{'fraction_non_alphanumeric': 0.028211586901763223, 'fraction_numerical': 0.0, 'mean_word_length': 5.225705329153605, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Toward a Scalable, Robust, and QoS-Aware Virtual-Link Provisioning in SDN-Based ISP Networks

In this paper, we propose a control framework for virtual-link provisioning in software defined networking (SDN)-based Internet service provider (ISP) networks. Within the problem’s scope, we have analyzed the traffic engineering (TE), quality of service (QoS) provisioning, network stability, and failure recovery issues. The proposed solution aims to optimize the network throughput subject to multiple QoS constraints and link-failure robustness constraints that are defined in service level agreements (SLAs), while minimizing the time-average rate of routing updates according to ISP preferences. In contrast to the conventional TE mechanisms which periodically optimize all the routing rules, our solution is based on a bi-objective optimization model which jointly optimizes the routing and the number of flow-table updates. In this way, the reconfiguration overhead of TE is reduced, thus the SDN controller could perform TE more frequently, in order to quickly and efficiently respond to traffic and topology changes. To generate a set of Pareto optimal solutions for the proposed optimization model we use the augmented $\epsilon $ -constrained method. The most efficient trade-off solution from the Pareto set is chosen by the Lypunov drift-plus-penalty algorithm. In order to make the proposed approach scalable enough for large network topologies, we also propose a heuristic TE algorithm that runs in polynomial time. The proposed solution is validated via simulations and experimentally, and it is shown that it outperforms conventional periodic TE techniques. The advantages of our proposal over a state-of-the-art TE technique in terms of the capability to adjust the reconfiguration rate based on the threshold set by ISP is demonstrated. In the analysis, a special attention is paid to the impact of proactive failure protection mechanisms on the network service capacity.