RapidIO® Connections - Q4 2006

Association News

Next Generation Spec Release: Supporting Current RapidIO Deployment with a Roadmap to Higher Performance and Greater Functionality

By Tom Cox, Executive Director, RapidIO Trade Association

Tom Cox Photo

The importance of a roadmap takes on different context for engineers and technology managers depending on many factors which are unique to each individual’s current challenges. For many having a roadmap to the next faster, smaller and more efficient product, service or technology provides an insurance that their solution is future-proof. For many others who live on the very brink of technology’s leading edge, it represents a solution they believe they need now or sooner.

The RapidIO standard has a strong history of serving today’s requirements with widely available, affordable technology while at the same time mapping out and delivering on a roadmap to meet the needs of tomorrow. RapidIO technology was created with a layered spec which forms the foundation for ‘future-proofing’. The three layers of the specification can be modified, updated and added to individually while maintaining backwards compatibility and with interoperability in mind.

The RapidIO physical layer is one of the most apparent examples of feature and function additions to the RapidIO technology suite. The first physical layer defined by the RapidIO standard in 2000 was the Parallel LVDS I/O. This provided the lowest latency and the highest data throughput, critical for very high performance computing, and enabled RapidIO technology to develop a strong presence in military applications. The second physical layer defined for RapidIO technology was the Serial 1 Gbps, 2.5 Gbps and 3.125 Gbps XAUI interface. With 1x and 4x pairs defined, this serial RapidIO interface today is found on dozens of devices ranging from DSPs, CPUs and switches to endpoints, ASICs and FPGAs. This serial interconnect generation will service the bulk of the requirements for a wide range of market applications for the next 10 years or more.

The future of the RapidIO physical layer story does not end there, however. The RapidIO Technical Working Group has been defining the next generation physical layer spec over the past two years. The next added option for high-speed fabric interconnects in RapidIO is 5 Gbps and 6.25 Gbps with added options to channel widths. To be released later this year, the specification is currently in ballot for final open industry standards ratification. For many, 5 Gbps and 6.25 Gbps are beyond the current needs of the applications they support, but they represent an important option for the future for interconnection between individual fabric switch chips. Of course for a few facing the most demanding application requirements, this high performance is a requirement not matched by any other available solution. With the full backward compatibility with any flavor of RapidIO protocol and the ability to mix and match speeds and widths to the problem at hand, more speed and added options for granularity are appealing.

The new RapidIO technology spec also adds important logical layer functions. These logical layer and transport layer functions enhance the RapidIO interconnects’ data management capability. Driven by key system OEMs’ the new RapidIO spec adds significant data plane enhancements to offer carrier grade data fabric performance. These features include new data streaming packet format, addition of virtual channels (VCs) to serial physical layer, new endpoint flow control arbitration, and virtual output queue (VoQ).

Deployment of RapidIO technology continues to focus on high bandwidth with low overhead, a complete set of transaction types including memory mapped I/O, message passing, globally shared memory, and streaming data. The new functions of the spec will enable carrier grade data fabric performance with deterministic latency with end-to-end data management in a higher level of quality of service. Whether you are looking for the next step forward in technology now or in the future, the RapidIO standard delivers!

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