated and used in the source MME/SGSN for this decision upon subsequent inter-RAT handover.

NOTE 5: If the SGSN needs to include the last used LTE PLMN ID in the Equivalent PLMN list it sends to the UE (see 3GPP TS 23.272 [21]), the SGSN shall derive the last used LTE PLMN ID from the Serving Network IE. If an MME or AMF needs to store the last used 5GS or EPS PLMN ID (respectively), the MME or AMF shall derive the last used 5GS or EPS PLMN ID (respectively) from the Serving Network IE.

NOTE 6: In shared networks, when the message is sent from the VPLMN to the HPLMN, the PLMN ID that is communicated in this IE shall be that of the selected Core Network Operator for supporting UEs, or that of the allocated Core Network Operator for non-supporting UEs. As an exception, based on inter-operator roaming/sharing agreement, if the information on whether the UE is a supporting or non-supporting UE is available, the PLMN ID that is communicated to the HPLMN for non-supporting UEs shall be the Common PLMN ID.
In shared networks, when the MME/S4-SGSN and PGW pertain to the same PLMN, the Primary PLMN ID shall be communicated in the ECGI to the PGW, and the Common PLMN ID shall be communicated in SAI/CGI to the PGW, for both supporting and non-supporting UEs. The Core Network Operator PLMN ID (selected by the UE for supporting UEs or allocated by the network for non-supporting UEs) shall be communicated in the TAI, RAI, UCI and the Serving Network.
See clause 4.4 of 3GPP TS 23.251 [55].

NOTE 7: A UE Usage Type IE with the length field equal to 0 is used for the receiver to differentiate the case where the sender does not support the Dedicated Core Network feature from the case where the sender supports the Dedicated Core Network feature but no UE Usage type was received in UE’s subscription.

NOTE 8: There may be a pending MT Short Message at the SMS-GMSC during a handover scenario, when the UE performs a Service Request towards the source MME/SGSN and a handover procedure occurs shortly afterward, before the SMS-GMSC is alerted to retransmit the pending MT Short Message.

NOTE 9: The target MME may compare the value of the Serving PLMN Rate Control received in the Forward Relocation Request message with the one configured locally, to determine if this parameter needs to be updated towards the SCEF. The Serving PLMN Rate Control does not apply to any SGi PDN Connection in this message.

NOTE 10: PDN connections with PDN Type "Ethernet" are not supported in GERAN/UTRAN. For PDN connections with PDN type "Ethernet", mobility to GERAN/UTRAN is not supported. See clause 4.3.17.8a of TS 23.401 [3].

The PDN Connection grouped IE shall be coded as depicted in Table 7.3.1-2.

Table 7.3.1-2: MME/SGSN/AMF UE EPS PDN Connections within Forward Relocation Request

Octet 1

PDN Connection IE Type = 109 (decimal)

Octets 2 and 3

Length = n

Octet 4

Spare and Instance fields

Information elements

P

Condition / Comment

IE Type

Ins.

APN

M

APN

0

APN Restriction

C

This IE denotes the restriction on the combination of types of APN for the APN associated with this EPS bearer Context. The target MME or SGSN determines the Maximum APN Restriction using the APN Restriction.

If available, the source MME/S4SGSN shall include this IE.

APN Restriction

0

Selection Mode

CO

When available, this IE shall be included by the source MME/S4-SGSN/AMF.

Selection Mode

0

IPv4 Address

C

This IE shall not be included if no IPv4 Address is assigned. See NOTE 1.

IP Address

0

IPv6 Address

C

This IE shall not be included if no IPv6 Address is assigned.

IP Address

1

Linked EPS Bearer ID

M

This IE identifies the default bearer of the PDN Connection.

EBI

0

PGW S5/S8 IP Address for Control Plane or PMIP

M

This IE shall include the TEID in the GTP based S5/S8 case and the uplink GRE key in the PMIP based S5/S8 case.

See NOTE 4.

F-TEID

0

PGW node name

C

This IE shall be included if the source MME, SGSN or AMF has the PGW FQDN.

FQDN

0

CO

This IE shall be included by the source MME over the N26 interface. See NOTE 6.

Bearer Contexts

C

Several IEs with this type and instance values may be included as necessary to represent a list of Bearers.

Bearer Context

0

Aggregate Maximum Bit Rate (APN-AMBR)

M

AMBR

0

Charging characteristics

C

This IE shall be present if charging characteristics was supplied by the HSS to the MME/SGSN, or by the UDM to the SMF, as a part of subscription information.

Charging characteristics

0

Change Reporting Action

C

This IE shall be included whenever available at the source MME/SGSN. See NOTE 5.

Change Reporting Action

0

CSG Information Reporting Action

CO

This IE shall be included whenever available at the source MME/SGSN.

CSG Information Reporting Action

0

H(e)NB Information Reporting

CO

This IE shall be included whenever available at the source MME/SGSN.

H(e)NB Information Reporting

0

Indication Flags

CO

This IE shall be included if any of the flags are set to 1.

  • Change Reporting support indication flag: This flag shall be set to 1 if the Source S4-SGSN/MME supports Location Change Reporting mechanism and if the S4-SGSN/MME has indicated the support for the Location Change Reporting mechanism to the PGW, during the session establishment and/or modification procedures. See NOTE 2.
  • CSG Change Reporting Support Indication flag: This flag shall be set to 1 if the Source S4-SGSN/MME supports CSG Information Change Reporting mechanism and if the S4-SGSN/MME has indicated the support for the CSG Informatoin Change Reporting to the PGW, during the session establishment and/or modification procedures. See NOTE 2.
  • Delay Tolerant Connection Indication flag: This flag shall be set to 1 on the S3/S10/S16 interface by the source MME/SGSN if the PGW indicated that this PDN Connection is delay tolerant.
  • Extended PCO Support Indication flag: This flag shall be set to 1 on S10/N26 interface by the source MME if the UE and the source MME support Extended PCO. It shall be set to 1 on the N26 interface during a 5GS to EPS handover.
  • NO 5GS N26 mobility Indication flag: This flag shall be set to 1 on S10 interface if the PDN connection cannot be moved to 5GS via N26.

Indication

0

Signalling Priority Indication

CO

The source SGSN/MME shall include this IE if the UE indicated low access priority when establishing the PDN connection.

Signalling Priority Indication

0

Change to Report Flags

CO

This IE shall be included by the SGSN if any one of the applicable flags is set to 1. See NOTE3.

Applicable flags:

  • Serving Network Change to Report: This flag shall be set to 1 if the source SGSN has detected a Serving Network change during a RAU procedure without SGSN change but has not yet reported this change to the PGW.
  • Time Zone Change to Report: This flag shall be set to 1 if the source SGSN has detected a UE Time Zone change during a RAU procedure without SGSN change but has not yet reported this change to the PGW.

Change to Report Flags

0

Local Home Network ID

CO

This IE shall be sent over the S3/S10/S16 interface if SIPTO at the Local Network is active for the PDN connection in the SIPTO at the Local Network architecture with stand-alone GW.

FQDN

1

Presence Reporting Area Action

CO

This IE shall be included if the PGW requested the source MME/SGSN to report changes of UE presence in a Presence Reporting Area. The source MME/SGSN shall include the Presence Reporting Area Identifier and, if received from the PGW, the list of the Presence Reporting Area elements.

Several IEs with the same type and instance value may be included as necessary to represent a list of Presence Reporting Area Actions. One IE shall be included for each Presence Reporting Area.

Presence Reporting Area Action

0

WLAN Offloadability Indication

CO

If the MME/SGSN supports WLAN/3GPP Radio Interworking with RAN rules then this IE shall be included on S3/S10/S16 if the UE has been authorized to perform WLAN offload for at least one RAT.

WLAN Offloadability Indication

0

Remote UE Context Connected

CO

The source MME shall include this IE on the S10 interface during an inter MME mobility procedure if such information is available.

Several IEs with the same type and instance value may be included as necessary to represent a list of remote UEs connected.

Remote UE Context

0

PDN Type

CO

The source MME/SGSN/AMF shall include this IE on the S10/S3/S16/N26 interface, for a Non-IP PDN Connection, during an inter MME/SGSN/AMF mobility procedure, if the target MME/SGSN/AMF supports SGi Non-IP or Ethernet PDN connections.

PDN Type

0

Header Compression Configuration

CO

This IE shall be sent over the S10 interface if the use of IP Header Compression for Control Plane CIoT EPS optimisations has been negotiated with the UE and the target MME is known to support CIoT EPS optimisations.

Header Compression Configuration

0

NOTE 1: For deferred IPv4 address allocation, if the MME/S4-SGSN receives the PDN address "0.0.0.0" from PGW during "eUTRAN Initial Attach", "PDP Context Activation", "UE requested PDN Connectivity", then the MME/S4-SGSN shall include this IPv4 address "0.0.0.0".

NOTE 2: 3GPP TS 23.401 [3] (e.g. clause 5.3.2.1) and 3GPP TS 23.060 [35] (e.g. clause 9.2.2.1) defines the MME/SGSN shall send the MS Info Change Reporting Support Indication to the PGW. In such case MME/SGSN shall use the Change Reporting Support Indication and/or CSG Change Reporting Support Indication (whichever is applicable), even if stage 2 refers to MS Info Change Reporting Support Indication.

NOTE 3: When UE is camping on the 3G and performs a Service Request procedure, as specified in the clause 6.12.1 of 3GPP TS 23.060 [35], if Service Type indicates Signalling, the signalling connection is established between the MS and the SGSN for sending upper-layer signalling messages, e.g. Activate PDP Context Request, but the resources for active PDP context(s) are not allocated, therefore the change of Serving Network or UE Time zone may not be reported to SGW/PGW for the existing PDP Contexts.

NOTE 4: For PMIP based S5/S8, the ‘PGW S5/S8 IP Address and TEID for user plane’ IE and the ‘PGW S5/S8 IP Address for Control Plane or PMIP’ IE shall contain the same uplink GRE key; the Interface Type in these IEs shall be set to the value 9 (S5/S8 PGW PMIPv6 interface).

NOTE 5: The target MME (respectively S4-SGSN) shall ignore this IE if it is received from an S4-SGSN (respectively an MME), i.e. over the S3 interface. In this case, the target serving node shall consider that no ULI change reporting is requested by the PGW for the target RAT, and the PGW shall request the target serving node to start ULI change reporting for the target RAT if so desired.

NOTE 6: The PGW Node Name is used by the target AMF in the NF Service Discovery procedure to find the combined PGW-C/SMF for the PDU Session during an MME to AMF mobility procedure.

The Bearer Context grouped IE shall be coded as depicted in Table 7.3.1-3.

Table 7.3.1-3: Bearer Context within MME/SGSN/AMF UE EPS PDN Connections within Forward Relocation Request

Octet 1

Bearer Context IE Type = 93 (decimal)

Octets 2 and 3

Length = n

Octet 4

Spare and Instance fields

Information elements

P

Condition / Comment

IE Type

Ins.

EPS Bearer ID

M

See NOTE 3.

EBI

0

TFT

C

This IE shall be present if a TFT is defined for this bearer.

Bearer TFT

0

SGW S1/S4/S12 IP Address and TEID for user plane

M

This IE shall contain the SGW S1/S4/S12 IP Address and TEID for user plane.

Over the N26 interface, the SMF (on behalf of the source AMF) shall set the IP address and TEID to the following values:

– any reserved TEID (e.g. all 0’s, or all 1’s);

– IPv4 address set to 0.0.0.0, or IPv6 Prefix Length and IPv6 prefix and Interface Identifier all set to zero.

See NOTE2, NOTE 4.

F-TEID

0

PGW S5/S8 IP Address and TEID for user plane

C

This IE shall be present for GTP based S5/S8.

F-TEID

1

CO

For PMIP-based S5/S8, this IE shall be included if the PGW provided an alternate address for user plane, i.e. an IP address for user plane which is different from the IP address for control plane.

When present, this IE shall contain the alternate IP address for user plane and the uplink GRE key.

See NOTE 1.

Bearer Level QoS

M

Bearer QoS

0

BSS Container

CO

The MME/S4 SGSN shall include the Packet Flow ID, Radio Priority, SAPI, PS Handover XID parameters in the TAU/RAU/Handover procedure, if available. See Figure 8.48-2. The Container Type shall be set to 2.

F-Container

0

Transaction Identifier

C

This IE shall be sent over S3/S10/S16 if the UE supports A/Gb and/or Iu mode.

TI

0

Bearer Flags

CO

Applicable flags:

  • vSRVCC indicator: This IE shall be sent by the source MME to the target MME on the S10 interface if vSRVCC indicator is available in the source MME.
  • ASI (Activity Status Indicator): the source S4-SGSN shall set this indicator to 1 on the S16 interface if the bearer context is preserved in the CN without an associated RAB.

Bearer Flags

0

SGW S11 IP Address and TEID for user plane

CO

This IE shall be present if available. See NOTE 2.

F-TEID

2

NOTE 1: For PMIP based S5/S8, the ‘PGW S5/S8 IP Address and TEID for user plane’ IE and the ‘PGW S5/S8 IP Address for Control Plane or PMIP’ IE shall contain the same uplink GRE key; the Interface Type in these IEs shall be set to the value 9 (S5/S8 PGW PMIPv6 interface).

NOTE 2: When separate IP address spaces are used for S1-U and S11-U, the MMEs shall include both S1-U SGW F-TEID in the SGW S1/S4/S12/S11 IP Address and TEID for user plane IE and S11-U SGW F-TEID in SGW S11 IP Address and TEID for user plane, when they are available; otherwise, the source MME shall include the SGW S1/S4/S12/S11 IP Address and TEID for user plane IE, since S1-U and S11-U SGW F-TEID are the same.

