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Wavelength by the slice
In a new twist on optical networking, carriers are learning how to provision individual wavelengths to customers, enabling them to manage their own bandwidth on their own terms
PAT BLAKE
You can slice it. You can dice it. You can cut it up and pass it around. Wavelengths may not exactly be the fruit de jour, but they are ripe for the picking in a new application called managed wavelength services.
This is the micromanaged approach to optical networking, where individual wavelengths are assigned either to specific protocols--such as ATM or IP--or to specific customers. Instead of selling capacity of an entire dark fiber, carriers lease individual wavelengths in what amounts to a wholesale venture from the optical layer. This highly efficient use of glass opens the door to a new way of thinking about serving up wavelengths.
Because offering such services can be tricky, most carriers seem to be in the early stages of deployment. A few U.S.-based carriers, such as Williams Communications and Metromedia Fiber Networks, are offering managed wavelength services, and the industry may learn a lesson or two from Global TeleSystems Group, which is deploying wavelength services in a European network that it is building out. And not surprisingly, many vendors are lining up to provide the optical equipment to help them get there.
Clean strands a la carte
The brokers of bandwidth usually choose a side of the geographic median, marketing either to the long-haul carriers or to the metro market. Williams proves more democratic by catering to both.
Debuting one of the first managed wavelength options, Williams is rolling out its Optical Wave Service--expected later this year--across its 17,600-mile fiber network. With Wave, Williams controls the bandwidth from which wholesale customers lease individual wavelengths of OC-48 speeds on a clear--or unprotected--channel (Figure 1). Subscribers either can co-locate in a Williams' point of presence (POP) or use long-reach interfaces to connect to the router and transponder equipment from Sycamore Networks.
In the Wave setup, customers provide a 1310 nm frequency and can connect to ATM equipment on their end. The service is best suited for data carriers that can use their equipment for protection switching and restoration. It's less expensive than Williams' private-line package with an overhead transparency that can complete the Sonet ring, if needed. Figure 2 shows how Williams' Wave service differs from traditional dark fiber offerings.
"The good part of this service is that it's low-cost, and it's provisioned essentially as an unprotected service," says Sunita Krishna, product manager for Williams. "It's different from Sonet because the Wave service does not have a work channel and a protect channel."
When it provides private-line services, Williams deploys Sonet equipment at the edge of the network, Krishna says. "The Sonet equipment provides equipment diversity, fiber diversity and route diversity," she says. "Because our Wave service is unprotected, customers need to use ATM if they need [redundancy]." In other words, customers can use their own ATM switch or an IP edge router to add equipment redundancy (Figure 3).
Managing the dark side
Known for its history in backbone bravado, Williams makes a wavelength play in the urban sprawl through a fiber swap with MFN. MFN is another groundbreaker in the managed bandwidth market.
In the mile-for-mile exchange, Williams gives MFN dark fiber in the WAN, and MFN supplies Williams with dark-fiber access to office buildings in 30 cities. Williams pitches Wave on the local scene through the MFN connection. Compact versions at OC-12 and possibly OC-3 are planned for the metro area some time next year.
In the meantime, MFN puts a private spin on its own version of wavelength management in the metropolitan last mile.
Instead of assigning separate wavelengths, MFN leases an entire dedicated dark fiber to each client. Customers then can purchase MFN's WaveChannel to route different protocols over each individual wavelength. "Customers can lease the underlying fiber infrastructure at a fixed price. That is our value proposition," says Nick Tanzi, senior vice president of MFN.
"They are not getting charged per byte whether they run 100 Mbytes or 100 terabits," Tanzi says. "It doesn't matter. They pay the same amount of money."
MFN uses Nortel Networks' OPTera family of products to lease its fiber. The company currently is building out its network in 12 of the U.S.'s largest cities and is entering the European market in Germany, Holland and the U.K.
From famine to feast
The limited number of domestic carriers prepared to unveil managed wavelength services is a sign of its complexity.
"We see a huge demand for what we call [the] wavelength-on-demand kind of applications," says Bob Goel, vice president of IP network engineering and advanced technology for Qwest Communications. Although the data-focused carrier has no near-term plans to deploy individual wavelengths, Goel says that the carrier is "definitely working toward that application and testing all the capabilities."
One of the sticking points in the development of managed wavelength services is the optical cross-connect.
"Right now, the optical cross-connects are still in the development stages. There's really not one out there that's ready for prime time, but we are working with a vendor to provide that feature," says Wayne Price, chief technology officer of network architecture for Williams.
An optical cross-connect solves two problems for the deployment of wavelength services, Price says. First, it gives carriers the ability to provision bandwidth automatically instead of deploying technicians into the field. Second, the optical cross-connect allows service providers to build mesh optical restoration, which gives them the flexibility of running different kinds of restoration in their networks.
