Tuesday, February 26, 2013

Extreme Ethernet: Where Science Clashes with Artistry & Magic

This article was originally published in September of 2012 on 10GbE.net.


There are three very different technologies which can be employed to pull the bits off 10 or 40Gigabit Extreme Ethernet, and deliver them to your application. The difference between them though is the difference between science, art and magic. Science is when something is completely understood, it can be reduced to a formula and replicated indefinitely. While art is science applied with creativity to produce a wider variety of solutions, but where the replication process is still chaotic. Magic on the other hand is a secretive craft approach to science taken to the extreme for the purpose of producing apparently unbelievable results. In ethernet these approaches map very nicely to: ASICs, processors & FPGAs.

The Application Specific Integrated Circuit (ASIC) is just what it’s name implies. An enormous collection of circuits etched onto a single chip to do a very specific well defined task. This is the science approach to Extreme Ethernet. Everything known by the design team is reduced to a fixed circuit architecture to produce a black box where one can easily map all the known inputs to very well defined outputs. Now to be fair there are often some additional registers, memory buffers, and circuits included in the design to make final adjusts and tweak things after the chip is in production. Once in production this approach is the least expensive and is in use by: Chelsio, SolarFlare, Mellanox, QLogic, Intel & Broadcom.

When you look at Extreme Ethernet as a form of artistry we’re talking processor instead of an ASIC. The difference between an ASIC and a processor is the difference between a cook and a chef. Both have access to ovens, appliances and ingredients, but a cook requires a recipe, while a chef can use any collection of fresh ingredients and produce a delightful dish. The difference is that the chef possesses knowledge, confidence and creativity. A chef knows what ingredients compliment each other, and can combine any number of ingredients together on the fly to create a never before seen meal without a recipe. At the core of the processor approach to Extreme Ethernet is the decision making engine which is in effect the chef. Often these processors have many of the same circuits found in the ASIC approach, your ovens, appliances & ingredients, but it is this decision making engine along with vast on chip memory buffers that separate it from ASICs. With a processor approach new recipes can be downloaded into these memory buffers to produce new solutions for ever evolving markets. Although this approach requires a substantially greater design effort, and is more expensive to produce it yields a far more flexible solution. Today only Myricom, and Emulex utilize this approach. 

Finally we have magic in the form of Field Programmable Gate Arrays (FPGAs). They combine the performance of a short order cook with the flexibility of a chef. FPGAs offer the speed of an ASIC, while enabling the ability to reflow the logical design on the fly to support new solutions or markets. Crafting new designs is non-trivial, some say magical, and requires real skills that are typically in short supply, and are very costly. Furthermore this flexibility often comes at a steep price. The hardware alone is often ten times that of a processor or ASIC based solution. Today Endace and Napatech are the lead vendors in this approach to the market.

So in the extreme ethernet market when you’re selecting a solution you can go ASIC, processor or FPGA. Which is like eating out at the Cheesecake Factory, McCormick & Schmick’s or the Magic Castle.

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