NOTE 3: The support of the 15 EPS Bearers shall be homogeneously supported within an MME Pool / SGW serving area. A source MME which supports the 15 EPS Bearers, shall know whether the target MME pool also supports that by local configuration. When the target MME is known to not support the 15 EPS Bearers, the source MME shall only transfer up to 8 EPS bearer contexts with the EBI value set between ‘5’ and ’15’ to the target MME and shall delete EPS bearer(s) which are not transferred, and if the default bearer is to be deleted, the corresponding PDN connection(s) shall be deleted by the source MME.

NOTE 4: During 5GS to EPS mobility procedures with N26 interface, the source AMF shall transparently transfer the MME/SGSN/AMF UE EPS PDN Connections IE received from the SMF as specified in clause 6.1.6.2.27 of 3GPP TS 29.502[88].

Table 7.3.1-4: Remote UE Context Connected within MME/SGSN UE EPS PDN Connections within Forward Relocation Request

Octets 1

Remote UE Context IE Type = 191 (decimal)

Octets 2 and 3

Length = n

Octets 4

Spare and Instance fields

Information elements

P

Condition / Comment

IE Type

Ins.

Remote User ID

M

See clause 8.123 for the description and use of this parameter

Remote User ID

0

Remote UE IP Information

M

See clause 8.124 for the description and use of this parameter

Remote UE IP Information

0

Table 7.3.1-5: MME UE SCEF PDN Connections within Forward Relocation Request

Octets 1

SCEF PDN Connection IE Type = 195 (decimal)

Octets 2 and 3

Length = n

Octets 4

Spare and Instance fields

Information elements

P

Condition / Comment

IE Type

Ins.

APN

M

APN

0

Default EPS Bearer ID

M

This IE shall identify the default bearer of the SCEF PDN Connection.

EBI

0

SCEF ID

M

This IE shall include the SCEF Identifier and the SCEF Realm for the APN.

Node Identifier

0

Table 7.3.1-6: Subscribed V2X Information within Forward Relocation Request

Octets 1

V2X Context IE Type = 208 (decimal)

Octets 2 and 3

Length = n

Octets 4

Spare and Instance fields

Information elements

P

Condition / Comment

IE Type

Ins.

LTE V2X Services Authorized

C

This IE shall be included to indicate the authorization status of the UE to use the LTE sidelink for V2X services.

Services Authorized

0

NR V2X Services Authorized

C

This IE shall be included to indicate the authorization status of the UE to use the NR sidelink for V2X services.

Services Authorized

1

LTE UE Sidelink Aggregate Maximum Bit Rate

C

This IE shall be included if the UE is authorized for LTE V2X services.

Bit Rate

0

NR UE Sidelink Aggregate Maximum Bit Rate

C

This IE shall be included if the UE is authorized for NR V2X services.

Bit Rate

1

PC5 QoS Parameters

C

This IE shall be included if the UE is authorized for NR V2X services.

PC5 QoS Parameters

0

Table 7.3.1-7: PC5 QoS Parameters within Forward Relocation Request

Octets 1

PC5 QoS Parameters IE Type = 209 (decimal)

Octets 2 and 3

Length = n

Octets 4

Spare and Instance fields

Information elements

P

Condition / Comment

IE Type

Ins.

PC5 QoS Flows

M

Several IEs with this type and same instance value may be included as necessary to represent a list of PC5 QoS Flows.

PC5 QoS Flow

0

PC5 Link Aggregated Bit Rates

O

This IE may be included for the non-GBR PC5 QoS Flows.

Bit Rate

0

7.3.2 Forward Relocation Response

A Forward Relocation Response message shall be sent as a response to Forward Relocation Request during S1-based handover procedure, Inter RAT handover procedures, SRNS Relocation procedure and PS handover procedures, EPS to 5GS handover and 5GS to EPS handover procedures, 5G-SRVCC from NG-RAN to UTRAN procedure.

Based on the List of Set-up Bearers IE in the Forward Relocation Response, the source MME/AMF shall determine whether the bearer contexts for SGi (IP, Non-IP or Ethernet) PDN connections were successfully transferred to the target MME/AMF.

Based on the List of Set-up Bearers for SCEF PDN Connections IE in the Forward Relocation Response, the source MME shall determine whether the bearer contexts for SCEF PDN connections were successfully transferred to the target MME, and initiate procedures to release the SCEF PDN connections which were not successfully handed over.

Table 7.3.2-1 specifies the presence requirements and conditions of the IEs in the message.

Cause IE indicates if the relocation has been accepted, or not. The relocation has not been accepted by the target MME/SGSN/AMF if the Cause IE value differs from "Request accepted". Possible Cause values are specified in Table 8.4-1. Message specific cause values are:

– "Relocation failure".

Table 7.3.2-1: Information Elements in a Forward Relocation Response

Information elements

P

Condition / Comment

IE Type

Ins.

Cause

M

Cause

0

Sender’s F-TEID for Control Plane

C

If the Cause IE contains the value "Request accepted", the target MME/SGSN/AMF shall include this IE in the Forward Relocation Response message.

F-TEID

0

Indication Flags

C

This IE shall be included if any of the flags are set to 1.

:

  • SGW Change Indication: this flag shall be set to 1 if the target MME/SGSN has selected a new SGW.
    This flag shall be set to 1 by the target AMF during the EPS to 5GS handover using N26 interface.

Indication

0

List of Set-up Bearers

C

The list of Set-up Bearers IE shall contain the EPS bearer Identifiers of the bearers that were successfully allocated in the target system during a handover procedure. This IE shall be included if the source and target access type is EUTRAN or NG-RAN and the Cause IE contains the value "Request accepted".

See NOTE 1.

Several IEs with this type and instance values shall be included as necessary to represent a list of Bearers.

Bearer Context

0

List of Set-up RABs

C

The list of Set-up RABs IE shall contain the RAB Identifiers of the RABs that were successfully allocated in the target system. This IE shall be included if the Cause IE contains the value "Request accepted" and

  • If the source access type is UTRAN and the target access type is E-UTRAN/UTRAN,
  • If the source access type is E-UTRAN and the target access type is UTRAN,

except over the S16 interface if the Forward Relocation Request did not include the MME/SGSN UE EPS PDN Connections IE.

See NOTE 1.

Several IEs with this type and instance values shall be included as necessary to represent a list of Bearers.

Bearer Context

1

List of Set-up PFCs

O

The list of Set-up PFCs IE shall contain the Packet Flow Identifies of the PFCs that were successfully allocated in the target system during a PS handover to/from GERAN or inter RAT handover to/from GERAN. If the Cause IE contains the value "Request accepted", this IE may be included.

See NOTE 1.

Several IEs with this type and instance values shall be included as necessary to represent a list of Bearers.

Bearer Context

2

S1-AP Cause

C

This IE shall be included if the cause value is received in an S1-AP message or derived from the cause value received in a NGAP message. Refer to the 3GPP TS 29.010 [42] for the mapping of cause values between S1AP, RANAP, BSSGP and NGAP.

F-Cause

0

RANAP Cause

C

This IE shall be included if the cause value is received in RANAP message. Refer to the 3GPP TS 29.010 [42] for the mapping of cause values between S1AP, RANAP and BSSGP.

F-Cause

1

BSSGP Cause

C

For handover to GERAN, if a cause value is received from the Target BSC, the BSSGP Cause IE shall be included and shall be set to the cause value received from the target BSC. Refer to the 3GPP TS 29.010 [42] for the mapping of cause values between S1AP, RANAP and BSSGP.

F-Cause

2

E-UTRAN Transparent Container

C

This IE shall be included to contain the "Target to Source Transparent Container" during a handover to E-UTRAN, 5GS to EPS handover and EPS to 5GS handover. If the Cause IE contains the value "Request accepted". The Container Type shall be set to 3.

F-Container

0

UTRAN Transparent Container

C

This IE shall be included to contain the "Target to Source Transparent Container" during a handover to UTRAN. If the Cause IE contains the value "Request accepted". The Container Type shall be set to 1.

F-Container

1

BSS Container

C

This IE shall be included to contain the Target BSS to Source BSS Transparent Container during a handover to GERAN. If the Cause IE contains the value "Request accepted". The Container Type shall be set to 2

F-Container

2

MME/S4-SGSN LDN

O

This IE may be sent by the MME/S4-SGSN to the peer MME/S4-SGSN on the S3/S10/S16 interfaces (see 3GPP TS 32.423 [44]), when communicating the LDN to the peer node for the first time.

Local Distinguished Name (LDN)

0

SGSN node name

CO

This IE shall be sent by the target SGSN on the S3 interface if both target SGSN and associated SGW support ISR. See NOTE 2.

FQDN

0

MME node name

CO

This IE shall be sent by the target MME on the S3 interface if both target MME and associated SGW support ISR. See NOTE 2.

FQDN

1

SGSN Number

O

This IE may be sent by the target S4-SGSN to the source MME/S4-SGSN as specified in 3GPP TS 23.271 [56].

Node Number

0

CO

This IE shall be included if the PMTSMI flag in the Forward Relocation Request message is set to 1.

SGSN Identifier

O

This IE may be sent by the target S4-SGSN to the source MME/S4-SGSN as specified in 3GPP TS 23.271 [56].

Node Identifier

0

MME Identifier

O

This IE may be sent by the target MME to the source MME/S4-SGSN as specified in 3GPP TS 23.271 [56].

Node Identifier

1

MME number for MT SMS

CO

This IE shall be included on the S10/S3 interface if the PMTSMI flag in the Forward Relocation Request message is set to 1.

Node Number

1

SGSN Identifier for MT-SMS

CO

This IE shall be included on the S16/S3 interface if the target S4-SGSN supports the Gdd reference point and if the PMTSMI flag in the Forward Relocation Request message is set to 1.

Node Identifier

2

MME Identifier for MT SMS

CO

This IE shall be included on the S10/S3 interface if the target MME supports the SGd reference point and if the PMTSMI flag in the Forward Relocation Request message is set to 1.

Node Identifier

3

List of Set-up Bearers for SCEF PDN Connections

CO

This IE shall contain the EPS bearer Identifiers of the Bearers of SCEF PDN connections that were successfully allocated in the target system during a handover procedure, if any.

Several IEs with this type and instance values shall be included as necessary to represent a list of Bearers.

Bearer Context

3

Private Extension

O

Private Extension

VS

NOTE 1: In the Forward Relocation Request message, the inclusion of "RAN Cause" indicates that the source access type is E-UTRAN. In the Forward Relocation Request message, the inclusion of "RANAP Cause" indicates that the source access type is UTRAN. In the Forward Relocation Request message, the inclusion of "BSSGP Cause" indicates that the source access type is GERAN.

NOTE 2: According to the 3GPP TS 23.401 [3], during an inter-RAT handover procedure for a UE with ISR activated, the source MME/SGSN should select the ISR associated CN node for this UE as the target CN node for the inter RAT HO when the ISR associated CN node can serve the target access. This parameter is exchanged when ISR is being activated and used in the source MME/SGSN for this decision upon subsequent inter-RAT handover.

Bearer Context IE in this message is specified in Table 7.3.2-2, the source system shall use this IE for data forwarding in handover.

Table 7.3.2-2: Bearer Context

Octet 1

Bearer Context IE Type = 93 (decimal)

Octets 2 and 3

Length = n

Octet 4

Spare and Instance fields

Information elements

P

Condition / Comment

IE Type

Ins.

EPS Bearer ID

C

This IE shall be included if the message is used for S1-Based handover procedure, 5GS to EPS handover or EPS to 5GS handover.

This IE shall be included if the message is used for SRNS relocation procedure and Inter RAT handover to/from Iu mode procedures.

EBI

0

Packet Flow ID

C

This IE shall be included if the message is used for PS handover and Inter RAT handover to/from A/Gb mode procedures.

Packet Flow ID

0

eNodeB/gNodeB F-TEID for DL data forwarding

C

This IE shall be included for the message sent from the target MME, if the DL Transport Layer Address and DL GTP TEID are included in the "SAE Bearers Admitted List" of the S1AP: HANDOVER REQUEST ACKNOWLEDGE and direct forwarding or indirect forwarding without SGW change is applied.

This IE shall be included during a 4G to 5G handover in the message sent from the target AMF, if the Data Forwarding Response E-RAB List IE is received in the NGAP HANDOVER REQUEST ACKNOWLEDGE and direct data forwarding applies.

F-TEID

0

eNodeB F-TEID for UL data forwarding

O

This IE may be included for the message sent from the target MME during the intra-EUTRAN HO, if the UL Transport Layer Address and UL GTP TEID are included in the "SAE Bearers Admitted List" of the S1AP: HANDOVER REQUEST ACKNOWLEDGE and direct forwarding or indirect forwarding without SGW change is applied.

F-TEID

1

SGW/UPF F-TEID for DL data forwarding

C

This IE shall be included when indirect data forwarding with SGW change is applied.

F-TEID

2

CO

This IE shall be included when using indirect data forwarding during an EPS to 5GS handover or a 5GS to EPS handover.

RNC F-TEID for DL data forwarding

C

This RNC F-TEID shall be included in the message sent from SGSN, if the target system decides using RNC F-TEID for data forwarding.

F-TEID

3

SGSN F-TEID for DL data forwarding

C

This SGSN F-TEID shall be included in the message sent from SGSN, if the target system decides using SGSN F-TEID for data forwarding.

F-TEID

4

SGW F-TEID for UL data forwarding

O

If available this SGW F-TEID may be included when indirect data forwarding with SGW change is applied, during the intra-EUTRAN HO.

F-TEID

5

NOTE: The Bearer Context IE for an SCEF PDN connection shall only contain the EPS Bearer ID IE.

7.3.3 Forward Relocation Complete Notification

A Forward Relocation Complete Notification message shall be sent to the source MME/SGSN/AMF to indicate the handover has been successfully finished.

Table 7.3.3-1 specifies the presence requirements and conditions of the IEs in the message.

Table 7.3.3-1: Information Elements in a Forward Relocation Complete Notification

Information elements

P

Condition / Comment

IE Type

Ins.

Indication Flags

C

This IE shall be included if any of the flags are set to 1.

