rier is simply trying to support automated fiber provisioning (off of a service order), medium-sized distributed OXCs controlled from a network management station will suffice. Depending on the per-cable fiber count and the number of fibers that are to be flexibly assigned, switching matrix size may start with 64X64. For real-time lambda switching/routing, a full-fledged optical switch will be needed. Wavelength-switching devices (A switches) enable the switching of each wavelength path independently; dynamic switching is supported via a signaling mechanism. Figure 7-9 illustrates the concept of optical label switching (OLS). To realize the full promise of OLS, additional technical advancements are needed, including efficient wavelength conversion, optical packet buffer- OLS Packet Forwarding Path Figure 7-9 SWAP label/header in packet The concept of OLS. Ingress Egress Edge LSR Edge LSR Core LSRs Add OLS header Remove OLS header OLS Packet Header MPLS Label Duration Flags All-Optical Networks ing, contention resolution technology, optical reamplify, reshape, and retime (3R) regeneration, and efficient burst-mode receivers. Observers indicate that efficient use of a WDM optical layer requires wavelengths to be viewed as a shared resource-not as individual pipes between edge devices. OLS holds the promise for switching optical packets on a per-packet, per-flow, and per-circuit basis.8 A retardant factor to the introduction of ION is that incumbent carriers are not motivated to crosscannibalize lower-speed services that have a high revenue per bit, such as T1s and Frame Relay, with high-speed lambda ser- vices.9 Unfortunately, many new-generation communications carriers who would provide such services have been forced out of business by the nega- tive environment created by the CLECs and Digital Subscriber Line LECs (DLECs) who promised gross margins of 80 percent to venture capitalists and payback (EBITDA positive) in one to two years. When the venture cap- italists discovered that these statements were completely