Stateless orchestrator synchronization in multi-layer multi-domain networks

Abstract

In a Multi-Layer Network (MLN), an orchestrator can be deployed to coordinate multiple layers, such as IP, OTN, and DWDM. Each layer is an administrative domain. Accurately updating the orchestrator’s network view is challenging in MLNs. Due to the hierarchical structure of MLNs, a single failure in an underlying layer can propagate to the upper layers, hence generating many alarms in each of these layers. These alarms may send incorrect updates of the root cause of the failure, which results in incorrect decisions of the orchestrator for routing and resource allocation. Therefore, setting up the order of updating by different layers is crucial in MLN to avoid confusion in the orchestrator’s network view. This task is challenging, due to the flexible mapping of links between different layers, and also to the failure propagation time from the underlying layers to the upper layers. In this thesis, we propose a method to update the orchestrator to ensure that the root cause is reported correctly, taking into account the dependency among different layers and failure propagation time. In particular, we optimize the frequency of sending update messages from layers to the orchestrator. Our proposed method can be implemented in the orchestrator to request updates from controllers periodically at an optimized rate. We formulate an integer nonlinear optimization problem for updating the orchestrator and then propose two algorithms to approximate the optimal failure probability for updating the orchestrator solution. Simulation experimental results show that our proposed MLNOU algorithm can obtain a near-optimal which approximates on average 11.3% different from the optimal solution, which demonstrates the significant effect of our algorithm on the orchestrator’s performance and clearly outperforms the baselines.

Date	28 Apr 2023
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Kim Khoa Nguyen (Supervisor) & Mohamed Cheriet (Co-supervisor)