Dynamic load balanced routing in IP networks

In this paper, we address the dynamic load balanced routing problem in IP networks. In current IP networks, shortest paths are selected for routing based on static link weight metrics. Due to the lack of stringent synchronization among routers, dynamically changing link weight would generate transient loops. How to perform dynamic load balanced routing without generating traffic loops become a challenging task. In this work, we propose two approaches, Local Traffic Rerouting (LTR) and Global Traffic Rerouting (GTR), to resolve the problem. Both approaches use a set of static link weight metrics. Each router obtains the metrics through standard link state routing protocol. Based on the link metrics, in each router, a directed acyclic graph (DAG) for each destination node is derived. Taking the advantage of the property that there is no loop in a DAG, each router can make its decision to dynamically select next hop node for routing. The major difference between LTR and GTR is that the former uses only local information while the latter uses global information on routing decision. In LTR, each router monitors its links to obtain the bandwidth utilization. In GTR, the local link utilization information is broadcast to the whole network through routing protocol so each node in the network knows the state of the whole network. We have conducted simulations and experiments to make performance comparisons among various routing approaches. The results indicate that LTR and GTR significantly outperform conventional static routing on minimizing link utilization of the most congested link. They also have performance close to a per flow based centralized controlled routing that is served for a lower bound for performance evaluations.