The Migration to Optical Networking

There are still many challenges to building a pure optical network. Optical networks are expensive and require a wide range of new equipment and systems, including Tbps switch routers, pure optical switches, DWDM and CWDM muxes, optical cross-connects, optical repeaters and regenerators, optical components and integrated photonic circuits, new generations of fiber-optic cable, new fiber construction approaches, and, of course, optical network maintenance and management tools.

Some of the challenges to building a pure optical network include the fact that incumbent carriers are not healthy financially. They traditionally build only when there's proven demand and return on investment. Many new entrants have basically gone bust. Carriers can no longer afford the "if you build it, they will come" strategy. There's a glut of optical bandwidth in the backbone already, with rapidly falling prices, and there is a lack of new, high-bandwidth killer applications (although, as discussed in Chapter 10, "Next-Generation Networks," we are finally beginning to see prices stabilize and demand for bandwidth grow). Nonetheless, many such applications are under development and increasingly entering the realm of commercial deployment. It's only a matter of time before we start to see the all-optical network come to be.

As discussed in this chapter, the goals of optical backbones include the migration from ring to mesh topologies; greater control of connections; the ability to provision circuit-switched bandwidth on demand; the extension of the reach of optical links to thousands of kilometers without amplification or regeneration; the integration of DWDM or CWDM with switches to reduce cost and complexity; support of increasingly higher speeds from OC-768, or 40Gbps, to levels we've not yet defined; and scaling of switches to hundreds or thousands of lambdas per fiber port. Given the continuing growth in processing power and storage, the development of bandwidth-hungry applications, the growing demand for broadband connectivity, and the unique properties of the optical spectrum, there is little question that the next-generation network infrastructure will be based on end-to-end optical networking.