SAN MATEO, Calif. Last year's crop of multiservice aggregation equipment for the metropolitan network is already being challenged, as new vendors promise similar gear that uses all-in-one switch fabrics rather than the multifabric boxes currently proposed.
Coriolis Networks Inc. (Boxborough, Mass.) announced such an architecture last week, and fellow startup Ocular Networks Inc. (Fairfax, Va.) is due to disclose some of its plans today, just in time for the Next Generation Networks conference in Washington. At the same time, semiconductor vendors such as ZettaCom Inc. (San Jose, Calif.) and Onex Communications Corp. (Bedford, Mass.) are developing the chips to drive these sorts of systems.
Being addressed is the variety of data that pours into the metro ring, carried by a multitude of protocols: Ethernet, asynchronous transfer mode or even plain time-division-multiplexed Sonet. The goal is to let carriers combine this traffic into a single stream often in Sonet form for transport into the metropolitan network.
Wave-division multiplexing allows carriers to provide multiple data streams on one fiber-optic cable by assigning different wavelengths of light to each stream. The problem is that most customers don't need a full wavelength's worth of bandwidth. So to get the most profit from their cables, carriers have to offer subwavelength services often at the DS-3 (45-Mbit/second) level.
Suppliers of multiservice provisioning platforms (MSPPs) in many cases are saying they are the ones that will efficiently merge all those services into larger pipes, allowing service providers to accommodate more customers.
"You need those aggregation boxes to provide those lower-bit-rate services and be able to aggregate them up," said Steve Georgis, chairman and chief executive officer of optical startup Network Photonics Inc. (Boulder, Colo.).
Systems from the first group of MSPP vendors the likes of Cyras Systems Inc. (Fremont, Calif.) or Metro-Optix Inc. (Santa Clara, Calif.) solved the problem with multiple switching fabrics inside one box. But critics maintain that the existing suppliers don't have the wide expertise required to handle every type of traffic.
"Quite a few of the MSPPs focus on one of the services first," said Paul Liesenberg, director of strategic marketing for ZettaCom. "I don't know of a single box that really will provide a huge number of services right away."
Also, in a multiservice box, the operator has to guess what proportion of the traffic will use each protocol and add line cards as necessary.
Freeing up slots
In addition, "You start adding those multiple switch fabrics, they start taking up slots that you need for port density," said Doug Green, vice president of marketing for Ocular. "Most of these multiservice platforms introduce a layer of complexity that cancels out the cost savings they bring."
Ocular claims to stand apart from other MSPP houses by putting hard emphasis on Sonet time-division multiplexing in its upcoming systems. TDM, the scheme telephone companies use to carry voice on fiber-optic lines, remains in high demand, but Green said that most of the multiservice platforms have had to add TDM as an afterthought.
"The people that build data products don't put timing or enforcement in them they don't want to take that on," Green said. Ocular says it hired TDM experts from the start, making it possible to fold TDM services as well as data-transport expertise into its architecture.
Ocular also is taking advantage of off-the-shelf parts wherever possible. The company is using a merchant network processor and a generic switch fabric, for example, putting its systems' switching intelligence into five ASICs, different combinations of which will go into different chassis.
"We are doing the minimum [silicon development] that we have to," Green said. "By distributing that function out in our ASICs and keeping the switch fabric itself simple, it helps us in scaling that product, because we don't have to attach switch fabrics from different vendors and figure out how to scale each one."
Ocular isn't yet disclosing which switch fabric and network processor it's using, nor is the company describing the functions of its five ASICs.
For its part, Coriolis' multiservice platform uses proprietary algorithms to pack traffic efficiently onto Sonet lines. The company's OptiFlow systems are similar to add-drop multiplexers, but they can pack multiple types of traffic onto one Sonet stream using a technique Coriolis calls optical space-division multiplexing (OSDM).
"The reason we're doing this over Sonet is because every carrier, to be successful, has to carry TDM traffic," even though that's not where the real money is, said Greg Wortman, Coriolis' vice president of marketing.
While Sonet handles data in increments of 1.5 Mbits/s, OSDM offers a 500-kbit/s granularity, making for more efficient packing of traffic, said Wortman. Statistical multiplexing and Coriolis' proprietary algorithms help achieve those results, he said.
"We don't attempt to go through the costly process of converting everything into cells or everything into packets. We transport everything in its native mode," Wortman said. "Most of the hybrid-traffic systems on the market today are doing protocol transition, and that adds overhead."
Under OSDM, TDM traffic is allocated in fixed, "nailed-up" connections, Wortman said. Various users also are allocated guaranteed bandwidth according to their service agreements. On top of that, Coriolis adds some wiggle room that can be allocated dynamically, accommodating sudden bursts of traffic on a best-effort basis.
The number of MSPP vendors is growing, and each company claims to have a unique spin on the concept. But even before that market jells, some companies see a new potential: to build the system that will switch MSPPs' output traffic around the metropolitan network.
That zone, loosely labeled the "metro core," is being targeted by Coriolis with its OptiFlow trunk units. But at least one startup is concentrating solely on the metro core: Network Photonics, which last week raised $106.5 million in venture financing. Network Photonics believes that as MSPP vendors improve the efficiency of traffic aggregation, a bottleneck will begin to form around the metro core, opening up a need for its products.
The company's switches "still a year out from introduction to the marketplace," chief executive Georgis said would be similar to those being developed for the long-haul network. But the company is targeting just the metro network for now.
"The core network can handle higher cost," Georgis said. "The low-cost nature of our technology makes us the only company capable of providing wavelength switching and routing in the metro [area]."
The big bucks Network Photonics garnered in its funding round stem in part from its ambitious plans: In addition to designing proprietary systems for dense wave-division multiplexing, the company is developing its own chips and even its own manufacturing tools.
Key to the whole operation is Network Photonics' proprietary all-optical switch fabric. Several companies are pursuing that kind of technology but haven't yet reached volume shipping. Georgis wouldn't say whether Network Photonics' all-optical fabric will bear similarities to existing schemes such as MEMS-based micromirrors or polarization filters.
"We're having to develop our own manufacturing process for that," Georgis said. "It's a very special, proprietary process. We're having to develop all of the tooling, all of the automation, in house."