F1 Application Protocol (F1AP)
F1AP is the signalling protocol used on the F1 interface between a 5G Centralised Unit and its Distributed Units.
What is F1 Application Protocol (F1AP)?
F1AP carries control messages between the CU and DU, for example to set up the DU, manage each user's context and pass on RRC messages. Because F1 is an open, standardised interface, CUs and DUs from different vendors can work together.