Vitalik Proposes Cross Rollups Solution to Help Layer 2 Protocols Communicate with Each Other
- Ethereum co-founder Vitalik Buterin proposes cross-rollups scaling as a solution to the burgeoning Ethereum gas fees while creating a unified crypto ecosystem.
In a post on Ethereum developers' GitHub channel, Vitalik wrote a proposal to allow platforms using rollups to communicate with each other. He proposes cross-rollup scaling solutions that will ease the rising Ethereum fees while maintaining interconnectivity and composability across the platforms.
Rollups are layer 2 scaling smart contract solutions on blockchains that store and process most of the information off-chain, which allows for faster and cheaper transactions on the blockchain. However, platforms that use different kinds of rollups, including zero-knowledge and optimistic rollups, cannot share this off-chain information with other rollups.
Vitalik’s proposal focuses on two projects that have integrated roll-up scaling but cannot communicate. One of the projects, “Rollup A,” has full smart contract support while another, “Rollup B,” can only perform simple transactions.
In an example of how the cross rollup solution will happen, Vitalik gives a hypothetical example of two platforms – an intermediary, named Ivan – who has funds on platforms on both Rollup A and Rollup B. Ivan fully controls his funds on Rollup A account, IVAN_A, and also has funds in his account on Rollup B, IVAN_B.
Vitalik proposes that the smart contract, IVAN_B, can be programmed to accept “memos” that hold data on anyone sending funds to it to connect the two accounts. This will keep a copy of any future transactions to the Rollup B.
The transactions history (memo) between the two rollups creates a layer that connects the two rollups allowing Rollup A and Rollup B to exchange information. Vitalik explained,
“The expected behavior is simple:
1. Alice sends a transaction to IVAN_A with N coins and a memo ALICE_B
2. Ivan sends a transaction sending TRADE_VALUE * (1 – fee) coins through IVAN_B to ALICE_B.”
Buterin further said the second step could also be executed immediately after the first, adding “contract can even have rules that allow the fee to be greater if Ivan shows proof that the timestamp difference between the second transaction and the first is very low.”
According to the post, the worst-case scenario happens when IVAN_A does not send the coins to ALICE_B. This can easily be solved by Alice waiting until the transaction on Rollup A to confirm, find a way to pay fees on Rollup B, and claim the funds owed to her directly.
The fees can be directly paid on Rollup B; Vitalik explained whether Alice would need to interact with L1 blockchains to reclaim her funds.
“All you need is for rollup B to have access to block hashes of the L1 chain before the previous batch (this can be done safely).”