and optical switches. Routing protocols-GMPLS uses routing protocols for selecting paths through the network. The routing protocols used include OSPF, IS-IS, and GMPLS deals with several interfaces: packet switch capable (the only interface supported by MPLS); Layer 2 switch capable, which recognize frames and cells; TDM, which forward data based on the data's time slot; lambda switch capable, which work on individual wavelengths much like optical cross connects; and fiber switch capable, which work on individual or multiple fibers. GMPLS is a peer-to- peer network in which every participating label-switched router sees the entire net- work design. The generic functions in the GMPLS control plane are mapped into different functional modules, including the resource management module, the connection module, the protection restoration module, and the main module. The resource management module is used for routing and wavelength assignment, for topology and resource discovery, and for support of QoS. It uses an OSPF-based routing protocol similar to that of GMPLS. The connection module is used for light path signaling and maintenance. In the GMPLS control plane, RSVP-TE or CR-LDP is used for the signaling. The protection restoration module is dedicated to fault monitoring and fast protection and restoration. The objective of the main module is to receive the incoming messages and work closely with other modules to pro- cess the requests. In summary, GMPLS allows service providers to dynamically provision resources and provide the necessary redundancy for implementing various protec- tion and restoration techniques. As Figure 11.17 shows, we're in the midst of evolution. Those practicing pure IP solutions today look toward MPLS and DiffServ to administer QoS and manage their networks effectively. The early optical net- IP Solution MPLS + DiffServ Optical IP+Optical GMPLS Figure 11.17 GMPLS, a unified end-to-end solution The IP+Optical Control Plane works look toward MPLS as a control plane. In the future, the marriage