SREP: Out-Of-Band Sync of Transaction Pools for Large-Scale Blockchains

August 21, 2023

Novak Boskov, Sevval Simsek, Ari Trachtenberg, and David Starobinski, Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts, USA

Synchronization of transaction pools (mempools) has shown potential for improving the performance and block propagation delay of state-of-the-art blockchains. Indeed, various heuristics have been proposed in the literature to this end, all of which incorporate exchanges of unconfirmed transactions into their block propagation protocol. In this work, we take a different approach, maintaining transaction synchronization outside (and independently) of the block propagation channel. In the process, we formalize the synchronization problem within a graph theoretic framework and introduce a novel algorithm (SREP – Set Reconciliation-Enhanced Propagation) with quantifiable guarantees. We analyze the algorithm’s performance for various realistic network topologies, and show that it converges on any connected graph in a number of steps that is bounded by the diameter of the graph. We confirm our analytical findings through extensive simulations that include comparison with MempoolSync, a recent approach from the literature. Our simulations show that SREP incurs reasonable overall bandwidth overhead and, unlike MempoolSync, scales gracefully with the size of the network.

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SREP: out-of-band sync of transaction pools for large-scale blockchains” won the Best Paper award at the 2023 IEEE International Conference on Blockchain and Cryptocurrency (ICBC). The conference itself has a competitive acceptance rate of 18.5%. (read the announcement)