Alpenglow Phase 1 - Votor

Q3 2026 • Solana Foundation

Solana is replacing its consensus protocol with Alpenglow, beginning with Votor. Alpenglow aims to simplify Solana consensus at network scale, improve performance, and provide faster finality. The target is roughly 150ms finality, compared with Solana's current roughly 400ms pre-confirmation latency and 12.8-second TowerBFT finality.

A later Alpenglow phase is expected to replace Turbine with Rotor, a new block propagation protocol.

Technical Details

Votor, Voting and Certificates

Voting on Alpenglow will work with a new voting algorithm called Votor. It can handle 20% of adversarial stake plus 20% of offline stake while still achieving consensus across the network.

TowerBFT needs a supermajority of greater than two-thirds of stake to achieve a confirmed status. Alpenglow is a marked improvement in terms of the overhead required to finalize a block.

Alpenglow will no longer use vote transactions. Votes are sent directly between validators, and observed votes and certificates are managed in a separate data structure called Pool, informing Votor and stored with Blokstor.

Voting proceeds in two rounds. In the fast path, a block can be finalized after one round if at least 80% of stake votes to notarize it. If that threshold is not reached, the protocol can continue into a second round, where certificates based on 60% stake thresholds determine notarization, finalization, or skipping.

There are five vote messages a validator can make:

• Notarization - Voting yes
• Notarization fallback - Voting yes during the second round
• Skip - Voting skip
• Skip fallback - Voting skip for second round
• Final - Voting to finalize the block

As voting happens, validators aggregate votes to one of the following quorum certificates depending on the vote state:

• Fast finalization - Received >= 80% of stake votes to notarize in first round. Finalize.
• Notarization - Received only >= 60% to < 80% of stake votes in first round. Ready for second round.
• Finalization - Received >= 60% of stake votes in the second round. Finalize.
• Notarization fallback - Received >= 60% of stake votes that either vote notarize or notarize fallback in the second round
• Skip - >= 60% of stake votes to either skip in the first or second round

Alpenglow Community Cluster

After running several tests for months, validators and the core development team are testing the new consensus algorithm on a community cluster. This will ensure a smooth migration from the old consensus protocol to the new one. There are already issues that were identified by the initiative and core devs are working to ensure that the network does not experience downtime during the transition.

Alpenglow SIMDs

Alpenglow is defined across several SIMDs. The original proposal introduces the new consensus protocol, while the follow-up SIMDs cover migration, vote account changes, fast leader handoff markers, and VAT implementation details.

Shipping timeline: Both the Alpenglow Validator Admission Ticket (VAT, SIMD-0357) and BLS Pubkey Management in Vote Account (SIMD-0387) ship in Agave 4.3, estimated Q3 2026. Validator operators must create and register their BLS key onchain before the VAT feature gate is activated — otherwise their validator will not be admitted under Alpenglow consensus.

Phase 2 - Rotor

Alpenglow in its next phase is expected to replace Solana Turbine with a new block propagation service called Rotor. It uses the same erasure coding idea and validator stake-adjusted bandwidth from Turbine. Rotor changes the block propagation plan from a tree of nodes to a single relay layer to minimize network latency. The plan is to make this upgrade at a later stage once Votor has already been adopted by the network.

About This Upgrade

Alpenglow represents a fundamental change to Solana's consensus layer, the first major consensus upgrade since TowerBFT. Not only does it improve on TowerBFT, but it makes the network competitive while also being safe.

This is a collaborative effort on the part of validators and core developers to ensure that the chain continues to deliver for users.

Alpenglow makes changes to how Solana thinks about blockspace, finality, voting, and rewards. Once the migration is complete, Solana will be a very different protocol.

Learn more: Solana Upgrades