For the past decades, data traffic demand considerably increased in volume and quality due tornthe advent of capable end-user devices and innovative data services. To accommodate thernhighly increasing data traffic volume and customer demand for service with better quality, anrnautomatic switched optical network (ASON) with different routing and wavelength assignmentrn(RWA) algorithms and resilience mechanisms are used. Previously different researchersrnevaluated performance of different resilience mechanisms and RWA algorithms separately byrnconsidering an ideal highly connected network with ideal uniform traffic demand/connectionrnrequest. This issue can force telecom operators including Ethio-telecom to implement theirrnbackbone network based on vendor recommendation. rnIn this thesis, first, performance of four adaptive RWA algorithms was evaluated consideringrnblocking probability and average throughput as QoS metrics under different three resiliencernmechanisms considering a practical Ethio-telecom north circle backbone network topology andrnits traffic demand scenario. Secondly, performance of the three resilience mechanisms wasrnevaluated under routing algorithm selected from routing algorithm evaluation consideringrnblocking probability, recoverability and average network throughput as QoS performancernmetrics. Finally, network topology connectivity degree effect on the performance of 1+1 DPPrnand restoration resilience mechanisms was evaluated by randomly adding 30 unidirectionalrnlinks to the reference network topology used in the above evaluations. To evaluate the RWArnalgorithms and resilience mechanisms, Net2Plan simulator is used. rnThe result of the evaluations shows that, at low connected network topology, restoration withrnalternate routing has on average 40 % lower blocking probability, higher average throughputrnand lower recoverability as compared to the other resilience mechanisms combined withrnalternate routing. An increase in network connectivity by 0.9 decreases the blocking probabilityrnand average throughput advantage of restoration by 10%. So considering the possibility ofrnimproving the recoverability of the network by preparing a pool of restoration path prior tornfault occurrence and its ability to protect against double link failure (DLF), restoration withrnalternate routing becomes more recommended for low connected network topologies at lowrntraffic load. But for highly connected network topologies with high traffic load using eitherrn1+1 DPP or hybrid becomes more recommended based on the need for DLF protection.