y the PVC service has seen wide- spread deployment and market interest. ATM supports both provisioned (PVC) and signaled (SVC) connections; only the PVC service has seen deployment of any scale.6 7.1.3 Mechanisms to Support ION In order to be able to enjoy dynamic bandwidth allocation (DBA), particu- larly in the core where you want to control traffic management, a control mechanism must be deployed. Historically, optical components are manu- ally configured and require a certain amount of time to affect a network- impacting reconfiguration; new control mechanisms (both in the transport plane and control plane) are needed. In addition, it is also important that all Table 7-1 IP Router/Label SW/Router OXC/Optical Switch Comparison of Routers and OXCs Forwards packets based on IP Switches optical signal from the input or label header port to output port Recognizes packet boundaries Does not recognize packet boundaries Electrical or optical interfaces Optical interfaces only O-E and E-O conversions for each May perform O-E-O or 0-0-0 for each packet entering/exiting the system signal entering/exiting the system IP control plane Control plane for dynamic reconfigura- tion of optical switch fabric Many sizes and speeds ranging from OC-48, OC-192, and OC-768 framed small metro access up to terabit signals All-Optical Networks the optical network elements involved be integrated into an end-to-end management system that facilitates full OAM&P functionality. The MPLS model developed by the Internet Engineering Task Force (IETF) can provide the signaling mechanism for IONs when applied to an optical network. MPLS is now a subset of GMPLS-one candidate to con- trol the OXCs and optical switches. A theoretical advantage to GMPLS is its capability to work with a single integrated control plane, controlling both the IP and the OTN in an IP over OTN network scenario, which basi- cally equates to the ION. Figure 7-8 shows this scenario. In such a wave- length-routed optical network, lightpaths are set up between endpoints to mee