Layer 2 Scaling
Ethereum processes roughly 15-30 transactions per second on Layer 1. Layer 2 (L2) solutions process transactions off the main chain while inheriting its security, dramatically increasing throughput and reducing fees.
Why Layer 2?
Layer 1 (Ethereum Mainnet):
┌──────────────────────────────────────┐
│ TPS: ~15-30 │
│ Gas Fees: $1-$50+ during congestion│
│ Finality: ~12-15 minutes │
│ Security: Maximum │
└──────────────────────────────────────┘
Layer 2 (Rollups):
┌──────────────────────────────────────┐
│ TPS: 2,000-4,000+ │
│ Gas Fees: $0.01-$0.10 │
│ Finality: Seconds to minutes │
│ Security: Inherited from L1 │
└──────────────────────────────────────┘
Rollup Types
Optimistic Rollups:
┌──────────────────────────────────────┐
│ Assume transactions are valid │
│ Post transaction data to L1 │
│ Challenge period: 7 days │
│ Fraud proof if dispute │
│ Examples: Optimism, Arbitrum │
└──────────────────────────────────────┘
Zero-Knowledge (ZK) Rollups:
┌──────────────────────────────────────┐
│ Prove validity with math (zk-SNARK)│
│ No challenge period needed │
│ Faster finality │
│ More complex to implement │
│ Examples: zkSync, StarkNet, Polygon │
│ zkEVM │
└──────────────────────────────────────┘
Other Scaling Solutions
State Channels: Two parties open a channel, transact off-chain, and settle on-chain. Example: Bitcoin Lightning Network.
Sidechains: Independent blockchains connected to L1 via bridges. Example: Polygon PoS, Gnosis Chain.
Plasma: Child chains that periodically commit state roots to L1. Largely superseded by rollups.
Bridging to L2
Moving assets to Layer 2:
┌────────────┐ Bridge ┌────────────┐
│ Ethereum │──── Lock ────►│ L2 Chain │
│ (L1) │◄── Unlock ───│ │
└────────────┘ └────────────┘
1. Deposit ETH/token into L1 bridge contract
2. Bridge mints equivalent on L2
3. Use L2 for fast, cheap transactions
4. Bridge back when ready to exit
⚠️ Bridge risk: Bridges are common attack targets