This dissertation aims to evaluate the changes that are occurring in the telecom operators’ optical network infrastructures to suit to the new services offered to their customers. These services demand increasingly flexibility, reliability and capacity from all optical network layers, from access to long-haul and metropolitan backbone, including aggregation layer. On access, the main transformation is the extension of the optical fiber to points closer to the customers using PON (Passive Optical Networks) technologies in order to offer higher bandwidths. With this strategy it is possible to enable applications and services diversification, like interactivity high definition video. It is also verified important changes on the metropolitan backbone. It is observed the need of improving the transport capacity (multiple 40 Gbps or 100 Gbps wavelengths) using DWDM (Dense Wavelength Division Multiplexing) and OTN (Optical Transport Network), with wavelength routing using ROADM (Reconfigurable Add-Drop Multiplexer) and electronic switching. This high-capacity network is connected directly to the access or aggregation networks, which are able to efficiently carry packet-based traffic. In this context, traditional solutions based on TDM (Time Division Multiplexing) are replaced by solutions best adapted for packet transport with reliable quality of service. This same high-capacity metropolitan network should also be connected with the regional and longhaul networks. This work will give special attention to the access network topologies and metro backbone described above, comparing architectures and related investments.