# AggLayer + Shared sequencers

**Published by:** [chandan](https://paragraph.com/@iamchandan/)
**Published on:** 2024-03-31
**URL:** https://paragraph.com/@iamchandan/agglayer-shared-sequencers

## Content

On Mar 30 sassal.eth tweeted that “AggLayer + shared sequencers If you're not paying attention to these things, you should be - this tech will further supercharge the already dominant Ethereum layer 2 ecosystem” In this article, let's look at what AggLayer and shared sequencers are individually, and then let's explore what we can achieve if we combine them. what is a Sequencer:Read transactions from the Layer 2 mempool and execute themBatch transactions together and send the batches to Layer 1Today, all sequencers are isolated and run by the Layer 2 team, as shown in the image below.We need to strive for decentralized sequencers, but they still don't solve the interoperability between Layer 2s. Enter Shared Sequencers: Shared sequencers operate a separate blockchain to perform the role of a decentralized sequencer for multiple rollups, introducing interoperability advantages.Decentralized sequencers = serve one chainShared sequencers = serve multiple chainsBenefits of Shared Sequencers (SS):Performing cross-chain transfersPerforming cross-chain DEX arbitrageCensorship resistanceEconomies of scaleCons for Developers:Not as performant as centralized sequencersLoss of sovereignty (Layer 2 developers give up control of their sequencer)AggLayer:How it Works:Each chain's sequencers execute transactions as usual (centralized or decentralized)Each chain's sequencer generates a ZK proof of its updated stateEach chain sends the proof to the AggLayer rather than the EthereumThe AggLayer aggregates all the proofs and generates a single, aggregated ZK proof, guaranteeing the validity of proofs for all chainsThe AggLayer posts that aggregated proof to EthereumThe AggLayer (aggregation layer) enables the same atomic transactions and cross-rollup interoperability as shared sequencers without forcing rollup developers to give up control of their sequencers and sovereignty. Now, the most important part: let's see how AggLayer and shared sequencers can help each other? Currently, building a shared sequencer with cross-chain transactions is complex. However, even without cross-chain transactions, shared sequencers make sense because they bring censorship resistance and economies of scale to the rollup. Additionally, shared sequencers can let the AggLayer solve the cross-chain transaction problem, decreasing the time to market for shared sequencers. Most of the info is taken from: https://gateway.pinata.cloud/ipfs/QmbvZY784N8fBcQz9NAC1STB2AUvpaQuHPMzR7e6nN24p3

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