  • Idle mode Signalling Reduction Activation Indication: This flag shall be set to 1 if the message is used for inter-RAT handover and the UE has ISR capability. This flag is set to indicate to the source MME/SGSN whether it shall maintain the UE’s context and whether it shall activate ISR.
  • Notify Source eNB Indication: This flag shall be set to 1 if the target MME receives this indication in the Handover Notify from the target eNodeB (see clause 5.5.1.2.2a of 3GPP TS 23.401 [3]).
  • Same IWK-SCEF Selected for Monitoring Event Indication: This flag shall be set to 1 to indicate that the same IWK-SCEF is selected for Monitoring Event by the target MME/SGSN. See NOTE.

Indication

0

Private Extension

O

Private Extension

VS

NOTE: If the same IWK-SCEF is selected by the target MME/SGSN, the source MME/SGSN shall not delete the Monitoring Event Configuration(s) on the IWK-SCEF.

7.3.4 Forward Relocation Complete Acknowledge

A Forward Relocation Complete Acknowledge message shall be sent as a response to Forward Relocation Complete Notification.

Table 7.3.4-1 specifies the presence requirements and conditions of the IEs in the message.

Possible Cause values are specified in Table 8.4-1.

Table 7.3.4-1: Information Elements in a Forward Relocation Complete Acknowledge

Information elements

P

Condition / Comment

IE Type

Ins.

Cause

M

Cause

0

Recovery

O

Recovery

0

Secondary RAT Usage Data Report

CO

If the PLMN has configured secondary RAT usage reporting, the MME shall include this IE on the S10 interface if it has received Secondary RAT usage data from the eNodeB in an S1-based handover with MME relocation.

Several IEs with the same type and instance value may be included, to represent multiple usage data reports.

Secondary RAT Usage Data Report

0

Private Extension

O

Private Extension

VS

7.3.5 Context Request

The new MME/SGSN shall send the Context Request message to the old MME/SGSN on S3/S16/S10 interface as a part of TAU/RAU procedure and UTRAN/GERAN to E-UTRAN/UTRAN (HSPA) SRVCC procedure to get the MM and EPS bearer Contexts for the UE.

NOTE 1: During UTRAN/GERAN to E-UTRAN/UTRAN (HSPA) SRVCC procedure as specified in 3GPP TS 23.216 [43], the GUTI, RAI IE, P-TMSI IE and P-TMSI Signature IE, are not received directly from the UE but from the MSC Server over Sv interface.

The new MME shall send the Context Request message to the old AMF on N26 interface as a part of an 5GS to EPS Idle mode Mobility using N26 interface procedure, to get the MM and EPS bearer Contexts for the UE.

The new AMF shall send the Context Request message to the old MME on N26 interface as a part of an EPS to 5GS Idle mode registration using N26 interface procedure, to get the MM and EPS bearer Contexts for the UE.

If the sending/new node is a MME, it shall include in the Context Request message:

– the GUTI IE and Complete TAU Request Message IE, if the GUTI or the indication of mapped or native GUTI received from UE indicates the old node is a MME, as specified in clause 2.8.2.2.2 and 2.10.2.1.2 of 3GPP TS 23.003 [2].

– the RAI IE and the P-TMSI IE, which are derived from the GUTI received from UE, and the P-TMSI Signature that was received intact from the UE, if the GUTI or the indication of mapped or native GUTI indicates the old node is an SGSN as specified in clause 2.8.2.2.2 of 3GPP TS 23.003 [2].

If the sending/new node is an SGSN, it shall include RAI IE, P-TMSI IE and P-TMSI Signature IE in the Context Request message. If the receiving/old node is an MME, it shall construct GUTI according to the RAI IE, P-TMSI IE and P-TMSI Signature IE (see the mapping relationship between RAI, P-TMSI, P-TMSI signature and GUTI defined in 3GPP TS 23.003 [2]), and find UE context via this GUTI.

If the sending/new node is an AMF, it shall include the GUTI IE, which is derived from the 5G-GUTI received from UE, and the Complete TAU Request Message IE in the Context Request message, if the AMF receives a mapped GUTI from the UE, that is indication that the old node is an MME, as specified in clause 2.10.2.2.2 of 3GPP TS 23.003 [2].

If the receiving/old node is an AMF, it shall construct 5G-GUTI from the GUTI IE (see the mapping relationship between GUTI and 5G-GUTI defined in 3GPP TS 23.003 [2]), and find UE context via this 5G-GUTI.

The new MME differentiates the type of the old node as specified in clause 2.8.2.2.2 of 3GPP TS 23.003 [2]. If the old node is an SGSN, the GUTI shall be mapped to RAI and P-TMSI by the new MME; if the old node is a MME, the new MME include GUTI IE and Complete TAU Request Message IE in the Context Request message. The Mapping between temporary and area identities is defined in 3GPP TS 23.003 [2].

The Target PLMN ID IE shall be used in old SGSN/MME in order to decide whether un-used authentication vectors to be distributed to new SGSN/MME/AMF or not. Distribution and use of authentication vectors between different serving network domains are specified in 3GPP TS 33.401 [12]. The AMF shall not transmit un-used authentication vectors to an MME and shall discard any un-used authentication vectors received from an MME, regardless of whether the MME and AMF pertain to the same or different serving network domains.

Table 7.3.5-1 specifies the presence requirements and conditions of the IEs in the message.

Table 7.3.5-1: Information Elements in a Context Request

Information elements

P

Condition / Comment

IE Type

Ins.

IMSI

C

IMSI shall be included if the UE has been successfully authenticated.

IMSI

0

GUTI

C

The new MME/AMF shall include this IE over S10/N26 interface.

GUTI

0

CO

This IE shall be included over S10 interface if available during UTRAN/GERAN to E-UTRAN/UTRAN (HSPA) SRVCC procedure as specified in 3GPP TS 23.216 [43].

Routeing Area Identity(RAI)

C

This IE shall be included over S3/S16 interface, if the GUTI or the indication of mapped or native GUTI indicates the old node is an SGSN, the new MME maps this IE from GUTI.

ULI (NOTE 4)

0

CO

This IE shall be included over S3/S16 interface if available during UTRAN/GERAN to E-UTRAN/UTRAN (HSPA) SRVCC procedure as specified in 3GPP TS 23.216 [43].

Packet TMSI(P-TMSI)

C

This IE shall be included over S3/S16 interface. For the S3 interface, if sent by the MME, this IE is derived by the MME from the GUTI received from the UE.

P-TMSI

0

CO

This IE shall be included over S3/S16 interface if available during UTRAN/GERAN to E-UTRAN/UTRAN (HSPA) SRVCC procedure as specified in 3GPP TS 23.216 [43].

P-TMSI Signature

C

This IE shall be included over S3/S16 interface if it is received from the UE.

P-TMSI Signature

0

CO

This IE shall be included over S3/S16 interface if available during UTRAN/GERAN to E-UTRAN/UTRAN (HSPA) SRVCC procedure as specified in 3GPP TS 23.216 [43].

Complete TAU request message

C

The new MME/AMF shall include this IE if available, and the old MME/AMF may use this IE for integrity check. See NOTE 3.

Complete Request Message

0

S3/S16/S10/N26 Address and TEID for Control Plane

C

This IE specifies the address and the TEID for control plane message which is chosen by the new MME/SGSN/AMF.

In case of SGSN pool, the IPv4 or the IPv6 address field shall be set to the same value of the Source IP address of the IP packet carrying this message, and the relaying SGSN shall not change the content of this IE when sending it to the old SGSN. See NOTE 1.

F-TEID

0

UDP Source Port Number

C

If an SGSN within the same SGSN pool as the old SGSN receives this message, the SGSN shall include the UDP Source Port number of the received message in this parameter if this IE is not present and relay the message to the old SGSN. The old SGSN shall use this UDP port as the UDP destination port of the Context Response message.

Port Number

0

RAT Type

C

The RAT Type indicates the Radio Access Technology which is used in the new system.

RAT Type

0

Indication

CO

This IE shall be included if any one of the applicable flags is set to 1.

Applicable Flags are:

– The MS Validated (MSV) flag, when set to 1, indicates that the new system has successfully authenticated the UE, or the new system has validated the integrity protection of the TAU request message. See NOTE 3.

– The ETHPDN flag, when set to 1, indicates that the target MME supports Ethernet PDN connection.

Indication

0

Hop Counter

O

If an SGSN within the same SGSN pool with the old SGSN receives this message, the SGSN shall decrement the Hop Counter if this IE is present in the received message; otherwise, the SGSN may include a Hop Counter with a value of max-1, and may relay the message to the old SGSN.

Hop Counter

0

Target PLMN ID

CO

If available, this IE shall be included in order to allow old MME/SGSN to make a judgment whether un-used authentication vectors to be distributed or not.

Serving Network

0

MME/S4-SGSN LDN

O

This IE is optionally sent by the MME/S4-SGSN to the peer MME/S4-SGSN on the S3/S10/S16 interfaces (see 3GPP TS 32.423 [44]), when communicating the LDN to the peer node for the first time.

Local Distinguished Name (LDN)

0

SGSN node name

CO

This IE shall be sent by the new SGSN on the S3 interface if both new SGSN and associated SGW support ISR. See NOTE 2.

FQDN

0

MME node name

CO

This IE shall be sent by the new MME on the S3 interface if both new MME and associated SGW support ISR. See NOTE 2.

FQDN

1

SGSN Number

O

This IE may be sent by the target S4-SGSN to the source MME/S4-SGSN as specified in 3GPP TS 23.271 [56].

Node Number

0

SGSN Identifier

O

This IE may be sent by the target S4-SGSN to the source MME/S4-SGSN as specified in 3GPP TS 23.271 [56].

Node Identifier

0

MME Identifier

O

This IE may be sent by the target MME to the source MME/S4-SGSN as specified in 3GPP TS 23.271 [56].

Node Identifier

1

CIoT Optimizations Support Indication

CO

This IE shall be sent by the new MME/SGSN on the S10/S3/S16/N26 interface if it supports at least one CIoT optimization.

This IE shall be sent by the new AMF on the N26 interface, with the AWOPDN bit set to 1 and, if Unstructured or Ethernet PDU session types are supported, with the SGNIPDN bit set to 1.

CIoT Optimizations Support Indication

0

Private Extension

O

Private Extension

VS

NOTE 1: The relaying SGSN shall forward the Context Request message to the interface of the old SGSN, where the interface type is matching what is indicated in the IE S3/S16/S10 Address and TEID for Control Plane.

NOTE 2: According to the 3GPP TS 23.401 [3], during an inter-RAT handover procedure for a UE with ISR activated, the source MME/SGSN should select the ISR associated CN node for this UE as the target CN node for the inter RAT HO when the ISR associated CN node can serve the target access. This parameter is exchanged when ISR is being activated and used in the source MME/SGSN for this decision upon subsequent inter-RAT handover.

NOTE 3: The Complete TAU request message IE is available except during UTRAN/GERAN to E-UTRAN/UTRAN (HSPA) SRVCC procedure as specified in 3GPP TS 23.216 [43]. In these procedures, the new MME shall set the Indication IE MSV (MS Validated) flag to 1.

NOTE 4: Only RAI field in the ULI IE type shall be present in the Routeing Area Identity (RAI) IE.

7.3.6 Context Response

A Context Response message shall be sent as a response to a previous Context Request message, in the scenarios identified in clause 7.3.5.

Possible Cause values are specified in Table 8.4-1. Message specific cause values are:

– "IMSI/IMEI not known"

– "P-TMSI Signature mismatch"

– "User authentication failed"

– "Target access restricted for the subscriber"

Based on the subscription profile, when the access to the target RAT is prohibited for the subscriber, the old MME/SGSN/AMF may reject the Context Request message with the cause "Target access restricted for the subscriber".

When the source MME/SGSN/AMF supports one or more of the CIoT optimization features as indicated through the CIoT Optimizations Support Indication IE specified in clause 8.125, and if the target node is a MME and the target MME has not set the AWOPDN bit of the CIoT Optimizations Support Indication IE set to 1 in the Context Request message as specified in clause 8.125, the source MME/SGSN/AMF shall reject the Context Request with a cause value of "Request Rejected" under the following conditions (conditions are mutually exclusive):

– If the UE is attached to the source MME/SGSN without any PDN connection through the SGW and PGW and without any SCEF PDN connection;

– if the UE is attached to the source MME/SGSN with only the PDN connection(s) of PDN type "non-IP", through the SGW and the PGW but the UE has not activated any SCEF PDN connection and the target MME/AMF has not set the SGNIPDN bit of the CIoT Optimizations Support Indication IE set to 1 in the Context Request message as specified in clause 8.125;

– if the UE is attached to the the source MME/SGSN with only the SCEF PDN connection(s) but the UE has not activated any PDN connection through the SGW and PGW and the target MME has not set the SCNIPDN bit of the CIoT Optimizations Support Indication IE set to 1 in the Context Request message as specified in clause 8.125;

– if the UE is attached to the source MME/SGSN with only PDN connection(s) of PDN type "non-IP", through the SGW and the PGW and at least one SCEF PDN connection and the target MME has neither set the SGNIPDN bit nor the SCNIPDN bit of the CIoT Optimizations Support Indication IE set to 1 in the Context Request message as specified in clause 8.125;

– if the UE is registered to the source AMF without any PDU session;

– if the UE is registered to the source AMF with only PDU session(s) of type "Unstructured" or "Ethernet", and the target MME has not set the SGNIPDN bit of the CIoT Optimizations Support Indication IE set to 1 in the Context Request message as specified in clause 8.125.

NOTE 2: Among the CIoT optimization features, only the support of SCEF Non-IP PDN connection and the support of SGi Non-IP PDN connection are applicable to a SGSN.

NOTE 3: 5GS supports Attach without PDU session. 5GS can also support Unstructured and Ethernet PDU session types, which are assimilated to "SGi Non-IP PDN connections" over N26 if Ethernet PDN connection type in EPC is not supported; otherwise, the Ethernet PDU session in 5GS can move to EPC seamlessly.

