Section: Annex D (normative): Interoperation with Gn/Gp SGSNs D.1 General Considerations
Content: This annex specifies interworking between the EPS and 3GPP 2G and/or 3G SGSNs, which provide only Gn and Gp interfaces but no S3, S4 or S5/S8 interfaces, i.e. these Gn/Gp SGSNs provide 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 Gn/Gp SGSNs are supported only with a GTP-based S5/S8. NOTE: PMIP-based S5/S8 may be used, but does not support handovers between the Gn/Gp SGSN and MME/S-GW. The S5/S8 interface for the Operator with Gn/Gp SGSNs will be GTP-based, but can be changed to PMIP-based S5/S8 when the Gn/Gp SGSNs evolve to S4 SGSNs. For these interoperation scenarios the GERAN/UTRAN has to support interoperation with E-UTRAN. TS 23.682[ Architecture enhancements to facilitate communications with packet data networks and applications ]  [74] defines the Monitoring Events feature, and TS 23.060[ General Packet Radio Service (GPRS); Service description; Stage 2 ]  [7] specifies that the Monitoring Events feature for the Gn/Gp SGSN is not supported. Therefore, during interoperation with Gn/Gp SGSNs Monitoring Event information shall not be expected by the MME/S4-SGSN from a Gn/Gp SGSN, nor shall the MME/S4-SGSN or the HSS transfer Monitoring Event information to a Gn/Gp SGSN. This applies to all operations defined in this annex.