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Optical/IP

Chips Brace for 40-Gig

Need proof that 40 Gbit/s is getting close? Folks at this week's Network Systems Design Conference were talking specifics about how the transition to OC768 is starting out and which technology aspects could be the most problematic.

The conclusion: In the transition to 40 Gbit/s, the pressure is on the electronics, not the optics.

Granted, some optics apologists were present -- the panelists were all from the chip industry, after all. But the point was this: Carriers want the network to not just handle 40 Gbit/s, but to be optimized for services such as IPTV, and to embody the network convergence they've been working on.

Many of the concerns at 40 Gbit/s stem from how to properly handle video and other applications in this environment. These jobs fall on the system electronics. "It really is more a features problem than an optics problem," said Anthony Torza, a systems architect with chip vendor Xilinx Inc. (Nasdaq: XLNX).

That's much different from the transition from 2.5 Gbit/s to 10 Gbit/s, where optics was the star. Torza was a board designer at Ciena Corp. (Nasdaq: CIEN back then, and he recalled how the company even had to build its own fiber Bragg gratings.

In contrast, the optics industry began preparations for 40 Gbit/s during the bubble and has been waiting for its chance to deliver ever since. (See 40-Gig Begins Its Ramp.)

Torza said another difference from the 10-Gbit/s transition is the 40-Gbit/s transition is happening in the metro market and not in the core. Carriers expect broadband video to drive most of this bandwidth demand, and video often comes from local sources, not the network core. "There are players in the long haul, but where the money is, is in the metro," he said.

So, what are these difficult jobs the chips are asked to do?

One is traffic management, which involves separating packets into queues and selecting which packet gets transmitted next. This is crucial when it comes to juggling VOIP or IPTV feeds. Bigger pipes mean more user flows are juggled, making the queuing more complex. How a designer solves that problem will have implications on the rest of a system.

"Traffic management is actually a system-level problem. We're talking about chips here, and it's often easy to overlook the fact that traffic management is not a complete solution. If you had the perfect traffic manager, it could still fail at the system level," said Ofer Iny, CTO of Dune Networks.

Similarly, interfaces become more challenging at 40 Gbit/s. There's less time available to shift data into and out of memory.

Chips might also face the usual challenges of power and speed as 40-Gbit/s requirements emerge. Often, these problems solve themselves as chips shrink, but that might not be the case here, said Bill Weisinger, director of sales and business development for Bay Microsystems Inc.

"You can't just rely on the manufacturing node to get you to the next point and the next speed," Weisinger said. "There's a question of how you get 40 Gbit/s in and out of a payload buffer."

But is 40 Gbit/s is really happening? According to the panelists, it's real, but they conceded that volumes remain low and prices high. What's important is that carriers are beginning to think they'll need OC768. "The market-perception perspective is happening right now. The price perspective is going to come later," Torza said.

For now, 40 Gbit/s is starting out as four lanes of OC192 rather than a single OC768 feed; systems geared for 40-Gbit/s links will have to support both approaches, panelists said.

— Craig Matsumoto, Senior Editor, Light Reading

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WildRumpus 12/5/2012 | 2:56:37 AM
re: Chips Brace for 40-Gig Craig:

There were once a lot of players in this space (e.g., Ample), many of whom didn't make it. Who's left or about to jump back in? Is it real this time?
Stevery 12/5/2012 | 2:56:36 AM
re: Chips Brace for 40-Gig Yes, 40-Gig was around a while back; the point here was that some of the nuts and bolts turn out to be a bit different than expected, because of the emphasis on services rather than force-fed bandwidth. Torza is the one who really pressed this point on the panel, and I thought it was an interesting one,

One item that seemed ambiguous in the article: None of the people/companies quoted have shipped any 40G to my knowledge. (Is this right?) So my first read of the article was "here is our excuse for not being able to pull this off yet." As the previous poster said, cisco has been doing 40G now for some time. So what exactly is the chip problem?

