Efficient Distributed and centralized RWA protocols for WDM networks

Abstract

All optical Wavelength Division Multiplexing (WDM) based networks have improved the overall communication capacity and provided an excellent choice for the design of backbone networks. A Routing and Wavelength Assignment (RWA) protocol is used in such networks to choose a lightpath to satisfy the request. In order to handle the high traffic load that each link can carry efficient routing, survivability against failures and grooming to handle the huge bandwidth mismatch between high capacity lightpaths and low-rate individual traffic requests is critically important in WDM networks. We have suggested a methodology called Compromise newlineof Least Congestion and Shortest Distance (CLCSD) which employs route distance newlineand congestion parameters in the design of RWA protocols. Using this methodology newlineunder distributed scheme, we have proposed an alternate, exhaust-eventual and exhaust-instant RWA protocols. Parallel processing, destination initiated reservation based on conflict information, grooming and backup path sharing are used in the design of these protocols to improve the network performance substantially. Centralized management scheme with single Centralized Management System newline(CMS) is another approach to get optimal route. However, it is useful for small newlinenetworks. It is also vulnerable even to a single point failure. We designed a centralized management scheme with two CMSs. Under this scheme, RWA protocols are developed using different routing methodologies. It is observed that the newlineperformance gets affected if the traffic load or network size increases substantially. newlineTo overcome this limitation a method is proposed in which larger network is divided newlineinto sector networks having individual CMSs and a backup CMS connected to all of the sectors. If any of the sector CMSs fails backup CMS will takeover. Backup CMS also takes over the data transmission when the primary lightpath fails between sector newlineCMSs. This improves the efficiency and reduces the blocking probability of larger newlinenetworks.