In the last decade we have witnessed a rapid growth in data center systems, requiring new and highly complex networking devices. The need to refresh networking infrastructure whenever new protocols or functions are introduced, and the increasing costs that this entails, are of a concern to all data center providers. New generations of Systems on Chip (SoC), integrating microprocessors and higher bandwidth interfaces, are an emerging solution to this problem. These devices permit entirely new systems and architectures that can obviate the replacement of existing networking devices while enabling seamless functionality change. In this work, we explore open source, RISC based, SoC architectures with high performance networking capabilities. The prototype architectures are implemented on the NetFPGA-SUME platform. Beyond details of the architecture, we also describe the hardware implementation and the porting of operating systems to the platform. The platform can be exploited for the development of practical networking appliances, and we provide use case examples.