Blockchain Peer-to-Peer Network: Performance and Security

Mistrusting nodes in a blockchain can reach consensus without the need of a trusted central entity. Instead, the nodes reach consensus through exchanging information on a peer-to-peer (P2P) network, without pre-established identities. Serving as the foundation of the blockchain, the P2P network plays critical roles in all performance and security aspects of the blockchain system. While P2P networks had been previously examined for many applications domains, including the file sharing systems, there is relatively less understanding on blockchain P2P networks that differs substantially from traditional P2P systems. In this chapter, we will cover different aspects of blockchain P2P networks from topology, peer discovery, known attacks, and defenses to improvement proposals to increase the throughput and reduce the latency in blockchain. Finally, we investigate theoretical limit on the throughput of blockchain systems in which nodes have heterogeneous capacities. We provide insights and discussion on how to construct a network to achieve the maximum theoretical limit in throughput.