Techniques are described for providing a scaled-out transport supported by interconnected data processing units (DPUs) that operates as a single system bus connection proxy for device-to-device communications within a data center. As one example, this disclosure describes techniques for providing a Peripheral Component Interconnect Express (PCIe) proxy for device-to-device communications employing the PCIe standard. The disclosed techniques include adding PCIe proxy logic on top of a host unit of a DPU to expose a PCIe proxy model to application processors, storage devices, network interface controllers, field programmable gate arrays, or other PCIe endpoint devices. The PCIe proxy model may be implemented as a physically distributed Ethernet-based switch fabric with PCIe proxy logic at the edge and fronting the PCIe endpoint devices. The interconnected DPUs and the distributed Ethernet-based switch fabric together provide a reliable, low-latency, and scaled-out transport that operates as a PCIe proxy.