If the target node is a MME and the target MME has not set the ETHPDN bit in the Indication IE to 1 in the Context Request message as specified in clause 8.12, or the target node is a SGSN, the source MME shall reject the Context Request with a cause value of "Request Rejected" if the UE is attached to the source MME with only PDN connection(s) of PDN type "Ethernet".

Table 7.3.6-1 specifies the presence requirements and conditions of the IEs in the message.

Table 7.3.6-1: Information Elements in a Context Response

Information elements

P

Condition / Comment

IE Type

Ins.

Cause

M

Cause

0

IMSI

C

The IMSI shall be included in the message except for the case:

  • If the UE is emergency or RLOS attached and the UE is UICCless.

The IMSI shall be included in the message but not used as an identifier

  • if UE is emergency or RLOS attached but IMSI is not authenticated.

IMSI

0

MME/SGSN/AMF UE MM Context

C

This IE shall be included if the Cause IE has the value " Request Accepted ".

MM Context

0

MME/SGSN/AMF UE EPS PDN Connections

C

This IE shall be included if there is at least a PDN connection for this UE through the SGW and PGW on the sending MME/SGSN, or if there is at least a PDU session for this UE on the sending AMF.

If the target MME/SGSN/AMF has not set the SGNIPDN bit of the CIoT Optimizations Support Indication IE to 1 in the Context Request, then the source MME/SGSN/AMF shall only include PDN Connections of IP PDN type (if any).

Several IEs with this type and instance values shall be included as necessary to represent a list of PDN Connections.

PDN Connection

0

Sender F-TEID for Control Plane

C

This IE shall be included if the Cause IE has the value "Request Accepted".

F-TEID

0

SGW S11/S4 IP Address and TEID for Control Plane

C

This IE shall be included if a SGW is being used by the old MME/SGSN, except if:

  • the source and target MME/S4-SGSN support the MME/S4-SGSN triggered SGW restoration procedure, and the source MME/S4-SGSN has not performed the SGW relocation procedure after the source SGW has failed as specified in 3GPP TS 23.007 [17].
  • across the S16 interface if there is no active PDP context
  • across the S10/N26 interface if the UE does not have any PDN connection through the SGW and PGW.

This IE shall not be included by an old AMF.

F-TEID

1

SGW node name

C

This IE identifies the SGW that was used by the old MME/SGSN and it shall be included by the source MME/S4-SGSN with the following exceptions:

  • the source and target MME/S4-SGSN support the MME/S4-SGSN triggered SGW restoration procedure, and the source MME/S4-SGSN has not performed the SGW relocation procedure after the source SGW has failed as specified in 3GPP TS 23.007 [17].
  • across the S16 interface if there is no active PDP context
  • across the S10/N26 interface if the UE does not have any PDN connection through the SGW and PGW.

This IE shall not be included by an old AMF.

FQDN

0

Indication Flags

C

This IE shall be included if any of the flags are set to 1.

Idle mode Signalling Reduction Supported Indication:

  • This flag shall be set to 1 if the Cause IE value indicates "Request accepted" and the old system (including old MME/SGSN and the associated SGW) has the ISR capability.

Unauthenticated IMSI:

  • This flag shall be set to 1 if the IMSI present in the message is not authenticated and is for an emergency or RLOS attached UE.

Change Reporting support indication flag:

  • This flag shall be set to 1 if the Source S4-SGSN/MME supports Location Change Reporting mechanism. See NOTE 1. See NOTE 2.

CSG Change Reporting support indication flag:

  • This flag shall be set to 1 if the Source S4-SGSN/MME supports CSG Information Change Reporting mechanism. See NOTE 1. See NOTE 2.

ISRAU:

  • This flag shall be set to 1 on S10/S16 interface if the ISR is activated for the UE before the UE moving to the new SGSN/MME.

Management Based MDT allowed flag:

  • This flag shall be set to 1 for the inter-MME TAU procedure over the S10 interface, if Management Based Minimization of Drive Tests (MDT) is allowed. See 3GPP TS 36.413 [10] and 3GPP TS 32.422 [18].

SGW Restoration Needed Indication (SRNI):

  • This flag shall be set to 1 if both source and target MME/S4-SGSN support the MME/S4-SGSN triggered SGW restoration procedure and the source MME/S4-SGSN has not performed the SGW relocation procedure after the source SGW has failed as specified in 3GPP TS 23.007 [17].

CSFB Indication (CSFBI):

  • when configured to support the return to the last used PLMN after CSFB, the MME shall set this flag to 1 on the S3 interface if the UE has been subject to CSFB recently (see clause 4.3.2 of 3GPP TS 23.272 [21]). See NOTE 4.

Buffered DL Data Waiting Indication (BDWI):

  • This flag shall be set to 1 on the S3/S10/S16/N26 interface, during TAU/RAU with or without SGW change procedures or during Idle mode mobility between 5GS and EPS with data forwarding, when it is required to forward to the UE DL data buffered in the (old) SGW or (V-)SMF/UPF, i.e. when the DL Data Buffer Expiration Time has not expired yet in the old MME/SGSN/(V-)SMF, as specified in clause 4.3.17.7 of 3GPP TS 23.401 [3] and in clauses 4.11.1.3.2A, 4.11.1.3.3A, 4.23.12.2a and 4.23.12.3a of 3GPP TS 23.502 [83].

Pending MT Short Message Indication (PMTSMI):

  • This flag shall be set to 1 on the S10/S16/S3 interface if the source S4-SGSN/MME knows that there is one (or more) pending MT Short Message(s) in the SMS-GMSC for the UE as specified in clause 10.1 of 3GPP TS 23.040 [75], Figure 17c).

LTE-M UE Indication (LTEMUI):

  • This flag shall be set to 1 if the MME/AMF knows that the UE is an LTE-M UE.
  • Return Preferred Indication: the MME or the AMF may set this flag to 1 on the N26 interface to indicate a preferred return of the UE to the last used EPS or 5GS PLMN (respectively) at a later access change to an EPS or 5GS shared network. See NOTE 4.

Indication

0

Trace Information

C

This IE shall be included over S10/S16/S3 when session trace is active for this IMSI/IMEI.

Trace Information

0

HRPD access node S101 IP address

C

This IE shall be included only if the HRPD pre registration was performed at the old MME

IP-Address

0

1xIWS S102 IP address

C

This IE shall be included only if the 1xRTT CS fallback pre registration was performed at the old MME

IP-Address

1

Subscribed RFSP Index

CO

This IE shall be included by the MME/SGSN/AMF, if received from the HSS or UDM.

RFSP Index

0

RFSP Index in Use

CO

This IE shall be included by the MME/SGSN/AMF, if it supports the feature.

RFSP Index

1

UE Time Zone

CO

When available, this IE shall be included by the source MME/S4-SGSN/AMF.

UE Time Zone

0

MME/S4-SGSN LDN

O

This IE is optionally sent by the MME/S4-SGSN to the peer MME/S4-SGSN on the S3/S10/S16 interfaces (see 3GPP TS 32.423 [44]), when communicating the LDN to the peer node for the first time.

Local Distinguished Name (LDN)

0

MDT Configuration

CO

This IE shall be sent by the source MME to the target MME on the S10 interface for inter-MME TAU procedure, if the Job Type indicates Immediate MDT. See 3GPP TS 32.422 [18] clause 4.4.

MDT Configuration

0

SGSN node name

CO

This IE shall be sent by the old SGSN on the S3 interface if both old SGSN and associated SGW support ISR. See NOTE 3.

FQDN

1

MME node name

CO

This IE shall be sent by the old MME on the S3 interface if both old MME and associated SGW support ISR. See NOTE 3.

FQDN

2

User CSG Information (UCI)

CO

This IE shall be sent by the source MME/S4-SGSN on the S3/S10/S16 interfaces if the source MME/SGSN has reported to the PGW that the UE is in a CSG or hybrid cell. It shall then contain the last User CSG information that the source MME/S4-SGSN has reported to the PGW.

The absence of this IE indicates that the UE has not been reported to the PGW as being in a CSG or hybrid cell.

See NOTE 5.

UCI

0

Monitoring Event Information

CO

This IE shall be sent by the source MME/S4-SGSN on the S3/S10/S16 interfaces if monitoring events are to be continued in the target MME/S4-SGSN.

More than one IE with this type and instance values may be included to represent multiple monitoring events.

Monitoring Event Information

0

Monitoring Event Extension Information

CO

This IE shall be sent by the source MME/S4-SGSN on the S3/S10/S16 interfaces if monitoring event extensions are to be sent to the target MME/S4-SGSN.

More than one IE with this type and instance values may be included to represent multiple monitoring event extensions.

Monitoring Event Extension Information

0

UE Usage Type

CO

This IE shall be set to the subscribed UE Usage Type, if received from the HSS, and sent by the old MME/SGSN on the S3/S10/S16 interfaces if the old MME/SGSN supports the Dedicated Core Networks feature specified in TS 23.401 [3].

This IE shall be set to the subscribed UE Usage Type, if received from the UDM, and sent by the old AMF on the N26 interface.

If the UE Usage Type is not available in the old MME/SGSN/AMF, the length field of this IE shall be set to 0.

See NOTE 6.

Integer Number

0

MME/SGSN UE SCEF PDN Connections

C

This IE shall be included if there is at least one SCEF PDN connection for this UE at the source MME/SGSN and if the target MME/SGSN has set the SCNIPDN bit of the CIoT Optimizations Support Indication IE to 1 in the Context Request as specified in clause 8.125.

Several IEs with this type and instance values shall be included as necessary to represent a list of SCEF PDN Connections.

SCEF PDN Connection

0

RAT Type

CO

This IE shall be included by the source MME, SGSN or AMF on the S10, S16, S3 and N26 interface to indicate the old RAT type where the UE was camping. See NOTE 7.

RAT Type

0

Serving PLMN Rate Control

CO

This IE shall be included by the old MME on the S10 interface if such Serving PLMN Rate control was enabled when there is at least one SGi or SCEF PDN connection with the Control Plane Only Indication set. See NOTE 8.

Serving PLMN Rate Control

0

MO Exception Data Counter

CO

This IE shall be included on the S10 interfaces if the source MME has not yet reported a non-zero MO Exception Data Counter to the PGW. The timestamp in the counter shall be set with the time at which the counter value increased from 0 to 1.

Counter

0

Remaining Running Service Gap Timer

CO

This IE shall be included on the S10 interface if the source MME has started a Service Gap Timer which has not expired yet, as specified in clauses 5.3.3.1 and 5.3.3.2 in 3GPP TS 23.401 [3].

The value of the IE indicates the remaining time before the Service Gap Timer expires in number of seconds. See NOTE 9.

Integer Number

1

Extended Trace Information

C

This IE shall be included over N26 when session trace is active for this user.

Extended Trace Information

0

Subscribed Additional RRM Policy Index

CO

This IE shall be included by the MME over the S10 interface if received from the HSS.

Additional RRM Policy Index

0

Additional RRM Policy Index in Use

CO

This IE shall be included by the MME over the S10 interface if the feature is supported by the MME.

Additional RRM Policy Index

1

IWK SCEF ID for Monitoring Event

CO

This IE shall be included on the S3/S10 interface if the source MME/SGSN has selected the IWK-SCEF to relay Monitoring Events.

Node Identifier

0

Private Extension

O

Private Extension

VS

NOTE 1: 3GPP TS 23.401 [3] (e.g. clause 5.3.2.1) and 3GPP TS 23.060 [35] (e.g. clause 9.2.2.1) defines the MME/SGSN shall send the MS Info Change Reporting Support Indication to the PGW. In such case MME/SGSN shall use the Change Reporting Support Indication and/or CSG Change Reporting Support Indication (whichever is applicable), even if stage 2 refers to MS Info Change Reporting Support Indication.

NOTE 2: The receiver shall ignore the per UE Change Reporting Support Indication and CSG Change Reporting Support Indication flags, as included within the Indication Flags IE above, if these flags are included per PDN connection i.e. within the Indication Flags IE of the MME/SGSN UE EPS PDN Connections IE.

NOTE 3: According to the 3GPP TS 23.401 [3], during an inter-RAT handover procedure for a UE with ISR activated, the source MME/SGSN should select the ISR associated CN node for this UE as the target CN node for the inter RAT HO when the ISR associated CN node can serve the target access. This parameter is exchanged when ISR is being activated and used in the source MME/SGSN for this decision upon subsequent inter-RAT handover.

NOTE 4: If the SGSN needs to include the last used LTE PLMN ID in the Equivalent PLMN list it sends to the UE (see 3GPP TS 23.272 [21]), the SGSN shall derive the last used LTE PLMN ID from the Old RAI IE received in the RAU request message. If an MME or AMF needs to store the last used 5GS or EPS PLMN ID (respectively), the MME shall derive the last used 5GS PLMN ID from the Old GUTI received in the TAU request message, the AMF shall derive the last used EPS PLMN ID from the 5GS mobile identity received in Registration request message.

NOTE 5: In shared networks, when the message is sent from the VPLMN to the HPLMN, the PLMN ID that is communicated in this IE shall be that of the selected Core Network Operator for supporting UEs, or that of the allocated Core Network Operator for non-supporting UEs. As an exception, based on inter-operator roaming/sharing agreement, if the information on whether the UE is a supporting or non-supporting UE is available, the PLMN ID that is communicated to the HPLMN for non-supporting UEs shall be the Common PLMN ID.
In shared networks, when the MME/S4-SGSN and PGW pertain to the same PLMN, the Primary PLMN ID shall be communicated in the ECGI to the PGW, and the Common PLMN ID shall be communicated in SAI/CGI to the PGW, for both supporting and non-supporting UEs. The Core Network Operator PLMN ID (selected by the UE for supporting UEs or allocated by the network for non-supporting UEs) shall be communicated in the TAI, RAI, UCI and the Serving Network.
See clause 4.4 of 3GPP TS 23.251 [55].

