Lightpath establishment without wavelength conversion based on aggressive rank accounting in multi-domain WDM networks

In multi-domain WDM networks, in order to establish inter-domain lightpaths across multiple domains without wavelength conversion, a lightpath establishment method based on rank accounting has previously been proposed. With the method, the inter-domain lightpaths are established with small blocking probability based on ranking databases for wavelengths; however, the performance of the method deteriorates when the ranking databases are not frequently updated. In this paper, we propose a lightpath establishment method based on aggressive rank accounting so that ranking databases are updated frequently. In the proposed method, border-node information is used in addition to wavelength usage information, and ranking databases for multiple nodes are updated simultaneously every time a lightpath establishment is processed. From the border-node information, accuracies of the wavelength usage information for each node are computed, and then the ranking database for each node is updated with the wavelength usage information and the computed accuracies. With the updated ranking database, each source node establishes an inter-domain lightpath without wavelength conversion to its destination node across multiple domains. We also present two implementations of the proposed method toward its practical use based on RSVP-TE signaling. We evaluate by simulation the performance of the proposed method, and we show that the proposed method provides smaller blocking probability than the conservative, conventional method when inter-domain lightpaths are not frequently established. We also show that the proposed method still provides smaller blocking probability even if routes of the inter-domain lightpaths change. Finally, we show that the performance of the proposed method is insensitive to the two implementations.