In this article, we present a watchdog blockchain network (WDN) that allows for simultaneous scalability and decentralization enhancements. Because of the blockchain trilemma, achieving high levels of security, scalability, and decentralization simultaneously is challenging. Typically, public blockchains are fully decentralized at the expense of scalability, whereas private blockchains achieve high scalability at the expense of decentralization. A WDN is proposed to compensate for the low-level decentralization of a private blockchain while maintaining its high-level scalability. A WDN may prevent arbitrary forgery, alteration, and deletion of distributed ledgers in private blockchains owing to weak decentralization. However, the transaction throughput gap between the WDN and the private blockchain can be a significant obstacle in operating a WDN with a private blockchain. Therefore, the WDN in this study has been designed to back up data on the private blockchain in real time over a distributed network environment. The WDN features a network-aware consensus protocol that can quickly complete the consensus process of the three phases. To this end, modern network technologies, such as GossipSub, quick UDP Internet connections (QUICs), and Google remote procedure call (GRPC), have been appropriately adopted for the WDN. To demonstrate the system performance of the WDN, a blockchain system was fully implemented in the form of docker containers. Furthermore, we verified the feasibility of the WDN by developing decentralized applications (DApps).
