Section: M.5 IAB inter-CU topology adaptation and backhaul RLF recovery procedure
Content: In case of the inter-CU migration as specified in TS 38.401[ NG-RAN; Architecture description ]  [78], the IAB-MT is migrated from a source IAB-donor-CU to a target IAB-donor-CU. The migrating IAB-node becomes a boundary IAB-node since its IAB-DU retains F1AP with the source IAB-donor-CU after its IAB-MT obtains RRC connectivity with the target IAB-donor-CU (c.f. TS 38.401[ NG-RAN; Architecture description ]  [78]). In case IPsec tunnel mode is used for F1 interface protection, the migrating/descendant/Recovery IAB-node may use MOBIKE (IETF RFC 4555 [111]) to migrate the IPsec tunnel to the new IP outer addresses as specified in TS 38.401[ NG-RAN; Architecture description ]  [78].