Optical Signaling and Control:  Opening the Door to New Ways of Building Networks
(continued)

In this simplified network example, it is easy to see the reduction of restoration capacity required for a mesh based architecture built with optical cross-connects (OXC) over an architecture based on SONET/SDH rings (SR). Each link shown interconnecting the nodes of the network represents optical channels provided over high capacity DWDM transmission systems that may extend over hundreds or even thousands of kilometers. Each optical channel can cost over $1 million to build. For this reason, the potential capital savings of mesh networks are greatest for service providers of long-haul optical networks. As the cost of the optical links increases, so does the potential for savings.

In addition to reducing costs, optical mesh networks give service providers new revenue opportunities. New services that address the increasingly dynamic nature of today’s end user’s service needs can be deployed providing true bandwidth on demand. Access to restoration capacity in optical mesh networks is readily available, and this capacity can be used to offer lower priority services and increase the revenue generating potential of the operator’s network. Today, the spare capacity required for restoration of SONET/SDH ring networks is difficult to access; establishing and managing services over that capacity is cost prohibitive.

The economic advantages of optical mesh networks are clear: increased revenue opportunities, lower capital costs, and reduced operating expenses. Hence, the deployment of optical switching technology promises increasing acceptance and growth over the next few years. According to an industry study released by RHK, the optical switching market is expected to exceed $5 billion annually by 2004. Already, major service providers like AT&T, Sprint, MCI, Qwest, and Level 3, just to name a few, have plans for significant investments in optical switching systems.

However, successful deployment of these dynamic networks presents service providers with a few key concerns. The complexity of planning, managing, and controlling optical networks based on mesh architectures is significantly greater than rings. The industry is begging for solutions that address these challenges. Emerging solutions with the capabilities to optimally plan, manage, and control optical mesh networks have the potential to remove obstacles to deployment and capture the value of efficient, flexible, and scalable optical mesh networks.

Quality of Service Must be Maintained

A significant barrier to realizing the equipment cost savings potential of optical mesh networks is high-speed restoration (less than 50 ms). In other words, mesh architectures must first be able to match the performance of SONET/SDH ring restoration before mesh networks can be realized. Without this capability, the quality of service required by many customers cannot be met, and the value of shared restoration capacity cannot be captured. This is a significant technical challenge requiring a high performance distributed processing environment coupled with a sophisticated signaling and control protocol. 

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