Stake-Weighted QoS (SWQoS)

A Quality of Service system introduced in Solana that allocates TPU packet bandwidth to staked validators proportionally to their stake weight, preventing unstaked or lightly staked nodes from flooding leaders with transactions at the expense of stake-backed traffic. Validators that have delegated stake can forward transactions and receive preferential access to leader bandwidth, making it economically meaningful to route transactions through staked RPC or validator nodes. SWQoS is a key defense against spam and denial-of-service attacks that plagued Solana during high-traffic periods.