Towards a Hybrid Next Generation NodeB.

5G Radio Access Networks consists of two key services: User Plane Function (UPF) and next generation NodeB (gNB). Though several papers have recently demonstrated that the high-level UPF can be described in P4, for the lowest-level gNB service it is more challenging and cannot purely be done with existing programmable switches. In this paper, we show that gNB requires functionalities such as Automatic Repeat Request (ARQ) and ciphering/deciphering that are not supported by the high speed P4-programmable switches available in the market. To overcome these limitations, we propose a hybrid approach where the majority of packet processing is done by a high speed P4-programmable switch while the additional functionalities are solved by external services implemented in DPDK. The coordination of packets among the services is also handled by the P4-switch. Our preliminary results include the identification of functionalities required by a gNB node for delivering user data, the design of a hybrid architecture, and the performance evaluation of the buffering and re-transmission service. Finally, our measurements demonstrate that the proposed hybrid approach is scalable and could be an alternative to existing gNB solutions in the future.