- Chainlink has floated a DAG-based single-broadcast consensus protocol.
- This new product is hinged an bolstering the efficiency of Chainlink across the board.
Chainlink (LINK) has introduced a single-broadcast consensus protocol on a Direct Acyclic Graph (DAG), aimed at simplifying DAG-based consensus. Compared to other existing DAG-based approaches, the protocol will exhibit reduced latency by several network trips. Markedly, Chainlink arrived at the development of this protocol after first analyzing the consensus problem.
Upon analysis, it was discovered that the network required a protocol that permits parallel transmissions where high-throughput and low latency becomes easier. The consensus logic running on the protocol is a thin layer over a novel broadcast primitive called Byzantine Broadcast With Commit-Adopt (BBCA) that leads to a single-broadcast consensus protocol referred to as BBCA-Chain.
BBCA is built over a causally-ordered Byzantine Reliable Broadcast (BRB) primitive for asynchronous systems with some Byzantine nodes. Also, the BBCA extension over BRB is an active Commit-Adopt probing API which usually interrupts a node from further participation in the broadcast protocol.
Also, the probing, which is a local action that requires no communication, provides reports on whether it has already locked a value.
The Superiority of Chainlink BBCA Over Other DAG-based Consensus
Owing to the lack of communication from probing, BBCA can utilize the same communication complexity on BRB while delivering the necessary guarantee, per the blog post made by Chainlink. Markedly, the BBCA-Chain delivers excellent throughput by allowing parallel block broadcast but has a few challenges with the DAG construction. This distinguishes the BBCA from other existing transmission approaches.
Other DAG-based broadcasts can also permit parallel transmissions but this is not without a complicated design with several invocations of a couple of multi-step broadcast primitives. It also comes with unnecessary latency. On the other hand, BBCA-Chain is a single broadcast on a DAG that simplifies the consensus logic while also reducing latency.
To create this single-broadcast consensus, the DAG in BBCA-Chain links in a chained framework of leader blocks that serve as references for each other and are transmitted through BBCA. This is how the BBCA powers the BBCA-Chain to achieve the consensus. It is worth noting that leader blocks are capable of committing on their own without interference from an additional vote or DAG layering. They will only utilize BBCA to transfer the blocks.
Seeing that the local DAGs of nodes in a distributed system will likely evolve differently, the Commit-Adopt feature of BBCA ensures the security of committed leader blocks. Non-leader blocks that intend to record high throughput are broadcast in parallel using best-effort broadcast. These blocks become committed by being transitively referenced from the backbone, similar to “uncle blocks” in Ethereum (ETH).
In DAG-based consensus, agreement is reached on a chained backbone of blocks. Noteworthy, IOTA’s Tangle technology is also a DAG consensus algorithm.
Specifically, the Tangle technology is DAG designed to facilitate microtransactions due to distinct characteristics. It improves security, mitigates performance issues, and eliminates any single point of failure. Similarly, Spacemesh uses a DAG consensus mechanism and these innovative DAG protocols underscores the entire essence why Chainlink’s debut into the scene is highly revered.
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