Dense Wave Division Multiplexing extends SAN's (In Practice)
By Elisabeth Putnam
Managed Wavelength Services, a new breed of broadband network based on Dense Wave Division Multiplexing (DWDM), promises to finally make it affordable for businesses to extend their SAN applications over fiber optic-based metropolitan area networks.
DWDM multiplexers such as Cisco's recently-announced ONS 15540, Nortel's OPTera Metro 5200 Multiservice Platform, Oni System's ONLINE family and Akara's OUSP 2000 divide a single fiber strand into dozens of channels, each of which can transparently support a different protocol/application. These protocols/applications include Fiber Channel, gigabit ethernet, Sonet or ATM.
This technology enables an enterprise or a service provider to distribute the high costs of deploying and maintaining a fiber infrastructure across multiple sites, applications, and users. A typical DWDM connection would support 64 unprotected or 32 protected channels (pairs of redundant channels for backup), each of which supports 2.5 Gbps or 10 Gbps.
DWDM also cuts the time required to deploy new bandwidth or services on an existing fiber strand down to weeks or even days, service providers say. In contrast, tariffed "lit fiber" services take 80 to 120 days to deploy.
Storage apps drive market
Storage applications will be a principal driver of this market, analysts and providers agree. Specifically, managed wavelength services target the many enterprises that want to manage storage resources across multiple sites, both to lower total cost of ownership and for disaster recovery.
"The advent of SANs has allowed companies to pool data and make it accessible to different user communities," says David Rush, a vice president at AT&T Solutions' DWDM-based Ultravailable Broadband Network service. "Now more and more companies feel the need to assure continuing availability and survivability of those resources by setting up mirroring and data replication across multiple data centers."
DWDM-based managed wavelength services provide customers with affordable fiber optic connections that have the high throughput and low latency required by Escon, Fiber Channel and Fiber Interconnection (Ficon).
Furthermore, in tests with leading SAN vendors like EMC and Brocade, DWDM boxes have successfully carried SAN traffic over 120 or even 200 kilometers?enough distance to ensure that a power outage or flood that affects one data center will not affect a remote backup site, for example.
EDS "absolutely sees a need," both internally and among its customers, for managed wavelength services for high end storage applications such as disaster recovery, says Jim Bonaquist, a senior engineer at the systems integrator. He adds, "As long as the fiber is already in the ground, it's relatively cheap."
At the moment, DWDM-based services are overwhelmingly concentrated in the tier 1 metropolitan areas such as New York, Chicago and Dallas. The main reason for this concentration pattern is the last mile problem: the cost of deploying new fiber out to customer sites means that service providers must target areas where many business sites are clustered.
Carrier will build out to customers
Competitive local exchange carrier XO Communications, for example, has extensive fiber installations in 62 cities, according to Jeff Le Sourd, broadband product manager. And if a customer site is not on its fiber network already, "We'll build out to them, as long as they give us enough business to justify the cost," he declares. This can be problematic, however, in cities like San Francisco, where it's extremely expensive to dig up streets, and Washington D.C., which has a moratorium on street construction.
In this early phase of the market, most of the contracts are being signed by service providers who want to get more bang from their fiber infrastructures, and storage service providers who want to resell wavelength service. Contracts are also being signed by extremely large companies in data-intensive vertical sectors such as financial and investment services.
A July 2001 Yankee Group report on Wavelength Service Providers projects that the market will only reach only $49 million in total revenue by year end. However, Yankee sees total revenues expanding to about $1.4 billion in 2004, and $3.65 billion in 2005. Already, established players like AT&T, Level 3, Metromedia Fiber Network, Williams Communications and Qwest are in the game, as well as startups such as Giantloop. [Add SBC]
DWDM service providers
Today's offerings also vary widely in terms of pricing structure, geographic distribution, and level of support, which means IT managers need to do some serious comparison shopping. Here are a few examples of what's out there now:
At the most basic level, a wavelength provider sets up a point-to-point, unprotected or protected DWDM connection and maintains it for the customer. Metromedia Fiber Network and XO both provide this type of offering. Their network operations centers take responsibility for the DWDM links, period. "Our demarcation point is the DWDM box," states XO's Le Sourd, adding it's up to the customer to manage how Fiber Channel and Escon connections and storage devices interact with the DWDM boxes.
MFN provides an unshared dark fiber connection. XO's Metro Wavelength Service, announced in July, provides capacities of OC-12 (622 Mbps), OC-48 (2.5 Gbps) and OC-192 (10 Gbps). Pricing is based on bandwidth commitments. For instance, if a user signs up for XO's 622 Mbps service, they will pay $12 to $19 per month per megabit. That amounts to $7,464 to $11,818 per month.
A typical pricing structure for a basic, protected (where each wavelength has a backup) 2.5 Gbps wavelength service is between $25,000 and $35,000 a month, with unprotected services as low as $10,000 per month, according to Nick Maynard, an analyst at Yankee Group. In contrast, a tariffed lit fiber single OC12 (622 Mbps) connection can run upwards of $100,000 a year. Based on conversations with a number of managed wavelength service providers, a Yankee Group report published in July estimates that basic, unprotected wavelength service runs 30 to 60% less than equivalent lit fiber bandwidth services.
A very different pricing structure applies to high-end managed wavelength services. AT&T Solutions' Ultravailable Broadband Network and Giantloop Network's PowerConnect typically enter into a multi-year contract in which the customer might pay anything from $7 million to $100 million over a five year period, according to a company spokesperson.
Service provider responsibilities
In return, the service providers will take end-to-end responsibility for a customer's DWDM-based network. This includes upfront design and deployment of equipment and circuits and ongoing operations, and maintenance and management that extends past the DWDM link to the customer's SAN and Escon installations. It further includes storage devices and applications. AT&T and Giantloop are also storage service providers who will host customers' storage resources on their own sites.
Once the infrastructure is deployed, the customer can add additional wavelengths at low incremental cost?between $2,000 to $5,000 per channel for AT&T's service. The idea is to leverage the fiber's multi-gigabit capacity as fully as possible with a variety of traffic, including Fiber Channel, Escon, gigabit ethernet, high-speed connections to the Internet and long-haul carriers' POPs.
"The more you scale up, the less cost per bit," reports Giantloop vice president Jon Oltsik. Customers generally get escalating discounts depending on volume of traffic, number of channels, and the term of the contract.
Customers are also paying for peace of mind. Both AT&T and Giantloop guarantee 99.999% availability managing not just for the wavelength, but for all the links and equipment.
Yankee's Maynard predicts a brisk demand for managed wavelength services. "Chances are, enterprise customers will want a more managed service because of the cost of finding or training skilled people to operate and maintain a private optical network," he comments.
Merrill Lynch, for example, recently signed up with AT&T to provide managed wavelength services among 11 major campuses in the New York, New Jersey metro area, Maynard notes. Economies of scale enable a managed service provider to run customers' connections much less expensively than can be done on an in-house basis, he added?even if the customer is a financial giant such as Merrill Lynch.
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