Autonomic Resource Management for Multiple-Spanning-Tree Metro-Ethernet Networks

Viking [13] is a multi-spanning-tree Ethernet architecture that is designed to leverage commodity Ethernet switches to support Metro-Ethernet services. In particular, it exploits VLAN switching to provide network-wide load balancing across a metro-area network. However, Viking assumes the traffic matrix is fixed; as time goes by, the input load may gradually deviate from the assumed traffic matrix because of addition/deletion of subscribers and/or changes in bandwidth requirements from existing subscribers. Therefore, dynamic resource management is required to accommodate such traffic load fluctuations. This paper describes the design, implementation and evaluation of an autonomic network resource management system called Viking2 that enables a Metro-Ethernet network to dynamically self-reconfigure itself, with minimal human intervention, to adapt to changing traffic loads. In particular, whenever possible Viking2 uses a local repair approach to eliminate congestion while minimizing the number of flows affected. If local repair cannot fix a congestion problem, Viking2 resorts to a global reconfiguration approach that recomputes a new path for every flow and deploys the new routing state in a way that reduces the disruption during the period of transition to the minimum. Simulation results show that compared with the original Viking, Viking2 can indeed significantly improve a network´s ability to dynamically adapt itself to changing traffic loads, to minimize the degree of congestion during normal network operation, and to increase the total effective network capacity.