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Scaling Ethereum & crypto for a billion users

A guide to the multi-chain future, sidechains, and layer-2 solutions

Coinbase

To compete or to complement?

The goal is to increase the number of transactions that openly accessible smart contract platforms can handle, while retaining sufficient decentralization. Remember, it would be trivial to scale smart contract platforms through a centralized solution managed by a single entity (Visa can handle 45,000 transactions per second), but then we’d be right back to where we started: a world owned by a handful of powerful centralized actors.

  • Sidechains (somewhat complementary to Ethereum)
  • Layer 2 networks (complementary to Ethereum)

Layer 1s

Ethereum is considered a layer 1 blockchain — an independent network that secures user funds and executes transactions all in one place. Want to swap 100 USDC for DAI using a DeFi application like Uniswap? Ethereum is where it all happens.

Leading non-ETH L1s by TVL
TVL of EVM compatible vs non-EVM compatible L1s

Sidechains

The distinction between sidechains and new layer 1s is admittedly a fuzzy one. Sidechains are very similar to EVM-compatible layer 1s, except that they’ve been purpose built to handle Ethereum’s excess capacity, rather than compete with Ethereum as a whole. These ecosystems are closely aligned with the Ethereum community and host Ethereum apps in a complementary fashion.

Layer 2s (Rollups)

Layer 1s and sidechains both have a distinct challenge: securing their blockchains. To do so, they must pay a new cohort of miners or proof of stake validators to verify and secure transactions, usually in the form of inflation from a base token (e.g. Polygon’s $MATIC, Avalanche’s $AVAX).

  • Validating and securing transactions is a complex and challenging task that your network is responsible for indefinitely

How rollups work

Layer 2s are commonly called rollups because they “rollup” or bundle transactions together and execute them in a new environment, before sending the updated transaction data back to Ethereum. Rather than have the Ethereum network process 1,000 Uniswap transactions individually (expensive!), the computation is offloaded on a layer 2 rollup before submitting the results back to Ethereum (cheap!).

Optimistic Rollups

When submitting results back to Ethereum, optimistic rollups “optimistically” assume that they’re valid. In other words, they let the operators of the rollup post any data they want (including potentially incorrect / fraudulent data), and just assume it’s correct — an optimistic outlook no doubt! But there are ways to fight fraud. As a check and balance, there is a window of time after any withdrawal where anyone watching can call out fraud (remember blockchains are transparent, anyone can watch what’s happening). In the event that one of these watchers can mathematically prove that fraud occurred (by submitting a fraud proof), the rollup reverts any fraudulent transactions and penalizes the bad actor and rewards the watcher (a clever incentive system!).

Arbitrum & Optimistic Ethereum

Arbitrum (by Off-chain Labs) and Optimistic Ethereum (by Optimism) are the two main projects implementing optimistic rollups today. Notably, both are still in their early stages, with both companies maintaining levels of centralized control but with plans to decentralize over time.

ZK Rollups

Where optimistic rollups assume the transactions are valid and leave room for others to prove fraud, ZK rollups do the work of actually proving to the Ethereum network that transactions are valid.

ZK Rollup Adoption

The ZK rollup landscape runs deep, with multiple teams and implementations in the works and in production. Some prominent players include Starkware, Matter Labs, Hermez, and Aztec. Today, ZK-rollups mainly support relatively simple applications such as payments or exchanges (owing to limitations on what types of applications ZK-rollups can support today). For example, derivatives exchange dYdX employs a ZK rollup solution from Starkware (StarkEx) to support nearly 5 million weekly transactions and $1B+ in TVL.

A fragmenting world

In the long run, these scaling solutions are necessary if smart contract platforms are to scale to billions of users. In the near term, these solutions, however, may present significant challenges for users and crypto operators alike. Navigating from Ethereum to these networks requires using cross-chain bridges, which is complex for users and carries latent risk. For example, several cross-chain bridges have already been the target of $100+ million dollar exploits.

An uncertain future

Will new layer 1s like Avalanche or Solana continue to grow to compete with Ethereum? Will blockchain ecosystems like Cosmos or Polkadot proliferate? Will sidechains continue to run in harmony with Ethereum, taking on its excess capacity? Or will rollups in conjunction with Ethereum 2.0 win out? No one can say for sure.

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