On the Routing Convergence Delay in the Lightning Network

Abstract: Nodes in the Lightning Network synchronise routing information through a gossip protocol that makes use of a staggered broadcast mechanism. In this work, we show that the convergence delay in the network is larger than what would be expected from the protocol's specification and that payment attempt failures caused by the delay are more frequent, the larger the delay is. To this end, we measure the convergence delay incurred in the network and analyse what its primary causes are. Moreover, we further investigate and confirm our findings through a time-discrete simulation of the Lightning Network gossip protocol. We explore the use of alternative gossip protocols as well as parameter variations of the current protocol and evaluate them by the resulting bandwidth usage and convergence delay. Our research shows that there are multiple ways of lowering the convergence delay, ranging from simple parameter changes to overhauling the entire protocol.