Industry Insights

Foreward to System Interconnect Fabrics: Ethernet Versus RapidIO Technology, White Paper

By Linley Gwennap, principal analyst of The Linley Group

"An important trend in the embedded industry is the move from proprietary solutions toward standard interconnects and mechanicals (e.g. ATCA, Ethernet, RapidIO). Traditionally, Ethernet is the incumbent interconnect technology for embedded systems, yet the existence of alternatives has been driven by the realization that some high-performance applications exceed the limits of this traditional protocol. The RapidIO standard, with growing switch, DSP and processor endpoint support, has been deployed in many applications and continues to gain widespread support. RapidIO is particularly popular in wireless infrastructure equipment, where DSP connectivity is critical. As Ethernet and RapidIO continue to evolve, a comprehensive review and comparison is needed to help designers evaluate and select the protocol that best suits their next-generation designs.

"This white paper, System Interconnect Fabrics: Ethernet Versus RapidIO Technology, is a comprehensive compilation of embedded interconnect information. It provides a high-level market perspective and delivers a detailed technical examination of these two technologies. The paper begins with a top-level description of market requirements for the logical, transport, and physical layers, then moves into a thorough discussion of each protocol. The author builds a foundation for comparison and discussion through an historical overview of both RapidIO and Ethernet. Understanding the origin of these two standards helps to clarify their current use in embedded applications. A hierarchical side-by-side comparison of the two technologies provides detailed technical data, starting with the logical layer, and then moving to the transport and physical layers. Within each comparison is a discussion of the various distinctions of the interconnects, highlighting significant differences.

"In addition to the protocol discussions, this paper examines practical considerations such as power usage, throughput and latency as well as economic factors related to silicon die size/cost, the volume of silicon shipped, and the size of the silicon and support ecosystems. The author makes the case for Ethernet to continue gaining strength in the WAN and Internet markets while RapidIO becomes the preferred choice for applications that demand higher levels of performance and quality of service (QoS). In closing, the author provides a list of value propositions that should be analyzed by system designers as they evaluate how each interconnect best meets specific application requirements.

"System Interconnect Fabrics: Ethernet versus RapidIO Technology delivers a clear and complete analysis that engineers will find useful well into the future of these two successful technologies."