NOTE 6: A UE Usage Type IE with the length field equal to 0 is used for the receiver to differentiate the case where the sender does not support the Dedicated Core Network feature from the case where the sender supports the Dedicated Core Network feature but no UE Usage type was received in UE’s subscription.

NOTE 7: The old RAT shall be used by the target MME/SGSN to determine if the RAT type has changed and, if so, to decide whether to maintain or deactivate the PDN connections of the UE based on the PDN-Connection-Continuity subscription parameter and operator policy, as specified in 3GPP TS 23.401 [3] and 3GPP TS 23.060 [35]. A target MME shall consider that the RAT type has changed if the target RAT is NB-IoT and a source MME (complying with an earlier version of the specification) does not include the RAT Type IE in the Context Response.

NOTE 8: The target MME may compare the value of the Serving PLMN Rate Control received in the Context Response message with the one configured locally, to determine if such parameter needs to be updated towards the SCEF and/or PGW.

NOTE 9: If the serving MME has changed after the TAU procedure, the target MME shall start Service Gap timer and should use a value that is slightly shorter than the value received in this IE.

Table 7.3.6-2: MME/SGSN/AMF UE EPS PDN Connections within Context Response

Octet 1

PDN Connection IE Type = 109 (decimal)

Octets 2 and 3

Length = n

Octet 4

Spare and Instance fields

Information elements

P

Condition / Comment

IE Type

Ins.

APN

M

APN

0

APN Restriction

C

This IE denotes the restriction on the combination of types of APN for the APN associated with this EPS bearer Context. The target MME or SGSN determines the Maximum APN Restriction using the APN Restriction.

If available, the source MME/S4 SGSN shall include this IE.

APN Restriction

0

Selection Mode

CO

When available, this IE shall be included by the source MME/S4-SGSN/AMF.

Selection Mode

0

IPv4 Address

C

This IE shall not be included if no IPv4 Address is assigned. See NOTE 1. See NOTE 5.

IP Address

0

IPv6 Address

C

This IE shall not be included if no IPv6 Address is assigned. See NOTE 5.

IP Address

1

Linked EPS Bearer ID

M

This IE identifies the default bearer of the PDN Connection.

EBI

0

PGW S5/S8 IP Address for Control Plane or PMIP

M

This IE shall include the TEID in the GTP based S5/S8 case and the uplink GRE key in the PMIP based S5/S8 case.

See NOTE 3.

F-TEID

0

PGW node name

C

This IE shall be included if the source MME, SGSN or AMF has the PGW FQDN.

FQDN

0

CO

This IE shall be included by the source MME over the N26 interface. See NOTE 6.

Bearer Contexts

M

Several IEs with this type and instance values may be included as necessary to represent a list of Bearers.

Bearer Context

0

Aggregate Maximum Bit Rate (APN-AMBR)

M

AMBR

0

Charging characteristics

C

This IE shall be present if charging characteristics was supplied by the HSS to the MME/SGSN, or by the UDM to the SMF, as a part of subscription information.

Charging characteristics

0

Change Reporting Action

C

This IE shall be included whenever available at the source MME/SGSN. See NOTE 4.

Change Reporting Action

0

CSG Information Reporting Action

CO

This IE shall be included whenever available at the source MME/SGSN.

CSG Information Reporting Action

0

H(e)NB Information Reporting

CO

This IE shall be included whenever available at the source MME/SGSN.

H(e)NB Information Reporting

0

Indication flags

CO

This IE shall be included if any one of the applicable flags is set to 1.

Applicable flags:

  • Subscribed QoS Change Indication: This flag shall be set to 1 if the subscribed QoS profile of the related PDN connection has changed in the old MME/SGSN when the UE is in ECM-IDLE state and ISR is activated.
  • Change Reporting support indication flag: This flag shall be set to 1 if the source S4-SGSN/MME supports Location Change Reporting mechanism and if the S4-SGSN/MME has indicated the support for the Location Change Reporting mechanism to the PGW, during the session establishment and/or modification procedures. See NOTE 2.
  • CSG Change Reporting Support Indication flag: This flag shall be set to 1 if the Source S4-SGSN/MME supports CSG Information Change Reporting mechanism and if the S4-SGSN/MME has indicated the support for the CSG Information Change Reporting to the PGW, during the session establishment and/or modification procedures. See NOTE 2.
  • Pending Subscription Change Indication flag: This flag shall be set to 1 if the source MME has received Subscribed QoS profile updates for QCI/ARP/APN-AMBR from the HSS but has deferred the reporting of these updates to the PGW/PCRF because the UE was not reachable.
  • Pending Network Initiated PDN Connection Signalling Indication flag: This flag shall be set to 1 by the source MME/SGSN if there is pending network initiated signalling for the PDN connection.
  • Delay Tolerant Connection Indication flag: This flag shall be set to 1 interface by the source MME/SGSN if the PGW indicated that this PDN Connection is delay tolerant.
  • Extended PCO Support Indication flag: This flag shall be set to 1 on S10/N26 interface by the source MME if the UE and the source MME support Extended PCO. It shall be set to 1 on the N26 interface during a 5GS to EPS Idle mode mobility.
  • Control Plane Only PDN Connection Indication: This flag shall be set to 1 if the PDN Connection is set to Control Plane Only.
  • NO 5GS N26 mobility Indication flag: This flag shall be set to 1 on S10 interface if the PDN connection cannot be moved to 5GS via N26.

Indication

0

Signalling Priority Indication

CO

The source SGSN/MME shall include this IE if the UE indicated low access priority when establishing the PDN connection.

Signalling Priority Indication

0

Change to Report Flags

CO

This IE shall be included by the MME/SGSN if any one of the applicable flags is set to 1.

Applicable flags:

  • Serving Network Change to Report: This flag shall be set to 1 if the source MME/SGSN has detected a Serving Network change during a TAU/RAU procedure without MME/SGSN change but has not yet reported this change to the PGW.
  • Time Zone Change to Report: This flag shall be set to 1 if the source MME/SGSN has detected a UE Time Zone change during a TAU/RAU procedure without MME/SGSN change but has not yet reported this change to the PGW.

Change To Report Flags

0

Local Home Network ID

CO

This IE shall be sent over the S3/S10/S16 interface if SIPTO at the Local Network is active for the PDN connection in the SIPTO at the Local Network architecture with stand-alone GW.

FQDN

1

Presence Reporting Area Action

CO

This IE shall be included if the PGW requested the source MME/SGSN to report changes of UE presence in a Presence Reporting Area. The source MME/SGSN shall include the Presence Reporting Area Identifier and, if received from the PGW, the list of the Presence Reporting Area elements.

Several IEs with the same type and instance value may be included as necessary to represent a list of Presence Reporting Area Actions. One IE shall be included for each Presence Reporting Area.

Presence Reporting Area Action

0

WLAN Offloadability Indication

CO

If the MME/SGSN supports WLAN/3GPP Radio Interworking with RAN rules then this IE shall be included on S3/S10/S16 if the UE has been authorized to perform WLAN offload for at least one RAT.

WLAN Offloadability Indication

0

Remote UE Context Connected

CO

The source MME shall include this IE on the S10 interface during an inter MME mobility procedure if such information is available.

Several IEs with the same type and instance value may be included as necessary to represent a list of remote UEs connected.

Remote UE Context

0

PDN Type

CO

The source MME/SGSN/AMF shall include this IE on the S10/S3/S16/N26 interface, for a Non-IP or Ethernet PDN Connection, during an inter MME/SGSN/AMF mobility procedure if the new MME/SGSN/AMF supports non-IP or Ethernet PDN connection using SGi as indicated in the Context Request message.

PDN Type

0

Header Compression Configuration

CO

This IE shall be sent over the S10 interface if the use of IP Header Compression for Control Plane CIoT EPS optimisations has been negotiated with the UE and the target MME has set the IHCSI bit of the CIoT Optimizations Support Indication IE to 1 in the Context Request as specified in clause 8.125.

Header Compression Configuration

0

NOTE 1: For deferred IPv4 address allocation, if the MME/S4-SGSN receives the PDN address "0.0.0.0" from PGW during "eUTRAN Initial Attach", "PDP Context Activation", "UE requested PDN Connectivity", then the MME/S4-SGSN shall include this IPv4 address "0.0.0.0".

NOTE 2: 3GPP TS 23.401 [3] (e.g. clause 5.3.2.1) and 3GPP TS 23.060 [35] (e.g. clause 9.2.2.1) defines the MME/SGSN shall send the MS Info Change Reporting Support Indication to the PGW. In such case MME/SGSN shall use the Change Reporting Support Indication and/or CSG Change Reporting Support Indication (whichever is applicable), even if stage 2 refers to MS Info Change Reporting Support Indication.

NOTE 3: For PMIP based S5/S8, the ‘PGW S5/S8 IP Address and TEID for user plane’ IE and the ‘PGW S5/S8 IP Address for Control Plane or PMIP’ IE shall contain the same uplink GRE key; the Interface Type in these IEs shall be set to the value 9 (S5/S8 PGW PMIPv6 interface).

NOTE 4: The target MME (respectively S4-SGSN) shall ignore this IE if it is received from an S4-SGSN (respectively an MME), i.e. over the S3 interface. In this case, the target serving node shall consider that no ULI change reporting is requested by the PGW for the target RAT, and the PGW shall request the target serving node to start ULI change reporting for the target RAT if so desired.

NOTE 5: For Non-IP or Ethernet PDN connections, neither an IPv4 address nor an IPv6 address shall be present.

NOTE 6: The PGW Node Name is used by the target AMF in the NF Service Discovery procedure to find the combined PGW-C/SMF for the PDU Session during an MME to AMF mobility procedure.

The Bearer Context shall be coded as depicted in Table 7.3.6-3.

Table 7.3.6-3: Bearer Context within MME/SGSN/AMF UE EPS PDN Connections within Context Response

Octet 1

Bearer Context IE Type = 93

Octets 2 and 3

Length = n

Octet 4

Sparae and Instance fields

Information elements

P

Condition / Comment

IE Type

Ins.

EPS Bearer ID

M

See NOTE 4.

EBI

0

TFT

C

This IE shall be present if a TFT is defined for this bearer.

Bearer TFT

0

SGW S1/S4/S12/S11 IP Address and TEID for user plane

C

The IE shall be present except if:

  • the source and target MME/S4-SGSN support the MME/S4-SGSN triggered SGW restoration procedure, and the source MME/S4-SGSN has not performed the SGW relocation procedure after the SGW has failed as specified in 3GPP TS 23.007 [17].

Over the N26 interface, the SMF (on behalf of the source AMF) shall set the IP address and TEID to the following values:

– any reserved TEID (e.g. all 0’s, or all 1’s);

– IPv4 address set to 0.0.0.0, or IPv6 Prefix Length and IPv6 prefix and Interface Identifier all set to zero.

See NOTE 2, NOTE3 and NOTE 5.

F-TEID

0

PGW S5/S8 IP Address and TEID for user plane

C

This IE shall be included for GTP based S5/S8.

F-TEID

1

CO

For PMIP-based S5/S8, this IE shall be included if the PGW provided an alternate address for user plane, i.e. an IP address for user plane which is different from the IP address for control plane.

When present, this IE shall contain the alternate IP address for user plane and the uplink GRE key.

See NOTE 1.

Bearer Level QoS

M

Bearer QoS

0

BSS Container

CO

The MME/S4 SGSN shall include the Packet Flow ID, Radio Priority, SAPI, PS Handover XID parameters in the TAU/RAU/Handover procedure, if available. The Container Type shall be set to 2.

F-Container

0

Transaction Identifier

C

This IE shall be sent over S3/S10/S16 if the UE supports A/Gb and/or Iu mode.

TI

0

SGW S11 IP Address and TEID for user plane

CO

This IE shall be present if available. See NOTE 3.

F-TEID

2

NOTE 1: For PMIP based S5/S8, the ‘PGW S5/S8 IP Address and TEID for user plane’ IE and the ‘PGW S5/S8 IP Address for Control Plane or PMIP’ IE shall contain the same uplink GRE key; the Interface Type in these IEs shall be set to the value 9 (S5/S8 PGW PMIPv6 interface).

NOTE 2: The MME shall set the interface type in this IE to 1, i.e "S1-U SGW GTP-U interface", for S1-U and S11-U bearers. This is done for backwards compatibility reasons, when the target serving node does not support CIoT optimizations.

NOTE 3: When separate IP address spaces are used for S1-U and S11-U, the MME shall include both S1-U SGW F-TEID in the SGW S1/S4/S12/S11 IP Address and TEID for user plane IE and S11-U SGW F-TEID in SGW S11 IP Address and TEID for user plane, when they are available; otherwise, the source MME shall include the SGW S1/S4/S12/S11 IP Address and TEID for user plane IE, since S1-U and S11-U SGW F-TEID are the same.

NOTE 4: The support of the 15 EPS Bearers shall be homogeneously supported within an MME Pool / SGW serving area. A source MME which supports the 15 EPS Bearers, shall know whether the target MME pool also supports that by local configuration. When the target MME is known to not support the 15 EPS Bearers, the source MME shall only transfer up to 8 EPS bearer contexts with the EBI value set between ‘5’ and ’15’ to the target MME and shall delete EPS bearer(s) which are not transferred, and if the default bearer is to be deleted, the corresponding PDN connection(s) shall be deleted by the source MME.

NOTE 5: During 5GS to EPS mobility procedures with N26 interface, the source AMF shall transparently transfer the MME/SGSN/AMF UE EPS PDN Connections IE received from the SMF as specified in clause 6.1.6.2.27 of 3GPP TS 29.502[88].

Table 7.3.6-4: Remote UE Context Connected within MME/SGSN UE EPS PDN Connections within Context Response

Octets 1

Remote UE Context IE Type = 191 (decimal)

Octets 2 and 3

Length = n

Octets 4

Spare and Instance fields

Information elements

P

Condition / Comment

IE Type

Ins.

Remote User ID

M

See clause 8.123 for the description and use of this parameter

Remote User ID

0

Remote UE IP Information

M

See clause 8.124 for the description and use of this parameter

Remote UE IP Information

0

Table 7.3.6-5: MME/SGSN UE SCEF PDN Connections within Context Response

Octets 1

SCEF PDN Connection IE Type = x (decimal)

Octets 2 and 3

Length = n

Octets 4

Spare and Instance fields

Information elements

P

Condition / Comment

IE Type

Ins.

APN

M

APN

0

Default EPS Bearer ID

M

This IE identifies the default bearer of the SCEF PDN Connection.

EBI

0

SCEF ID

M

This IE shall include the SCEF Identifier and the SCEF Realm for the APN.

Node Identifier

0

7.3.7 Context Acknowledge

A Context Acknowledge message shall be sent as a response to a previous Context Response message, only if the previous Context Response message is received with the acceptance cause.

Possible cause values are specified in Table 8.4-1. Message specific cause values are:

– "User authentication failed".

– "Relocation failure due to NAS message redirection".

– "Denied in RAT".

Upon receiving cause value other than the request was accepted, the old MME/S4-SGSN shall continue as if the Context Request was never received.

Table 7.3.7-1 specifies the presence requirements and conditions of the IEs in the message.

Table 7.3.7-1: Information Elements in a Context Acknowledge

Information elements

P

Condition / Comment

IE Type

Ins.

Cause

M

Cause

0

Indication flags

C

This IE shall be included if any one of the applicable flags is set to 1.

Applicable Flags are:

  • SGW Change Indication: This flag shall be set to 1 on the S3/S10/S16 interfaces if a new SGW has been selected. The old MME/old SGSN marks in its context that the information in the GWs and the HSS are invalid.
    This flag shall also be set to 1 by the new AMF/new MME during the Idle mode Mobility between 5GS and EPS using N26 interface.
  • Idle mode Signalling Reduction Activation Indication: If set to 1, this flag indicates to the old system that it shall maintain the UE’s contexts. This flag shall be set to 1 on the S3 interface if the Cause IE value indicates "Request accepted" and ISR is activated as specified in 3GPP TS 23.401 [3].
  • Same IWK-SCEF Selected for Monitoring Event Indication: This flag shall be set to 1 to indicate that the same IWK-SCEF is selected for Monitoring Event by the target MME/SGSN.

See NOTE 1, NOTE 2.

Indication

0

Forwarding F-TEID

CO

This IE shall be included if only one bearer context was transferred in the Context Response message and data forwarding of DL data buffered in the old SGW or (V-)SMF/UPF is required, i.e. when the BDWI flag is set in the Context Response message and

– the SGW is changed, during TAU/RAU procedure with SGW change and data forwarding as specified in clause 5.3.3.1A of 3GPP TS 23.401 [3]; or

– upon idle mode mobility between EPS and 5GS with data forwarding, as specified in clauses 4.11.1.3.2A, 4.11.1.3.3A, 4.23.12.2a and 4.23.12.3a of 3GPP TS 23.502 [83].

The interface type of the Forwarding F-TEID should be set to either:

  • 23 ("SGW/UPF GTP-U interface for DL data forwarding") for indirect forwarding,
  • 0 (" S1-U eNodeB GTP-U interface") or 3 ("S12 RNC GTP-U interface"), if the eNB or RNC supports such forwarding, or
  • 15 ("S4 SGSN GTP-U interface").

F-TEID

0

Bearer Contexts

CO

This IE shall be included if multiple bearer contexts were transferred in the Context Response message and data forwarding of DL data buffered in the old SGW or (V-)SMF/UPF is required, i.e. when the BDWI flag is set in the Context Response message and

– the SGW is changed, during TAU/RAU procedure with SGW change and data forwarding as specified in the clause 5.3.3.1A of 3GPP TS 23.401 [3]; or

– upon idle mode mobility between EPS and 5GS, as specified in clauses 4.11.1.3.2A, 4.11.1.3.3A, 4.23.12.2a and 4.23.12.3a of 3GPP TS 23.502 [83].

Several IEs with this type and instance value may be included as necessary to represent a list of Bearers.

Bearer Context

0

SGSN Number

CO

This IE shall be included on the S16/S3 interface if the PMTSMI flag in the Context Response message is set to 1.

Node Number

0

MME number for MT SMS

CO

This IE shall be included on the S10/S3 interface if the PMTSMI flag in the Context Response message is set to 1.

Node Number

1

SGSN Identifier for MT SMS

CO

This IE shall be included on the S16/S3 interface if the target S4-SGSN supports the Gdd reference point and if the PMTSMI flag in the Context Response message is set to 1.

Node Identifier

0

MME Identifier for MT SMS

CO

This IE shall be included on the S10/S3 interface if the target MME supports the SGd reference point and if the PMTSMI flag in the Context Response message is set to 1.

Node Identifier

1

Private Extension

O

Private Extension

VS

NOTE 1: For the Indication Flags, the combination (SGW Change Indication, Idle mode signalling Activation Indication) = 1,1 shall be considered as an error if received.

NOTE 2: If the same IWK-SCEF is selected by the target MME/SGSN, the source MME/SGSN shall not delete the Monitoring Event Configuration(s) on the IWK-SCEF.

Table 7.3.7-2: Bearer Context within Context Acknowledge

Octet 1

Bearer Context IE Type = 93 (decimal)

Octets 2 and 3

Length = n

Octet 4

Spare and Instance fields

Information elements

P

Condition / Comment

IE Type

Ins.

EPS Bearer ID

M

EBI

0

Forwarding F-TEID

M

The interface type of the Forwarding F-TEID should be set to either:

  • 23 ("SGW/UPF GTP-U interface for DL data forwarding") for indirect forwarding,
  • 0 (" S1-U eNodeB GTP-U interface") or 3 ("S12 RNC GTP-U interface"), if the eNB or RNC supports such forwarding, or
  • 15 ("S4 SGSN GTP-U interface").

F-TEID

0

7.3.8 Identification Request

If the UE identifies itself with temporary identity and it has changed SGSN/MME since detach in Attach procedure, the new MME/SGSN shall send an Identification Request message to the old SGSN/MME/AMF over S3, S16, S10 or N26 interface to request IMSI. A new AMF may also send an Identification Request message to the old MME over the N26 interface, during a registration procedure (see clause 4.11.5.2 of 3GPP TS 23.502 [83]).

Table 7.3.8-1 specifies the presence requirements and conditions of the IEs in the message.

If the sending/new node is an MME, it shall include in the Identification Request message:

– the GUTI IE and Complete Attach Request Message IE, if the GUTI or the indication of mapped or native GUTI received from UE indicates the old node is a MME, as specified in clause 2.8.2.2.2 of 3GPP TS 23.003 [2].

– the RAI P-TMSI, which was derived from the GUTI received from UE, and the P-TMSI Signature that was received intact from the UE, if the GUTI or the indication of mapped or native GUTI indicates the old node is an SGSN as specified in clause 2.8.2.2.2 of 3GPP TS 23.003 [2].

If the sending/new node is an SGSN, it shall include RAI IE, P-TMSI IE and P-TMSI Signature IE in the Identification Request message. If the receiving/old node is an MME, it shall construct GUTI according to the RAI IE, P-TMSI IE and P-TMSI Signature IE (see the mapping relationship between RAI, P-TMSI, P-TMSI signature and GUTI defined in 3GPP TS23.003[2]), and find UE context via this GUTI.

If the sending/new node is an AMF, it shall include the GUTI IE and Complete Attach Request Message IE in the Identification Request message. The AMF shall construct the GUTI IE from the old 5G-GUTI received from the UE (mapped from the EPS GUTI by the UE), as specified in clause 2.10.2.2.3 of 3GPP TS 23.003 [2].

The new MME differentiates the type of the old node as specified in clause 2.8.2.2.2 of 3GPP TS 23.003 [2]. If the old node is an SGSN, the GUTI shall be mapped to RAI and P-TMSI by the new MME; if the old node is a MME, the new MME include GUTI IE and Complete Attach Request Message IE in the Identification Request message. The Mapping between temporary and area identities is defined in 3GPP TS 23.003 [2].

The GUTI IE shall not coexist with any of the RAI IE, P-TMSI IE and P-TMSI Signature IE in an Identification Request message. If this occurs, the receiving node shall return a corresponding cause value in the response message.

The Target PLMN ID IE shall be used in old SGSN/MME in order to decide whether un-used authentication vectors to be distributed to new SGSN/MME or not. Distribution and use of authentication vectors between different serving network domains are specified in 3GPP TS 33.401 [12].

If the receiving/old node is an AMF, it shall construct the 5G-GUTI from the GUTI IE (see the mapping relationship between GUTI and 5G-GUTI defined in clause 2.10 of 3GPP TS 23.003 [2]), and find UE context via this 5G-GUTI.

Table 7.3.8-1: Information Elements in an Identification Request

Information elements

P

Condition / Comment

IE Type

Ins.

GUTI

C

The new MME/AMF shall include this IE over the S10 and N26 interfaces.

GUTI

0

Routeing Area Identity(RAI)

C

This IE shall be included over S3/S16 interface, if the GUTI or the indication of mapped or native GUTI received from the UE indicates the old node is an SGSN, the new MME maps this IE from GUTI.

ULI (NOTE 1)

0

Packet TMSI(P-TMSI)

C

This IE shall be included over S3/S16 interface. For the S3 interface, if sent by the MME, this IE is derived by the MME from the GUTI received from the UE.

P-TMSI

0

P-TMSI Signature

C

This IE shall be included over S3/S16 interface, if it is received from the UE.

P-TMSI Signature

0

Complete Attach Request Message

C

The new MME/AMF shall include this IE over the S10 and N26 interfaces, and the old MME/AMF may use this IE for integrity check.

Complete Request Message

0

Address for Control Plane

O

If an SGSN within the same SGSN pool with the old SGSN receives this message, the SGSN shall include the old IP address of the received message in this optional parameter if this IE is not present and relay the message to the old SGSN.

IP Address

0

UDP Source Port Number

C

If an SGSN within the same SGSN pool as the old SGSN receives this message, the SGSN shall include the UDP Source Port number of the received message in this parameter if this IE is not present and relay the message to the old SGSN. The old SGSN shall use this UDP port as the UDP destination port of the Identification Response message.

Port Number

0

Hop Counter

O

If an SGSN within the same SGSN pool with the old SGSN receives this message, the SGSN shall decrement the Hop Counter if this IE is present in the received message; otherwise, the SGSN may include a Hop Counter with a value of max-1, and may relay the message to the old SGSN.

Hop Counter

0

Target PLMN ID

CO

If available, this IE shall be included in order to allow old MME/SGSN/AMF to make a judgment whether un-used authentication vectors to be distributed or not.

Serving Network

0

Private Extension

O

None

Private Extension

VS

NOTE 1: Only RAI field in the ULI IE type shall be present in the Routeing Area Identity (RAI) IE.

7.3.9 Identification Response

The old SGSN/MME/AMF shall send an Identification Response message to the new MME/SGSN/AMF as a response to a previous Identification Request message over S3/S10/S16/N26 interface.

Table 7.3.9-1 specifies the presence requirements and conditions of the IEs in the message.

For Intra Domain Connection of RAN Nodes to Multiple CN Nodes, if an old SGSN within an SGSN pool receives an Identification Request message that contains the optional parameter Address for Control Plane, the old SGSN shall use this address as destination IP address of the Identification Response message.

Possible Cause values are specified in Table 8.4-1. Message specific cause values are:

  • "P-TMSI Signature mismatch"
  • "User authentication failed"

Only the Cause information element shall be included in the response if the Cause contains another value than "Request accepted".

Table 7.3.9-1: Information Elements in an Identification Response

Information elements

P

Condition / Comment

IE Type

Ins.

Cause

M

Cause

0

IMSI

C

This IE shall be included if the Cause contains the value "Request accepted".

IMSI

0

MME/SGSN UE MM Context

C

This IE shall be included if the integrity check or the P-TMSI signature check for the Attach Request succeeds.

MM Context

0

Trace Information

CO

This IE shall be included over S10/S16/S3 when session trace is active for this IMSI/IMEI.

Trace Information

0

UE Usage Type

CO

This IE shall be set to the subscribed UE Usage Type, if received from the HSS, and sent by the old MME/SGSN on the S3/S10/S16 interfaces if the old MME/SGSN supports the Dedicated Core Networks specified in TS 23.401 [3]. It shall also be sent by the AMF on the N26 interface, if received from the UDM.

If the UE Usage Type is not available in the old MME/SGSN/AMF, the length field of this IE shall be set to 0.

See NOTE 1.

Integer Number

0

Monitoring Event Information

CO

This IE shall be sent by the source MME/S4-SGSN on the S3/S10/S16 interfaces if monitoring events are to be continued in the target MME/S4-SGSN.

More than one IE with this type and instance values may be included to represent multiple monitoring events.

Monitoring Event Information

0

Monitoring Event Extension Information

CO

This IE shall be sent by the source MME/S4-SGSN on the S3/S10/S16 interfaces if monitoring event extensions are to be sent to the target MME/S4-SGSN.

More than one IE with this type and instance values may be included to represent multiple monitoring event extensions.

Monitoring Event Extension Information

0

Extended Trace Information

C

This IE shall be included over N26 when session trace is active for this user.

Extended Trace Information

0

Private Extension

O

Private Extension

VS

NOTE 1: A UE Usage Type IE with the length field equal to 0 is used for the receiver to differentiate the case where the sender does not support the Dedicated Core Network feature from the case where the sender supports the Dedicated Core Network feature but no UE Usage type was received in UE’s subscription.

7.3.10 Forward Access Context Notification

A Forward Access Context Notification message shall be sent from the Old SGSN to the New SGSN over the S16 interface to forward the RNC contexts to the target system, or sent from the Old MME to the New MME over the S10 interface to forward the RNC/eNodeB contexts to the target system.

