Network Elements™ Debugs Complex Optical Networking Design with Novas
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Background
Network Elements is leading the drive to 10Gb/s optical networks through innovations in modular integration, high-speed optics, high-speed electronics, and wirespeed protocol processing ICs. These products address the core, metropolitan area, edge, server and test markets, providing the highest levels of performance and integration. Network Elements' products enable new classes of optical networking equipment based on flexible, scalable and configurable architectures.
Market demands solutions
As a widening variety of new and traditional services converge across shared inter-networking transport structures, there is a critical need for the Internet to simultaneously deliver high bandwidth, increasingly reliable service and greater deployment flexibility. Network Elements manages these complex demands by bringing a wide body of services together in a compact, highly configurable optical networking subsystem. In the high-speed, optics-based, multiprotocol Internet infrastructure, Network Elements' products provide efficient, reliable interconnection of high-performance routing and switching systems.
Internal IC design a key differentiator
In addition (and integral) to developing some of the most flexible and advanced optical networking subsystems in the industry, part of Network Elements' competitive advantage is its internal IC development team. This team is responsible for designing most of the unique silicon-based functionality that power the company's products. Network Elements' ICs are the core of their award-winning 10Gb/s modules.
Don Primrose, director of digital IC development at Network Elements, leads a team of IC designers at the company's Portland, Oregon headquarters. The IC development team is responsible for logic design, verification and debugging for designs that can approach 2 million gates in complexity. The team uses sophisticated design methodologies based on internally-developed IP.
"Our designs are large, complex and very datapath oriented - designed to accommodate multiple protocol standards," says Primrose. "In order to deal with this complexity we use an approach that provides quick and easy navigation through the hierarchies."
Newcomer introduces Network Elements to Debussy
It was the need to traverse hierarchies that first led Network Elements to Novas Software and its pioneering Debussy® Knowledge-Based Debug System. A new member of Network Elements' IC team was given the assignment to debug a large design portion without the benefit of having worked on the project directly. The employee agreed to tackle the challenge, suggesting the company equip him with Debussy, which he used at a previous company.
"We couldn't believe how quickly he was able to work through a completely unfamiliar design, investigating a wide array of problems," said Primrose. "After seeing how well Debussy functioned during its initial implementation, we've all started using it in our work. You can really see how effective Debussy is from the minute you start using it. It's extremely accurate."
Optimized for top-down design
Featuring the ability to link between its multiple design views, Debussy offers an impressive advantage for Network Elements' designers. "One of the major benefits Debussy provides is the ability to traverse seamlessly between waveform viewing and the RTL code itself," said Primrose. "It speeds up the process of finding bugs immeasurably. We can move from different views and quickly understand relationships between design elements. There are so many features in Debussy that let us reach into the design to analyze pins, ports, and nets - it gives us a very comprehensive view into the design."
Debussy includes tools for source tracing, schematic visualization and waveform viewing, as well as state machine analysis tools. It provides a highly intuitive method to trace and visualize design structure and correlate it with simulation results. This provides the ability to build a mental image of a design's behavior. Compared to waveform tools, Debussy dramatically cuts debug time, particularly at higher levels of abstraction.
Once the design is sufficiently verified at the RTL (Register Transfer Level), it goes through place-and-route and then is re-verified at the gate-level. Debussy plays a key role here, particularly through the use of the nSchema feature, a debug-specific schematic visualization tool tailored for use at the gate level of abstraction. nSchema also generates interactive logic diagrams that show the structure of selected portions of a design.
Network Elements uses an internally developed standard cell library for their ICs that also support the Debussy symbol library. "Once the library symbols are accurately represented, nSchema provides a schematic that is very user-friendly and easy to traverse," says Primrose.
Nuts and bolts in the lab
Network Elements' IC development team leverages Debussy's flexibility at multiple levels of abstractions and points in the design process. Using a Verilog-based methodology, they develop individual blocks at the RTL, using Debussy to debug at this level of abstraction, first. These blocks are then integrated at the chip-level and additional test benches are written to verify the design as a whole. The team especially likes the ability to store signal histories in Debussy's FSDB (fast signal database), which gives them the ability to optimize simulation speed, dump file size, and viewer load time while simultaneously capturing and storing the results from the designers' simulations. Network Elements also uses Debussy during static timing analysis, which helps complex connectivity and constraint issues.
Debussy helps in rolling out breakthrough product
Network Elements' IC team relied heavily on Debussy to meet a
demanding 
schedule
for its breakthrough design for the company's LiMPM, the
industry's first 10Gb/s optical networking module, integrating
multi-protocol processing with optical physical layer
functionality.
The Lithium IC, which powers the LiMPM, is also offered as a standalone multi-protocol chip with a 2-million gate design that features low power dissipation (typically <7 watts), advanced packet filtering and flexible SONET overhead processing. The Lithium IC provides configurable protocol termination for 10 Gigabit Ethernet, OC-192c Packet-over-SONET, and OC-192c SONET systems. The Lithium IC incorporates an OIF SPI-4 phase 2 interface for transferring system-side packets, an OIF SFI-4/802.3ae XSBI interface for connecting to PHY modules, an 802.3ae XGMII interface for connecting to PCS/PMD modules, and a 16-bit control interface.
"The Lithium IC demonstrates how we integrate high layer functionality into our products. It is a very critical technology for the company and key to our success in the future. We started using Debussy near the beginning of the Lithium IC project and saw a marked decrease in the time it took to address bug fixes. Our success is based largely on the rate at which we can identify a bug, fix it and move on with the design. Debussy allows us to do that very quickly."
Network Elements also benefited from Novas' commitment to customer support. "We routinely push the envelope in all of our designs, so we need a tool that is flexible and backed by quality customer support. We can't afford to be dealing with bugs in the tools we use. Novas Software offers quality products and Debussy is as stable a design tool as you will find," Primrose concluded.
Results that count
After racking up a bevy of awards and recognition* for their 10Gb/s designs, Network Elements is testimony that extreme attention to detail occurs at every level of product development, with rewards for those who exceed the industry standard. Novas Software's Debussy Knowledge-Based Debug System is a key component in Network Elements' arsenal of competitive differentiators, giving the company the edge it needs to win business while pushing the technological envelope.
*2002 R&D 100 Awards -R&D Magazine; 2001 Product of the Year -Electronic Products Magazine; 2001 Best of Show -N+I Conference/Network Computing Magazine; 2001 Finalist -Innovation of the Year -EDN Magazine