6.18 Procedures to support Dedicated Core Networks

23.0603GPPGeneral Packet Radio Service (GPRS)Release 17Service descriptionStage 2TS

6.18.1 NAS Message Redirection Procedure

This procedure is described in the clause 5.19.1 of TS 23.401 [89].

6.18.2 Attach and RAU procedure for Dedicated Core Network

When DCNs are used, modification to the Attach and RAU procedures described in the clause 5.19.2 of TS 23.401 [89] apply to the procedures described in the following clauses of this specification:

– 6.5.3 Combined GPRS / IMSI Attach procedure

– 6.9.1.2.2 Inter SGSN Routeing Area Update

– 6.9.1.2.2a Inter SGSN Routeing Area Update and Combined Inter SGSN RA / LA Update using S4

– 6.9.1.3.2 Combined Inter SGSN RA / LA Update

– 6.9.2.1 Routeing Area Update Procedure

– 6.13.1.1.1 Iu mode to A/Gb mode Intra SGSN Change using Gn/Gp

– 6.13.1.1.2 Iu mode to A/Gb mode Intra SGSN Change using S4

– 6.13.2.1.1 Iu mode to A/Gb mode Inter-SGSN Change using Gn/Gp

– 6.13.2.1.2 Iu mode to A/Gb mode Inter-SGSN Change using S4

– 6.13.2.2.1 A/Gb mode to Iu mode Inter-SGSN Change using Gn/Gp

– 6.13.2.2.2 A/Gb mode to Iu mode Inter-SGSN Change using S4

6.18.2a Impacts to Relocation Procedures

When DCNs are used, the impacts to the relocation procedures are captured as below.

– Forward Relocation Request message: When SGSN changes during relocation, in the step where Forward Relocation Request message is sent from the Source SGSN to Target SGSN, the source SGSN also includes the UE Usage Type, if available, in the message. This change applies to the following clauses and step:

– 6.9.2.2.1 Serving RNS Relocation Procedure: Step 3

– 6.9.2.2.2 Combined Hard Handover and SRNS Relocation Procedure: Step 3

– 6.9.2.2.3 Combined Cell / URA Update and SRNS Relocation Procedure: Step 3

– Selection of new SGW: In the step, subsequent to the Forward Relocation Request message, in which the target S4-SGSN determines if the Serving GW is to be relocated, if the target S4-SGSN supports DCN, the target S4-SGWN also determines if the existing Serving GW supports the DCN for the UE based on UE Usage Type of the UE, locally configured operator’s policies as well as UE related context information available at the target network, e.g. information about roaming. This applies to the following clauses and step:

– 6.9.2.2.1a Serving RNS Relocation Procedure, Combined Hard Handover and SRNS Relocation Procedure, and Combined Cell / URA Update and SRNS Relocation Procedure Using S4: Step 1

– Relocation from service area where DCN is not used to an area where DCN is supported: When relocation occurs from a service area where DCN is not used to a service area where DCN is supported, the target SGSN obtains the UE usage type information from the HSS during the subsequent RAU procedure. If the target SGSN determines that the Serving GW does not support the UE Usage Type, the target SGSN triggers the Serving GW relocation as part of the handover procedures described in clause 6.9.2. If the target SGSN does not serve the UE Usage type, the relocation procedure should complete successfully and then the target SGSN may use the procedure in TS 23.401 [89] clause 5.19.3 Step 5 onwards, to change the serving DCN of the UE.

6.18.3 SGSN or HSS initiated Dedicated Core Network Reselection

The HSS initiated core network reselection for DCNs is described in the clause 5.19.3 of TS 23.401 [89].