When the old SGSN receives the RANAP message Forward SRNS Context, the old SGSN shall send a Forward Access Context Notification message to the new SGSN. The new SGSN shall forward the message to the target RNC using the corresponding RANAP message.

When the old SGSN receives a BSSGP message PS handover Required and the acknowledged peer-to-peer LLC operation is used for the Bearer Context or when "delivery order" is set in the Bearer Context QoS profile, the old SGSN shall send a Forward Access Context Notification message with the PDU Number IE to the new SGSN. The new SGSN shall forward the message to the target RNC/ target BSS using the corresponding RANAP message only for PS handover to Iu mode.

When the old SGSN receives a BSSGP message PS handover Required from source BSS/RNC for PS handover to A/Gb mode, the value part of RAB Context IE shall be empty according to its defined minimum length.

Table 7.3.10-1 specifics the presence requirements and conditions of the IEs in the message.

Table 7.3.10-1: Information Elements in a Forward Access Context Notification

Information elements

P

Condition / Comment

IE Type

Ins.

RAB Contexts

C

This IE shall be included for S16 only. Several IEs with this type and instance values shall be included as necessary to represent a list of Bearers.

For each RAB context in the received RANAP message, the old SGSN shall include this IE in the message.

RAB Context

0

Source RNC PDCP context Info

C

If available, the old SGSN shall include an Source RNC PDCP context info in the message.

Source RNC PDCP context Info

0

PDU Numbers

C

This IE only applies to S16. The old SGSN shall include this IE in the message if the acknowledged peer-to-peer LLC operation is used for the Bearer Context or when "delivery order" is set in the Bearer Context QoS profile in A/Gb mode to Iu/A/Gb mode PS handover.

PDU Numbers

0

E-UTRAN Transparent Container

C

This IE shall be included over S10 to contain the "eNB Status Transfer Transparent Container" as specified in3GPP TS 36.413 [10].

Container Type shall be set to 3.

F-Container

0

E-UTRAN Transparent Container

C

This IE shall be included over S10 to contain the "eNB Early Status Transfer Transparent Container" as specified in 3GPP TS 36.413 [10].

Container Type shall be set to 3.

F-Container

1

Private Extension

O

Private Extension

VS

7.3.11 Forward Access Context Acknowledge

A Forward Access Context Acknowledge message shall be sent to the old MME/SGSN as a response to Forward Access Context Notification.

Possible Cause values are specified in Table 8.4-1.

Table 7.3.11-1 specifics the presence requirements and conditions of the IEs in the message.

Table 7.3.11-1: Information Elements in a Forward Access Context Acknowledge

Information elements

P

Condition / Comment

IE Type

Ins.

Cause

M

Cause

0

Private Extension

O

Private Extension

VS

7.3.12 Detach Notification

A Detach Notification message shall be sent from an MME to the associated SGSN, or from an SGSN to the associated MME as a part of Detach procedure if the ISR is activated between the MME and SGSN for the UE.

Possible Cause values are:

  • "Local Detach".
  • "Complete Detach".

A Detach Notification message shall also be sent from an SGSN to the associated MME as a part of Detach procedure if the ISR is activated between the MME and SGSN for the UE.

Possible Cause values are:

  • "IMSI Detach only".

"Local Detach" indicates that this detach is local to the MME/SGSN and so the associated SGSN/MME registration where the ISR is activated shall not be detached. The MME/SGSN that receives this message including this Cause value of "Local Detach" only deactivates the ISR. This Cause value shall be included in the procedures:

  • MME/SGSN-initiated Detach Procedure in case of implicit detach.

"Complete Detach" indicates both the MME registration and the SGSN registration that the ISR is activated for, shall be detached. This "Complete Detach" Cause value shall be included in the procedures:

  • UE-initiated Detach Procedure.
  • MME/SGSN-initiated Detach Procedure in case of explicit detach.

For the purpose of SGs handling, the SGSN shall include Detach Type in the Detach Notification message for "Complete Detach" when the UE is combined IMSI/EPS attached and the ISR is activated.

Possible Detach Type values are:

  • "PS Detach".
  • "Combined PS/CS Detach".

"PS Detach" indicates that the MME shall perform explicit IMSI detach from EPS service as specified in clause 5.4, 3GPP TS 29.118 [22]. "Combined PS/CS detach" indicates that the MME shall perform explicit IMSI detach from non-EPS service as specified in clause 5.5, 3GPP TS 29.118 [22].

"IMSI Detach only" indicates that combined IMSI/EPS attached UE initiates IMSI only GPRS detach from non-GPRS service as specified in clause 4.7.4.1, 3GPP TS 24.008 [5], and both the SGSN/MME registration shall be remained. The MME shall perform explicit IMSI detach from non-EPS service for the SGs handling purpose, which is specified in clause 5.5, 3GPP TS 29.118 [22]. This "IMSI Detach only" Cause value shall be included in the procedures:

  • UE-initiated Detach Procedure for GERAN/UTRAN for "IMSI Detach only".

Table 7.3.12-1 specifics the presence of the IEs in the message.

Table 7.3.12-1: Information Elements in a Detach Notification

Information elements

P

Condition / Comment

IE Type

Ins.

Cause

M

Cause

0

Detach Type

CO

This IE shall be included by SGSN when the Cause indicates "Complete Detach" for the combined IMSI/EPS attached UE.

Detach Type

0

Private Extension

O

Private Extension

VS

7.3.13 Detach Acknowledge

A Detach Acknowledge message shall be sent as a response to a Detach Notification message during Detach procedure.

Possible Cause values are specified in Table 8.4-1.

Table 7.3.13-1 specifics the presence of the IEs in the message.

Table 7.3.13-1: Information Elements in a Detach Acknowledge

Information elements

P

Condition / Comment

IE Type

Ins.

Cause

M

Cause

0

Recovery

O

Recovery

0

Private Extension

O

Private Extension

VS

7.3.14 Change Notification Request

3GPP TS 23.401 [3] and 3GPP TS 23.060 [4] specify that if PGW has requested ECGI/eNodeB ID/TAI/CGI/SAI/RAI Change Reporting or reporting of change of UE presence in Presence Reporting Area(s) or User CSG information Change Reporting and if MME/S4-SGSN supports the feature, then MME/S4-SGSN shall send the Change Notification Request message on the S11/S4 interface to the SGW. If SGW supports the feature, the SGW forwards the message on the GTP based S5/S8 interface to the PGW as part of location dependent charging related procedures.

In this version of the specification, the sender shall set the header TEID value to that of the peer node’s Control Plane TEID on S11/S4 interface or to the peer node’s Control Plane TEID on S5/S8 interface. However a receiver shall be prepared to receive messages in which the header TEID value is set to zero from implementation conforming to earlier versions of this specification. When that is the case, the receiver identifies the subscriber context based on the included LBI, IMSI, and/or MEI IEs.

The MME shall increment the "MO Exception Data Counter" by one each time the MME has received the RRC cause "MO Exception data". The MME may defer sending a Change Notification Request message to report a non-zero value for the "MO Exception Data Counter" based on local configuration.

If the PLMN has configured secondary RAT usage reporting and if PDN GW Secondary RAT reporting is active, the MME shall send the Change Notification Request message and include "Secondary RAT Usage Data Report" on the S11 interface to the SGW when it has received Secondary RAT usage data from the eNodeB in the following procedures, regardless of whether ULI shall be reported or not:

  • Connection Suspend
  • eNodeB initiated S1 release
  • E-UTRAN to UTRAN Iu mode Inter RAT handover
  • E-UTRAN to GERAN A/Gb mode Inter RAT handover
  • MME triggered Serving GW relocation
  • MME to 3G SGSN combined hard handover and SRNS relocation
  • The MME may also send the send the Change Notification Request message and include "Secondary RAT Usage Data Report" on the S11 interface to the SGW when it has received periodic reporting of Secondary RAT usage data from eNodeB or as part of an MME initiated S1 release from the eNodeB, as described in 3GPP TS 23.401 [3] clause 5.7A. The SGW shall forward the "Secondary RAT Usage Data Report" to the PGW if the IRPGW flag is set to "1".

Table 7.3.14-1: Information Element in Change Notification Request

Information elements

P

Condition / Comment

IE Type

Ins.

IMSI

C

The MME/SGSN shall include IMSI in the message except for the case:

– If the UE is emergency attached and the UE is UICCless.

The IMSI shall be included in the message but not used as an identifier

– if UE is emergency attached but IMSI is not authenticated.

If the SGW receives this IE, it shall forward it to the PGW on S5/S8.

IMSI

0

ME Identity (MEI)

C

The MME/SGSN shall include the ME Identity (MEI) IE:

– If the UE is emergency attached and the UE is UICCless

– If the UE is emergency attached and the IMSI is not authenticated

If the SGW receives this IE, it shall forward it to the PGW on S5/S8.

MEI

0

Indication Flags

CO

This IE shall be included if any one of the applicable flags is set to 1.

Applicable flags are:

  • Unauthenticated IMSI: This flag shall be set to 1 if the IMSI present in the message is not authenticated and is for an emergency attached UE.

Indication

0

RAT Type

M

See NOTE 2.

RAT Type

0

User Location Information (ULI)

C

The SGSN shall include the User Location Information IE if the MS is located in a RAT Type of GERAN, UTRAN or GAN and shall include the CGI, SAI and/or RAI.

ULI

(NOTE 1)

0

CO

The MME shall include the User Location Information IE if the UE is located in a RAT Type of E-UTRAN and shall include the ECGI and/or TAI, or TAI and Macro eNB ID, or Macro eNB ID depending on the Change Reporting Action provided to the MME.

CO

If the SGW receives this IE it shall forward it to the PGW, if it supports this feature.

User CSG Information (UCI)

CO

The SGSN/MME shall include the User CSG Information IE if the MS is located in the CSG cell or the hybrid cell and the P-GW/PCRF decides to receive the CSG Information.

If the SGW receives this IE it shall forward it to the PGW, if it supports this feature.

UCI

0

PGW S5/S8 GTP-C IP Address

C

This IE shall be sent on S4.

IP Address

0

CO

This IE shall be sent on S11.

LBI

CO

This IE, identifying the PDN connection, shall be sent by the MME/SGSN on S11/S4.

If the SGW receives this IE, it shall forward it to the PGW on S5/S8.

EBI

0

Presence Reporting Area Information

CO

The MME/SGSN shall include this IE on the S11/S4 interface if:

  • the PGW/PCRF/OCS has just requested to start or modify reporting of change of UE presence in a Presence Reporting Area and the MME/SGSN supports such reporting. The MME/SGSN shall then indicate whether the UE is inside or outside the newly started or modified Presence Reporting Area(s), or indicate the Presence Reporting Area(s) is inactive. Several IEs with the same type and instance value may be included as necessary to represent a list of Presence Reporting Area Actions. One IE shall be included for each Presence Reporting Area newly started or modified.
  • if the PGW/PCRF/OCS requested to report changes of UE presence in a Presence Reporting Area, the MME/SGSN supports such reporting and the UE enters or leaves the Presence Reporting Area(s). Several IEs with the same type and instance value may be included as necessary to represent a list of Presence Reporting Area Information. One IE shall be included for each active Presence Reporting Area that the UE has newly entered or left.

Presence Reporting Area Information

0

CO

The SGW shall include this IE on S5/S8 if it receives the Presence Reporting Area Information from MME/SGSN.

MO Exception Data Counter

CO

The MME shall include this IE on the S11 interface when it needs to send a non-zero counter value for the MO Exception Data Counter. The timestamp in the counter shall be set with the time at which the counter value increased from 0 to 1.

Counter

0

CO

The SGW shall include this IE on S5/S8 if it receives the MO Exception Data Counter from MME.

Secondary RAT Usage Data Report

CO

If PDN GW Secondary RAT reporting is active, the MME shall include this IE on the S11 interface if it has received Secondary RAT usage data from eNodeB in a Connection Suspend, or eNodeB initiated S1 release procedure, or an MME triggered Serving GW relocation, or an E-UTRAN to GERAN A/Gb mode Inter RAT handover, E-UTRAN to UTRAN Iu mode Inter RAT handover, MME to 3G SGSN combined hard handover and SRNS relocation, or Routing Area Update procedures. In these cases, the MME shall also set the IRSGW flag to "0" and the IRPGW flag to "1".

The MME shall also include this IE on the S11 interface when it has received Secondary RAT usage data from eNodeB, e.g. as periodic reporting or in an MME initiated S1 release procedure. In these cases, the MME shall set the IRSGW flag to "1", and if PDN GW Secondary RAT reporting is active, the IRPGW flag shall be set to "1".

Several IEs with the same type and instance value may be included, to represent multiple usage data reports.

Secondary RAT Usage Data Report

0

O

The SGW shall forward this IE on the S5/S8 interface if it receives the Secondary RAT Usage Data Report with the IRPGW flag set to "1" from MME.

Several IEs with the same type and instance value may be included, to represent multiple usage data reports.

Private Extension

O

Vendor or operator specific information

Private Extension

VS

NOTE 1: In shared networks, when the message is sent from the VPLMN to the HPLMN, the PLMN ID that is communicated in this IE shall be that of the selected Core Network Operator for supporting UEs, or that of the allocated Core Network Operator for non-supporting UEs. As an exception, based on inter-operator roaming/sharing agreement, if the information on whether the UE is a supporting or non-supporting UE is available, the PLMN ID that is communicated to the HPLMN for non-supporting UEs shall be the Common PLMN ID.
In shared networks, when the MME/S4-SGSN and PGW pertain to the same PLMN, the Primary PLMN ID shall be communicated in the ECGI to the PGW, and the Common PLMN ID shall be communicated in SAI/CGI to the PGW, for both supporting and non-supporting UEs. The Core Network Operator PLMN ID (selected by the UE for supporting UEs or allocated by the network for non-supporting UEs) shall be communicated in the TAI, RAI, UCI and the Serving Network.
See clause 4.4 of 3GPP TS 23.251 [55].

