Abstract
Blockchains are inherently broadcast networks which means that every block published by a block-producer is propagated to all the other nodes in the network. In PoW chains, blocks are required to be propagated fast enough to keep orphan rates low. High orphan rates reduce security and also encourage centralization. On the other hand, PoS chains with 1-2 second block times restrict the size of the network to a few hundred nodes or lesser.
Peer to peer networking, today, follows an unincentivized commons model which isn't incentive compatible for the parties involved. Full nodes in the network which are the backbone of decentralized and censorship-resistant propagation are not incentivized for the same in the absence of which block producers have conflicting interests when forwarding blocks. An unincentivized model further adds uncertainty onto the time by which blocks reach every interested party.
We address these issues by proposing an incentivized and efficient relay networking protocol called Marlin Relay. Marlin Relay creates incentives for nodes in a network to compete with one another to propagate blocks. We believe that a blockchain-agnostic incentive-compatible relay network can increase the network-layer security of individual blockchains while also boosting their throughputs by pooling bandwidth resources and reducing tail latency.
Introduction
Blockchain is a replicated state machine with a consensus protocol for all the nodes to have a common view of the system. Each block added to the replicated state machine is broadcasted across the network to ensure consistent view. Blocks in PoW chains especially, have to be propagated fast enough so that the other miners mine on top of the latest block instead of mining at the same height as already mined. Blocks hop on a number of flaky nodes with unstable internet connections and pass through trans-continental submarine links as they make their way to other nodes spread across the globe. Unsurprisingly, the transmission requires some time (due to packet losses and consequent retransmissions) leading to the occasional discovery and transmission of a competing block at the same height in the midst known as forks. The occurrence of forks compromise open networks in two more ways: