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Use Case and Reference Architecture

The 5G xHaul architecture encompasses three physical segments referenced as Fronthaul, Midhaul, and Backhaul. Refer to Figure 1 .

Figure 1: 5G xHaul Reference Network A diagram of a computer network Description automatically generated

Fronthaul segment enables Layer 2 connectivity between the Open Radio Unit (O-RU) and Open Distributed Unit (O-DU) (shown as RU and DU in the Figure 1 ) in the RAN. This allows them to communicate for control, data, and management traffic to ensure time and frequency synchronization between RAN elements. Because low latency is crucial (must be below 150µs from RU to DU), the Fronthaul segment has very few network elements, typically limited to one or two hops.

The advancement of the RAN involves different architectures for 4G, including distributed, centralized, and virtual setups, which need to coexist with the 5G disaggregated O-RAN. These diverse ecosystems provide flexibility for the placement of components such as O-DU and O-CU. This JVD does not cover all possible scenarios but closely aligns with O-RAN split 7.2x, where the O-RU connects to the CSR and the O-DU is located within the HSR infrastructure. If needed, additional insertion points can be implemented to support disaggregation between the Midhaul and Backhaul segments by extending appropriate services.

Figure 2 summarizes the deployment scenarios for the RAN according to the ITU-T for simultaneous support of 4G and 5G as proposed by the O-RAN Alliance.

Figure 2: RAN Deployment Scenarios for Simultaneous Support of 4G and 5G A screenshot of a computer Description automatically generated

The ACX7024 Universal Cloud Metro Router is ideally built for the CSR role, supporting 24 ports of 1/10/25 GbE and 4x100 GbE shared across 360 Gbps system throughput. The use case under consideration is the insertion of the ACX7024 as part of the 5G xHaul solution (5G Fronthaul Network Using Seamless MPLS Segment Routing and 5G Fronthaul Class of Service JVDs) and validation of its scale, performance, and functional capabilities when used as a CSR in the 4G/5G Fronthaul network.