990. It was very important to the RBOCs: Earlier systems were proprietary, SO a given route was locked in to a single vendor's gear. SONET was a standard that allowed multiple-vendor interoperability and thus allowed for more com- petitive bidding. The first round of SONET gear installed in the early 1990s ran at OC-48 (2,488 Mbps). That was technologically exotic and difficult to The Deuteronomy Networks implement, given that the microprocessors of the day only ran at about 2% of that speed. But as semiconductor and optical technology improved, faster speeds became possible. The next major speed bump in SONET was to OC-192, almost 10 Gbps. And OC-768, near 40 Gbps, has been produced. These speeds do not run reliably, at least not very far, on some of the oldest single-mode fibers, but the boom years were accompanied by improvements in fiber itself, SO these speeds are achievable. But that is not the only way to increase fiber capacity. Because the semi- conductor lasers used for fiber optics transmit on precisely a specified wavelength ("lambda") [12], it is possible to have multiple wavelengths of light share a sin- gle strand of fiber. In the earliest systems, it was possible to have two, four, or maybe eight lambdas. This WDM was the trick that everybody had up their sleeve. But as the boom moved along, WDM technology improved. Optical engineers were able to position the lambdas very close together-100 GHz apart, in some systems-such that a single fiber could carry several dozen lambdas. This came to be known as dense wavelength division multiplexing (DWDM). Investors rushed in, buoyed by forecasts of massive Internet growth. But of course the demand did not happen. Few carriers actually needed DWDM. Most of the fibers in the ground still were not lit with even a single lambda. The upshot was that by the early 2000s, the industry began to emphasize "coarse" WDM (CWDM), with only a few lambdas on the fiber. CWDM is cheaper to implement and adequate for most users. In the unlikely event of a fiber shortage, DWD