nment. For example, it is the gNB-CU-UP rather than the gNB-CU-CP that allocates TNL addresses for a UE during initial access or handover procedures, which allows an arbitrary part of the gNB-CU-UP to serve the particular gNB-DU that the UE was attached to - a feature essential for resource virtualization and pooling. More details and examples are provided in the subsequent section. Full details about the E1AP control-plane protocol can be found in 3GPP TS 38.463. 4.4.3.1.1 Interface Management Procedures Interface management procedures are used to establish, to release, and to reset (when and if needed) the E1 interface, and also to allow a gNB-CU-CP and a gNB-CU-UP to update configuration information. These procedures are: gNB-CU-CP E1 Setup and gNB-CU-UP E1 Setup gNB-CU-CP Configuration Update and gNB-CU-UP Configuration Update Reset, Error Indication, and Release gNB-CU-UP Status Indication. One noticeable difference compared with the F1 Setup discussed previously (which can be only initiated by the gNB-DU), is that both the gNB-CU-CP and the gNB-CU-UP are allowed to initiate the E1 Setup procedure once a TNL association between the gNB-CU-CP and gNB-CU-UP becomes operational. This generally follows the design principle of other NG-RAN horizontal interfaces (e.g. Xn) and is meant to facilitate the case in which more control- and user-plane capacity is added by an operator when the network evolves. Conse- quently, a race condition can occur if both a gNB-CU-CP and a gNB-CU-UP simultaneously perform the E1 Setup procedure. To resolve the issue, the specification clarifies that the net- work node that initiates the TNL association shall also initiate the E1 Setup procedure. If the setup procedure fails, the other network node may respond with the E1 Setup Failure message, carrying the "time to wait" indication during which it is not allowed to attempt reinitiation of the E1 Setup procedure. This is normally used during load spikes or tempo- rary issues, which are expected to pass within a reasonable time and pre