Changing the rules for developing optical solutions

Oct. 1, 1999

The development of optical networking will require new ways of thinking about technology.

The U.S. standard railroad gauge is 4 ft, 8.5 in. Instead of a figure that is easy to remember, or a round number that is quick to measure, 4 ft, 8.5 in is, and always has been, the distance between the rails of our railroad system. Why? England built its railroads using the measurement, and U.S. railroads were built by English expatriates.

England's pre-railroad tramways used the same gauge. The tramway builders used the same jigs and tools used for building wagons, and the wheel spacing on the wagons was 4 ft, 8.5 in. That odd wheel spacing allowed the wagon to travel on long-distance roads because it matched the old wheel ruts in the roads. The old rutted roads were built by the Romans and have been used ever since. Roman war chariots first made the ruts that everyone else matched to avoid destroying their wagons. Since the chariots were made for Imperial Rome, they all had the same wheel spacing. The chariots were made wide enough to accommodate the back-ends of two war-horses. As result, the U.S. standard railroad gauge of 4 ft, 8.5 in is derived from an original specification for an Imperial Roman army war chariot.

Few have questioned the logic behind railroad design--and, therefore, our railroad system serves as a perfect example of our common sense urge to avoid fixing what essentially isn't broken. The problem with that mentality is that it rarely leads to innovation. If you always do what you've always done, you'll always get what you've always gotten.

Creating innovative optical solutions in the transport layer is the next big challenge in the telecommunications industry. To do this, we must resist doing things as we've always done them. The appetite for bandwidth, services, and applications is growing at a rate that is unprecedented. Harking back to the old "4 ft, 8.5 in" days isn't good enough anymore. We must provide virtually unlimited bandwidth that is both cost-effective and reliable. Optical networking is the answer.

To be of value, optical networking can't be based on any particular technology; it must be based on certain characteristics or attributes that benefit the customer.

First, the next-generation optical-transport network must support multiple protocols, like Internet protocol (IP) and Asynchronous Transfer Mode (ATM). Second, it must provide flexibility in architecture and protection. Third, the network must be manageable. Current Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) systems excel in providing diagnostics to measure signal quality and locate network faults. New optical-networking equipment must provide the same level of manageability. Fourth, a degree of speed and protocol transparency in the optical-networking layer is needed in this new-age network. Fifth, accurate monitoring that can supervise signal performance is needed to get the advantages of implementing true optical networking for short- or long-haul networks. Sixth and most importantly, network technologies cannot take us backwards. The new technology must support not only future capabilities, but also those capabilities we enjoy today.

Achieving these attributes won't come easily. For example, an optical network needs crossconnects that allow information to come in on one wavelength and leave on another. A truly innovative optical network should have scalable devices with the ability to add or drop any wavelength at any location around a physical loop. Capturing four-fiber bidirectional line-switched ring SONET quality without replicating SONET technology also poses great challenges.

We have 100 years of experience switching electrical circuits but very little experience switching optical circuits.

Those are the challenges. Many companies say they are too great to overcome. They want to continue traveling on rails spaced at 4 ft, 8.5 in. A recent Forrester survey of 20 top long-haul and local service providers showed 75% did not believe optical technology will replace the existing SONET infrastructure. Their concerns included the infancy of optical products, as well as the need for scaleable devices. While we at Sprint share these concerns, we believe the solutions are at hand. The rewards are just too great not to move forward.

To begin, an optical solution can provide considerable cost savings by eliminating the SONET/SDH equipment in the backbone network. Reduced space and power requirements for fewer network components create cost savings. Also, fewer layers of equipment are needed if there is a common layer for all transport needs. Elimination of equipment also eliminates failure points, increasing network reliability, and dependability. Finally, increased bandwidth availability is perhaps the greatest benefit enabled by optical networking. An optical strategy--using the versatility and expansive potential of light--is the best way to provide multigigabits of bandwidth across the network.

Without core technologies like SONET/SDH and DWDM in the backbone, and without the determination and commitment to continually improve its ability, carriers cannot provide the bandwidth needed to run futuristic, bandwidth-hungry applications. Optical networking will allow the core network to scale in order to provide the consistent quality and availability of service our customers expect.

An optical solution is the next step in the evolution of the network because it allows the wide-scale use of future communications tools like Sprint's Integrated On-Demand Network (ION). Sprint ION is a next-generation communications platform that provides virtually unlimited bandwidth for simultaneous voice, video, fax, Internet, and data services over a single connection to business and residential customers.

Success is often earned with the perseverance and confidence to take intelligent risks, the risk in stating a vision, supporting it, and finding partners to help achieve it. We cannot afford to wait for 10 to 15 years to develop the next stage of the communications network. If we aggressively take this revolutionary jump, we are not guaranteed success. But if we do not move forward, we are guaranteed failure.

Because the future is not dependent upon one company, one person, or one idea, winning entails collaboration with partners. Vendor ingenuity is one of the primary necessities to developing useful optical-transport network solutions. It is incumbent upon us to find ways to work together to develop and deploy economical and technological innovations that stretch the capabilities of the network even further to produce the services and applications that businesses and consumers are demanding.

Industry alliances are critical to developing standards that make innovation useful. However random it was to build our railroad based on the specifications of a Roman war chariot, it was critical to the growth of transportation that everyone agreed on one standard to enable progress.

The same is true for our communications networks. Today, we call it interoperability. We must collaborate as an industry and agree upon standards that move us forward and leverage that synergy to reach new heights of invention.

Fred Harris is director of network planning and design at Sprint (Westwood, KS).

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