Original author: Haotian

Recently, @VitalikButerin said that Cross-L2 interoperability is no longer a problem. Although he did not specify the specific project, combined with the wonderful discussion in the comment area, I summarized some solutions that can solve the cross-layer 2 interoperability, as follows:

1）Based-Rollup

In the Ethereum layer 2 camp, there are some projects that pursue compatibility equivalence. By allowing layer 2 and layer 1 to share components as much as possible, they achieve maximum compatibility with EVM, allowing layer 2 to directly hand over the sorter function to the main network.

Specifically, when retrieving Mempool transactions, the Proposer of the main network can use a special route similar to MEV-Boost to capture the Rollup Batch transactions, and then directly complete the sorting and chaining on the main network.

@taikoxyz

2）CrossChain-Rollup

The powerful ZK technology provides a possibility to establish a trust-free mechanism for homogeneous/heterogeneous chains in complex environments, including interoperability between homogeneous chains such as EVM-Compatible. Cross-L2 belongs to this category. In addition, ZK technology can also connect the interoperability of complex non-smart contract-based chains such as EVM and Non-EVM.

Specifically, the ZK technical framework will become an underlying communication protocol, which allows homogeneous/heterogeneous chains to complete absolutely secure and reliable message transmission through proofs without checking each other's specific data and only verifying proofs. ZK-Rollup is essentially the process of layer 2 off-chain calculating a large amount of data into proofs, and then letting the mainnet Rollup contract directly verify and finalize. Representative project: @ProjectZKM's Entangled Rollup Network unified liquidity layer.

3）Intent-Rollup

Intent trading has always been regarded as the key to the Crypto market's embrace of Mass Adoption. It can accommodate many related directions such as account abstraction, chain abstraction, AI Agent, Pre-Confirmation, etc. Intent trading is essentially to "abstract" the user's needs to achieve programmable characteristics, and then use a decentralized Solver platform to execute the user's needs on behalf of the user to optimize the user-side transaction experience.

Intent will be the final destination of the ideal transaction, which can lower the threshold for users to onboard into the Crypto market and attract incremental users to the industry. The intent track is not difficult to understand, but it is a huge challenge to program the user's vague and complex needs and have them executed perfectly by the agent program, which requires a huge solver processing network. Representative project: @dappOS_com

4）Layer 2 Based-layer 3 

As we all know, leading layer 2 projects such as Arbitrum, Starknet, and Optimism have successively launched layer 3 application chain strategies. Layer 3 application chains are customizable, have their own independent Tokenomics, and can customize Gas, but they rely on layer 2 basic components to provide services, the most typical of which is interoperability.

The layer 2 chain can provide a cross-application chain communication foundation for the layer 3 application chain based on its own shared sequencer, shared prover, etc. Representative projects:

@arbitrum Orbit

5）Cosmos IBC Based -Rollup

Cosmos' IBC communication framework provides a basic interoperability capability for all chains connected to the Cosmos Hub. If the capabilities of Cosmos IBC are focused on the Ethereum layer 2 ecosystem, a layer 2 interoperability layer based on Cosmos IBC interoperability will be achieved.

This solution will directly retain the core code of Cosmos SDK, reducing development costs while also enabling targeted additional development for the Ethereum ecosystem, allowing Cosmos' universal interoperability to be perfectly implemented in the Ethereum ecosystem. Representative project: @Polymer_Labs

6）AVS Based -Rollup

Eigenlayer's middleware service protocol implements the ability for Ethereum mainnet Validators to commercialize their own consensus and deliver it to other Rollup layer 2 or other homogeneous/heterogeneous chains.

This solution essentially allows Ethereum validators to repeatedly stake LST tokens, and constrains validators based on a set of reward and punishment economic mechanisms to expand outside the chain to construct a secure consensus on other chains. If layer 2 uses AVS to construct consensus, it is equivalent to another economically driven Based-Rollup, and the main network components can participate in the cross-chain interactive process of layer 2. Representative project: @alt_layer

7）Modular-Rollups

When modularization reaches a certain level, the Rollup as a Service paradigm will drive the prosperity of the layer 2 one-click chain launch market. At that time, a layer 2 network may share Celestia's DA data availability layer, as well as shared execution layers such as Solana's VM or Ethereum EVM, and use Ethereum as the shared settlement layer of these Rollups. In order to achieve absolute modular collaboration, cross-chain collaborative communication between different modules or different chains is a basic prerequisite. Representative projects:

@AvailProject

……other

Note: These are just a few of the directions I am familiar with, and they may not be complete. There are many projects working on the same direction and with differences. You can add them in the comments section. (All of them aim to eliminate centralized cross-chain bridges and CEX asset transfer stations)

I hope Vitalik can speak out more often, but please don’t point to a specific project. To Vitalik’s innovation is definitely not based on Vitalik’s endorsement. Of course, there are some projects that will challenge Ethereum’s core position, but the future of Ethereum must break away from the Ethereum-centric thinking. Only by looking beyond Ethereum and looking at the Ethereum “ecosystem” can we see the whole picture, right?

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