Availability-Based Survivability Study In Optical Networks

High-capacity and large-scale optical networks are the trend of continuousdevelopment. At the same time, the probability of network failures, especiallywhen multiple faults occur simultaneously is also rising. To address theproblem of persistent transportation of services, survivable optical networksemerge, as the times require.Currently survivability mechanisms mainly focus on a single link failure.However, the expansion of the network makes multiple faults occurringsimultaneously more and more often, which means current mechanismsdesigned for single link failure are difficult to guarantee the survivability ofservices. In contrast, providing quality of service (QoS) guarantees isbecoming more and more important for service provides. Availability is animportant measure of network survivability and QoS, specified in the servicelevel agreement (SLA), which is defined as the probability that the service isin the operating state. Just because of this, we study the availability analysismodel and the availability-based survivability algorithm in survival opticalnetworks, respectively, for quantitatively evaluating QoS on availability andoptimizing network resources while ensuring QoS on availability.Availability-based survivability evaluation model for optical networkssynthesizes the state space analysis and reliability block diagram analysis. Bythe approximation to the actual network, it is solved to quantitatively evaluateconnection availability under shared risk link group constraints when differentsurvivability mechanisms are used. Simulation results show that the accuracyof the model is much higher than existing models, and the theoretical valuesthat the model predicts and the simulation values are highly consistent.For the availability-based survivability algorithm design in opticalnetworks, the existing research splits the problem into two problems (i.e.,survivability algorithm design and connection availability evaluation). Different from that, we first calculate the contribution of every link (orchannel) in the protection path to the whole connection unavailability. Set thevalue as the link cost, then the availability-guaranteed survivability algorithmdesign problem is turned into the survivability algorithm design problem. Onthis basis, the algorithm using shared path protection strategy is proposed.Simulation results show that the algorithm is better than dedicated pathprotection mechanism, and currently shared path protection mechanism onAvailability Satisfaction Rate, Resource Overbuild and Blocking Rate.