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Weak Blocks#

As of August 2023, lighter clients have seen considerable advancements with versions 5.0.12 and 5.0.13 of the reference client offering support for bootstrapping with UTXO set snapshots and NiPoPoWs. While Layer 0 (L0) optimizations continue to be a hot topic, there is an increasing demand for faster transaction confirmations.

Weak-blocks are block candidates in the Ergo blockchain that have a lower difficulty threshold compared to standard blocks. For end-users, the introduction of weak-blocks aims to significantly speed up transaction confirmations to around 20 seconds and better utilize network bandwidth, ultimately providing a more efficient and responsive user experience. This document delves into the technical details, advantages, and the strategic plan for implementing weak-blocks using sidechains in Ergo.

The Scalability Dilemma#

While there are many proposals claiming to improve scalability, such as switching to Proof-of-Stake or DAG structures, the real issue often boils down to two key areas:

  1. Propagation Efficiency: How well transactions and blocks propagate through the peer-to-peer network.
  2. Network Load: Optimizing the network so that it remains decentralized and efficient.

Proof-of-Work, while not requiring additional messages for block creation, still needs improvement in how blocks and transactions propagate through the network.

Why Not Microblocks or Bitcoin-NG?#

Bitcoin-NG was initially considered in Ergo's 2017 roadmap but later abandoned due to competing proposals. The principle behind Bitcoin-NG was to use microblocks to follow an empty PoW block, which serves merely as a leader election signal. Although microblocks can improve network utilization, alternative solutions like compact blocks offer similar results. Therefore, Ergo is considering the use of "weak-blocks" as an alternative.

What are Weak-Blocks?#

Weak-blocks are essentially block candidates with lower difficulty than a regular block. For instance, if a weak-block has 1/128th of a regular block's difficulty, we could expect one weak-block to be generated per second on average.

Advantages#

  1. Optimal Network Utilization: Weak-blocks are sent around the network along with new transaction IDs, utilizing the network bandwidth optimally.
  2. Faster Confirmation: A transaction could be considered weakly confirmed with fewer confirmations from the majority hashrate, in practical terms, under about 20 seconds.
  3. Incentivization: Weak-blocks can commit to sidechains, making fast sidechains possible and providing miners with additional rewards.

Sidechains#

Sidechains allow for segregated, dedicated chains where specific tasks or applications can be run. This offloads the main Ergo chain, providing another avenue for scalability. Weak-blocks can commit to these sidechains, adding another layer of efficiency and speed to the Ergo ecosystem.

Implementation Plan#

  • Use weak-blocks instead of microblocks for optimal network utilization and faster confirmations.
  • Distribute weak-blocks in a cut-through way similar to other efficient block propagation techniques.
  • Incentivize the reporting of weak-blocks by linking them to sidechain commitments.

Conclusion#

Weak-blocks and sidechains present an efficient approach to address some of the fundamental scalability issues in proof-of-work blockchains like Ergo. By focusing on these, Ergo aims to improve both the network efficiency and transaction confirmation speed without compromising decentralisation.

References#