"What we're trying to do is also build a network that will offer quality of service over the optical infrastructure; a network that guarantees restoration," Price says. "So if you want Sonet-like restoration, you can get it in 50 milliseconds using cross-connects, but you can also do re-routable, which would give you two to three second restoration. Then you could do unprotected service, and each one of these levels would have different costs associated with them."
Cross-connects and other optical enablers garner their fair share of attention. But to focus solely on these elements may be putting the cart before the horse.
"People jump to rearranging wavelengths and optical cross-connects because it's sexier," says Kathy Szelag, vice president of marketing for Lucent Technologies' optical networking group. "But the hard and fundamental problem is being able to deal with each wavelength individually, to know its personality. If you can't do that, an optical cross-connect does you no good."
To understand what's happening on the wavelength, it must be monitored. Then it can be routed and rearranged across different carriers' networks. That capability takes intelligence.
In June, standards bodies agreed on a way to add such intelligence to the optical layer. They selected WaveWrapper--the nonproprietary approach written by Lucent--which uses a digital wrapper or header that is attached to every wavelength. As the wavelength moves around the network, the nodes read the header. It scans for originating and terminating details, information about whether it's an IP or ATM signal and commands such as strong forward error correction.
"That's the first step: to add enough intelligence to the optical layer so that you can do the same kind of things you can do with Sonet now," Szelag says.
Protection and restoration top the menu of favorite items that carriers lack without the Sonet layer. That's why near-term network designs still will make accommodations for Sonet. Its huge embedded investment also will keep carriers' purse strings tied to this standard approach until their networks are robust enough to operate without it.
Standing room only
Differentiation among vendors is already part of the blossoming field of wavelength services and optical services in general. Their varied means of enhancing access to the wavelengths all work toward the same end: easily assigning specific slices to individual customers and protocols. Although many of these solutions still are in the development stage, vendors are poised to launch products that will help lead carriers to offer managed wavelength services.
Ciena--the first to create a 16-channel dense wave division multiplexing (DWDM) system--is hammering away at the bottleneck that backs up the access. "A huge amount of bandwidth in the long-distance network comes to a choke point when you hit the access area," says Denny Bilter, director of marketing for Ciena. Ciena's solution is a single platform that eliminates the need for much of the traditional equipment such as add/drop multiplexers (ADM), channel banks and routers.
Likewise, Avici Systems aims to decrease the number of boxes on a network with its terabit switch router. But its philosophy promotes virtual private line services on top of packet infrastructures.
With a minority interest owned by Cisco Systems, Corvis stakes out its territory in the ultra long-distance and optical switching of wavelengths. And Monterey Networks--which soon will be a sister company to Corvis, thanks to its acquisition by Cisco--employs its proprietary wavelength routing protocol to increase network intelligence in its Series 20,000 Wavelength Router (Figure 4).
"At a basic level, our hardware for the wavelength router is no different than that for a classic cross-connect. The difference is the protocol intelligence," says Michael Zadikian, co-founder and vice president of marketing for Monterey. "Without this intelligence, every device is a cross-connect."
Traditionally, for a carrier to create end-to-end connections, it must give explicit commands to each of the devices along the way, telling them to connect one port to another, Zadikian says. "[Our product] allows all the wavelength routers to communicate with one another rather than having a human being tell them at every junction, 'Make this connection mapping between this wavelength and the other.' These decisions are made automatically."
In the metro area, Optical Networks offers an optical transport system and data networking capabilities that emphasize multiplexer flexibility.
"We deliver wavelengths to any point within a city, connected in either point-to-point rings or meshes," says Hugh Martin, president and CEO of Optical Networks. "We do this with a WDM system and other equipment that provides functionality like dynamic optical [ADM]. You can have a wavelength that initiates at a tera-POP and needs to go to one location. At a later point, you can say, 'I don't want that dropped there. I want it to drop somewhere else.' We have the ability to do dynamic optical add/drop. And this is a key functionality if you are delivering a wavelength to a customer."
Across the pond
Global TeleSystems Group has a lesson for all newcomers to the slice-'em-up world of wavelengths. Although GTS is based in Washington, its current primary market is in Europe. The carrier encircles that continent with several photonic alternatives, including putting IP directly onto the optical layer. It also sells raw wavelengths to customers who add their own synchronous digital hierarchy equipment and then manage that slice themselves.
GTS' no-frills offering was rolled out in the spring to an enthusiastic audience. The response was so overwhelming, in fact, that twice the amount of capacity was used for the service than GTS originally expected, says Jim Reynolds, president of network services for GTS.
"It's not an issue for us to turn on twice the capacity. So at a cost level, we don't worry terribly about it. But what we've discovered is that we were wrong by a factor of two in terms of how much bandwidth would be consumed at the price point. So our first issue in moving to wavelengths was nothing to do with the technology. It was all to do with making the commercial decision [of how much] to sell the thing."
With the cost of optical components down by 40% in 1998 and expected to drop another 40% in 1999, watch for a veritable smorgasbord of wavelength management entrees to take shape.
Pat Blake is a freelance writer based in Cedar Rapids, Iowa. |
