Accuracy and Dynamics of Hash-Based Load Balancing Algorithms for Multipath Internet Routing

This paper studies load balancing for multipath Internet routing. We focus on hash-based load balancing algorithms that work on the flow level to avoid packet reordering which is detrimental for the throughput of transport layer protocols like TCP. We propose a classification of hash-based load balancing algorithms, review existing ones and suggest new ones. Dynamic algorithms can actively react to load imbalances which causes route changes for some flows and thereby again packet reordering. Therefore, we investigate the load balancing accuracy and flow reassignment rate of load balancing algorithms. Our exhaustive simulation experiments show that these performance measures depend significantly on the traffic properties and on the algorithms themselves. As a consequence, our results should be taken into account for the application of load balancing in practice

Accuracy and Dynamics of Multi-Stage Load Balancing for Multipath Internet Routing

Flow-based load balancing algorithms for multipath Internet routing are often used for traffic engineering. However, the target load distribution and the load balanced result agree only on average, and there is a significant inaccuracy over time due to stochastic effects. Dynamic load balancing reduces this inaccuracy by relocating flows to other paths in regular time intervals. This causes packet reordering. Therefore, the flow reassignment rate should be kept low. In this paper we consider load balancing in networks. It differs from load balancing at a single node by the fact that several load balancing steps may be performed at consecutive nodes in series. This affects the flow reassignment rate and the load balancing accuracy due to interdependencies and polarization effects. We quantify the impact by simulation results, explain the observed phenomena, and give recommendations for load balancing in practice