QoS Performance Evaluation of RWA Algorithms under Different Resilience Mechanisms: in the Case of EthioTelecom Backbone Network
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Date
2019-12
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Addis Ababa University
Abstract
For the past decades, data traffic demand considerably increased in volume and quality due to
the advent of capable end-user devices and innovative data services. To accommodate the
highly increasing data traffic volume and customer demand for service with better quality, an
automatic switched optical network (ASON) with different routing and wavelength assignment
(RWA) algorithms and resilience mechanisms are used. Previously different researchers
evaluated performance of different resilience mechanisms and RWA algorithms separately by
considering an ideal highly connected network with ideal uniform traffic demand/connection
request. This issue can force telecom operators including Ethio-telecom to implement their
backbone network based on vendor recommendation.
In this thesis, first, performance of four adaptive RWA algorithms was evaluated considering
blocking probability and average throughput as QoS metrics under different three resilience
mechanisms considering a practical Ethio-telecom north circle backbone network topology and
its traffic demand scenario. Secondly, performance of the three resilience mechanisms was
evaluated under routing algorithm selected from routing algorithm evaluation considering
blocking probability, recoverability and average network throughput as QoS performance
metrics. Finally, network topology connectivity degree effect on the performance of 1+1 DPP
and restoration resilience mechanisms was evaluated by randomly adding 30 unidirectional
links to the reference network topology used in the above evaluations. To evaluate the RWA
algorithms and resilience mechanisms, Net2Plan simulator is used.
The result of the evaluations shows that, at low connected network topology, restoration with
alternate routing has on average 40 % lower blocking probability, higher average throughput
and lower recoverability as compared to the other resilience mechanisms combined with
alternate routing. An increase in network connectivity by 0.9 decreases the blocking probability
and average throughput advantage of restoration by 10%. So considering the possibility of
improving the recoverability of the network by preparing a pool of restoration path prior to
fault occurrence and its ability to protect against double link failure (DLF), restoration with
alternate routing becomes more recommended for low connected network topologies at low
traffic load. But for highly connected network topologies with high traffic load using either
1+1 DPP or hybrid becomes more recommended based on the need for DLF protection.
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Keywords
Network Resiliency, QoS, Recovery, Resource Utilization, RWA, Survivability