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Wide area all-optical networks are emerging as practical and future-proof solution to the enormous bandwidth requirements of today's end-users. Over the past few years, the field of all-optical networks has experienced tremendous amount of research, development, and prototyping activities. Control and management issues of all-optical networks, which are getting increasing attention in the research and development communities, are considered in this paper. We present a new approach for modeling call blocking probability in wavelength- routed wide-area all-optical networks. When an optical connection (lightpath) request arrives at a node, first a route and a wavelength along that route is selected to establish the requested connection. If an available route or wavelength doesn't exist then the connection is blocked at the source node. If a route and an available wavelength along that route are found then the wavelength along the different links of the route are reserved as soon as possible. However, reserving the selected wavelength on all the links of the route takes finite amount of time which is dependent on the propagation delays of the links and processing speeds of the nodes along the route. Hence, the selected wavelength on one or more of the links along the route might be reserved by another lightpath request while the set-up procedure of the previous one is in progress. One of the primary goals of this work is to study blocking of lightpath requests at intermediate nodes. Note that, although several researchers have studied blocking at source node in optical networks, to our knowledge blocking characteristic at intermediate nodes has not been studied earlier. A new lightpath set-up approach is also proposed. Simulation results show that the proposed approach can reduce blocking at intermediate nodes. Numerical results from analytical as well as simulation models are presented for various network configurations.
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