Impairment aware routing in metropolitan area optical networks

Impairment aware routing is considered to be a necessary precondition for the migration from opaque to all-optical networks. In opaque networks, the signal is regenerated at each node so that signal impairments are eliminated. However, in transparent optical networks, the optical signal reaches the receiver without having been regenerated, and, therefore, it accumulates all the impairments that have occurred along the path. The selection of paths that guarantee the required signal quality, taking into account physical impairments, does not always provide the best solution in terms of network parameters (e.g., blocking probability). We propose a new scheme that integrates routing and wavelength assignment (RWA) with a new impairment constraint based routing (ICBR) algorithm to achieve an optimal combination of physical and networking performance. This new scheme also takes into account chromatic dispersion and filter concatenation impairments (not used by previous ICBR schemes). The proposed RWA also helps in network savings by requiring less equipment in managed reach networks (e.g., transceivers, dispersion compensators, etc.). Performance engineering studies with the proposed scheme have been done on metro networks, both transparent and managed reach networks.