Ciena's coherent path to 100G and beyond

Staff Writer
14 Mar 2011

Packet-optical technology isn’t just about 100G data speeds, says Ciena VP and general manager for APAC, Anthony McLachlan. It’s about cost-effective, scalable, automated mesh architectures that simplify network management.

Let's define our terms first, because vendors approach this differently: What is Ciena’s vision/concept of a packet-optical solution?

Anthony McLachlan: Most of our new and existing customers tend to have some form of existing TDM or Sonet/SDH infrastructure. So if you look at that from a photonics point of view, it means migrating the TDM and Sonet/SDH components into an OTN and Ethernet aggregation switching infrastructure. Coupled with that is a mesh architecture, so you get better utility from the capex, better network performance, and the ability to drive automation across that. For Ciena, that means things like control plane capabilities to provide simplicity and better user interfaces for customers.

What are the traffic trends driving 40G and 100G?

There are several trends here playing out. Clearly carriers are accelerating deployments of broadband access networks both wired – we’re seeing a lot of PON rollouts, for example, and faster DSL speeds – and wireless networks. And on the wireless side, smartphones and video are driving a lot of that. That’s creating a challenge for carriers because typically their backhaul, distribution, and bandwidth management networks were all being dimensioned around TDM-based voice traffic.

Also, in the business markets we’re seeing Fast Ethernet connections to the premises or the desk all the way to 1GE connections, and in some cases 10GE connections. That can also include video and backup/recovery-based requirements, as well as businesses driving towards the cloud. That’s putting pressure on the metro networks and then back into the distribution networks. Carriers in the wholesale market have to cope with this as well, in terms of how they scale their networks. Another group with an interesting perspective on it is the content and media providers, who are buying bigger chunks off carriers.

Cost has been a typical barrier for 40G. How is that changing?

We have seen volumes increasing and you do get some cost advantages there from economies of scale, but it’s also about how collapsing networks onto a 40G or 100G channel knocks off a lot of other network costs attached to a 10G wave, in terms of provisioning or how you dimension the line systems – though in our case we don’t need to do that. But customers are looking for better capital efficiencies, and going from 10G to 40G, or 40G to 100G, is providing that.

Ciena describes its packet-optical solutions as “Coherent 40G and 100G”. What exactly does that mean?

In the simplest terms, “coherent” is really a receiving technique that allows us to provide greater reach over a network instead of having to regenerate the signal. With Telstra, for example, we did 2,000 km at 100G with our coherent technologies, without the need for regeneration. And with 40G, we looped it around and brought it back again to show we could go the ultimate distance. The other aspect is that there’s a lot more spectral efficiency for the fiber to get better fill.

In addition, we have a DSP technology which we call EDC (Electronic Dispersion Compensation), that is about software techniques to manage chromatic dispersion and PMD (Polarized Mode Dispersion) within the fiber electronically, rather than replacing the fiber or managing it with fiber spooling through the line system. That provides a lot more flexibility and, coupled with the coherent technology, you get better utilization on older fiber, as well as new fiber, to be able to get the reach and performance at higher bit rates. There’s no lack of innovation in this space, and we’re working in our labs to drive this even further to terabit levels. The ActivFlex 6500 Packet-Optical Platform is now on its seventh generation, and there’s a lot of runway left on it.

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