e vendor position is determined by the fact that ION implementations require more network equipment and Customer Premises Equipment (CPE) than OTN implementations. Currently, optical communication is mainly limited to dense wave divi- sion multiplexing (DWDM) point-to-point systems. All-optical networks are expected to see increased penetration in the next few years. These trans- parent optical networks (which eliminate optical-to-electrical-to-optical [O-E-O] conversions) offer the cost-effectiveness that is necessary for infra- structures supporting near-term as well as long-term services. However, when Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) networks are replaced, the optical network needs to provide SONET-like functions such as protection; switching/routing; Operations, Administration, Maintenance, and Provisioning (OAM&P); and perfor- mance monitoring. IONs require a control mechanism to support dynamic session estab- lishment and routing over the underlying optical network. One of the ques- tions of interest in ION scenarios is whether the lightpath establishment must be end to end (thereby affording the customer complete service con- trol) or only in the core of the network (thereby affording the carrier ease of backbone provisioning). These two scenarios appear in Figure 7-1. Control mechanisms have been proposed for adoption from intranet-based routing developments in multiprotocol label switching (MPLS). MPLS is an enabling technology for next-generation networks that was originally con- ceived to combine the flexibility of Internet Protocol (IP) hop-by-hop routing with the quality of service (QoS) and traffic-engineering benefits of connec- tion-oriented cut-through Layer 2 protocols such as Asynchronous Transfer Mode (ATM). In its generalized manifestation, MPLS is becoming one of the central elements of the ION architecture. The carriers' acceptance of end-to- end user session establishment remains to be demonstrated, however. Pre- vious efforts at signaling for packet s