l domain and interacts only with the directly adjacent optical node. In the overlay model, the actual physical light path is decided by the optical network and not by the router. In the peer model, the IP/MPLS layer operates as a full peer of the optical transmission layer. Specifically, the IP routers are able to determine the entire path of the connection, including through the optical devices. The following resources may be included: Switching resources - packet switches FR, ATM, IP, time switches/SONET/SDH, wavelength switches, OXC, optical cross-connect, PXC, photonic cross-connect. Transmission resources - transmission resources are expressed in LSP hierarchies. Large LSPs carry smaller ones. Aggregation is performed upwards in the network in discrete units, 1 to 10 Mbit/s, 100 Mbit/s. Business aspects - GMPLS is expected to help operators dynamically provision band- width and capacity, improve network restoration capabilities and reduce operating expenses. Services such as optical VPNs may become profitable. backbone layer 3 and 2 Internet, Intranet Access 1 Access n Later: GMPLS integrating layer 1 to 3 SONET/SDH network or shim Fibre with windows Figure 12.20 An evolving view of the packet backbone, managing all kinds of traffic Understanding Changing Telecommunications - Building a Successful Telecom Business Demand for GMPLS should grow as IP traffic and services increase. A challenge for operators is to coordinate optical transport and IP administrative domains. For management a link management protocol (LMP) has been developed. There will be thousands of LSP to manage. Other supporting standards are: OSPF-TE (TE = traffic engineering) - auto-discovery of network topology RSVP-TE for establishment of LSP CR-LDP - constraint-based routing Figure 12.20 illustrates a possible MPLS/GMPLS based packet backbone design as an element of an all-service and all-access network. Access Network 13.1 OBJECTIVES The main objective of this chapter is to create an improved understanding of access networks at an overvi