Biblio

Optical burst switching (OBS) is a candidate switching paradigm for future backbone all-optical networks. However, data burst contention can be a major problem especially as the number of lightpath connections as well as the overall network radius increases. Furthermore, the absence of or limited buffering provision in core nodes, coupled with the standard one-way resources signaling aggravate contention occurrences resulting in some of the contending bursts being discarded as a consequence. Contention avoidance as well as resolution measures can be applied in such networks in order to resolve any contention issues. In that way, the offered quality of service (QoS) as well as the network performance will remain consistent and reliable. In particular, to maintain the cost effectiveness of OBS deployment, restricted intermediate buffering can be implemented to buffer contending bursts that have already traversed much of the network on their way to the intended destination. Hence in this paper we propose and analyze a restricted intermediate Node Buffering-based routing and wavelength assignment scheme (RI-RWA) scheme to address contention occurrences as well as prevent deletion of contending bursts. The scheme primarily prioritizes the selection of primary as well as deflection paths for establishing lightpath connections paths as a function of individual wavelength contention performances. It further facilitates and allows partial intermediate buffering provisioning for any data bursts that encounter contention after having already propagated more than half the network's diameter. We evaluate the scheme's performance by simulation and obtained results show that the scheme indeed does improve on key network performance metrics such as fairness, load balancing as well as throughput.

Physical impairments in long-haul optical networks mandate that optical signals be regenerated within the (so-called translucent) network. Being expensive devices, regenerators are expected to be allocated sparsely and must be judiciously utilized. Next-generation optical-transport networks will include multiple domains with diverse technologies, protocols, granularities, and carriers. Because of confidentiality and scalability concerns, the scope of network-state information (e.g., topology, wavelength availability) may be limited to within a domain. In such networks, the problem of routing and wavelength assignment (RWA) aims to find an adequate route and wavelength(s) for lightpaths carrying end-to-end service demands. Some state information may have to be explicitly exchanged among the domains to facilitate the RWA process. The challenge is to determine which information is the most critical and make a wise choice for the path and wavelength(s) using the limited information. Recently, a framework for multidomain path computation called backward-recursive path-computation (BRPC) was standardized by the Internet Engineering Task Force. In this paper, we consider the RWA problem for connections within a single domain and interdomain connections so that the quality of transmission (QoT) requirement of each connection is satisfied, and the network-level performance metric of blocking probability is minimized. Cross-layer heuristics that are based on dynamic programming to effectively allocate the sparse regenerators are developed, and extensive simulation results are presented to demonstrate their effectiveness.