Section: D.2.1 Roaming interoperation scenario
Content: In the roaming scenario the vPLMN operates Gn/Gp 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 Gn/Gp 2G and/or 3G SGSNs and an MME/S-GW are enabled by: - Gn functionality as specified between two Gn/Gp SGSNs, which is provided by the MME, and - Gp functionality as specified between Gn/Gp SGSN and Gn/Gp 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 Gn/Gp SGSNs in the non-roaming case is illustrated in Figure D.2.1-1. Figure D.2.1-1: Roaming architecture for interoperation with Gn/Gp SGSN