 next hop. At the egress side of the MPLS cloud (the MPLS network point from where the forwarded packet must exit the MPLS network), the last LSR on the path will remove the label altogether and traffic will be forwarded using traditional IP-routing proto- col mechanisms. MPLS networks also use the concept of Forwarding Equivalency Class (FEC), which is a group of packets sharing the same attributes while traveling through the MPLS cloud. For example, these attributes can be the same destination address, some indication of QoS, or the identification of a spe- cific VPN. All packets belonging to the same FEC receive the same label from the LSR. Different pro- tocols such as the Label Distribution Protocol (LDP) exist that enable the LSRs to exchange the information that associates FECs with labels. The MPLS architecture enables carriers and service providers to offer new services, such as VPNs and service-level agreements (SLAs) with their cus- tomers, based on the sophisticated TE functions. The TE-related MPLS-TE capabilities are important in order to understand the concept of the Multiprotocol Lambda Switching (MPLmS) architecture, which is being developed to provide dynamic wavelength provisioning in the optical transport network that starts to take shape as part of the converged network. In addition, when the new optical networks are implemented, wavelength routers are used. These routers are made up of wavelength switching cross-connect matrix fabric pro- viding optical interfaces. Depending on the technology used for the switching backplane, the routers can be electrical wavelength routers, hybrid wavelength routers, and optical wavelength routers. 61,62 Electrical wavelength routers are usually deployed; however, hybrid wavelength routers are now appearing as a transition technology. All-optical wavelength routing seems to be the trend of the future technology, but many features and characteristics must still be researched and improved before this technology gains market acceptance. Even before intranets w