Churn in the Bitcoin Network: Characterization and Impact

Efficient and reliable propagation of blocks is vital for ensuring the scalability of the Bitcoin network. As a result, several schemes have been proposed over the last few years to speed up the block propagation, most notably the compact block protocol (BIP 152). Despite this, we show experimental evidence that (i) the vast majority (97%) of Bitcoin nodes exhibit intermittent network connectivity (churn), and (ii) this churn results in significant numbers of unsuccessful compact blocks, roughly twice the figure for continuously connected nodes. Specifically, we conduct experiments on the Bitcoin network that show that churn results in a 135% average increase in block propagation time (i.e., 336.57 ms vs 142.62 ms), and can lead to as high as an 800-fold increase in the worst case. To effect our analysis, we develop a statistical model for churn based on empirical network data, and use this model to actuate the live test nodes on the Bitcoin network. The performance of the system is measured by means of a novel framework that we develop for logging the internal behavior of a Bitcoin node and share for public use.