It has been a decisive goal in the compilation of this thesis to make us capable of realizing the future national and regional telecommunication networks in an efficient and resource optimal way. By future telecommunication network is assumed an all optical network where the information in transit are kept optical and not converted into the optical domain. The focus is on the scientific results achieved throughout the Ph.D. period. Five subjects – all increasing the understanding of optical networks – are studied. Static wavelength routed optical networks are studied. Management on terms of lightpath allocation and design is considered. By using statistical models (simultaneous analysis of many networks) the correspondence between parameters determining the network topology and the performance of the optical network is found. These dependencies are important knowledge in the process of designing a network. It is also seen (statistically) found that the effect of wavelength converters on the performance of static wavelength routed optical networks is negligible. Dynamic wavelength routed optical networks are simulated and analyzed. Manangement of dynamic networks is a more complex task than the static case. Several strategies are considered. The alternative study with reel networks as alternative to computer simulations would have been extremely costly or impossible. Different routing methods have been used and studied. The effect of wavelength conversion has been analyzed and contrary to static optical networks the effect of wavelength converters on dynamic optical networks is significant. The effect on blocking probability of multiple fibers on each link is shown to be significant, and it is concluded that neither limited-range nor full wavelength conversion will find any significant use in all-optical network. Fairness is suggested as a new measure for network performance in line with network blocking probability. Teletraffic is studied for several purposes. Erlang’s fixed point equations have been used verify some results of simulation of dynamic optical networks. An explicit solution for network blocking probability has been derived, and fixed point equations for alternate routing are derived. Secondly is self similar traffic studied and the effect on optical networks considered. The Synchronous Optical Hierarchy is suggested as a new type of network to overcome the technological hurdles of packet switched optical networks and without the capacity granularity problem in wavelength routed optical networks. This new proposal is exactly formulated and experiments are performed to estimate the strengths. In networks, where the typical size of a traffic demand between two nodes is up to two wavelengths, significant capacity savings are possible. Network planning in the form of optimal design of national and regional telecommunication networks is thoroughly studied and promising computer programs and methods are developed. In the optimization process are both duct, fiber, and switch equipment cost considered. The contribution in network planning are one of the most important contributions with direct usability.