Is it an inability to do the 40G design or a system definition issue?

Anyway, in light of the fact that there are 40G chips already out there, your article left me confused. (which is not that hard to do, I admit. :)
Pete Baldwin 12/5/2012 | 2:56:36 AM
re: Chips Brace for 40-Gig Gotman -- Thanks for the comments. Yes, I thought about the 100-Gig Ethernet stuff while writing this, but the topics are a bit different. The discussion at NSDC centered around the more pragmatic details of 40-Gig, rather than the more research-level 100-GigE.

Plus, a lot of the discussion on 100-GigE is about preliminaries, such as where the standard ought to go -- it's still very early (not that that's going to stop us from doing a 100-GE story or two between now and New Year's.)

Yes, 40-Gig was around a while back; the point here was that some of the nuts and bolts turn out to be a bit different than expected, because of the emphasis on services rather than force-fed bandwidth. Torza is the one who really pressed this point on the panel, and I thought it was an interesting one, especially given his past perspective at Ciena ... your mileage may vary, as always.
gotman 12/5/2012 | 2:56:36 AM
re: Chips Brace for 40-Gig First, i'm surprised that Craig didn't start off by discussing his own artical. LR staff: what's the story? I've noticed a trend the last few month of you guys starting a thread or asking a question about the topic you just wrote about, why can't you make "that" interesting question part of your artical?

To the topic, 40G is nothing ground braking anymore, i'm surprised these folks are winging about the challanges of building 40G chips, transponders or whatever.. We start off the week with ground braking 100GE from Lucent and we end it with "I can't get my head around building 40G". Cisco had 40G chips and optics for 3 years, why can't these guys do it...
Drew Lanza 12/5/2012 | 2:56:34 AM
re: Chips Brace for 40-Gig I just don't get this OC-768 40 Gbps thing. I never did and I never will.

I get 100 Gbps Ethernet, although I think the actual deployment of it in any volume is a long, long, long way off.

What am I missing? CMOS can barely handle 10Gbps. It'll be another two or three generations before it can handle 40 Gbps.

It's a heck of a lot cheaper to multiplex in the optical domain using WDM than it is to multiplex in the time domain (TDM). And OC-192 WDM technology is mature.

I'll make a wager that that the OC-768 market NEVER exceeds the OC-192 market, either in dollars or in ports shipped. And I'll make a wager that 100 Gbps Ethernet doesn't exceed 10 Gbps Ethernet in dollars or ports in my lifetime (I turn 50 next year).

Dinner at Birk's. Any takers?

Drew
Roshani 12/5/2012 | 2:56:33 AM
re: Chips Brace for 40-Gig I think that the challenge isn't about making 40G work in one system vendor's lab. It is more about making it commercially available and viable. So you need more than a single source supplier for various components needed for a 40G solution across various platforms (not just the core router blade in Cisco's case).
Stevery 12/5/2012 | 2:56:33 AM
re: Chips Brace for 40-Gig
And when do you think OC-192 will exceed OC-48?
Scott Raynovich 12/5/2012 | 2:56:32 AM
re: Chips Brace for 40-Gig yeah good point. duh. Either way it's dinner with "geezer Drew" or "Dead Drew." This ain't happening soon.

Drew, bad bet for you!

o-man 12/5/2012 | 2:56:32 AM
re: Chips Brace for 40-Gig Drew,

Dinner at Birks is a very cheap way to get your attention to discuss a real topic like "PON". Knowing that you are one of the first people to actively discuss the PON topic...
you probably have really great insights!
paolo.franzoi 12/5/2012 | 2:56:32 AM
re: Chips Brace for 40-Gig
Scott,

Wrong way round.

If higher speeds win, that will have to be before Drew dies. And you win a dinner.

If lower speeds win, that will occur at Drew's death. And you take his ghost to dinner.

seven
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