Blocking-Differentiated Path Provisioning in Semi-Dynamic Survivable WDM Networks

Abstract

A post path calculation process considering the flexibility of rerouting backup paths is proposed in this paper to achieve blocking-differentiated path provisioning for two classes of connection requests in semi-dynamic optical networks. IntroductionIntelligent optical networks, supported by wavelength division multiplexing (WDM) technology, are widely considered to be the direction of infrastructure migration for future backbone networks. With the tremendous bandwidth offered by WDM, network survivability has become one of the most critical requirements for seamless service provisioning since a single fiber cut can cause a large amount of traffic loss. Among the various survivability techniques developed, shared path protection (SPP) is a promising candidate due to its resource efficiency property resulting from backup capacity sharing.When serving dynamic lightpath demands in shared-path-protected (SPPed) WDM networks, research work focuses on new and improved routing algorithms [1] to reduce the blocking probability, which is a key measure of network performance as well as quality of service (QoS) provided to service subscribers. It is desirable to have lower blocking probability because a rejected connection request means reduced network revenue and degraded service satisfaction. The work in [2] proposed to reduce the blocking probability of incoming connection requests which cannot be accommodated at the arrival instant by retrying the provisioning within their tolerable connection setup time specified in the service level agreements (SLAs). For a decrease in blocking probability up to 30 percent, the average delay tolerance is set to 0.2 times of the average holding time. However, the tolerance value might be too large and thus unacceptable for the customers when the average holding time of the requests is on the order of several days (e.g. 100 hours), referred to as semi-dynamic lightpath demands in this paper.Meanwhile, with the advances of optical networking technologies, various differentiated service provisioning frameworks were developed to offer multiple levels of service performance. Such frameworks are significant to network operators because these frameworks provide feasible solutions for the network operators to increase their revenue from their infrastructure by accommodating different QoS requirements of different clients [3].Could service be prioritized in terms of blocking probability? A lightpath length estimation based scheme was proposed in [4] to provide differentiated request blocking performance for two classes of label-switched-path (LSP) demands in overlay IP/MPLS-over-WDM networks. In this paper, we propose an approach for achieving blocking-differentiated lightpath provisioning in SPPed WDM networks with two connection request classes. The basic idea of the approach is to maximize the carrying of high-class requests by allowing backup path rerouting of the existing flows. With the in-service working paths stay unaffected, the backup paths could be rearranged as often as one wishes [...