Proposal of Applying Transaction Server to Each Shard in Ethereum

A sharding framework has been proposed by Ethereum 2.0, and researchers have tried to enhance its applicability and scalability to real blockchain networks. Each shard can execute transactions requested by users, so the number of transactions dealt with by the shard-based blockchain grows as the number of shards increases. Dealing with cross-shard transactions, however, is a major hindrance to blockchain performance, because each such transaction requires cooperation among different shard validators in the network. Given this background, this paper proposes a novel cross-shard architecture in which each shard has its own transaction server (TS) and each TS has the role of dealing with transaction requests/results coming from different users or different shards. In this architecture, it is possible for each validator to concentrate on dealing with the transactions in its own shard, so there is no need to multicast transaction information to the other shard validators. We describe the proposed cross-shard framework in detail and demonstrate how a cross-shard transaction can be executed using the hierarchically connected smart contract functions. In the proposed architecture, the interactions among different shard validators can be reduced by having each validator select its neighbors from among members of its own shard after each epoch. This frequent change of neighbors for each validator makes it robust against eclipse attacks. In addition, this architecture speeds up the validation process of transactions/blocks in each shard; we show the effect by measuring the block transmission delays in the proposed architecture in a simulation environment.