The 10X10 MSA: Niche, Distraction or the Right Answer?

By Vipul Bhatt, Guest Blogger

{For today’s blog, our guest author is Vipul Bhatt. Lisa has known Vipul for several years, since when he was the Director of High Speed Optical Subsystems at Finisar. He has served as the Chair of Optical PMD Subgroup of IEEE 802.3ah Ethernet in the First Mile (EFM), and the Chair of Equalization Ad Hoc of IEEE 802.3ae 10G Ethernet. He can be reached at vjb@SignalOptics.com.}  

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Last week, Google, JDSU, Brocade and Santur Corp announced the 10X10 Multi-Source Agreement (MSA) to establish sources of 100G transceivers. It will have 10 optical lanes of 10G each. Their focus is on using single mode fiber to achieve a link length of up to 2 km. The key idea is that a transceiver based on 10 lanes of 10G will have lower power consumption and cost because it doesn’t need the 10:4 gearbox and 25G components. But is this a good idea? What is the tradeoff? Based on my conversations with colleagues in the industry, it seems there are three different opinions emerging about how this will play out. I will label them as niche, distraction, or the right answer. Here is a paraphrasing of those three opinions.

It’s a niche: It’s a solution optimized for giant data centers – we’re talking about a minority of data centers (a) that are [already] rich in single mode fiber, (b) where the 100-meter reach of multi-mode 100GBASE-SR10 is inadequate, and (c) where the need for enormous bandwidth is so urgent that the density of 10G ports is not enough, and 100G ports can be consumed in respectable quantities in 2011.

It’s a distraction: Why create another MSA that is less comprehensive in scope than CFP, when the CFP has sufficient support and momentum already? Ethernet addresses various needs – large campuses, metro links, etc. – with specifications like the LR4 that need to support link lengths of well beyond 2 km over one pair of fiber. We [do] need an MSA that implements LR4, and the SR10 meets the needs of a vast majority of data centers, so why not go with CFP that can implement both LR4 and SR10? As for reducing power consumption and cost, the CFP folks are already working on it. And it’s not like we don’t have time – the 10G volume curve hasn’t peaked yet, and may not even peak in 2011. Question: What is the surest way to slow down the decisions of Ethernet switch vendors? Answer: Have one MSA too many.

It’s the right answer: What is the point of having a standard if we can’t implement it for two years? The CFP just isn’t at the right price-performance point today. The 10X10 MSA can be the “here and now” solution because it will be built with 10G components that have already traversed the experience curve. It can be built with power, density and cost figures that will excite the switch vendors, which may accelerate the adoption of 100G Ethernet, not distract it. As for 1-pair vs. 10-pairs of fiber, the first swelling of 100G demand will be in data centers where it’s easier to lay more fiber, if there isn’t plenty installed already. The 2-km length is sufficient to serve small campuses and large urban buildings as well.

Okay, so what do I think? I think the distraction argument is the most persuasive. An implementation that is neither SR10-compliant nor LR4-compliant is going to have a tough time winning the commitment of Ethernet switch vendors, even if it’s cheaper and cooler than the CFP in the short term.