NOTE 2: The PGW may ignore RAT Type as the MME/SGSN always informs the PGW about RAT Type change with the Modify Bearer Request message.

7.3.15 Change Notification Response

The Change Notification Response message may be sent on the S11/S4 interface by the SGW to the MME/SGSN and is sent on the S5/S8 interface by the PGW to the SGW as part of location dependent charging related procedures to acknowledge the receipt of a Change Notification Request.

If SGW does not support the feature (see clause 7.3.14 "Change Notification Request"), SGW may silently discard Change Notification Request message from MME/SGSN. If the MME/ SGSN does not receive Change Notification Response, the MME/SGSN may either send Change Notification Request to the same SGW next time UE location changes, or not (marking SGW as not supporting the feature).

The Cause value indicates whether or not the Change Notification Request was received correctly. Possible Cause values are specified in Table 8.4-1. Message specific cause values are:

  • "Request accepted".
  • "Request accepted partially".
  • "IMSI/IMEI not known".

In this version of the specification, the sender shall set the header TEID value to that of the peer node’s Control Plane TEID on S11/S4 interface or to the peer node’s Control Plane TEID on S5/S8 interface. However a receiver shall be prepared to receive messages in which the header TEID value is set to zero from implementation conforming to earlier versions of this specification. When that is the case, the receiver identifies the subscriber context based on the included LBI, IMSI, and/or MEI IEs.

If the IMSI is unknown, or the IMEI is unknown when the UE is emergency attached and UICCless or the UE is emergency attached but the IMSI is not authenticated for the receiving GTP-C entity, then the message shall be silently discarded and no further processing of the IEs shall continue.

If the MME/SGSN receives Change Notification Response containing a Cause value of "IMSI/IMEI not known" and CS bit set to 1, this indicates that the associated PDN connection does not exist within the PGW. The Change Reporting mechanism shall be stopped in the receiving SGSN/MME for all Bearers of the associated PDN connection. The SGSN/MME shall then initiate PDN disconnection for all of these PDN Connections.

If the PDN Connection associated of the Change Notification Request message received by the SGW does not exist within the SGW, the SGW shall return Change Notification Response with the CS bit set to 0 to the MME/SGSN. The Change Reporting mechanism shall be stopped in the receiving SGSN/MME for all Bearers of the associated PDN connection, and the MME/SGSN shall then locally delete the PDN connection and release all associated resources.

If the location Change Reporting mechanism is to be stopped or modified for this subscriber in the SGSN/MME, then the PGW shall include the Change Reporting Action IE in the message and shall set the value of the Action field appropriately.

If the MME has sent the "MO Exception Data Counter" for the RRC Cause "MO Exception data" in the Change Notification Resquest, the MME shall reset the counter value when receiving the Change Notification Response message.

Table 7.3.15-1: Information Element in Change Notification Response

Information elements

P

Condition / Comment

IE Type

Ins.

IMSI

C

The IMSI shall be included in the message if it is received in the Change Notification Request message.

IMSI

0

ME Identity (MEI)

C

The ME Identity (MEI) shall be included in the message if it is received in the Change Notification Request message.

MEI

0

Cause

M

Cause

0

Change Reporting Action

C

This IE shall be included with the appropriate Action field If the location Change Reporting mechanism is to be started or stopped for this subscriber in the SGSN/MME.

Change Reporting Action

0

CSG Information Reporting Action

CO

This IE shall be included with the appropriate Action field if the location CSG Info reporting mechanism is to be started or stopped for this subscriber in the SGSN/MME.

CSG Information Reporting Action

0

Presence Reporting Area Action

CO

This IE shall be included on the S5/S8 and S11/S4 interfaces with the appropriate Action field if reporting changes of UE presence in a Presence Routing Area is to be started, stopped or modified for this subscriber in the MME/SGSN.

Several IEs with the same type and instance value may be included as necessary to represent a list of Presence Reporting Area Actions. One IE shall be included per Presence Reporting Area to be started, stopped or modified.

Presence Reporting Area Action

0

Private Extension

O

Private Extension

VS

7.3.16 Relocation Cancel Request

A Relocation Cancel Request message shall be sent from the source MME/SGSN/AMF to the target MME/SGSN/AMF on S3/S10/S16/N26 interface as part of the Inter-RAT handover Cancel procedure, S1 Based handover Cancel procedure, SRNS Relocation Cancel Procedure, EPS to 5GS handover cancel procedure and 5GS to EPS handover cancel procedure.Table 7.3.16-1 specifics the presence of the IEs in the message.

Table 7.3.16-1: Information Elements in Relocation Cancel Request

Information elements

P

Condition / Comment

IE Type

Ins.

IMSI

C

The IMSI shall be included in the message except for the case:

– If the UE is emergency or RLOS attached and the UE is UICCless.

The IMSI shall be included in the message but not used as an identifier

  • if UE is emergency or RLOS attached but IMSI is not authenticated.

IMSI

0

ME Identity (MEI)

C

The MME/SGSN/AMF shall include the ME Identity (MEI) IE:

– If the UE is emergency or RLOS attached and the UE is UICCless

– If the UE is emergency or RLOS attached and the IMSI is not authenticated

MEI

0

Indication Flags

CO

This IE shall be included if any one of the applicable flags is set to 1.

Applicable flags are:

  • Unauthenticated IMSI: This flag shall be set to 1 if the IMSI present in the message is not authenticated and is for an emergency or RLOS attached UE.

Indication

0

RANAP Cause

C

This IE shall be present in the case of SRNS relocation cancel procedure. It shall contain the cause value received from the source RNC in the Relocation Cancel message received over the Iu interface.

F-Cause

0

Private Extension

O

Private Extension

VS

7.3.17 Relocation Cancel Response

A Relocation Cancel Response message shall be sent as a response to a previous Relocation Cancel Request message(see clause 7.3.16).

Possible Cause values are specified in Table 8.4-1. Message specific cause values are:

– "IMSI/IMEI not known".

Table 7.3.17-1 specifics the presence of the IEs in the message.

Table 7.3.17-1: Information Elements in Relocation Cancel Response

Information elements

P

Condition / Comment

IE Type

Ins.

Cause

M

Cause

0

Private Extension

O

Private Extension

VS

7.3.18 Configuration Transfer Tunnel

A Configuration Transfer Tunnel message shall be used to:

– tunnel eNodeB Configuration Transfer messages from a source MME to a target MME over the S10 interface. The purpose of the eNodeB Configuration Transfer is to transfer information from an eNodeB to a target eNodeB or an en-gNB connected to a target eNB in unacknowledged mode (see 3GPP TS 36.413 [10]).

– tunnel eNodeB Configuration Transfer messages from a source MME to a target AMF, or to tunnel Uplink RAN Configuration Transfer messages from a source AMF to a target MME, over the N26 interface. This is to transfer RAN configuration information or inter-system SON configuration information between an eNodeB and a gNB in unacknowledged mode (see 3GPP TS 36.413 [10] and 3GPP TS 38.413 [84]).

Table 7.3.18-1 specifies the presence requirements and conditions of the IEs in the message.

Table 7.3.18-1: Information Elements in a Configuration Transfer Tunnel Message

Information elements

P

Condition / Comment

IE Type

Ins.

E-UTRAN Transparent Container / EN-DC Container / Inter-system SON Container

M

This IE shall contain:

– the "SON Configuration Transfer" as specified in 3GPP TS 36.413 [10]. In this case, the Container Type shall be set to 3.

or

– the "EN-DC SON Configuration Transfer" as specified in 3GPP TS 36.413 [10]. In this case the Container Type shall be set to 5. (NOTE 1)

or

– the "Inter-system SON Configuration Transfer" as specified in 3GPP TS 36.413 [10] and 3GPP TS 38.413 [84]. In this case the Container Type shall be set to 6. (NOTE 2)

F-Container

0

Target eNodeB ID / en-gNB ID / gnB ID

M

This IE shall contain the ID of the target eNodeB, en-gNB or gNB.

This IE shall encode a target en-gNB ID over the S10 or N26 interface during:

– a TNL address discovery request of a candidate en-gNB via the S1 interface or via inter-system signalling.

This IE shall encode a target eNodeB ID:

– over the S10 interface, when no EN-DC SON Configuration Transfer IE is received from the source eNB;

– over the S10 or N26 interface, during a TNL address discovery response of a candidate en-gNB via the S1 interface or via inter-system signalling.

This IE shall encode a target eNodeB ID or a target gNB ID over the N26 interface when transferring Inter-system SON configuration Transfer information from a gNB to an eNodeB or from an eNodeB to a gNB respectively.

See clauses 22.3.6.2 and 22.3.6.3 of 3GPP TS 36.300 [19].

Target Identification

0

Connected Target eNodeB ID

CO

This IE shall be present during an TNL address discovery request of a candidate en-gNB via the S1 interface (see clauses 22.3.6.2 of 3GPP TS 36.300 [19]) if the source eNB provided the ID of a target eNB connected to the target en-gNB ID.

Target Identification

1

NOTE 1: An EN-DC Container shall only be sent towards MMEs known to support TNL address discovery of a candidate en-gNB via the S1 interface or via inter-system signalling (see clauses 22.3.6.2 and 22.3.6.3 of 3GPP TS 36.300 [19]).

NOTE 2: An Inter-system SON Container shall only be sent towards MMEs and AMFs known to support transfer of Inter-system SON configuration transfer (see clause 15.5.2 of 3GPP TS 38.300 [84]).

7.3.19 RAN Information Relay

The RAN Information Relay message shall be sent on S3 interface between SGSN and MME to transfer the RAN information received by an SGSN from BSS or RNS (or GERAN Iu mode) or by an MME from eNodeB. The procedures are specified in 3GPP TS 23.401 [3].

This message shall also be sent on S16 interface to transfer the RAN information between GERAN or GERAN Iu mode or UTRAN.

For handling of protocol errors the RAN Information Relay message is treated as a Response message.

Table 7.3.19-1 specifies the presence requirements and conditions of the IEs in the message.

Table 7.3.19-1: Information Elements in a RAN Information Relay

Information elements

P

Condition / Comment

IE Type

Ins.

BSS Container

M

All information elements from the BSSGP RIM PDU, starting from and including the BSSGP "PDU type", shall be contained within the BSS Container and forwarded to the destination MME/SGSN in the RAN Information Relay message. The Container Type shall be set to 2.

F-Container

0

RIM Routing Address

C

This IE shall be included if the RIM Routing Address information is included in the message sent from the source RAN node.

This IE identifies the destination RAN node where the RAN Information needs to be relayed to. It contains:

  • the destination RNC Identity when the target is GERAN Iu mode or UTRAN; or
  • the destination Cell Identity when the target is GERAN; or
  • the Target eNodeB ID when the target is E-UTRAN.

Target Identification

0

Private Extension

O

None

Private Extension

VS

7.3.20 ISR Status Indication

A ISR Status Indication message shall be sent on the S3 interface by the MME/SGSN to the ISR associated SGSN/MME as part of the following procedures:

– the Restoration of PDN connections after an SGW failure for UEs with ISR as specified in 3GPP TS 23.007 [17];

– the HSS Based P-CSCF restoration procedure for 3GPP access (for both basic and PCO extension) as specified in 3GPP TS 23.380 [61].

Table 7.3.20-1 specifies the presence of the IEs in the message.

Table 7.3.20-1: Information Elements in an ISR Status Indication

Information elements

P

Condition / Comment

IE Type

Ins.

Action Indication

M

This IE shall include one of the applicable Values:

  • Deactivation Indication: If the value is set to 1, this indicates a request to the ISR associated MME/SGSN to deactivate ISR and remove the UE resource locally. See 3GPP TS 23.007 [17].
  • Paging Indication: If the value is set to 2, this indicates a request to the ISR associated MME/SGSN to page the UE in IDLE state. See 3GPP TS 23.007 [17].
  • Paging Stop Indication: If the value is set to 3, this indicates to the ISR associated MME/SGSN to stop paging the UE. See 3GPP TS 23.380 [61].

Action Indication

0

Private Extension

O

Private Extension

VS

7.3.21 UE Registration Query Request

The direction of this message shall be from S4-SGSN to MME (see Table 6.1-1).

This message shall be used to support CS/PS coordination for shared UTRAN and GERAN access. When an S4-SGSN receives a UE Registration Query from a RAN node, including an indication to also query MMEs, and if the UE (identified by IMSI) is not registered in the S4-SGSN, the S4-SGSN shall send a UE Registration Query Request message to all MMEs that may hold the UE’s context, as specified in the clause 7.1.6 of 3GPP TS 23.251 [55].

NOTE: How the S4-SGSN determines which MMEs it will query, is based on local configuration.

Table 7.3.21-1 specifies the presence of IEs in this message.

Table 7.3.21-1: Information Elements in UE Registration Query Request

Information elements

P

Condition / Comment

IE Type

Ins.

IMSI

M

IMSI

0

Private Extension

O

Private Extension

VS

7.3.22 UE Registration Query Response

The UE Registration Query Response message shall be sent as a response to a UE Registration Query Request, to report whether the inquired UE is registered in the MME and if so, with which Core Network Operator, as specified in the clause 7.1.6 of 3GPP TS 23.251 [55].

Possible Cause values are specified in Table 8.4-1. Message specific cause values are:

– "Request accepted", to be used when the UE is registered in the MME

– "IMSI/IMEI not known", to be used when the UE is not registered in the MME.

The IMSI received in the UE Registration Query Request message shall be included in the response, to allow correlation in the SGSN.

The Selected Core Network Operator Identifier identifies the core network operator currently serving the UE, and shall be included if the inquired UE is registered in the MME.

Table 7.3.22-1 specifies the presence of IEs in this message.

Table 7.3.22-1: Information Elements in UE Registration Query Response

Information elements

P

Condition / Comment

IE Type

Ins.

Cause

M

Cause

0

IMSI

M

IMSI

0

Selected Core Network Operator Identifier

M

PLMN ID

0

Private Extension

O

Private Extension

VS