E1 Application Protocol (E1AP)
E1AP is the signalling protocol used on the E1 interface between the control-plane and user-plane parts of a 5G Centralised Unit.
What is E1 Application Protocol (E1AP)?
When a gNB's Centralised Unit is split, the CU-CP uses E1AP to set up, change and release bearer contexts in the CU-UP. This means the two parts can be scaled and located independently, and can even come from different suppliers.