Adaptive bandwidth allocation: impact of routing and load balancing on tunnel capacity requirements

In this paper, we consider adaptive bandwidth allocation (ABA) for capacity tunnels as an effective means for multi-hour network design. Traffic engineering (TE) tunnels established in a network from border-to-border (b2b) can be used not only for route pinning between ingress/egress node pairs but also for efficient implementation of resilient network admission control. If static bandwidth allocation (SBA) based on peak-rate traffic assumptions is used to dimension the b2b tunnels, fluctuations of the network traffic can lead to under- or overprovisioning of network capacity in the tunnels. If ABA is used instead, the tunnel sizes are dynamically adapted to current traffic conditions. The efficient use of network capacity assigned to TE tunnels strongly depends on the structure of these tunnels. The contribution of this paper is an assessment of the bandwidth savings that are achievable with ABA in comparison to SBA for various tunnel structures with different path layouts and load balancing strategies. Our results show that the capacity savings due to ABA depend on the routing and load balancing schemes provisioned in the network and that these savings may be increased by appropriately chosen tunnel implementations