Efficient Recovery from False State in Distributed Routing Algorithms

Malicious and misconfigured nodes can inject incorrect state into a distributed system, which can then be propagated system-wide as a result of normal network operation. Such false state can degrade the performance of a distributed system or render it unusable. In the case of network routing algorithms, for example, false state corresponding to a node incorrectly declaring a cost of 0 to all destinations (maliciously or due to misconfiguration) can quickly spread through the network, causing other nodes to (incorrectly) route via the misconfigured node, resulting in suboptimal routing and network congestion. We propose three algorithms for efficient recovery in such scenarios and prove the correctness of each of these algorithms. Through simulation, we evaluate our algorithms when applied to removing false state in distance vector routing, in terms of message and time overhead. Our analysis shows that over topologies where link costs remain fixed, a recovery algorithm based on systemwide checkpoints and a rollback mechanism yields superior performance. We find that a different algorithm – one that selectively purges false routing state network-wide – yields the best performance in scenarios where link costs change.