ervices based on the User-Network Interface (UNI), Frame Relay services, and ATM services have all received lackluster market response (and carrier support) in spite of the copious developments in the standards arena. Nearly all Frame Relay and ATM services are based on permanent virtual connections. This would point to a value of ION in the core tier of the overall network as a mechanism for a All-Optical Networks Figure 7-1 Top: Lightpath establishment by carrier only Bottom: User-accessible lightpath establishment ION options. GMPLS GMPLS carrier's internal traffic engineering and restoration, rather than an end-to- end capability. It is not that the concept is unsound any more than the con- cepts of International Telecommunication Union Standardization Sector (ITU-T) Q.931/ISDN, Q.933/FR, or Q.2931/ATM are unsound;1 it is just that accepted cost-effective solutions are historically lacking in the market. The control mechanism per se will be covered in the discussion of Generalized MPLS (GMPLS) in Chapter 8, "GMPLS in Optical Networks." Chapter 7 7.1 Background and Drivers for ION This section looks at the business and user landscape within which optical networks have to be deployed. Innovation in optical components and trans- port technologies has been steady over the last few years and the same is true of optical switching. The optical industry has advanced the concept of ION as a control apparatus for the OTN. ION affords a transition from hybrid electro-optical networks to fully optical networks. This technology also supports a dynamic, multiwavelength, mesh-oriented design with a real-time signaling mechanism. Data-oriented handoffs such as Gigabit Ethernet (GbE) and 10 GbE are increasingly becoming an important end- user requirement for intranet connectivity across a wide area network (WAN). ION is an approach to optical networking that enables the delivery of services, such as the ones just mentioned, over lightpaths (lightpaths are high-capacity, all-optical channels). Specifically, ION maps services o