Anexo D 23.401 3Gpp

Release 8
Annex D (normative):
Interoperation with SGSNs of earlier 3GPP standards releases
D.1 General Considerations
This annex specifies interworking between the EPS and 3GPP 2G and/or 3G SGSNs, which conforms to an earlier 3GPP standards release than Rel-8, i.e. these SGSNs provides no functionality that is introduced specifically for the EPS or for interoperation with the E-UTRAN.Interoperation scenarios for operating E-UTRAN with a PLMN maintaining pre-Rel8 SGSN is supported only with a GTP-based S5/S8.
NOTE: PMIP-based S5/S8 may be used, but does not support handovers between the pre-Rel8 SGSN and MME/SGW.
The S5/S8 interface for the Operator with pre-Rel8 SGSNs will be GTP-based, but can be changed to PMIP-based S5/S8 when the pre-Rel8 SGSNs evolve to Rel8 SGSNs.
D.2Interoperation Scenario
D.2.1 Roaming interoperation scenario
In the roaming scenario the vPLMN operates pre-Rel-8 2G and/or 3G SGSNs as well as MME and S-GW for E-UTRAN access. The hPLMN operates a P-GW.
Roaming and inter access mobility between pre-Rel-8 2G and/or 3G SGSNs and an MME/S-GW are enabled by:
- Gn functionality as specified between two pre-Rel-8 SGSNs, which is provided by the MME,and
- Gp functionality as specified between pre-Rel-8 SGSN and pre-Rel-8 GGSN that is provided by the P-GW.
All this Gp and Gn functionality bases on GTP version 1 only.
The architecture for interoperation with pre-Rel8 SGSNs in the non-roaming case is illustrated in Figure D.2.1-1.

Figure D.2.1-1: Roaming architecture for interoperation with earlier 3GPP standards releases
D.2.2 Non-roaminginteroperation scenario
In the non-roaming scenario the PLMN operates pre-Rel-8 2G and/or 3G SGSNs as well as MME and S-GW for E-UTRAN access.
Intra PLMN roaming and inter access mobility between pre-Rel-8 2G and/or 3G SGSNs and an MME/S-GW are enabled by:
- Gn functionality as specified between two pre-Rel-8 SGSNs, which is provided by the MME, and
- Gn functionality as specified betweenpre-Rel-8 SGSN and pre-Rel-8 GGSN that is provided by the PGW.
All this Gn functionality is based on GTP version 1 only.
The architecture for interoperation with pre-Rel8 SGSNs in the non-roaming case is illustrated in Figure D.2.2-1.

Figure D.2.2-1: Non-roaming Architecture for interoperation with earlier 3GPP standards releases
NOTE: If the Rel-7 SGSN applies Direct Tunnel there is a userplane connection between PGW and UTRAN.
D.3 Interoperation procedures
D.3.1 General
The interoperation procedures describe information flows for pre-Rel-8 SGSNs and Rel-8 EPS network elements. All messages between SGSN and MME, between SGSN and HSS and between SGSN and P-GW as well as the therein contained information elements are the same as specified for the adequate TS 23.060 [7] procedures.These messages and procedure step descriptions are taken from TS 23.060 [7] for explanatory purposes only. These descriptions are in blue text colour and shall not be modified by the interoperation procedures. It cannot be assumed that the messages and procedure step descriptions that are taken from TS 23.060 [7] will be updated when modifications or corrections are performed for TS 23.060 [7]. Ifthere are any discrepancies for these messages and procedure step descriptions TS 23.060 [7] takes precedence. The messages between the MME and any other node than the pre-Rel-8 SGSN as well as the therein contained information elements are the same as specified in the main body of this technical specification for the inter RAT Routeing Area Update procedure. If there are any discrepancies forthese messages the descriptions from the main body of this Technical Specification take precedence.
D.3.2 Tracking Area Update between Pre-Rel 8 UTRAN and EUTRAN
D.3.2.1 Pre-Rel 8 UTRAN Iu mode to E-UTRAN Tracking Area Update
The Pre-Rel-8 UTRAN to E-UTRAN Tracking Area Update procedure takes place when a UE that is registered with a Pre-Rel-8 3G-SGSN selects an E-UTRAN cell. In this case, the UE...