# Programmable Data Plane Applications in 5G and Beyond Architectures: A Systematic Review
## 4 Findings and Discussion
### Characteristics of the Reviewed work  
[PERSON] et al. [44] propose a transparent edge gateway (EGW) for MEC in LTE or 5G networks. This solution is implemented on P4 smart NICs, enabling content delivery at the edge of the transport network by parsing the inner IP headers of GTP-U messages. In their subsequent work [45], the authors incorporated mobility support for the handover process, aiming to minimize the number of application state migrations. [PERSON] et al. [46] introduce a GTP engine for MEC in 5G networks, which offloads the encapsulation and decapsulation of the tunneling protocol to a P4 FPGA board. [PERSON] et al. [47] present a P4 switch that implements stateless translation functions for both GTP and SRv6 (Segment Routing IPv6) protocols. This approach enables the coexistence of both protocols within a 5G network, facilitating a gradual transition towards full adoption of SRv6. [PERSON] et al. [48] implement evolved packet gateway (EPG) offloading by employing P4 switches to perform functions such as GTP and VXLAN (virtual extensible local area network) encapsulation/decapsulation, IP routing, and stateless firewall. In their follow-up work [49], the authors present a hybrid pipeline design for 5G gNB and UPF. P4 smart NICs and switches were used to handle most of the packet processing, while unsupported functions such as ARQ (automatic repeat request) and cryptography were performed using DPDK (data plane development kit). [PERSON] et al. [50] introduce a hybrid approach to packet processing in gNB that employs a P4 switch for most of the workload and outsources additional tasks, such as ARQ and  
Figure 10: Use case distribution of implementations from reviewed articles. Figure 9: Architecture placement distribution of implementations from reviewed articles. ciphering, to DPDK external services. This approach allows for a more efficient utilization of hardware resources and better scalability of the system. [PERSON] et al. [51] present a P4-based solution to improve the performance of the edge-to-core network data path in 5G multi-tenant environments. The proposed solution leverages P4 FPGA boards to handle encapsulation protocols such as VXLAN, GTP, and GTP over VXLAN, enabling efficient traffic routing and forwarding. In their subsequent works [88; 89], the authors introduce a firewall system for 5G multi-tenant scenarios that supports traffic detection, differentiation, and selective blocking in the backhaul network. The firewall rules are stored in the TCAM (ternary-content-addressable memory) table of the P4 FPGA boards. Moreover, in [72; 73], the authors design and implement a network slicing framework for the edge-to-core network segment that allows for the creation of different slices based on a 6-tuple consisting of user source and destination IPs, user source and destination ports, differentiated services code point (DSCP), and GTP tunnel ID. The framework is deployed in a smart grid self-healing automatic reconfiguration use case in [74], i.e., uRLLC traffic. [PERSON] et al. [52] leverage P4 switches to implement a network slicer and a UPF for handling different types of traffic in a 5G testbed. Specifically, they use P4 switches to implement the transport network slicing functionality as well as the data plane functions required for supporting mMTC, eMBB, and CIoT traffic. NIKSS [53] is a software switch implemented in P4. It features a PSA (portable switch architecture) eBPF compiler that translates P4 programs into executable code. This device has been programmed to function as a 5G UPF for evaluation purposes, demonstrating its capability to handle a range of protocols, including IP, UDP, and GTP-U. [PERSON] et al. [54] implemented two 5G UPFs. The first is a model UPF implemented as a P4 software switch, with the PFCP interface defined as a series of match-action tables based on packet metadata. This approach provides developers with a useful starting point for creating full-fledged UPF implementations for specific hardware targets.