ng uplink TNL address information for S1-U or NG-U (for comparison, in the one-step procedure the Bearer Context Setup Request message contains downlink TNL address information for F1-U, as well as uplink TNL address information for S1-U or NG-U). 2. The gNB-CU-UP responds with a Bearer Context Setup Response message, containing uplink TNL address information for the F1-U and downlink TNL address information for the S1-U or NG-U it has assigned. The message indicates that one or more bearers are established in the gNB-CU-UP. 3. The F1 UE Context Setup procedure is performed to set up one or more bearers in the gNB-DU. 4. The gNB-CU-CP sends a Bearer Context Modification Request message, containing the downlink TNL address information for F1-U. 5. The gNB-CU-UP responds with a Bearer Context Modification Response message, indi- cating that one or more bearers, which are terminated at the gNB-DU, are established in the gNB-CU-UP. Bearer Context Modification Required Procedure The purpose of the Bearer Context Mod- ification Required procedure is to allow the gNB-CU-UP to inform the gNB-CU-CP that the Bearer Context Modification procedure has been completed or that a modification is required. Relevant E1AP messages include Bearer Context Modification Required and Bearer Context Modification Confirm. Similar to Bearer Context Setup procedure, TNL address information is still one of the most important IEs defined for these messages. The procedure is arguably another design relevant to virtualization, as it can be executed when the gNB-CU-UP needs to modify a bearer context and to inform the gNB-CU-CP, due to, for example local problems or virtual machine (VM) migration. It is well established that 4 NG-RAN Architecture cellular networks have so-called tidal effects where the traffic periodically and significantly changes over time. When the network is underutilized, performing VM migration to con- solidate computing resources and shut down unused VMs could save energy. The details of live VM migration including transf