Approximate distributed Bellman-Ford algorithms [computer network routing]

Routing algorithms based on the distributed Bellman-Ford algorithm (DBF) suffer from exponential message complexity in some scenarios. Two modifications to the algorithm are proposed which result in polynomial message complexity without adversely affecting the response time of the algorithm. However, the new algorithms may not compute the shortest path. Instead, the paths computed can be worse than the shortest path by at most a constant factor (<3). The modifications proposed to the original algorithm are simple and easy to implement. The message complexity of the first algorithm, called the multiplicative approximation algorithm, is O(nm log (nΔ)), where Δ is the maximum length over all edges of an n-nodes m-edges network. The message complexity of the second algorithm, called the additive approximation algorithm, is O(Δ/δ nm), where is δ is the minimum length over all edges in the network