Section: 5.1.2.6 UE - P-GW user plane with Control Plane CIoT EPS Optimisations
Content: Legend: - GTP-u (GPRS Tunnelling Protocol User plane): This protocol tunnels user data between MME and the S-GW as well as between the S-GW and the P-GW in the backbone network. GTP shall encapsulate all end user packets. End user Ethernet packets are only used with a combined PDN GW+SMF (as specified in TS 23.501[ System architecture for the 5G System (5GS) ]  [83]). - UDP/IP: These are the backbone network protocols used for routing user data and control signalling. - NAS: this is the Non-Access Stratum Layer used to carry Data between UE and MME and may include Header compression and security functions of user plane IP data. Whether a convergence protocol sublayer may be required for this purpose is a stage 3 matter. Figure 5.1.2.6-1: User Plane with Control Plane CIoT EPS Optimisations