sport standards (3GPP 38.461 and 38.462) which define any SCTP/IP-based packet interface. 3GPP 38.463 defines the E1AP specification-th defines the CP signaling over the El interface including signaling procedures and information elements. Similarly, 3GPP 38.470 defines the F1 general aspects and principles-this is a high-level summary of the F1 interface including links to the related more detailed interfaces. These include the F1 interface Layer 1 and signaling (CP) transport standards (3GPP 38.471 and 38.472) which define any SCTP/IP-based packet interface. For data (UP) transport, 3GPP 38.471 and 38.474 define use of the GPRS Tunneling Protocol (GTP) to encapsulate frames. 3GPP 38.473 defines the FIAP specification-this defines the CP signaling over the F1 interface, includ- ing signaling procedures and information elements. 3GPP 38.425 defines the generic UP protocol (Option 2: RRC, PDCP) CU-CP CU-UP DU (Option 2: RLC, MAC, PHY) FIGURE 2-7 CU-associated interfaces. CU, central unit. Chapter 2 System components, requirements, and interfaces 51 that also covers the F1 interface as well as the Xn (and X2 for LTE) interfaces. This standard references 3GPP 29.281 for the definition of GTP. 3GPP 38.425 carries control information related to user data flow management of radio bearers: the UP procedures. Each instance is unique per radio bearer/GTP tunnel and instantiated together with the associated GTP tunnel. 3GPP 38.420 defines Xn general aspects and principles, for both CP and UP aspects including mobility management, DC/multiconnectivity aspects, and other procedures. These include the Xn interface Layer 1 and signaling (CP) transport standards (3GPP 38.421 and 38.422) which define any SCTP/IP-based packet interface. 3GPP 38.424 defines the use of the GTP to encapsulate UP frames. 3GPP 38.425 carries control information related to user data flow management of radio bearers: the UP procedures. Each instance is unique per radio bearer/GTP tunnel and instantiated together with the associated GTP tunnel. 3GPP 38.4