Inter-chain nesting or customized expansion: How to correctly understand the significance of layer 3 expansion

I watched the heated discussion about "layer3" in overseas communities and found it particularly interesting: some people saw inter-chain matryoshka dolls where data is repeatedly compressed, while others saw ZK as the underlying technology architecture for atomic communication between multi-chain applications. capabilities, some people see wider application scenarios for Eigenlayer’s AVS staking + reward and punishment mechanism. How to understand the extended meaning of layer3? Let me explain my understanding:

1. Since layer2 and layer3 theoretically rely on mainnet settlement, a common assumption is that layer3 first compresses the data and then submits it to layer2 for secondary processing. Secondary compression is equivalent to Rollup on top of Rollup. This method has been criticized and questioned because once layer4 and layer5 are imagined with a similar architecture, this method will be squeezed into a dead end. After all, the data cannot be compressed all the time.  

2. In fact, the interaction between layer3 and layer2 may not necessarily require compression and then compression. In the layer3 strategy planned by many layer2 stacks such as Arbitrum and zkSync, layer3 is defined as a specific application chain and will be highly autonomous in terms of consensus mechanism, Gas Fee selection, economic model, etc. The problem is that autonomy does not mean complete Independent, its underlying architecture will most likely be constrained by using the basic infra built by layer2. For example, it shares key components such as Sequencer and Prover with the layer2 chain.

This means that layer3 transactions will be directly packaged and submitted to the mainnet via layer2's Sequencer for final status confirmation. What layer2 undertakes more is the interoperability function between layer3 multi-chains. The so-called "settlement layer" is only the settlement of data packaging, not the final and final settlement in the true sense. Transactions in layer 3 also need to be queued and packaged on layer 2. Make Sense by treating the layer 3 application chain as a special Sequencer pipeline.  

3. If it is assumed that layer3 is all in the form of an inter-chain matryoshka, the scalability will naturally be limited. However, this practical approach is only a theoretical assumption. If layer2 and layer3 share key components such as Sequencer and Prover, , there are many ways to horizontally expand layer3's multi-chains, especially after the interoperability between chains is improved.

1. As zkSync founder @gluk64 said, ZK technology is used as the basis for interoperability between multiple chains. ZK technology allows two Counterparties to verify without disclosing specific information. Regarding the authenticity of the information, when layer3 transfers cross-chain assets to layer2, the atomic transfer of assets between chains can be realized through the ZK bridge without superimposing inter-chain consensus or other processing.

The bridging technology supported by ZK technology can provide the foundation for layer3’s multi-chain expansion, because no matter how many layer3 appear, “technical settlement” is achieved directly with layer2 through ZK Proof, and will not affect layer2 The relationship with the main network; 

2. As Eigenlayer founder @sreeramkannan explained, letting Eigenlayer’s AVS active nodes coordinate the consensus between different chains across chains is equivalent to letting the same A batch of nodes participate in consensus construction among multiple chains. In this case, as long as AVS is given a layer of reward and punishment Slash mechanism, it will theoretically reduce the possibility of nodes doing evil themselves. When the node approves the flow of assets from layer3 to layer2, if there is any evil behavior, it will be Slashed.

This type of reward and punishment economic mechanism will also be applied to trust issues in multi-chain environments. Although it cannot be 100% trustworthy like ZK, it can generally create a trustworthy environment based on economic models. .

4. @VitalikButerin also jumped out to reiterate his own point of view in response to the discussion of everyone's own position. Layer3 cannot simply be a stack and extension of layer2, which does not bring effective scalability. Because layer3 relies on layer2 for infrastructure, layer2 cannot expand endlessly, let alone layer3. But in some specific scenarios, such as privacy, layer3 specific privacy application chains can solve the privacy preferences of some transactions.

In short, layer3 is a highly customized function with the possibility of customized expansion. In my opinion, the extension of layer3 should be customized and developed to meet the needs of application scenarios. The development paradigm similar to one-click chain sending will not work in the multi-chain direction of layer3 applications.