This paper presents architecture for a user plane function (UPF) in the mobile packet core (MPC) targeting 5G deployments. This paper’s discussion begins by analyzing the various functions required in UPF by modeling packet streams, architectural partitioning of functionalities between software and hardware, and how various packet sizes affect the UPF’s overall performance. From the analyses, several functions are identified in which packet processing can be efficiently optimized by using various software and hardware designs. The functions are integrated to achieve a high-performance UPF architecture using standard rackmount servers and leveraging network functions virtualization (NFV) technology. In particular, using a single unit of rackmount server, Intel and SK Telecom: • Decomposed the user plane pipeline into smaller functional modules • Analyzed how different partitions and pipelines affect performance of packet processing • Iteratively developed and aggregated modules for software and hardware • Estimated an eventual greater than 200 Gbps throughput